Reproduction Flashcards
costs of sexual reproduction
r = 1/2
gamate production is expensive
compeition for mates
benefits of sexual reproduction
variation in genes (recombination)
faster evolution
Muller’s Rachet
Muller’s Rachet
individuals will accumulate mutations (if sexual, it’ll they’ll be weeded out)
Red Queen Hypothesis
arm’s race - predatory, prey, parasite (need to change to beat other species)
dioecious
two distinct sexes
anisogamy
sperm and eggs are different sizes
isogamy
egg and sperm are the same size (fungi, plants)
limitations to reproductive success
males (access to females - quantity)
females (physiology, egg production and gestation - quality)
primary sex ratio
sex ratio at conception (males usually higher)
secondary sex ratio
sex ratio at birth/hatching (usually 1:1)
operational sex ratio
ratio of reproductively active males to females
Fisher’s Theory
sex ratio you produce influences the # of grandchildren - want to produce the rarer sex
deviations from Fisher’s Theory
haplodiploidy (expect 3:1 bc of indirect fitness)
Local Mate Competition (lots of sibling mating/incest - wasps produce females unless rarer sex is male)
Local Resource Competition (dispersal/nest helpers)
Trivers-Willard Hypothesis (maternal condition influences the reproductive success of offspring)
maternal condition influences the reproductive success of offspring
Trivers-Willard Hypothesis
Getting Sex Ratios
timing of conception (strong mate at the beginning of a season, weak mate later)
condition (hormones)
primary sex ratio (if a mom is strong, males won’t die and the ratio will be male biased)
Sexual Selection
process by which individuals vary in their reproductive success due to variability in their ability to secure a mate
intersexual (epigamic) selection
one sex chooses the other
non-genetic resources
intersexual (epigamic) selection nuptial gifts (courtship feeding) resource monopolization (can only get access to breeding site or food resource if with a certain male) parental care (courtship feeding/nest materials)
genetic benefits
intersexual (epigamic) selection
good genes hypothesis (sexy son)
secondary sexual characteristics (females choose based on visual characteristics)
Runaway Selection
FISHER (SSC - intersexual)
snowball effect - coevolution of female preference and male trait (stops when costs>benefits)
Handicap Hypothesis
ZAHAVI (SSC - intersexual)
SSC’s are costly to produce, may make you more vulnerable
if a male can survive with them, they must have overall quality
Hamilton-Zuk
SSC’s all about parasite resistance (intersexual)
show no sign of parasites - high resistance and good genes
Fluctuating Asymmetry
SSC’s - intersexual
symmetry shows no stress or ability to overcome it
Intrasexual Selection
one sex competes for access to the other
Before Mating: Intrasexual Selection
Male to male competition
Sexual Dimorphism
male to male competition
fighting - winner gets female (strength, size, testosterone, weapons)
After Mating: Intrasexual Selection
1st Male (prevent others from mating)
mate guarding, copulatory plug, antiaphrodisiacs
2nd Male
structure to remove prior sperm,
hypodesmic insemination (injection), sperm ejection, sperm volume
high sperm competition
large penis and testes
male to male aggression
small penis and testes
After Conception: Intrasexual Selection
infanticide
Bruce Effect
Bruce Effect
female abort offspring
Parental Investment
investment by a parent in offspring that increases the offspring’s survival and reproduction while reducing the parent’s ability to invest in more offspring
