exam 1 answers Flashcards
in species that have haplodiploid sex determination and the female mates once, what is the expected proportion of homologous alleles shared between…
a) mother and daughter?
b) sisters
a) 0.5
b) 0.75
kin selection predicts cooperative behavior will be observed…
more frequently among sisters
Will the expected proportion of homologous alleles shared between sisters increase or decrease if the female (their mother) mates twice?
decrease
Imagine an island with two habitats- a dry area and a wet area. Only one species of flying
squirrel lives on the island but the squirrels in the dry habitat have only short hairs on their tails
and squirrels in the wet habitat all have long hair on their tails. You decide to test if natural selection favors the differences of tails among squirrels in dry and wet areas.
a) describe an experiment that will test if the trait (harness of tails) has a heritable component)
b) if you find there’s no heritability for the hairness of tails, what is the most reasonable explanation for the difference?
a) cross fostering. remove baby squirrels from parental nest. put them in foster parent nest in the other environment so offspring from dry habitat nests and short haired parents are raised by long haired adults in wet habitats. if the offspring grow up with tails that look like their parents, the trait is genetic/heritable. If they look more like the foster parents, the trait is environmental/
b) hairness varies a lot or is entirely determined by environment
The data below are from an experiment on two species of Drosophila native to
North America, D. subquinaria and D. recens. Describe carefully, using sexual selection theory,
why this pattern occurs.
this shows reinforcement. sexual selection theory predicts females should be more selective about mates because they have greater investment (gametes, time, etc). if the female mates with a male of the wrong species, her cost will be even greater because the offspring probably won’t live or be able to reproduce. Thus, according to sexual selection, a female should be more likely to choose a mate of the correct species when they live symmetrically with other species. The figure shows this becuase X axis shoes female D. subquinaria from pops that occur sympatrically or allopatrically with D. recens. Y axis shows prop of females that mated with male D recens. As predicted, female D. subquinaria that lived sympatrically with D. recens chose the correct species more often than the female D. subquinaria that lived allopatrically from D. recens.
imagine a pop of 100 butterflies and you find 45 homozyguous dominant, 20 hetero, and 35 homozyguous recessive. calculate p and q
p = [(42 x 2) + 20]/200
q = [(35 x 2) + 20]/200
describe in words the next steps to determine if the pop is in hardy weinberg equilibrium or not?
the next would be a cross of the heterozygotes and then compare if the proportion of genotypes was dif/same as the genotypic frequency in the original pop. hardy weinberg equilbria are reached in one generation so if the proprtion changed, the original pop was not in hw eq.
why is it not possible for science to study if a supreme deity created all life on earth?
there wouldn’t be any fossil record, homologuous structures, vestigial structures, or other evidence of evolution. without evidence, the question can’t be supported or rejected.
compare/contrast descent with modification and natural selection
DWM: pattern obs among living orgs generated by accumulation of genetic changes passed between generations and speciation events.
NS: mechanism that favors individuals in a pop with traits that best match the enviro. these individuals eventually make up a larger proportion of the population
Dif: DWM is a pattern generated by heritable changes among individuals in a pop and among species related through a common ancestor. NS is one of these mechanisms.
compare/contrast stabilizing selection and purifying selection
stabilizing: selection on phenotypes that are well adapted ti the enviro; selection for average traits
purifying: occurs at the molecular level in codons where synonymous mutations are favored over non synonymous ones
Dif:stabilizing acts on trait with a variance and mean; purifying acts at the molecular level
compare/contrast paralguous genes and analogous genes
paralogous: gene copies that are the result from a gene duplication event
analogous: genes that evolved for similar functions but not through a common ancestor
dif: dif evo histories; paralogous genes arose
from an original gene in a common ancestor while analogous genes share no evo history.
Imagine that you find a population that all individuals have a dominant mutation
that is slightly deleterious.
a) What can you infer about its recent population size?
b) explain why NS can’t eliminate the deleterious mutation
a) deleterious genes are usually weeded out by natural selection in large pops, but in small pops, genetic drift can lead to fixation of deleterious genes. Since the population is fixed at a deleterious mutation, it was probably small
b) no variation in the pop for NS to act on since the deleterious mutation is fixed and all individuals have it
what form of NS occurred in the following generation of the pop below?
directional
redraw the graph for the following generation if the pop underwent stabilizing selection
- should look the same
redraw the graph for the following generation of beak depth had 0 heritability
- should look the same
