Ethology and Reproductive Behavior Lecture Notes

Vocabulary-style flashcards covering migration, principles of communication, reproductive systems, parental behavior, and social evolution.

Migration

Movement away from and subsequent return to the same location on an annual basis, seen in approximately $40\%$ of bird species such as bar-headed geese.

Tropical Origins Hypothesis

The theory that avian migration began when tropical species moved north to exploit seasonal food abundance for breeding before returning to the tropics.

Temperate Origins Hypothesis

The theory that avian migration began when temperate-zone species moved south to the tropics during the non-breeding season to find a milder climate.

Signal

A message that has specially evolved to contain information.

Cue

An unintentional transfer of information occurring between a sender and a receiver.

Honest Signaling

A cooperative form of communication where both the sender and receiver gain a benefit ($+/+$).

Deceitful Signaling

A communication form where the sender manipulates the receiver for a fitness benefit, while the receiver incurs a cost ($+/-$).

Eavesdropping

When a receiver benefits from detecting information while the sender incurs a fitness cost ($-/+$), typically involving cues.

Preexisting Traits

Behavioral, physiological, or morphological characteristics already present in a sender that provide informative cues to receivers.

Preexisting Biases

Inherited sensory systems of a receiver that evolved in a specific environment, making them naturally sensitive to specific sounds, colors, or movements.

Sensory Bias

The natural, inherited inclination of a receiver to detect and respond to particular types of stimulus.

Sensory Exploitation

An evolutionary process where senders develop signals that take advantage of a receiver's preexisting sensory biases.

Spermatophores

A packet containing sperm and nutrients provided by a male for a female during reproduction, such as in water mites.

Preexisting Trait Hypothesis

The idea that signals evolve from existing biological traits that served as cues and underwent ritualization into formal messages.

Preexisting Bias Hypothesis

The idea that signals evolve specifically to exploit the sensory biases already present in a receiver's perceptual system.

Novel Environment Hypothesis

A possible explanation for maladaptive responses to deception, suggesting the environment changed too quickly for the species to evolve a defense.

Net Benefit Hypothesis

The argument that animals respond to deceitful signals because the response still provides a net fitness advantage on average.

Good Genes Model of Sexual Selection

A framework where female preference for male ornaments allows them to select mates with high-quality genes to enhance offspring fitness.

Hamilton and Zuk Hypothesis

A sub-model of the good genes hypothesis where prominent male traits are viewed as indicators of hereditary resistance to parasites or pathogens.

Runaway Selection Model of Sexual Selection

An evolutionary mechanism where a female preference and a male trait become genetically linked, causing both to escalate rapidly across generations.

Ornaments

Sexually selected morphological traits used primarily to attract members of the opposite sex.

Armaments

Sexually selected morphological weapons, such as antlers or horns, used in intrasexual contests to battle rivals.

Reproductive Variance

The level of inequality regarding reproductive success within a group.

Anisogamy

Sexual reproduction involving the fusion of highly unequal gametes: small, abundant sperm and large, scarce eggs.

Bateman’s Principle

The concept that male reproductive success increases linearly with the number of mates, while female success is limited by egg production.

Parental Investment

The energy, time, and resources spent on current offspring at the cost of the parent's ability to invest in future offspring.

Operational Sex Ratio

The ratio of sexually active, receptive males to receptive females in a population at any given time.

Sex Role Reversal

A scenario where females compete for mates and males are highly selective, often because males provide the majority of parental care.

Nuptial Gift

A food item or physical resource provided to a partner to secure a mating opportunity.

Sexual Selection

Natural selection stemming from heritable trait variations that affect an individual's ability to attract or compete for mates.

Intrasexual Selection

Competition occurring between members of the same sex for access to mates.

Intersexual Selection

Mate choice involving discrimination by members of one sex when choosing a partner from the opposite sex.

Sexual Dimorphism

Noticeable differences in appearance, size, or structure between males and females of the same species.

Dominance Hierarchy

A ranking system within a social group where higher-ranking individuals gain priority access to mates or food.

Conditional Mating Tactics

Behaviorally flexible reproductive choices made based on current physical status, age, or environment.

Alternative Mating Strategy

A fixed reproductive strategy that is genetically distinct and maintained alongside standard strategies in a population.

Sperm Competition

Postcopulatory competition between the sperm of two or more males over the fertilization of a single female's eggs.

Mating Plugs

A physical or gelatinous barrier deposited in a female's tract after copulation to prevent further matings by other males.

Extra-Pair Copulations

Matings that take place outside of a socially monogamous pair bond.

Cryptic Female Choice

A postcopulatory process where a female biases which male's sperm fertilizes her eggs.

Mate Guarding

Behavior where an individual tracks or defends their partner to prevent rivals from mating.

Direct Benefits

Material benefits like food, protection, or territory given to the choosing mate that enhance her immediate reproductive output.

Indirect Benefits

Genetic advantages passed to offspring that enhance their fitness rather than the choosing parent's immediate survival.

Sexual Conflict

An evolutionary clash where a trait that is optimal for the fitness of one sex reduces the fitness of the other sex.

Coercive Mating

Forced copulation or harassment by one partner to overcome the resistance of the other.

