Chapter 19: Evolution Mechanisms

Question 1

Equilibrium

Answer 1

Population is stable

Question 2

Allele

Answer 2

Code for a specific genotype trait

Question 3

Locus

Answer 3

Specific physical spot on chromosome where gene exists

Question 4

Population genetics

Answer 4

Investigates how offspring pop. genotype frequencies relate to parental pop. genotype frequencies

Question 5

Sexual selection

Answer 5

Form of natural selection
Selective force is either choice in mates or competition for mates
Intrasexual and Intersexual

Question 6

Intrasexual selection

Answer 6

Competition between members of the same sex

Male-Male competition

Question 7

Intersexual selection

Answer 7

CHOICE in one sex for mates in the opposite sex

Female Mate

Question 8

Mutation

Answer 8

Genomic and chromosomal

Point mutation, frame shift, deletions and insertions

Question 9

Migration

Answer 9

Aka gene flow, movement of genes within pop.

Tends to homogenize (uniform) but asymmetry can occur

Question 10

Genetic drift

Answer 10

The tendency for sampling error among genes in small populations.

Question 11

Stabilizing selection

Answer 11

FOR: moderate traits against BOTH extremes
’Stabilizes’ the trait, reduces variants
2 peaks but one is really high

Question 12

Directional selection

Answer 12

FOR: one extreme against one extreme in the other direction

2 peaks

Question 13

Diversifying selection

Answer 13

FOR: BOTH extremes against the moderate trait

Bimodal distribution, 3 peaks

Question 14

Frequency-dependent selection

Answer 14

Organisms co-evolving with each other
Uses cyclical (wave) dynamics
Ex. Host/Parasite Coevolution, Predator/Prey Coevolution, three male morphs competing for females.

Question 15

Gregor Mendel

Answer 15

Discovered dominance

Question 16

Evolution

Answer 16

occurs when genotype frequencies change over time in a population.

Question 17

Hardy -Weinberg model

Answer 17

null model; tells us what happens when evolutionary change is NOT occurring
Independently developed by Hardy and Weinberg

Question 18

H.W. Equilibria

Answer 18

1. frequencies of A1 and A2 do not change over time.
2. Can predict equilibrium genotype freq in a pop in which evolutionary processes are not acting
3. IF no evolutionary processes are operating, a locus that is initially not at H-W equilibrium will reach H-W equilibrium in a single generation.

Question 19

Mechanisms of evolution

Answer 19

Genetic drift
migration
Mutation
Natural selection & subtypes

Question 20

The Modern Synthesis

Answer 20

Book published in 1942 by Julian Huxley

Question 21

Assumptions ab HW

Answer 21

1. Natural selection NOT operating on traits affected by locus in question
2. Indv have no preference for mating (random) with respect to locus
3. No mutation occurring
4. No migration in/out of populations
5. Genetic drift is not occurring

Question 22

Hardy Weinberg Equation

Answer 22

P2+2PQ+Q2=1
P2= AA freq
2PQ= Aa freq
Q2= aa freq
p= A freq
q= a freq

Question 23

Natural selection

Answer 23

Selective force causes alteration in genotype frequencies within a pop
A mechanism of evolution
Subtypes:
freq-dependent, directional, stabilizing, diversifying

Question 24

Female vs Male Gametes

Answer 24

Females produce fewer, but they’re larger

Males produce more, but they’re smaller