bio133 week 7

sexual selection

a form of natural selection where traits increase mating success rather than survival

intrasexual selection

competition within the same sex (often male vs male) for mates

intersexual selection

mate choice, typically where one sex selects based on traits

sexual dimorphism

physical differences between males and females of a species

mate choice

selection of partners based on traits indicating fitness

honest signal

a trait that reliably indicates an individual's quality

handicap principle

costly traits signal higher fitness because only strong individuals can afford them

lek

an aggregation where males display and females choose mates

monogamy

mating system with one male and one female pair bond

polygyny

one male mates with multiple females

polyandry

one female mates with multiple males

promiscuity

multiple mating partners without long-term bonds

inclusive fitness

total genetic success including direct and indirect reproduction

kin selection

natural selection favoring behaviors that benefit relatives

altruism

behavior that benefits another at a cost to oneself

coefficient of relatedness

probability that two individuals share genes

reciprocal altruism

cooperation where individuals help each other with expectation of return

Hamilton's rule

altruism evolves when rb > c

optimal foraging theory

animals maximize energy gained per unit time

cost-benefit analysis

weighing energy gained vs energy spent

marginal value theorem

predicts when a forager should leave a resource patch

predation risk

likelihood of being eaten while foraging

territoriality

defense of a specific area against others

home range

area an animal uses but does not defend

dominance hierarchy

ranking system that determines access to resources

agonistic behavior

conflict-related behavior between individuals

communication

transfer of information between individuals

signal

behavior or structure used to convey information

pheromone

chemical signal used for communication

visual signal

communication through body language or coloration

acoustic signal

communication through sound

fixed action pattern

instinctive behavior triggered by a stimulus

sign stimulus

external cue that triggers a fixed action pattern

imprinting

early-life learning during a critical period

habituation

decreased response to repeated stimulus

classical conditioning

learning by associating two stimuli

operant conditioning

learning through rewards and punishments

cognition

mental processing of information

reproductive success

passing genes to the next generation

fertilization

fusion of sperm and egg

external fertilization

fertilization outside the body

internal fertilization

fertilization inside the body

oviparity

egg-laying reproduction

viviparity

live birth reproduction

ovoviviparity

eggs hatch inside the parent

gonads

organs that produce gametes (testes and ovaries)

gamete

reproductive cell (sperm or egg)

zygote

fertilized egg

embryo

early developmental stage

larva

immature stage different from adult

metamorphosis

transformation from larva to adult

spermatogenesis

production of sperm

oogenesis

production of eggs

testosterone

hormone associated with male traits

estrogen

hormone associated with female traits

progesterone

hormone involved in maintaining pregnancy

menstrual cycle

hormonal cycle regulating female reproduction

ovulation

release of an egg from the ovary

follicle

structure that contains developing egg

corpus luteum

structure that produces hormones after ovulation

parental investment

time and energy spent raising offspring

r-selected species

produce many offspring with low parental care

K-selected species

produce few offspring with high parental care

semelparity

reproducing once before death

iteroparity

reproducing multiple times

hermaphroditism

individuals possess both male and female reproductive organs

sequential hermaphroditism

changing sex during lifetime

protandry

male to female transition

protogyny

female to male transition