GLOSSARY: Ethological Terms

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Term Definition

in DEVELOPMENT, according to Piaget, existing structures change to accommodate to the new information. This dual process, assimilation-accommodation, enables the child to form schema.(see Assimilation and Equilibration)

Action potential

cell membrane changes conductances for various ions when stimulated. Sodium ions rush in, and the electrical charge across the membrane becomes positive. Local membrane depolarization stimulates the neighboring region to depolarize and then returns to its resting state.


a trait that contributes to fitness, BUT the term also refers to the process by which that trait has come about.

The processes by which organisms or groups of organisms maintain homeostasis in and among themselves in the face of both short-term environmental fluctuations and long-term changes in the composition and structure of their environments.” (Rappaport, 1971)

Its several definitions are all unified by the idea of compensation for change, either short-term (such as a stimulus or life experience) or long term adaptations (such as climate change)

Other (complementary) definitions are: “an adaptation is an anatomical, physiological, or behavioral trait that contributes to an individual’s ability to survive and reproduce (“fitness”) in competition with conspecifics in the environment in which it evolved” (Williams, G. 1966.Adaptation and Natural Selection Princeton). and “a regulatory or advantageous change in response to an environmental stress by an individual or by a species in the course of evolution”(Bullock 1977)

sensory adaptation is when receptors are less responsive to stimuli after long term exposure to them –e.g., the smell of food or the feel of clothes. a form of non-associative learning

and see exaptation

Adaptive radiation

(relatively rapid) evolutionary changes in the branches of a phyletic line that enable branches to survive and thrive in specific niches or adaptive zones.

Adaptive zone

An environment in which some selection pressures and constraints are reduced allowing organisms to prosper in new ways and in which adaptive radiation is enabled. But also the “range of tolerance” within the limits of which organisms can more-or-less thrive. Implicit in the way this term is usually used is the idea that interspecific competition is “relaxed.”


Most simply, affect is emotion or feeling. It can be inferred in others by outward expressions of posture, expression, or reflexes of the autonomic nervous system. It can “energize” motivation. Along with motivation and cognition constitute a useful “triad” of psychological functions. Associated with the limbic system in the brains of vertebrates.


the signal or information from the sense organs, regardless of the type or cause of sensory stimulation. (see Efference and Reafference)


The expression of force by an animal in order to accomplish a specific end, as in obtaining or defending resources such as food, territory, reproductive opportunity or mate, and protecting offspring

Allee Effects

When the growth rate of a population is affected by population size. In small populations birth rate may decline because (e.g.) mates may be hard to find. In some species populations aggregate so that synchronized birthing/hatching can swamp potential predators with prey so that at least some will survive.(from Adrian Barnett’s essay, “Safety in Numbers,” in New Scientist (2001)


an alternate form of a gene at the same locus. (see gene)


maintaining physiological stability by changing set point for regulation. “. . . a fundamental process through which organisms actively adjust to both predictable and unpredictable events. Allostatic load refers to the cumulative cost to the body of allostasis, with allostatic overload being a state in which serious pathophysiology can occur.” (McEwen 2003)


young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.” (see precocial)


the actions of one individual towards another in which the altruist reduces its own apparent fitness while increasing that of the recipient.


adults spend lives at sea and return to freshwater to spawn


resemblance in characteristics (e.g., body form, behavior) as a consequence of independent adaptation to the same or similar environmental conditions and not due to common ancestry [more]

Animal behavior

The ways in which animals interact with each other, with members of other species, and with the environment.


the attribution of human characteristics to inanimate objects, animals, forces of nature, and others. (from the Greek words, anthrôpos, meaning human, and morphé, meaning shape or form) Can be adapted to the projection from any relatively well understood system to a less well understood system — as in “homeothermomorphism” projection of traits from warm-blooded to cold blooded animals.


“warning sign.” It refers to color or other signal that any organism might use to advertise the danger of preying upon it. Some aposematic species have come to resemble each other(Müllerian mimicry), some harmless animals have come to resemble aposematic species (Batesian mimicry).


in DEVELOPMENT, according to Piaget, Assimilation involves the incorporation of new events into preexisting cognitive structures. (see Accommodation and Equilibration)

Associative Learning

The association of events such as stimuli and responses with positive or negative consequences which leads to a change in behavior. Involves behavioral and its underlying neural plasticity.Associative learning is distinguished from non-associative learning such as change in behavior as a result of habituation or sensitization. –see Classical Conditioning andOperant Conditioning


focusing cognitive processes on a specific stimulus, set of stimuli, or percept. Attention and “selective attention” is arguably at the heart of understanding cognition and consciousness. [The Reticular Formation (RF) is the collective name for a diffuse network of nerve cells running through the core of the brainstem (medulla, pons), up through the midbrain (central parts of the thalamus and hypothalamus). It maintains muscle tone, keeps the higher brain in a state of alert wakefulness (reticular activating system), and filters incoming stimuli. And it controls the sleep/wake cycle, a special case of arousal/attention controlled by the RF.] Associated phenomena are selective attention (exercising conscious control over attentional processes) and search image (focusing on the most efficient of alternative stimuli to meet a specific motivational goal)[more from E&S]

Autonomic nervous system

“a division of the vertebrate nervous system serving internal organs such as the heart, blood vessels, lungs, intestines and also certain glands. The sympathetic nerve pathways have an emergency function and become active under stress (the adrenal medulla in many vertebrates is really a part of the sympathetic system). They have the effect of accelerating heart rate, dilating air passages to the lungs, increasing the blood supply to the muscles, reducing the activity of the intestines. (The parasympathetic pathways serve a recuperative function restoring the blood supply to normal and countering the effects of the sympathetic activity.)

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Term Definition
Balanced Polymorphism

the maintenance of two or more alleles for a trait in a population at a more or less constant frequency ratio due to the selective advantage of heterozygotes. For example, the persistence of the sickle-cell trait, deadly in homozygotes is attributable to the advantage provided by the heterozygote.

Bateman’s Principle

“…variance in net reproductive success will be greater in the sex with the smaller per-offspring investment.” This sex will also likely be subjected to more intense sexual selection (Wilson 1975:163)


all coordinated actions and responses of an individual


a movement in psychology that advocates the use of strict experimental procedures to study observable behavior (or responses) in relation to the environment (or stimuli)


The solving of practical problems using whatever materials happen to be at hand. Adapted by Claude Levi-Strauss from the word “bricoleur” –French for the kind of handyman that can brings formidable ingenuity to bear on making difficult repairs by exploiting whatever materials . Evolution often seems to proceed in this way –solving adaptive problems with whatever resources the organism has available. (see “Panda Principle“)

Bruce effect

A possible form of Postcopulatory competition In some taxa, a strange male (or his odor) can cause a female to abort (previous male’s fetus) and make the female receptive. (e.g., Bruce 1966 in mice; Hrdy 1977 with langur monkeys; Packer 1986 with lions)

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Term Definition
Carrying Capacity

(K) an environment’s maximum persistently supportable load (Catton 1986); a way to characterize the environment in terms of how many organisms it can support.

Circadian Clock

An inherent timekeeping mechanism with a capacity to drive or coordinate a circadian rhythm

Circadian Rhythm

Biological rhythms with a period of approximately 24 hours (circa-dian)

Classical Conditioning

a type of associative learning in which a stimulus comes to affect a pre-existing stimulus-response relationship as a result of frequent exposure to it; an organism comes to associate a new (often arbitrary) stimulus (such as a bell) with a well-learned, reflexive, or automatic response (such as salivating when food is presented); e.g., a person who has had painful experiences at the dentist’s office may become fearful at just the sight of the dentist’s office building. Also called Pavlovian conditioning — compare with Operant Conditioning. [more]

Closed Genetic Program

“Genetic programs” are the genes that influence the expression of a phenotypic trait. “Closed” programs of genes are not flexible in their expression and not easily influenced by the environment. (Ernst Mayr 1982). A common example is the genetically determined anatomical morphology which enables speech (including specialized anatomical and neurophysiological traits) which is the result of a relatively inflexible or “closed” genetic program. The particular language learned, on the other hand, is a common example of the result of a relatively “open” or environmentally determined trait.