Sexual Arms Race (Sexually Antagonistic Coevolution)

Evolutionary escalation where one sex develops traits for manipulation or coercion while the other develops defensive adaptations.

Mate Limitation Hypothesis

The idea that monogamy evolves because potential mates are scarce or widely dispersed.

Mate Guarding Hypothesis

The idea that monogamy evolves because guarding a single female is required to prevent other males from fertilizing her eggs.

Mate Assistance Hypothesis

The idea that monogamy evolves because offspring survival requires significant investment from both parents.

Infanticide Hypothesis

The idea that monogamy or mate guarding evolves so the male can protect his offspring from being killed by rivals.

Good Genes Hypothesis (Polyandry)

The idea that females mate with multiple males to secure superior genes for their offspring.

Genetic Compatibility Hypothesis

The idea that females mate with multiple males to find a genetic profile that optimally complements their own DNA.

Genetic Diversity Hypothesis

The idea that females mate with multiple males to increase genetic variation in their offspring to shield against environmental unpredictability.

Inbreeding Avoidance Hypothesis

The idea that females mate with multiple partners to avoid reproductive failures caused by mating with close relatives.

Additional Resources Hypothesis

The idea that females engage in polyandry to obtain extra material resources or nuptial gifts.

Additional Care Hypothesis

The idea that females mate with multiple males to enlist more individuals to provide care or protection for her brood.

Female Defense Polygyny Hypothesis

The idea that polygyny evolves when females cluster for safety, allowing a dominant male to monopolize them.

Resource Defense Polygyny Hypothesis

The idea that polygyny evolves when males can defend a clump of critical resources that multiple females need.

Lek Polygyny Hypothesis

The idea that polygyny evolves when males gather at a communal display arena (lek) because resources and females are dispersed.

Scramble Competition Polygyny Hypothesis

The idea that polygyny evolves when males must race to find widely-scattered females because neither resources nor females are clustered.

Hotspot Hypothesis

The theory that leks are established in high-traffic locations where females naturally pass through.

Hotshot Hypothesis

The theory that subordinate males cluster around a highly attractive male to intercept females drawn to him.

Female Preference Hypothesis

The theory that leks form because females prefer visiting clusters of males to efficiently assess multiple options.

Polygyny

A mating system where one male mates with multiple females.

Monogamy

A mating system involving a prolonged pair bond between one male and one female.

Polyandry

A mating system where one female mates with multiple males.

Polygynandry

A mating system where multiple males form exclusive pair bonds and mate with multiple females.

Promiscuity

A mating system where members of both sexes mate indiscriminately without forming pair bonds.

Social Monogamy

A social arrangement where a pair shares a territory and raises a brood, despite potentially engaging in extra-pair matings.

Genetic Monogamy

A strict reproductive system where the social parents are the biological parents of all offspring in their clutch.

Lek

A communal area where males occupy small, resource-free territories to display for females.

Explosive Breeding Assemblage

A temporary gathering, such as in wood frogs, where synchronized female receptivity leads to intense scrambling for mates over a short period.

Reproductive Value

The expected relative contribution of an individual at a specific age or condition to future generations' genetic makeup.

Precocial

Offspring that are born relatively mature, mobile, and self-sufficient.

Altricial

Offspring that are born helpless, blind, and dependent on parents for survival.

Interspecific Brood Parasites

Species that lay their eggs in the nests of different host species to shift the costs of parental care.

Coevolutionary Arms Race (Parental)

A reciprocal process where hosts develop defenses like egg rejection while parasites counter with adaptations like egg mimicry.

Signal of Need Hypothesis

The idea that parents allocate food to the hungriest chicks based on begging displays that signal true hunger.

Signal of Quality Hypothesis

The idea that parents selectively invest in the highest-quality chicks based on displays of health and vigor.

Paternity Assurance Hypothesis

The idea that males provide more parental care when they have higher certainty that the offspring are genetically their own.

Mafia Hypothesis

The behavior where parasitic birds like great spotted cuckoos destroy the nests of magpies that reject the parasite's egg.

Eusociality

An extreme social organization with overlapping generations, cooperative brood care, and division of labor into reproductive and non-reproductive castes.

Altruism

A behavior that increases the recipient's direct fitness while imposing a direct fitness cost on the actor.

Coefficient of Relatedness ($r$)

The probability that a copy of a gene is shared between two individuals due to common descent.

Direct Fitness

Genetic contribution through an individual's own personal reproductive success.

Indirect Fitness

Genetic contribution made by helping non-descendant relatives successfully rear offspring.

Inclusive Fitness

The sum of an individual's direct fitness and indirect fitness.

Hamilton’s Rule

The mathematical formula ($rB > C$) explaining that altruism evolves if the genetic benefit to the recipient ($B$) multiplied by relatedness ($r$) outweighs the cost to the actor ($C$).

Haplodiploidy

A sex-determination system where males develop from unfertilized haploid eggs and females develop from fertilized diploid eggs. This alters relatedness coefficients and predisposes some social insects toward altruism.

Caste

A specialized behavioral or morphological class within a social colony, such as non-reproductive workers versus breeding queens.