Animal Behavior Exam 1

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Natural Selection (direct selection)

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The process that occurs when individuals differ in their traits and the differences are correlated with differences in reproductive success. Natural selection can produce evolutionary change when these differences are inherited

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Adaptation

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A characteristic that confers higher inclusive fitness to individuals than any other existing alternative exhibited by other individuals within the population; a trait that has spread or is spreading or is being maintained in a population as a result of natural selection or indirect (kin) selection

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Adaptationists

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A behavioral biologist who develops and tests hypotheses on the possible adaptive value of a particular trait. Persons using an adaptationist approach test whether a given trait enables individuals to propagate their special genes more effectively than if they had an alternative trait

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Genes

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A segment of DNA, typically one that encodes information about the sequence of amino acids that makes up a protein

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Alleles

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A form of a gene. Different alleles typically code for distinctive variants of the same enzyme

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Darwinian puzzles

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A trait that appears to reduce the fitness of individuals that possess it. Traits of this sort attract the attention of evolutionary biologists

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Eusocial

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Refers to species in which colonies contain specialized non reproducing castes that work for the reproductive members of the group

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Altruism

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Helpful behavior that raises the recipient's direct fitness while lowering the donor's direct fitness

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Intelligent Design Theory

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The argument that biological features are too complex to have evolved by natural processes, such as natural selection, and that therefore an intelligent designer, such as a god, is required to account for the existence of these complex features

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Group Selection

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The process that occurs when groups differ in their collective attributes and the differences affect the survival chances of the groups

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Coefficient of Relatedness

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The probability that an allele present in one individual will be present in a close relative; the proportion of the total genotype of one individual present in the other, as a result of shared ancestry

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Fitness

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A measure of the genes contributed to the next generation by an individual, often stated in terms of the number of surviving offspring produced by the individual

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Indirect selection (kin selection)

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The process that occurs when individuals differ in their traits and the differences are correlated with differences in reproductive success. Natural selection can produce evolutionary change when these differences are inherited

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Direct selection

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Natural selection; a term that refers to selection that results from hereditary differences between individuals in the production of surviving offspring

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Indirect Fitness

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The genes contributed by an individual indirectly by helping nondescendent kin, in effect creating relatives that would not have existed without the help of the individual

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Direct Fitness

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The genes contributed by an individual via personal reproduction to the bodies of surviving offspring

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Inclusive Fitness

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The sum of an individual's direct and indirect fitness

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Behavioral Strategies

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A genetically distinctive set of behavioral decision-making rules exhibited by individuals

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Hamilton's rule

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The argument made by W.D. Hamilton that altruism can spread through a population where rB>C (with r being the coefficient of relatedness between the altruist and the individual helped, B being the fitness benefit received by the helped individual, and C being the cost of altruism in terms of the direct fitness lost by the altruist due to its actions)

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Haploid

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Having only one copy of each gene in the genotype, as for example in the sperm and eggs of diploid organisms

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Diploid

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Having two copies of each gene in one's genotype

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Theory of Descent with Modification

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Darwin's argument that over evolutionary history, changes accumulate gradually in ancestral species, altering them more and more as these ancestral species evolve into more recent forms derived from their predecessors

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Phylogeny

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An evolutionary genealogy of the relationships between a number of species or clusters of species that can be used to develop hypotheses on the evolutionary history of a given trait

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Cooperation

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A mutually helpful action that may have immediate benefits for both parties or postponed benefits for one of the cooperators

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Reciprocity (Reciprocal Altruism)

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A helpful action is repaid at a later date by the recipient of assistance

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Prisoner's Dilemma

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A game theory construct in which the fitness payoffs to individuals are set such that mutual cooperation between the players generates a lower return that defection, which occurs when one individual accepts assistance from the other but does not return the favor

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Nondescendent Kin

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Relatives other than offspring

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By-product hypothesis

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An explanation for a maladaptive or nonadaptive attribute that is said to occur as a by-product of a proximate mechanism that has some other adaptive consequence for individuals

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Facultative Altruism

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Altruism that the helper can employ at its discretion

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Obligate Altruism

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Helpers are locked into providing assistance to others

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Sensory exploitation

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The evolution of signals that happen to activate established sensory systems of signal receivers in ways that elicit responses favorable to the signal sender

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Honest Signal

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A signal that conveys accurate information about some aspect of the signaler's quality, such as its fighting ability or value as a potential mate

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Illegitimate Signalers

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An individual that produces signals that may deceive others into responding in ways that reduce the fitness of the signal receiver

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Pheromone

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A volatile chemical released by an individual as a scent signal for another

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Eavesdropping

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The detection of signals from a legitimate signaler by an illegitimate receiver to the detriment of the signaler and the benefit of the receiver

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Illegitimate Receivers

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An individual that listens to the signals of others, thereby gaining information that it uses to reduce the fitness of the signaler

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Fitness Costs

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The aspect of a trait that tends to reduce the inclusive fitness of individuals

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Fitness benefits

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The aspect of a trait that tends to raise the inclusive fitness of individuals

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Adaptive Value

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The contribution that a trait or gene makes to inclusive fitness

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Arms race

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The result of selection acting on two parties that are in opposition to one another, as in the increasing sophistication of defensive mechanisms in a species that is preyed upon by an increasingly sophisticated predator

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Reproductive Success

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The number of surviving offspring produced by an individual; direct fitness

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Comparative Method

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A procedure for testing evolutionary hypotheses based on disciplined comparisons among species of known evolutionary relationships

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Divergent Evolution

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The evolution by natural selection of differences between closely related species that live in different environments and are therefore subject to different selection pressures

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Convergent Evolution

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The independent acquisition over time through natural selection of similar characteristics in two or more unrelated species

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Dilution Effect

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Safety in numbers that comes from swamping the ability of local predators to consume prey

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Selfish Herd

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A group of individuals whose members use others as living shields against predators

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Operant Conditioning

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A kind of learning based on trail and error, in which an action, or operant, becomes more frequently performed if it is rewarded

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Cost-benefit Approach

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A method for studying the adaptive value of alternative traits based on the recognition that phenotypes come with fitness costs and fitness benefits. An adaptation has a better cost-benefit ratio than alternative versions of that trait