Coefficient of relatedness

The proportion of genes shared by two individuals (attributable to descent). Also known asdegree of relatedness, and symbolized byr’ coefficient of relatedness.


the process that describes the adaptive changes that occur when two species act as strong selective forces on each other. The evolutionary way the influence each other, particularly in competition. An evolutionary “arms race” (recalling the US/USSR cold war competition to trump each other’s weapons and defenses)


The attending to, identifying or categorizing, and acting upon information derived from environmental or internal information. The mental processes coordinated to selectively acquire, organize, and selectively apply information. Sensory information is transformed into perceptions which are then categorized and organized, stored, recovered, abstracted or combined, and used. Cognition includes the use of memory (a “trace” of a past experience) to guide behavior and “thinking” (the retrieval of stored bits of information and its manipulation to ascertain relationships between them and (often) new information). Along with affect and motivationconstitute a useful “triad” of major neurobehavioral functions. Associated with the cerebral cortex in mammals. The term cognition is plagued with multiple meanings.

Cognitive Dissonance

The state of possessing knowledge or beliefs about oneself or the world that is inconsistent with evidence about the nature of the world or one’s self. Individuals are motivated to minimize or eliminate these inconsistencies. People do this by (1) adding new cognitions or (2) change existing cognitions, or (3) expressing behavioral patterns that have cognitive consequences favoring consonance, such as seeking new information. A common dissonance is a mismatch between the model of the world (or self) in one’s mind and the external reality that is not in accord with that model. [Festinger, L.A. (1957): A Theory of Cognitive Dissonance. Stanford University Press][more]

Collateral Effect

an unintended or unexpected consequence concomitant with or accompanying another phenomenon; a side-effect. A collateral or side-effect of certain arches in architecture is the spandrel, a feature which is “available” for uses other than the main function of the arches which created them.

Collective Behavior

social behavior that appears to be spontaneous and is a departure from the norm but is not deviant (in the sense of violating norms); typically occurs when norms are ambiguous or conflicting. Resembles quorum behavior.

Command neurons

cells which are capable of producing produce complex behavior patterns in the absence of any meaningful external stimuli


“an action on the part of one organism (or cell) that alters the probability pattern of behavior in another organism (or cell) in a fashion adaptive to either one or both of the participants”(Wilson 1975); “the transmission of a signal from one animal to another such that the sender benefits, on average, from the response of the recipient” (Slater 1983).[more] and seemetacommunication


mechanisms that allow you to find a particular direction, see map

Complex System

a group of relatively simple but interconnected elements which enables the emergence of a higher order phenomenon. It is also a research perspective that is open to an integrative view of phenomena that makes a more holistic view possible.

Configurational stimulus

a specific combination of stimuli that derive their potency to elicit a response by virtue of their specific relationship to each other; typically a pattern of presentation to which a specific reaction pattern is tuned. The mother herring gull’s bill has the red spot and a certain shape.

Confirmation bias

a selective attention to information that tends to confirm one’s beliefs and/or a selective inattention, ignorance, or undervaluing information that tends to contradict a specific belief.[more] Related to cognitive dissonance [more]


“Consciousness is a graded integration of multiple cognitive functions yielding a unified representation of the world, our bodies, and ourselves” (Alan Hobson, 2000). “. . . but in addition, it includes that ineffable feeling of experiencing oneself as an active agent in the perceived events of the world” (Antonio Damasio, 2001).


Consilience is when beliefs derived from alternative ways of studying a phenomenon reinforce or corroborate each other. It is literally a “jumping together” of knowledge across disciplinary boundaries; a transcendence which can, like a successful mating dance of mutual accommodation and assimilation, result in a unifying accord that can be one of the supreme experiences of science.The term was devised by William Whewell in 1840 to describe the corroboration of a belief (actually an induction) derived from one class of facts by a belief derived from another class of facts. [more]

Cooperative Breeding

when more-or-less closely related relatives assist in raising young; communal nestinginvolves sharing nest, or other resources, including, in some cases, milk. Examples exist in most taxa and include rats and ostriches.

Core Area

the part of an animal’s home range of heaviest use. Core areas typically center on a resource such as a nest or refuge, water or food source.

Critical Anthropomorphism

critical anthropomorphism is an ethologically informed source of hypotheses about the causes and consequences of behavior in other organisms. Since the minds of other taxa (indeed other humans) are ultimately unknowable, it builds on shared characteristics while remaining to the often profound differences.

Cumulative Selection

most complex behavioral patterns arose gradually from less complex behavioral patterns by a long slow pattern of accretion, or accumulation. (Alcock’s Animal Behavior, 7th edition, 2001:283)


a motivational prerequisite for exploratory behavior Berlyne (1960)

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Term Definition
DEEP ethology

Consideration of the causes and consequences of a behavioral pattern from the converging perspectives of Developmental biology, Ecology, Evolutionary biology, and Physiology.

Developmental biology emphasizes change within an individual’s lifespan: ONTOGENY and EXPERIENCE,
Ecology emphasizes biotic and abiotic ENVIRONMENT;
Evolutionary biology emphasizes changes across generations and involves transmission of biological information to subsequent generations utilizing GENES and (possibly) MEMES; “ultimate” causes and consequences involve changes that occur across generations;
Physiology involves the proximate NEUROPHYSIOLOGICAL and ENDOCRINE causes and consequences of behavior.“Proximate” and “ultimate” causes of behavior are sometimes distinguished depending on the number of intervening steps between a putative cause and an effect. The more steps that intervene, the more problematical the connection.


belief held with strong conviction despite superior evidence to the contrary. (Wikipedia)

Density-dependent selection

population density becomes a selection pressure affecting the fitness of individuals in a population. For example, an overcrowded population may decrease average fitness leading to underpopulation, possibly evoking the “Allee effect.”


Ideas about how a phenomenon came to be the way it is. “The roots of the notion of determinism surely lie in a very common philosophical idea: the idea that everything can, in principle, be explained, or that everything that is, has a sufficient reason for being and being as it is, and not otherwise (Stanford Encyclopedia of Philosophy). It is often expressed in terms of dichotomies such as nature/nurture or genetic/environmental, reflecting the relative fixity or flexibility of processes leading to a given outcome. see Determinism in DEEP ethology

Direct Fitness

probability of reproductive success through one’s own offspring. see Inclusive Fitness, Fitness, Indirect Fitness


Travel of Individuals, Ecological process affecting distribution, and genetic process affecting geographic differentiation and variation

Displacement Activity

behavior patterns seemingly unrelated to the behavioral context in which it occurs


The transformation of organisms attributable to multiple generations of human breeding, the selection pressure being some specific human need.Wikipedia 2005

Domestication typically renders organisms more docile and less aggressive, “possibly all secondary to an evoked paedomorphism (retaining juvenile characteristics into adulthood) [For example, in silver foxes that were bred into “tail-wagging, hand-licking pets by Soviet geneticists breeding for passivity (begun by Dmitri Belyaev in 1959 and continued today by Lyudmila N. Trut). There are also less stress-related hormones such as corticosteroids, more serotonin (which seems to inhibit aggression), and (remarkably) a longer breeding season.] Over the 20,000 years of our“domestication,” we have much less inter-group aggression (Richard W. Wrangham) –evidenced in part by now smaller jaws and teeth, year-round breeding, and lots of sexuality (reproductive motivation in females at times other than ovulation) compared to our nearest rather than our immediate ancestors. (Much like bonobos who use sex for conflict resolution and social bonding –Frans B.M. de Waal). (Thanks to Michael Shermer’s column, “Skeptic” – in Sept 2003:40, “The Domesticated Savage.”)


