lecture 12 - sexual selection

define anisogamy 

fusion of gametes differing in size and form (basis of sexual reproduction)

difference between protandry and protogyny

protandry = starts life as a male, later becomes female - larger females can produce many eggs, small males can still fertilize them so starting as male and becoming female later maximizes lifetime reproductive output

protogyny = starts life as a female, later becomes male - large males control harems, starting as a small female and becoming a dominant male when big increases mating opportunities 

both are types of sequential hermaphroditism (maximizes reproductive success under changing social or environmental conditions)

what is social monogamy vs genetic monogamy

social monogamy = pair bond but not exclusive genes

genetic monogamy = strict fidelity

why did monogamy evolve

high offspring care needs, limiting resources, rare partners, co-parenting benefits

distinguish intrasexual and intersexual selection

intrasexual = same sex competition (antlers)

intersexual = mate choice (peacock tail)

explain Andersson’s widowbird experiment

longer tails → more mates; female preference = intersexual selection

describe trade offs of ornamentation

higher predation risk, energy cost, and reduced growth for sexual advantage

what did guppy experiments reveal

predation limits male ornamentation despite female preference → balancing selection

what is sexual conflict

evolutionary arms race between male persistence and female resistance due to unequal mating costs

how can plants experience sexual selection

through pollen competition and maternal choice in fertilization (wild radish)