Sex and Evolution Flashcards
(19 cards)
why does sex matter evolutionarily?
we have to consider intraspecies and interspecies orders of organization
also sexual selection facilitates weird traits that help us study evolution
genetic differentiation of sex can be
XY vs XX (mammals and most insects)
ZW vs ZZ (birds and butterflies)
XX vs X0
undifferentiated sex chromosomes (some amphibians, fish and crustaceans)
haplodiploidy (hymenoptera, isoptera)
environmental sex determination/hermaphroditism can be based on
temperature, pH, background color, social cues
sex ratios tend to be 50/50 because
frequency dependent selection of rarer sex - balancing selection of the population
primary sexual traits
directly relevant to mating and can be dimorphic
secondary sexual traits
not part of reproduction, but increase reproductive success, and are fast evolving
can be dimorphic
males often have _____ traits because
showier; females have the rate-limiting gamete, males benefit more from multiple matings
males have greater variance in reproductive success so they can evolve faster
when males do the brooding…
they are the choosier sex (seahorse mannerisms mention!)
sexual selection often involves ____ vs _____
reproductive success vs survival
types of male competition
mating behaviors, ie a-b-γ males in that one weird isopod
sperm competition
infanticide
caring for offspring
female choice
based on any phenotype of the female that biases the type of male she mates with - ex. male detectability, display of fitness, pleiotropic links to traits that are relevant to fitness
female choice may have evolved from
the need to mate within one’s species
why sex!!?!?!
allows beneficial mutations to segregate separately from deleterious mutations
Muller’s ratcher
accumulation of deleterious mutations in asexual species
clonal interference _____ evolution
slows down
reproduction of organisms with complex life cycles
asexual reproduction for dispersal, and sexual reproduction when there is environmental change
self-fertilization benefit
gene segregation w/o finding a mate
self-incompatibility
evolved by hermaphrodites to avoid inbreeding depression
ex. pollen tube of flower will grow if the pollen allele differs from the style alleles
clonal interference
two or more beneficial alleles spread through a population at the same time