see social dominance


The “energy” that activates a Motivational system in order to meet a real or perceived biological need. [see “motivation” and “instinct” … “The Standard Edition of Freud’s works in English confuses two terms that are different in German, Instinkt (“instinct”) and Trieb (“drive”), often translating both as instinct. ‘This incorrect equating of instinct and Trieb has created serious misunderstandings’[4]] The term “drive reduction” is used by learning theorists to characterize the biological aspects of learning (e.g., Clark Hull)

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Term Definition
Ecological Homeostasis

A dynamic balance between multiple systems that maintains stability within an ecosystem. Adapted by Odum (1971) from the idea of homeostasis in physiology in which the stability of the internal environment of the body is maintained by multiple systems that are constantly interacting by means of their effects on each other. Ecosystems have powers of self-maintenance and self-regulation –so homeostasis can be said to be true of them also; They resist change and remain in a state of equilibrium


A genetically distinct population that has adapted to local conditions; for example, the heavy metal, zinc was leaching into the soil from the galvanized metal in a fence and the grass just beneath it was metal tolerant.


the signal or information that is used to control the motor output, usually represented as a signal in the output side of the nervous system. (see Reafference)

Emergent property

A property or quality of a phenomenon (such as an organism) that could not have been predicted on the basis of a knowledge of its constituent parts. (see Complex System and more)


permanent movements out of a specific region. When the movements are sudden they are termed “irruptions.” Apparently there are alternative behavioral patterns that depend on population density to trigger a tendency to disperse. Irruptions seem most common in places where species are subjected to climatic extremes (arctic, desert). [more]


The “Emotions are coordinated states, shaped by natural selection, that adjust physiological and behavioral responses to take advantage of opportunities and to cope with threats that have recurred over the course of evolution –Nesse & Berridge (1999) [more]


The “ability to recognize and understand the emotion of another. As the states of mind, beliefs, anddesires of others are intertwined with their emotions, one with empathy for another may often be able to more effectively divine another’s modes of thought and mood. [Wikipedia, 2006] It is thought to be influenced by “mirror neurons”. Disorders of empathy are associated withsociopathy. [more] Unlike sympathy, empathy may not require true consciousness of another’s emotion.

Endocrine system

combination of neural and glandular mechanisms which control physiological functions/behavior via the secretion of hormones, carried in the blood. Hormones only affect those cells that have specific receptors for them.


An organism’s response to environmental cues such as light that enables resetting of the clock

Environment of Evolutionary Adaptedness (EEA)

It is unlikely that any biotic environment in which an adaptation emerged is still intact — the adaptive peak is always receding: That is, no contemporary trait can be adaptive (in Reeve and Sherman’s (1993) sense) because they were selected for in an environment that no longer exists.This is sometimes called the “environment of evolutionary adaptedness” (EEA). Often applied to the environment in which a particular species evolved, but perhaps more usefully applied to a particulartrait. [more]


Interaction of genes and their environment in determining the expression of traits during development, including behavioral traits; involves specific effects of environment on activation (or inactivation) of specific genes [more] [examples]


A secondary or collateral phenomenon that results from and accompanies another. Also in medicine, a condition or symptom in the course of a disease, not necessarily connected with the disease. They are often hard to predict [see collateral effect]


in DEVELOPMENT, according to Piaget, Equilibration involves a balance restored during development between the individual and the environment by assimilation and accommodation. “When a child experiences a new event, disequilibrium sets in until he is able to assimilate and accommodate the new information and thus attain equilibrium.

There are many types of equilibrium between assimilation and accommodation that vary with the levels of development and the problems to be solved. For Piaget, equilibration is the major factor in explaining why some children advance more quickly in the development of logical intelligence than do others” (from: (Jean Piaget: Intellectual Development) see
Assimilation and Accommodation.


comprehensive compilation of the behavioral repertory of a species, a catalogue of actions as complete and precise as possible, generally showing relationships between units (flow charts) and the context(s) in which they occur. Sometimes a simple list of behavioral patterns is referred to as a “catalog” or “inventory” of behavioral patterns, and “ethogram” is reserved for a description of the relationship between the elements of the inventory. [example]


The biology of behavior; the pursuit an understanding of the causes and consequences of behavior from the integrated consideration of developmental, ecological, evolutionary, and physiological variables. This is most valid in a natural context. see DEEP ETHOLOGY.


“a science that investigates methods to ameliorate the genetic composition of the human race, a program to foster such betterment; a social movement; and in its perverted form, a pseudo-scientific retreat for bigots and racists” (Lundmerer 1978). “. . . by 1935 “eugenics had become `hopelessly perverted’ into a pseudoscientific facade for `advocates of race and class prejudice, defenders of vested interests of church and state, Fascists, Hitlerites [Nazis], and reactionaries generally'” (Kevles 1985)


a specific social system (especially prominent in several insect species of wasps, bees, or ants but also a species of shrimp and naked mole rats) that shows (1) cooperation in caring for young, (2) reproductive castes cared for by non-reproductive castes (3) overlapping generations such that offspring assist parents in raising siblings.


a processes by which living things first appeared on earth and have since diversified and changed. It involves change of gene frequency within populations, which ultimately result in behavioral and phenotypic changes

Evolutionarily Stable Strategy (ESS)

this is a strategy which, if adopted by most of a population, cannot be displaced by any alternate strategy, and will therefore tend to become established by natural selection. Related to Game Theory


a companion concept for adaptation – this separates historical origins from current utility of a trait – he defined it as “a feature, now useful to an organism, that did not arise as an adaptation for its present role, but was subsequently co-opted for its current function” (Buss et al 1998:539 quoting Gould 1991:47). These “now useful” traits could have originated for some other adaptive purpose – a “co-opted adaptation,” or they could have derived from a non-adaptive by-product or side-effect (collateral effect) of an adaptive trait, a “spandrel,” an artefact.


An experiment involves operations designed to determine the extent and nature of the causal relation between two variables. The independent variable is varied and its effect on thedependent variable is observed. The aim of experiments is to design them in such a way that the effect of the dependent variable can be attributed only to the manipulations of the independent variable – these are controls. Controls will help to eliminate alternative explanations of the results. Controls can be done by randomization or systematic control of extraneous variables. see Natural Experiment

Exploratory Behavior

investigating or otherwise gathering information about an unfamiliar or novel environment; equal or closely related to curiosity. Functions to minimize and possibly mitigate the stress associated with novelty; or to enhance autonomic tone in concert with Risk Taking.

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Term Definition

A measure of biological success in terms of contribution to subsequent generation, typically quantified by numbers of successful (surviving) offspring. The probability that an animal of a particular genotype and phenotype will reproduce; see Inclusive Fitness, Direct Fitness, and Indirect Fitness.

Fixed Action Pattern (FAP)

coordinated responses (often motor patterns) that have a fixed form and need not be learned. Within a species, different individuals will produce almost identical behavioral responses to a specific sign stimulus; once initiated FAPs continue until completed (=Erbkoordination) [see “motor programs” and “instinct”]

Folie à deux

a shared delusional system (can be more than two mutually corroborative individuals, as in folie en famille or even folie à plusieurs) (Wikipedia) (how many individuals must share the belief before it is no longer considered “delusional?”)

