Parental Care and Altruism in Evolution

These flashcards cover key concepts related to parental care, altruism, social behavior, and evolutionary strategies in biology.

Parental care

Any behavior by a parent that increases the survival and future reproduction of offspring, usually at a cost to the parent’s own time, energy, or future reproduction.

Maternal care

Parental care performed by the mother, such as gestation, lactation, feeding, or protection of offspring.

Paternal care

Parental care performed by the father, such as guarding, feeding, or defending offspring.

Biparental care

A system in which both parents contribute significantly to raising offspring.

Parental investment

Any parental effort that increases offspring survival or quality but reduces the parent’s ability to invest in other offspring.

Signals of need (offspring)

Cues like begging, calling, or gape color that reflect how urgently an offspring needs resources right now.

Signals of quality (offspring)

Traits like larger body size, better condition, or brighter coloration that indicate an offspring’s long-term survival and reproductive potential.

Trivers–Willard hypothesis

The idea that parents in good condition should invest more in the sex with higher variance in reproductive success (often males), while parents in poor condition should invest more in the 'safer' sex (often females).

Siblicide

When one sibling kills another, often to monopolize limited parental resources.

Brood parasitism

A strategy in which a female lays her eggs in the nest of another individual, leaving the host to provide parental care.

Altruistic behavior

A behavior that decreases the actor’s direct fitness but increases the fitness of another individual.

Group selection theory

The idea that traits evolve because they benefit the group or species, even if they reduce individual fitness.

Direct fitness

Fitness gained from an individual’s own reproduction (surviving offspring produced by the individual).

Indirect fitness

Fitness gained by helping related individuals reproduce, because they share copies of the helper’s genes.

Inclusive fitness

The sum of direct fitness and indirect fitness gained from helping relatives.

Coefficient of relatedness (r)

The probability that two individuals share an allele that is identical by descent.

Hamilton’s rule

A rule stating that an altruistic behavior can evolve when rB > C (relatedness × benefit to recipient > cost to actor).

Eusociality

A social system with cooperative care of young, overlapping generations, and a reproductive division of labor (some individuals reproduce, others do not).

Caste (in eusocial species)

A distinct group of individuals within a social species that performs specific roles (e.g., queen, worker, soldier), often with different morphology or behavior.

Caste determination (proximate mechanisms)

The developmental processes (e.g., nutrition, hormones, pheromones, temperature, genetics) that cause individuals to become a particular caste.

Haplodiploidy

A sex-determination system where males are haploid (from unfertilized eggs) and females are diploid (from fertilized eggs), common in ants, bees, and wasps.

Totipotent worker (caste)

A worker that retains the potential to become reproductive under certain conditions (e.g., if the queen dies).

Obligate worker (caste)

A worker that is permanently non-reproductive due to irreversible developmental or morphological specialization.

Altruism (social behavior category)

Social behavior where the actor’s fitness decreases and the recipient’s fitness increases (–/+).

Mutualism/Cooperation

Social behavior where both actor and recipient gain fitness benefits (+/+).

Selfish behavior

Social behavior where the actor benefits and the recipient pays a fitness cost (+/–).

Spite

Social behavior where both the actor and recipient suffer fitness costs (–/–).

Prisoner’s Dilemma

A game theory model in which mutual cooperation yields the best joint outcome but individuals are tempted to defect for short-term gain.

Reciprocity (reciprocal altruism)

Helping another individual now with the expectation that the other will help you in the future, usually in repeated interactions.

Social group

A set of individuals that live together and interact regularly, often sharing space, resources, and social relationships.

Cooperative breeding

A system in which some individuals (helpers) assist in raising offspring that are not their own, often delaying or foregoing personal reproduction.

Helper (in cooperative breeders)

An individual that contributes care (e.g., feeding, defending, babysitting) to others’ offspring instead of or in addition to reproducing.

Singular cooperative breeder

A cooperative breeding system with one dominant breeding pair per group and nonbreeding helpers.

Plural cooperative breeder

A cooperative breeding system in which multiple individuals or pairs within the same group reproduce, often along with helpers.

Grandmother effect

Increased survival and reproductive success of grandchildren due to help from post-reproductive grandmothers.

Menopause (evolutionary context)

The cessation of female reproduction before the end of life, thought to be adaptive when post-reproductive females gain more inclusive fitness by helping descendants.