Chpt 22: Evolution By natural selection Flashcards
Evolution
what happens when there is a change in allele frequency from generation to generation
Sexual dimorphism
any trait that differs between males and females
Pattern
1 of 2 mechanisms of intersexual selection
when traits that attract members of the opposite sex are much more highly elaborated in males.
Differential Reproduction
when individuals with favorable traits can/reproduce more
Non-Adaptive Evolution
random/unpredictable
involves gene flow, genetic drift, and mutation
Heritability formula (with selection diff and response to selection diff)
h^2 = R/S
where R is delta mean response to selection
and
S is delta mean selection differential
Frequency
part of a whole; percent
exp. allele frequency for rr is 25%
Viability
Likelihood that an individual bearing a genotype will survive
Cutoff of saying a heritability score means evolution by natural selection has occurred
0.2 or bigger
Intersexual selection
1 of 2 types of sexual selection
when an individual is chosen by the opposite sex (i.e. penguins mate selection up to the female)
Fecundity
Number of gametes per individual
Selection differential formula
S = P* - Pbarr basically trait final - trait initial
where P* is trait frequency after event and Pbarr is the trait frequency before the event
Differential Survival
when individuals with favorable traits can/survive more
Mating success
Defined by number and quality of mates
Heritability (formula)
H^2 = Vgenetic/(Vgenetic + Venvironmental)
or
H^2 - Vgenetic/Vpopluation
Fitness
defined by the average reproductive output (Rbarr) of all individuals bearing a given genotype
rate at which certain alleles make it into the next generation
certain alleles can confer greater fitness
Fertilization success
Defined by number of
Environmental/Ecological Selection
favors traits that increase success in surviving in/adapting to the environment,
Relative Fitness
how to calculate it
Rbarr / Fitest genotype’s Rbarr
exp, mommy’s Rbarr / daddy’s Rbarr = 0.5
Cross foster/Common Garden Experiments
When you can orgs. out of one pop and drop them into another one (to determine if their phenotypes are genetic or environmental)
Adaptive Evolution
Non-random/predictable
involves natural selection
Sexual selection
(natural) selection based on success in courtship
Favors traits that increase success in mating (rather than ones that increase success in adapting to the environment)
Selection differential
Quantification of a trait before and after a selection event
e.g. delta mean beak size or beak size final - beak size initial
Fundamental asymmetry of sex
the idea that females’ fitness is low bc she spends a ton of energy taking care of whatever babies she already has
AND
the males fitness is high bc they don’t contribute much work raising the babies and are thus free to make tons of babies.