Fundamental Niche

set of resources and physical factors required for survival and reproduction of individuals of a species – see also Realized Niche

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Term Definition
Game Theory

“… a mathematical tool that is used when the “payoff” an individual receives for undertaking an action is dependent on what behavior others adopt” (Dugatkin, Principles of Animal Behavior 2004) related tooptimality and evolutionarily stable strategy (ESS)


Genes are specific combinations of DNA at a specific site on a chromosome (its LOCUS). They embody an assemblage of nuclei acids that constitutes a “code” for the synthesis of proteins, the building blocks of all living things. The cellular processes that begin with the activation of genes eventually ends with the expression of a manifest trait. They are not simply on/off switches, but can be variable in their expression depending on context, especially the activity of a biochemical support system (seeepigenesis). An ALLELE is an alternate form of a gene at the same locus. Most genes are pleiotropic.[In February of 2001, the most complete draft of the human genome identified 34,000 genes responsible for directing the assembly of about a million proteins. — the “proteome”]

Gene Flow

The exchange of genes between different groups (species or populations); an influence on “microevolution.”

Genetic Assimilation

when a phenodeviant can flourish because of an unusually empowering environment that lasts long enough for the underlying genetic representations to stabilize; the environment can be encountered by chance or the phenodeviant might in some way (behavioral or other ways) change the environment. The term is associated with C.H. Waddington. (EOW 1980:34)

Genetic Drift

an alteration in frequencies of alleles attributable to chance (=”sampling error”); most pronounced (or noticeable) in smaller populations; an influence on “microevolution.”


The aggregate of specific genes an organism possesses. These may or may not be manifest as a specific phenotype.

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Term Definition

any part of the biosphere where a species can successfully live and reproduce


gradual decline in response after repeated exposure to a stimulus without specific significance; a kind of non-associative learning

Hamilton’s Rule

The idea that the genetic relatedness of the performer of an altruistic act to the recipient is a key consideration in a costs/benefits analysis of its likeliness to be performed and in its evolution.
Hamilton’s Rule” can be expressed as b/c > 1/r (where b = benefits (extra relatives that exist as a result of the altruism), c = costs (in terms of number of offspring not produced), and r = coefficient of relatedness))

Handicap hypothesis

The idea that apparently harmful traits in males become attractive to females because they indicate the male’s capacity to cope with them.

Hardy-Weinberg law

“gene frequencies in a population remain constant (regardless of changes in population size) as long as there are not chance fluctuations or outside influences.”


an estimate of the degree of genetic determination of a particular trait; Broad sense Heritabilityrefers to the total proportion of genetic variance in a trait; Narrow-sense heritability refers to the proportion of phenotypic variance that can be attributed to additive genetic variance (that is the proportion of genetic variance that is accessible to natural selection — it is associated with the average effects of substituting one allele for another).


see Allostasis

Hierarchical selection

An idea championed by S J Gould “that selection can act at any level in the biological hierarchy, from single genes to entire ecosystems.(H. Allen Orr (2004) “A Passion for Evolution.” Essay review of A Devil’s Chaplain by Richard Dawkins. NYRB 51(3) Feb 26 2004)


when there are multiple levels or layers of organization, control, or information flow; higher levels emerge out of or are supported by lower ones, but lower levels are then at least partly controlled by the higher ones. Systems of thought, military, ecclesiastical, political, and social systems are typically hierarchical.


The idea that whole entities (like organisms) are greater than the sum of their parts; or that whole entities take their specific natures from the manner in which their constituent parts are interconnected (see emergent property; reductionism)

Home range

area which an individual, pair, or group occupies or regularly returns to, see Territory


dynamic balance between multiple systems that seeks stability; maintained by negative feedback loops such that increases or decreases in one variable evokes a compensating response by another. (more). see heterostasis or allostasis


the ability to return to a home site after being displaced, see Kinesis, Navigation, Orientation, Piloting, Taxis


resemblance in characteristics (e.g., body form, behavior) as a consequence of common ancestry; [more]

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Term Definition
Ideal Free Distribution

Individuals should distribute themselves among habitats so that every individual maximizes its net rate of return


capacity to learn specific types of information at certain critical periods in development


preferential mating between relatives, extreme inbreeding: mating between sibs, half-sibs, parent-offspring, see Outbreeding

Inclusive Fitness

the sum of Direct fitness, and Indirect fitness

Indirect Fitness

probability of reproductive success through non-descendent relatives. see Fitness, Inclusive Fitness, Direct Fitness

Individual distance

defended area surrounding the individual’s own body


the developmental process leading to the expression of a single individual’s specific traits. Can be viewed as in a dialectical tension with “socialization” “essential tension” between INDIVIDUATION and SOCIALIZATION


referring to built-in, inborn, hereditary, it is no longer used and has been replaced by the spectrum of “open” vs. “closed” developmental systems more

Innate releasing mechanism

see Releasing mechanisim


The term strongly implies an inborn, genetically controlled mechanism, but most “instincts” studied closely reveal the influence of learning. [Hailman]. see also “Fixed Action Pattern. William James begins chapter 24 of the Principles of Psychology (1890) with ” . . . the faculty of acting in such a way as to produce certain ends, without foresight of the ends, and without previous education in the performance . . . ” and then critically reviews them [complete text] [see “drive” and “motivation” … “The Standard Edition of Freud’s works in English confuses two terms that are different in German,Instinkt (“instinct”) and Trieb (“drive”), often translating both as instinct. ‘This incorrect equating ofinstinct and Trieb has created serious misunderstandings’[4]]

Intention Movement

behavior patterns that precede or prepare for other behaviors

Interspecific Interactions

interactions among organisms of different species (inter = between, among)

Intraspecific Interactions

interactions among organisms of the same species (intra = within, inside)


the repeated production of offspring at intervals throughout the life cycle. It is usually contrasted withSemelparity, where each individual reproduces only once during its life.

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Term Definition
Key Stimulus

see Sign Stimulus

Kin Selection
selection for traits that lower an individual’s personal fitness, but raise a relative’s fitness
K-selected traits

K is an attribute of an environment: in equations describing the environment in which a species’ population dynamics are at play, K represents the “carrying capacity” of that environment A trait that is “K-selected is one that has helps an organism maximize its capacity to survive and thrive very close to that carrying capacity. Contrast to r-selection

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Term Definition
Law of Effect

behaviors that are followed by a positive outcome are repeated, while those followed by a negative outcome or none at all are extinguished (Edward L. Thorndike)


“change in behavior as a result of experience.” Adaptive modification of behavior in response to specific experiences during an individual’s life. Acquiring knowledge or developing the ability to perform new behaviors. kinds of learning are Associative and Non-associative and (more recently) Perceptual Learning [more]


a communal mating area in which individuals hold small territories solely for courtship and copulation

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Term Definition

representation of the traits or landmarks of an area that helps an organism find its way, seeCompass

Maternal Effects

influences of the mother on an offspring’s behavior that are not due to direct genetic inheritance

Meiotic Drive

Unequal representation of alleles attributable to the mechanics of meiosis, also calledsegregation distortion; an influence on “microevolution.”


