Mt2 Flashcards
(62 cards)
What is a big source of fitness variation?
Deleterious mutations
What mutations are enriched amongst the rarest alleles in the R species
Loss of function mutations- selection should depress the frequency
Heterozygote advantage/overdominance
Heterozygote has highest fitness; heterozygote could be unflavored where disease is not prevalent; result in stable/protected polymorphism; will inevitably maintain both alleles
Negative frequency dependent selection
Fitness is negatively correlated with frequency (fitness goes down as it becomes more common); rare genotypes are favored by NS; frequency increases then its not rare anymore
Self incompatibility
Method to reduce self-fertilization/inbreeding; allergic variation at S-locus
Spatially varying selection
Fitness of a phenotype or genotype will vary depending on where it is in some geographic region
Sperm are…
- less energetically expensive than eggs
- made in much greater numbers
SO a male’s fitness may be greatly increased as the number of matings increases
FEMALE MAY SUFFER reduced fitness if she mates with lower quality male
Sexual selection is…
A kind of NS (component of); male variance in mating success is often very high
Male fitness
Correlated with the number of MATES that a male has
Sexually selected trait properties
- restricted to one sex
- appear only at sexual maturity
- may only be present during breeding season
NS and Sexual selection; maximized fitness
Selection favors mating displays that maximize a male’s lifetime fitness; may be a compromise between what maximizes survival and what maximize mating success
Where do female preferences come from?
May evolve preference due to direct or indirect benefits; ex. high quality territories
Sexual selection on male biology
Male genitalia have elaborate morphology; one of the traits that evolves the fastest
“Good genes”
Indirect benefit ex.
- females should evolves preferences for male traits that are correlated with high genetic quality
- predicts that male traits are COSTLY and thus “honest indicators” of male quality
- predicts that males preferred by females should sire higher quality offspring
Runaway sexual selection
As individuals with the preferred trait are more likely to mate and pass on their genes, the trait becomes increasingly common in the population, even if it may be impractical or even detrimental in terms of survival. male traits could become so extreme that natural selection pushes back
Feedback loop and female preference
female that are expressing preferences for more and more exaggerated traits are mating with males who have those traits
Inbreeding effect on populations that experienced sexual selection
Not go extinct as quickly; more intense sexual selection has EXPOSED DELETERIOUS mutations that aren’t exposed when its not present; more chances for these mutations to be erased
Do traits evolve for the good
Not always expected to evolve for the good
Group selection
Trait occurs and the expression of it is bad for the individual, but good for others in the species
Williams idea
if you have a population composed entirely of selfish individuals it will give rise give right to a population composed of selfish individuals and may go extinct
In group selection…
Group heritability is likely low
More birth/death of individuals than groups per unit time
Kin selection
An apparently altruistic act is associated with a fitness cost to the actor and a fitness benefit to the recipient
Hamilton’s rule for when altruistic traits will evolve
Rb>c
R=degree of relatedness between actor and recipient
B=benefit to recipient
C=cost to actor
Species selection
differential survival and proliferation of entire species based on their characteristics and traits, rather than just individual organisms within those species. It operates on a similar principle to natural selection but operates at a higher level of biological organization.
