Evolution In Space

Question 1

Cline

Answer 1

A smooth change in space of a trait mean or an allele frequency

Question 2

Bergmanns rule

Answer 2

Populations in colder climates tend to have a larger body mass

Question 3

Small cline

Answer 3

Local adaption

Question 4

Gene flow

Answer 4

Mixing of alleles from different populations
Results in homogenization of allele frequencies
Results from dispersal

Question 5

Dispersal vs migration

Answer 5

Dispersal = movement of individuals and gametes
Migration = movement of alleles
-migration results from dispersal
-migration only occurs when an organism travels to another location and leaves a genetic signature

Question 6

Fst

Answer 6

Measures the fraction of the total genetic variance found across two or more populations that result from genetic differences between them
S = sub-population
T = total population

Question 7

Fst values

Answer 7

0 = populations identical
1 = differential fixation of alleles
-increases as the geographic distance between populations increases
—> isolation by distance

Question 8

Fst = 0.12

Answer 8

12% of genetic variation between populations is caused by the differences among them
88% can be found in any typical population

Question 9

Tension of evolutionary forces

Answer 9

Selection enhances differences between populations
Gene flow erodes such differences
Clines and other spacial genetic patterns represent compromises between the two forces

Question 10

Mutation-drift equilibrium

Answer 10

Mutation increases genetic variation in a population
Drift decreases genetic variation in a population
Neutral alleles often reach this equilibrium
-rate of addition of new alleles (mutation) = rate of removal/fixation (drift)

Question 11

Near-neutral theory of molecular evolution

Answer 11

Acknowledges that natural populations are rarely in HWE

Nearly all alleles are subject to at least a small selective force

Question 12

Single migrant per generation

Answer 12

Prevents drift from acting on a population regardless of population size
As long as selection is absent

Question 13

Limits species ranges without physical barrier

Answer 13

Lack of genetic variation available for selection and adaption
Migration from other parts of species range may result in gene swamping
Biotic interactions: predator ranges, competitors, pathogens
Climate change

Question 14

Gene swamping

Answer 14

When migration is much stronger than selection
Frequency of locally adapted allele evolves to 0 and is lost entirely
-gene flow overwhelms local adaption