A unit of information that can be communicated to human minds, possibly altering their behavior and possibly thereby propagating themselves (Dawkins’ idea to emphasize an analogy with “gene”) “Individual slogans, catch-phrases, melodies, icons, inventions, and fashions are typical memes. An idea or information pattern is not a meme until it causes someone to replicate it, to repeat it to someone else. All transmitted knowledge is memetic. ” see thePrincipia Cybernetica’slexicon of memes


Representation of past experience of which we may or may not be conscious; each unique memory is likely a unique pattern of neural activity, reactivated when called for but potentially vulnerable to neuroplastic changes. The several forms of memory are each mediated by different patterns of wiring often associated with different regions of the brain. Two forms are often distinguished, short term (“working”) memory and long term memory that is accessible after years. [more]


the set of all environmental factors that are significant for a species, whether or not they are actually perceptible: “the set of things it might care about, if only it knew about them; the objective universe that impinges on existence •• We would say Merkwelt is a species’ context: the more complex the creature’’s contextual sensitivity, the more complex its structure.” TermMerkwelt coined by von Uexküll in the 1920s see Umwelt


“Communication which underlies or takes place alongside a given act of communication, and serves to supplement or enhance it; an instance of this. Also: discourse about communication.”(OED)


seasonal (typically annual) movements of animals from place to place, usually the same places each season. It allows animals to take advantage of different sites with different qualities- such as seasonally available food, safety from predation (especially when breeding) or conserving energy by finding a climate that does not require as much energy to cope (particularly when food resources become scarce). [more]

Mirror Neurons

neurons which fire when performing a specific behavior or watching another perform that behavior. when an animal performs an action and when the animal observes the same action performed by another (especially conspecific) animal. Thus, the neuron “mirrors” the behavior of another animal, as though the observer were himself performing the action. These neurons have been observed in primates, in some birds, and in humans. In humans, they have been found in Broca’s area and the inferior parietal cortex of the brain. There is much speculation that they may underlie important aspects of empathy and education.

Mismatch Theory

traits (including behavioral patterns) are assumed to have been preserved by natural selection because of their adaptive function in a specific environment. When that environment changes, organisms may find themselves progressively “mismatched” to the new environment.[“mismatch” theory]


A selective, simplified representations of the things that are most important (or about which you are most interested) about a phenomenon. It is a kind of abstraction (like abstract art selectively representing or emphasizing aspects of its subject, or the abstract at the beginning of an article). wiktionary definition


Processes that account for the direction, intensity, and persistence of effort expended to meet needs or attain a goal. Along with affect and cognition constitute a useful “triad” of psychological functions. Associated with the hypothalamus in the brains of vertebrates. [see “drive” and “instinct” … “The Standard Edition of Freud’s works in English confuses two terms that are different in German, Instinkt (“instinct”) and Trieb (“drive”), often translating both asinstinct.This incorrect equating of instinct and Trieb has created serious misunderstandings’[4]]

Motor Program

chained sequence of specific (discrete) reflexes or motor responses; often seen in FIXED ACTION PATTERNS (FAPs)

Multiple parallel processing

the simultaneous movement (or activation) of information through more than one “information pathway.” For example, there are multiple (sensory) sources of information about the world operating simultaneously, approximately in parallel. At certain points, these paths sometimes compete with each other to dominate behavior. The idea is important also in computer science.

Mutation Pressure

Changes in gene frequencies attributable to differential mutation rates alone; an influence on “microevolution.”


A relationship between two (or more) different kinds of organisms in which both derive some degree of benefit. Mutualism is usually temporary or not obligatory. See also: parasitism,symbiosis.

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Term Definition
Natural Experiment

A natural experiment does not involve active manipulation of the independent variable by the experimenter. The variables are manipulated by circumstance — for example, insights about ecological colonization might derive from populations of a species isolated from each other on islands due to rising sea-levels, or the relative effects of genetics and environment on specific traits might be clarified by identical twins separated at birth and brought up in very different environments.

Natural Selection

the process by which environmental effects lead to varying degrees of reproductive success among individuals of a population of organisms with different hereditary characters, or traits. The characters that inhibit reproductive success decrease in frequency from generation to generation [more]

Naturalistic Fallacy

The idea that “whatever is, is right” is an inappropriate equating of a phenomenon with a moral judgement — equating what is with what ought to be (Hume)


an animal moves about using external cues to determine its position relative to a goal.


compound that is released at a synapse and diffuses across the synaptic cleft to act on a receptor located on the membrane of a postsynaptic cell, which may be another neurone, a muscle cell or a specialized gland cell. It is released from nerve endings by nerve impulse activity at morphologically distinguishable synaptic junctions producing suitable changes in the excitability of the postsynaptic membrane.


The ability of neurons to change, manifest in altered cellular activity and connectedness with related neurons in the nervous system. Can be modest (as in learning) or striking (as in reconfiguring connectedness after trauma)

More on Neuroplasticity


compound that is released at a synapse and diffuses across the synaptic cleft to act on a receptor located on the membrane of a postsynaptic cell, which may be another neurone, a muscle cell or a specialized gland cell. It is released from nerve endings by nerve impulse activity at morphologically distinguishable synaptic junctions producing suitable changes in the excitability of the postsynaptic membrane.


all aspects of an organism’s environment that enable it to survive and reproduce; Function of a particular species in an ecological community; – see also Fundamental Niche vs. Realized Niche and Ontogenetic Niche


when “a colony of organisms pursues an irregular and essentially unpredictable course (typically in a search for food) which does not involve a return to a home territory.” [more]

Non-associative Learning

a change in behavior as a result of exposure to stimuli that are not associated with positive or negative consequences — examples are habituation and sensitization

Norm of reaction

The range of phenotypic possibilities for a single genotype, as influenced by the environment – seepolymorphism.

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Term Definition
Occam’s Razor

The idea that explanations should be no more complicated (involve no more “steps”) that absolutely necessary Simplicity in explanation is one of science’s most sought after ideals [more]

Ontogenetic niche

the niche occupied by a specific organism during a specific stage in its ontogeny; this can include the multitude of ecological and social (including parental) characteristics of the environment; adaptive plasticity in ontogeny might allow an organism to spend more-or-less time in one niche before moving on to the next one as it matures. This is most dramatic in animals that change dramatically as they develop by (for example) going through a larval stage (see also West & King 1987)


the progressive expression of programmed developmental change, from conception to death.Sometimes contrasted with experience, expression of change as a result of accommodation to the vagaries of a specific environment.

Open genetic program

“Genetic programs” are the genes that influence the expression of a phenotypic trait. “Open” programs of genes are flexible in their expression and relatively easily influenced by the environment. (Ernst Mayr 1982). The particular language people learn is a common example of an open program, and can be contrasted with its enabling anatomical morphology (including neuroanatomy and neurophysiology) which is the result of a relatively inflexible or “closed” genetic program.

Operant Conditioning

a form of associative learning in which behavior changes as a result of an action that leads to a specific consequence (e.g. rewarding, noxious), (same as trial-and-error learning, instrumental conditioning); that is, there is a contingency between the response and the presentation of the reinforcer. –compare with Classical Conditioning [more]

Optimality Theory, Optimization

A way of thinking about the influences that might affect the implementation of a specific behavioral pattern in terms of their costs and benefits to the animal’s inclusive fitness — used to great profit by behavioral ecologists. It has three parts: a list of possible alternative behavioral patterns; the values (such as time or energy) of specific aspects of an alternative; and the constraints that limit an animal’s options) [more]


the way in which an individual positions itself with regard to external cues, see Homing, Kinesis, Navigation, Piloting, Taxis


preferential mating between non- relatives, see Inbreeding

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Term Definition

An internal timekeeping mechanism capable of generating or coordinating circadian rhythms

Panda Principle

The evolutionary principle using biological traits at hand to solve adaptive problems. Named after Stephen J Gould’s essay about the “panda’s thumb.” (The panda’s “thumb” is really a wrist bone thatfunctions as a thumb. The first digit was not available to respond to a dietary selection pressure (which could be coped with by an ability to strip bamboo leaves from stalks); this influenced the evolution of a wrist-bone “thumb” because in the panda’s ancestors the “real” thumb was incorporated into a foot adapted for running. (see Bricolage)


A set of beliefs that complement each other to create a model of how the world works or even a comprehensive world-view

Paradigm shift

A change in one’s paradigm precipitated by a growing awareness of inconsistencies within the set of beliefs that supports it. The shift to a new paradigm that better accommodates the most salient of inconsistent beliefs. Beliefs that do not fit within a paradigm are dissonant and can contribute to a growing unease [see cognitive dissonance] that is mitigated by a shift to a more harmonious interpretation or paradigm. Reduced dissonance and harmony of beliefs within a paradigm is promoted by behavioral mechanisms that reduce cognitive dissonance such as selective perception of supportive beliefs and relative insensitivity to dissonance provoking beliefs. [Thomas Kuhn, The Structure of Scientific Revolutions]


A relationship between two organisms, in which one, the parasite,benefits at the expense of thehost.. Parasitism can be considered as a special case of predation. Parasites that live inside the body of the host are called endoparasites and those that live on the outside are called ectoparasites.Social parasites, take advantage of a host population of animals such as ants or termites;kleptoparasitism is when the parasite steals food or other resources from the host. See also:mutualism, symbiosis.

