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cost of males

could produce 2x as many females

cost of meiosis

recombination breaks up favorable gene comlpexes

costs associated with sex

cost of males, cost of meiosis, gonads are expensive to reproduce and maintain, mating is risky and costly, often involving elaborate behaviors

asexual reproduction

leads to greater contributions to subsequent generations

benefits of sex

novel gene combinations are created, prevents Mullers ratchet

Red Queen Hypothesis

need to create new gene arrangements to combat pathogen evolution

Muller's Ratchet

mutations will accumulate in asexual lineages because there is no recombination

anisogamy

gametes of unequal size

isogamy

gametes of equal size

evolution of anisogamy

selection pressures to produce bigger gametes, more gametes.

conflict of interest between sexes

differ in amount of investment, bigger gametes (more parental investment), more gametes (less parental investment

bateman's principle

male fitness increases with number of mating events, female fitness does not change with mating events, thus female (eggs) are a limiting resource- so males will compete for mating opportunities

parental investment

investment on offspring that increase their chance of survival at the cost of future offspring

sex determination

influences the degree to which a female can alter the sex ratio of her offspring

heterogamety

sex chromosomes are different for each sex (Female; XX , Male; XY)

haplodiploidy

type of sex-determination system, sex is determined by the number of chromosomes an individual receives. Haploid males develop from unfertilized eggs, diploid females develop from fertilized eggs.

environmental sex determination

temperature of incubation influences sex determination (mainly reptiles)

social sex determination

many fish can undergo sex changes. Ex CA sheephead, all born female, dominant female changes into males when a male disappears

maternal condition

individual sex allocation depends on condition (if mom is in good condition they give more parental care to sons than daughters b/c dominant sons can sire more offspring, if in poor condition should produce more daughters.

local mate competition

mating occurs near hatching site (brothers compete for mating), produce few sons.

local resource competition

offspring that stay near their birth site may compete with their parents for resources (produce more dispersing sex)

local resource enhancement

in some species offspring of one sex remain at the nest to help parent raise their species.

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