Final Flashcards
What do the differences in reproductive success lead to?
Differences in sex allocation and sexual selection
Isogamy
Gametes of same size
Anisogamy and what does it result in
Gametes of different size. Leads to differential investment in reproduction
What limits female and male RS
Female RS is limited by the number of eggs produced while male RS is limited by the number of eggs fertilized
What simplifying assumptions does Fisher’s 1:1 sex ratio make
large population, random mating, external mating, and no paternal care
Shaw-Mohler Theorem
For a mutant with a different sex allocation than the resident population to invade, its total fitness must be greater than the residents’
Explain the viviparous mite’s sex allocation
has one son and ~20 daughters in which the son fertilizes the eggs of sisters, once eggs hatch, they eat mother until she bursts and male dies before leaving the mother. Only need one male to fertilize daughters thus, want maximum number of females as possible
Explain the correlation between mormon crickets and OSR
Males produce a spermatophore that contains sperm but also a large amount of protein making it very expensive thus, the limiting factor. In many insects, females store the sperm of different partners. Males evolved to ensure that females cannot use sperm of other males such as a penis that scrapes the sperm out of other males or that packs the sperm of other males into the corners
Operational Sex Ratio (OSR)
ratio of sexully competing males to sexually receptive females (the less of one sex, the more intense competition is and thus selection for better secondary sex characteristics)
Explain intersexual selection in drosophila
More that males mate, the more offspring they have but females can only have as many offspring as the number of eggs they produce. When females mate more often they have shorter life spans because males have toxic seminal fluid to increase the number of eggs they fertilize since females optimize the rate of egg laying thus, if they die sooner will have more offspring at one time
Explain the effect of male competition on intersexual selection in drosophila
Females came from a control population while males were allowed to evolve. Led to increased male fitness and sperm defense such that female survival decreased due to increased toxicity in sperm
Explain the effect of monogomy on intersexual selection in drosophila
males typically have higher genetic representation since they can mate multiple times but when taken away their seminal fluid becomes less toxic thus, female reproduction, surivival, and fecundity was higher
What does sexual selection lead to
traits that have no function other than to attract mates
Fisher’s runaway hypothesis
assuming there is a female preference for a trait, she will mate with males that have that trait and her daughters will carry the gene for the preference and her sons will have the trait
When does natural selection occur
When there is heritable variation among replicating units and there is non-random survival and reproduction is associated with the variable phenotype
On what levels can natural selection occur
populations of replicating units (genes and organelles), individual organisms, populations of population of individuals, and groups of species/lineages
At what levels of selection can conflict occur
- Traits can increase the fitness of genes/organelles but also decrease the fitness of the organsim
- Traits that benefit an entire population may not be the most for the individuals in the population
What level of selection is the most powerful and why
individual since there tends to be higher inheritability and faster reproduction
What characteristics allow selection to operate efficiently
large population size, high level of variation, strong heritable components to traits, and short generation time
What are the two types of selfish genes and how common are they
Segregation distorters (when one allele is overrepresented in gametes) and transposable elements (sequences of DNA that can change its position)
How do segregation distorters work and explain an example in drosophila
Sperm created from a diploid (aA) is unequally distributed. In flies there is dominant gene that decreased fertility in males by 50% thus, on the genic level is very hard to get rid of but on the individual level is not helpful as it decreases fertility
What are the types of transposable elements work
- Type 1: copy and paste genes into the genome
- Type 2: cut and paste DNA (can be sloppy and take other parts of DNA wtih it, or leave some behind)
- Both can be mutagenic if inserted in the middle of protein coding regions
At what levels does organelle selection occur
- cells in a multicellular organism
- mitochondrial DNA
What is the possible condition if the mitochondrial DNA of A and a replicate at the same rate and equally distributed
Normal conditions