Parental Investment

“any behavior towards offspring that increases the chances of the offspring’s survival at the cost of the parent’s ability to invest in other offspring” (EO Wilson 1975). Also, any resources (such as energy) utilized by parents in bearing and raising young. Since parents seek to maximize their fitness, they must utilize their limited resources in ways that assures that young that have been produced will prosper but does not diminish the availability of resources available for additional offspring (see Bateman’s pinciple). Males and females have different physiological and behavioral constraints and possibilities and it is reasonable that they would distribute their resources to relatives or offspring in ways that will increase their own “inclusive fitness” (Trivers 1972). [more]

Perceptual Learning

A change in the way in which events are perceived as a result of experience; may involveAssociative and non-associative learning. more


Elapsed time before a rhythm repeats itself


The manifest expression of the genotype in morphology or behavior; the external expression of latent possibilities of the genotype as evoked (or suppressed) by the interactions of genes with their environment (epigenesis); the aggregate of all describable traits.


limited dispersal where average propagule moves less than 10 home ranges away from natal site


from philosophia, lover of wisdom: the term is applied to any body of doctrine or opinion as to the nature and ultimate significance of human experience considered as a whole. More specifically, the word is properly applied to the critical evaluation of all claims to knowledge – including its own – as well as anything about its own nature and task. In this latter respect of total self-evaluation, philosophy differs fundamentally from all other disciplines. What philosophy is – what methods the philosopher should use, what criteria a person should appeal to and what goals a person should set for themselves – is as perennial a question for the philosopher as any other.

Traditionally philosophers have concerned themselves with four main topic areas:

  • Logic – The study of formal structures of valid arguments.
  • Metaphysics – Usually defined with ontology, the study of the nature of Being or ultimate reality.
  • Epistemology – Or theory of knowledge. Sometimes treated as a branch of metaphysics.
  • Axiology – Or theory of value which includes: Aesthetics – the philosophy of taste (especially as applied to the arts), Ethics – moral philosophy and Political Science.” (based on the Greek word for “worth”)
The New American Desk Encyclopedia

The origin and ancestral succession constituting the evolutionary descent of a species, or class of species. It traces the evolutionary origins and transformations by identifying Homologies


active travel between locations using familiar landmarks to reach a goal, also see Homing, Kinesis, Navigation, Orientation, Taxis


an apparent developmental expression of motor patterns that appear to function primarily to exercise and improve economy of movements (efficiency) and endurance by coordinating activities with appropriate environmental and internal signals. Three types are often distinguished: object play, locomotor play, and social play.


as an attribute of a gene, possesses potential for influencing multiple effects; in concert with polygeny, it characterizes the complex possibilities of the genetic control of phenotype.


an attribute of a trait that underscores its determination by multiple genes; in concert with pleiotropy, characterizes the complex possibilities of the genetic control of phenotype.

Polygyny threshold

some species have a monogamous mating system, BUT when circumstances are right females may choose to enter into a polygynous relationship; presumably determined by environmental cues that the female uses to select this alternate mating system. Environmental cues seem to be assessed to determine if the switch might be more advantageous.


One of alternative “morphs” or variations of a trait that are present within a population sharing a common genotype (but multiple alleles of a specific gene) (related =?= to polyphenism, “adaptations in which a genome is associated with discrete alternative phenotypes in different environments“) [more]


One of alternative phenotypes that is not attributable to genetic differences, although “silent” genes may be capacitated or enabled by epigenetic processes. Mainly developmental, polyphenisms are postulated where discrete alternative phenotypes are seen in different environments[more][wikipedia]

Post-Copulatory Competition

Competition between males does not necessarily end after mating. One consequence of mating can be deposition of a copulation plug, left in a female’s vagina to thwart subsequent copulators (but female fox squirrels (Sciurus niger) groom their genitals after copulation and can remove a plug shortly after mating (John Kaprowski) possibly representing a conflict of reproductive strategies between the sexes.
see also the Bruce effect and sperm competition


young are born “relatively mature and mobile from the moment of birth or hatching.” (see altricial)


when characterizing learning, “prepared” refers to the relative ease with which a change in behavior as a result of experience might occur. Very rapid learning might be regarded as “highly prepared” while associations that are made only with great difficulty (if at all) would be “contraprepared.” Preparedness for certain associations may change with ontogenetic stage and implies underlying changes in neurophysiological competence.

Proximate cause (and consequence)

“Proximate” (as opposed to “ultimate”) causes and consequences of behavior are those most intimately associated with the behavior; thus the proximate cause of a reflexive or deliberate movement involves the nervous system; the proximate consequence of neural activation may be a muscle movement. Distance from the specific event — tracking a chain of causes or consequences as far as possible can lead to the complexities of real life.


use of behavioral assays to establish sensory capabilities of an individual

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Term Definition
Quorum Sensing

a type of decision-making process used by decentralized groups to coordinate behavior of the entire group; most common examples are bacteria and eusocial insects, where a threshold number of individuals (quorum) “cooperate” in influencing the behavior of the entire local population; often appears spontaneous or sudden and involves a departure from routine activity (see Collective Behavior)

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Term Definition

The component of sensory input an animal receives as a consequence of its own movements. (Thus, in the case of movement of the limbs, reafference is the proprioceptive or visual sensation that arises as a direct consequence of the motor act. “process of relaying messages from limbic system via entorhinal cortex to sensory cortices, in parallel with limbic commands to motor systems, serving (1) to compensate in advance for changes in sensory input accompanying actions, and (2) to sustain states of expectancy and attention.” — from Freeman, Societies of Brains) (see Afference andEfference)

Realized Niche

the set of resources and physical habitats actually used by individuals of a species in an area (a subset of the Fundamental Niche)


manifest when an entity or trait (including a process) incorporates subsequent representations of itself . As when there is a “story within a story” or the outcome of a process becomes incorporated into its “parent” process. An example is the Matryoska (Russian nesting) dolls or when the outcome of a physiological process feeds back into the process that led to it and thereby modifies subsequent iterations — as in “reafference” when the output of a neuro-muscular circuit makes adjustments depending in part on its previous activity. An organism’s genes reflect ancestral genes. “The term has a variety of meanings specific to a variety of disciplines ranging from linguistic to logic. The most common application of recursion is in mathematics and computer science, in which it refers to a method of defining functions in which the function being defined is applied within its own definition. In a recursive formula, the preceding term is part of the definition of the next term of the sequence. See also mis en abyme


the idea that complex phenomena can be explained (at least in large measure) by reducing it to its constituent parts. Some qualities of phenomena do not seem explainable on the basis of its constituent parts — see holism)

Releasing mechanism (RM)

a functionally organized, neural circuit that recognizes a specific sign stimulus and produces the appropriate response. previously the RM was called the “Innate releasing mechanism”, see for discussion of “Innate” See Stimulus.


the precision and consistency of data, as well as representation in an appropriate resolution (as opposed to Validity)


