Microevolution II

Question 1

Microevolutionary studies

Answer 1

examine how processes such as mutation, natural selection, recombination, migration, non-random mating, and genetic drift determine as well as change the genetic composition of populations

Question 2

5 assumptions of HWE

Answer 2

1. There is no mutation
2. The population is infinitely large
3. Mating among individuals is random
4. Individuals are not moved into or out of population
5. All individuals have equal probabilities of survival and of reproduction

Question 3

What 2 processes produce the variation in gene pools that contribute to differences in individuals?

Answer 3

mutation and sexual recombination

Question 4

Synonymous mutations

Answer 4

mutations that don’t change the encoded amino acid

Question 5

Non-synonymous mutations

Answer 5

changes in nucleotides that change amino acids

Question 6

Factors that vary rates of mutation

Answer 6

1. sex
2. generation time
3. environment
4. stress

Question 7

2 principal ways to not have random mating

Answer 7

1. Assortative mating
2. Inbreeding

Question 8

Assortative mating

Answer 8

like genotypes mate w/ each other or avoid each other

Question 9

Inbreeding

Answer 9

mating among individuals that are more closely related than those drawn by chance from the population

Question 10

Positive assortative mating

Answer 10

-decreases heterozygosity for the gene affecting the trait
-heterozygotes are decreased by half each generation w/ complete positive assortative mating

Question 11

Negative assortative mating

Answer 11

-increases heterozygosity for the gene(s) affecting that trait

Question 12

Effect of inbreeding

Answer 12

-changes genotype frequencies by increasing the proportion of homozygotes and reduces the proportion of heterozygotes across the entire genome
-most extreme case (selfing): has effects just like positive assortative mating but across the WHOLE genome

Question 13

Evolutionary consequences of non-random mating

Answer 13

1. The genotype changes caused by assortative mating affect only the loci contributing to the phenotype
2. The genotype changes caused by inbreeding affect all loci in the genome
3. Inbreeding results in genome-wide loss of heterozygosity (loss of diversity)
4. Inbreeding and assortative mating only affect genotype frequencies so their effects may be quite ephemeral or temporary
5. Inbreeding reduces fitness by generating offspring homozygous for deleterious alleles (inbreeding depression)

Question 14

Self-fertilizing species typically exhibit _______ levels of diversity

Answer 14

lower

Question 15

Inbreeding depression

Answer 15

Inbreeding reduces fitness through the generation of offspring homozygous for deleterious alleles

Question 16

Genetic drift

Answer 16

-basic mechanism of evolution
-evolutionary equivalent of a sampling error
-definition: variation in the relative frequency of different genotypes in a small population, owing to the chance disappearance of particular genes as individuals die or do not reproduce

Question 17

Long-term patterns of genetic drift

Answer 17

1. population bottleneck
2. founder effect

Question 18

Population bottleneck

Answer 18

when a population goes through a period of unusually small population size
-greatly reduces genetic variation
-many genes may be lost

Question 19

Founder effect

Answer 19

when a population does through this period of unusually small population size at a time when it arrives to a new, uncolonized area
-may have a non-random sample of the genes present in the original population and/or reduced genetic variation from the original population
-Ex: Canadian Mennonites

Question 20

5 effects of genetic drift

Answer 20

1. Genetic drift is significant in small populations
2. Genetic drift can cause allele frequencies to change at random
3. Genetic drift can lead to loss of genetic variation within populations
4. Genetic drift can lead to differentiation among populations
5. Genetic drift can cause harmful alleles to become fixed

Question 21

Gene flow

Answer 21

the transfer of alleles into or out of a population due to the movement of fertile individuals or their gametes
-can also change allele frequencies