“any entity in the universe which interacts with its world, including other replicators, in such a way that copies of itself are made. A corollary of the definition is that at least some of these copies, in their turn, serve as replicators, so that a replicator is, at least potentially, an ancestor of an indefinitely long line of identical descendant replicators” (Richard Dawkins. 1978. Replicator selection and the extended phenotype. Z. Tierpsychol. 47:61-76)

Resting membrane potential

neuronal membrane with differential conductance for different ions produces unequal concentrations of ions inside and outside the cell. This results in an electrical potential across the membrane with the inside around -70 mV relative to outside


the process by which a functional behavior pattern (such as a fragment of a motor pattern or an autonomic reflex) or structure(color at tip of wing, feathers, dewlaps, many secondary sexual characteristics) is transformed into a communication signal

Romer’s Rule

“the initial survival value of a favorable innovation is conservative, in that it renders possible the maintenance of a traditional way of life in the face of changed circumstances.” (Hockett & Asher 1964:137)

r-selected traits

r is an attribute of an organism. In equations describing population dynamics r represents “the intrinsic rate of population growth.” A trait that is “r-selected is one that has helps an organism maximize expression of that intrinsic rate (rate that would be manifest if there were no limiting factors). Contrast to K-selection

Runaway sexual selection

the process in sexual selection by which positive feedback between an ornamental trait in a male and the female preference for the trait can lead to very elaborate, even burdensome ornaments

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Term Definition
Search image

Restriction of an animal’s interest to a single class of object as a consequence of focused attention on particular stimuli

Segregation Distortion

see meiotic drive


in Biol., used by C. Darwin (Origin of Species, 1859) and subsequent writers, to designate any process, whether artificial or natural, which brings about a particular modification of an animal or vegetable type by ensuring that in successive generations the individuals that reproduce their kind shall be those that have transmissible variations from the ancestral form in the direction of this modification. — OED; “change in relative frequency in genotypes due to differences in the ability of their phenotypes to obtain representation in the next generation” (EOW 1975, 1980)

(natural selection: the operation of natural causes; sexual selection: that kind of natural selection which arises through the preference by one sex of those individuals of the other sex; see selection pressure; hierarchical selection; units of selection)

Selection Pressure

an environmental variable with which an organism must cope in order to survive and thrive (maximize its fitness). The “pressure” is for an individual or species to cope with limitations imposed by this variable (e.g., climate, geology, predators, prey, conspecifics) in competition with other organisms in the same environment. In “domestication” the selection pressure is a specific human need.

Selective attention

apparent responsiveness to a specific subset of all the stimuli that are in principle detectable by anorganism

Selfish herd

A herd can consist of individuals that act to minimize danger to themselves by moving into the center of a herd. Thus the herd appears well integrated but actually reflects the behavior of self-seeking individuals

self-organizing system

An aggregate of components (living or otherwise) on which “the constraints on form are internal to the system and result from the interactions between the components, whilst being independant of the physical nature of those components. The organisation can evolve either in time or space, can maintain a stable form or can show transient phenomena. General resource flows into or out of the system are permitted, but are not critical to the concept.(link at Univ Wisc) “organisms and their environments taken together organize themselves. (Von Foerster, 1960). “… a self-organizing system [is a] system consisting of the organism and environment taken together. (Ashby, 1960)

“The concept of a self-organizing system has changed over time. In the early days it was defined as a system which changes its basic structure as a function of its experience and environment. … [now] it is important to note that an organism does not organize itself independent of its environment.” — Principia Cybernetica Web 12/2012)


the occurrence of a single act of reproduction during an organism’s lifetime. Most semelparous species produce very large numbers of offspring when they do reproduce, and normally die soon afterwards.Contrasted with Iteroparity.


“… tendency to seek novel, varied, complex, and intense sensations and experiences and the willingness to take risks (e.g., physical and social) in order to have such experiences..” (Sensation Seeking and Risky Behavior By Marvin Zuckerman. American Psychological Association, 2007, xix + 309pp. ISBN: 1–59147–738–7)


An enhanced responsiveness to a stimulus as a result of exposure to it. e.g., drug-induced sensitization is believed to underlie certain aspects of drug addiction. A kind of Non-associative Learning. [sensitization to an allergen can result in enhanced responsiveness over time; “behavioral sensitization to a drug refers to a progressively increased responsiveness that develops as after repeated exposure and which can remain even after long periods of withdrawal [more]; attributable to changes in the brain; cross-sensitization is when one stimulus makes the organism more responsive to a different stimulus]

Sensory Adaptation

decreased signalling of a peripheral sense organ with continued exposure to a stimulus

Sensory bias/sensory exploitation

Congenital or developed dispositions for some stimuli over others based on sense organs: In the evolution of social signals (see “ritualization”), preferences for a specific sensory stimulus often precedes its development into a signal. Most experiments use “supernormal stimuli.” (Basolo 1990 Sci 250:808)

The “sensory exploitation hypothesis” predicts that the evolution of a trait utilized in communication will take advantage of preexisting sensory bias or preference. (see Bricolage)

Sensory filter

neural mechanisms that discriminate more-or-less salient stimuli that are detected by sensor organs; a low level mechanism of selective attention; may help prevent “sensory overload.”

Sensory selectivity

subset of stimuli, which an animal detects and responds to

Sensory transduction

chain of physiological reactions which convert environmental energy presented to the sense organs into electrochemical energy which can be transmitted by the nervous system and affect physiological variables such as the stability of polarized cells (such as neurons)

Sexual Selection

the process by which changes in gene frequencies result from individuals that are better than others at either competing for or at attracting mates — i.e. the evolution of traits based on differences in mating success

Sign Stimulus

small subset of features or complex environmental cues that are sufficient to elicit a FAP, also see Stimulus; a stimulus to which a specific reaction pattern is tuned


Physical coding of a message for transmission through environment.
Signals can be discrete or graded (digital (easily distinguished units) or analog (an apparent continuum). They can also be combined to create a new meaning (composite signals are “combinations” of units) or have their meaning altered by varying syntax (changing the order of presentation of units)

Skinner Box

An animal placed inside the box is rewarded with a small bit of food each time it makes the desired response, such as pressing a lever or pecking a key. A device outside the box records the animal’s responses, see Operant Conditioning


A state of inactivity during which animals are not responsive to external stimuli.

Social dominance

an individual’s exercise of priority of access to a resource [more]

Social hierarchy

a form of social organization which manifests the relative social rank of individuals. They can be linear “peck-order” or arborizing (branching as when one individual influences multiple individuals of lower rank)


the developmental process leading to the accommodation of an individual to other individuals and integration into a social group “…the sum total of social experiences that alter the development of an individual.” A term with subtly different meanings in various disciplines. In ethology or sociobiology it goes beyond culturally transmitted/learned behavior to include “morphogenetic socialization” (e.g., caste determination), learning species-typical behavior, and enculturation. (EO Wilson 1975) Can be viewed as in a dialectical tension with “individuation” “essential tension” between INDIVIDUATION and SOCIALIZATION


A group of individuals of the same species that is organized in a cooperative manner. It is coordinated by reciprocal communication extending beyond sexual and parental care.


“The systematic study of the biological basis of social behavior.” (EO Wilson 1975). Sociobiology emphasizes an ecological and evolutionary perspective, including population biology. The emphasis on genetic influences on behavior invited vigorous controversy about determinism.


Sociopathy has also been called “antisocial personality disorder” and “psychopathy.” It is characterized by a pervasive pattern of disregard for the rights of others, lying, deception, impulsivity, aggressive behavior, lack of empathy, and lack of remorse.

In A&O and E&S, sociopaths (and synesthetes) are used to illustrate the difficulty in knowing what another individual is truly feeling (as opposed to what is indicated by their manifest behavior). It appears that there are degrees the deficits sociopaths manifest and clear sociopathy may be the end of a continuum; not all those so constituted are necessarily antisocial. Sociopaths have extremely impaired understanding of the emotional consequences of their actions and they learn how to relate to others by direct consequences; because this appears to impair the intrinsic sense of responsibility, morality, or concern for others they may commit criminal acts, sometimes of an “inhuman” nature. (but not all those deficient in these attributes of consciousness are sociopaths)”

Spectrum disorder

The expression of a potentially dysfunctional trait that varies in intensity.

Sperm competition

a form of post-copulatory competition which occurs when ejaculates from more than one male might be in female’s reproductive tract. The “competition” can be affected by several factors including: sperm number (the more sperm a male transfers the greater the chance of fertilization);sperm quality (sperm from one male may have greater longevity or motility); mating order(sometimes the last male to mate with the female fathers the most offspring); cryptic female choice(a female may be able to preferentially use one male’s sperm rather than another’s). 


any form of energy that can be detected by the body, requires Sensory Transduction

SIGN STIMULUS. Any stimulus that activates an innate releasing mechanism (IRM)responsible for evoking a fixed action pattern (FAP) or species-typical behavioral pattern. (This used to be called key stimulus recalling the idea of lock & key specificity)
CONFIGURATIONAL SIGN STIMULUS. A stimulus, the effects of which are dependent upon relationships between its elements. Examples: (a) Hawk-Goose model or (b) human face
RELEASER. A sign stimulus emanating from a conspecific Examples: (a) Red spot on gull’s bill, (b) Lizard dewlap display.
see Supernormal stimulus


Distinguish STRESSOR from STRESS RESPONSE: The stressor is a real or perceived environmental or physiological condition that threatens an organism’s ability to meet its needs, the most urgent of which is homeostasis. The stress response consists of interacting neural and endocrine mechanisms by which the organism physiologically or behaviorally copes with the stressor. The principal mechanisms involve (a) the “SAMS axis” — the sympathetic nervous system, adrenomedullary axis involving the release of epinephrine and norepinephrine, key elements of the “emergency response” to stress) and (b) the “HPA axis” — the hypothalamus, anterior pituitary gland, and adrenal cortex involving corticotrophin releasing factor (CRF), adrenocorticotrophic hormone (ACTH) and adrenal steroids (glucocorticoid hormones, cortisol or corticosterone)

Successful dispersal

dispersal is successful if propagule obtains opportunity to breed and raise young (i.e. genes migrate)

Supernormal stimulus

(in animal behavior) A stimulus that produces a more vigorous response than the normal stimulus eliciting that particular response. For example, a female herring gull will brood a giant egg in preference to its own eggs, which are smaller. A supernormal stimulus is an exaggerated sign stimulus.
(in neurophysiology) A stimulus that is more intense than a normal stimulus and is capable of inducing a response in a nerve fibre during the relative refractory period.


A relationship between two or more organisms that might be parasitic (one benefits at the expense of the other), mutualistic (both find the relationship advantageous — often necessary to one or both and not harmful to either) or commensal, in which one member of the association benefits while the other is not affected. ectosymbionts live on the body surface of the host (including inside the digestive tract or the ducts of exocrine glands; endosymbionts live in the intracellular space of a host. See also:mutualism, parasitism.


to suffer together” when a person’s feelings reflect or are like those of another. Sympathy exists when the feelings or emotions of one person give rise to similar feelings in another person, creating a state of shared feeling.” Unlike empathy, which could simply mirror those feelings or the outward signs of them, sympathy requires consciousness of another’s experience [more]

Synaptic plasticity

changes in excitability and transmitter release at synaptic junctions between neurons


In A&O and E&S, synesthetes are used to illustrate the difficulty in knowing what another individual istruly experiencing. Synesthetes possess an atypical blending of the senses: the stimulation of one modality is perceived in a different modality, so (for example) one may hear colors, feel sounds and taste shapes. [more]

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Term Definition

the act of orienting towards some external stimulus or combination of stimuli. Spatial orientation, aided by different sensory modalities, is described by the corresponding term e.g. relative to light (phototaxis), smell (chemotaxis), sound (phonotaxis), or gravity (geotaxis). If orientation is towards the source, it is called a positive taxis, and away from the source a negative taxis. In such instances individuals move in a directed fashion along a particular stimulus gradient until they reach a perceived optimal range. see Homing, Kinesis, Navigation, Orientation, Piloting


any defended area; an area of more or less fixed boundaries from which rival conspecifics are excluded, see Home range

Tip-of-the-Tongue (presque vu)

a sense that the retrieval of something you are trying to remember is imminent, associated with activity of the anterior cingulate, right dorsolateral prefrontal cortex, and right inferior cortex, amongst other sites. (Wikipedia)


a manifest morphological or behavioral attribute of an organism. Traits that are demonstrably adaptive are often termed adaptations. An ETHOLOGICAL TRAIT is a behavioral pattern and PHENOTYPIC in that it is the MANIFEST expression of multiple converging streams of information. These originate in the activation of specific genes and as the paths taken by the products of their activation are transmitted through the organism: most genes are PLEIOTROPIC (have multiple effects), most traits are POLYGENIC (affected by multiple genes). Genes activation or suppression is the result of their immediate environments and known as EPIGENETICS.  To be studied, any particular trait must be described as precisely as possible given its LEVEL OF ORGANIZATION, from cellular to social.

Trial-and-error learning

behavioral plasticity, see Operant conditioning

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Term Definition
Ultimate cause (and consequence)

“Ultimate” (as opposed to “proximate”) causes and consequences of behavior are those most distantly removed from the behavior with which it is associated; thus the ultimate “cause” of a behavioral pattern is often viewed as the selection pressure that first influenced its presence in the organism, possibly in some very remote (ancient, ancestral) evolutionary scenario; the ultimate consequence of a behavioral pattern can only be hypothesized on the basis of its likely contribution to fitness in a future evolutionary scenario.


the unique “sensory world” of a specific organism — the stimuli to which an animal is responsive in a given motivational state. It is often presumed that the sensory receptors and neural apparatus for extracting meaning from sensations (perceptions) has, in any particular species, evolved to respond to those stimuli that are or were relevant to fitness. Term coined by von Uexküll in the 1920s. seeMerkwelt [more]

Unit of Selection

level of organization at which selection operates: group selection, kin selection, individual selection(see Hierarchical selection)

[WD Hamilton: I don’t think one can say there is a unit of selection. Any selection process selects on units at various levels, starting with ultimate replicators such as the gene, the individual, the community in which the individual is. All these things could be considered units of selection that are being selected simultaneously, and all of them are changing the frequency of the ultimate atom of selection, which is the gene, but it is not possible to say that the gene is the soul [sic] unit of selection.” (from Evolution 3rd ed, by Mark Ridley –]

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Term Definition
Vacuum activity

the performance of consummatory behavior in the absence of any of the stimuli that are normally necessary for its occurrence.


wide dispersal where average propagule moves more than 30 home ranges away from natal site


the accuracy and specificity of data, as well as its applicability to the question being asked (as opposed toReliability) Validity is often characterized as internal or external depending on whether it applies to the case(s) at hand or to a larger, more general set of case (such as “this individual or all members of the population;” or “this species or all members of the genus”)

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Term Definition
Williams Rule of Parsimony

“when considering any adaptation, we should assume that natural selection operates at that level necessary to explain the facts, and no higher.Developed in the belief that the phenomena he considered in describing the idea of “group selection” in evolution could be explained at the level of the parents and their young. (from George Williams, “Adaptation and Natural Selection” 1966 ) resembles the famous general principle in logic called “Occam’s Razor”

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Term Definition

“time-giver” — cue that triggers an organism’s coordination with an environmental rhythm


migratory restlessness

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