Lecture 14

Question 1

Different Mating Systems

Answer 1

Sexual Reproduction or Asexual Reproduction
Isogamy or Anisogamy
Self-fertilization or Outcross
Hermphroditic or Separate Sexes
Sex switching or not
Alternative Male Strategies

Question 2

Anisogamy

Answer 2

Sexual reproduction by the fusion of dissimilar gametes

What is the selective advantage of anisogamy?
What does anisogamy lead to?

Question 3

Mating System

Answer 3

Combination of different mating possibilities

Question 4

How does sexual reproduction increase genetic variation?

Answer 4

Through generation of novel genotypes, and through recombination

Question 5

Is sexual reproduction better than asexual reproduction?

Answer 5

Data states that sexual reproduction is usually better

Question 6

Parthenogenesis

Answer 6

Offspring develop from a single cell, an unfertilized egg

Question 7

Assumptions of Sexual Reproduction

Answer 7

1. Reproductive mode does not affect the number of offspring produced
2. Reproductive mode does not affect the number that survive
   These assumptions are violated in species that provide resources/parental care

Question 8

Difficulty in securing a mate

Answer 8

Competition for mates
STD's
Search Costs
Predation Risk
Resources (nuptial gifts)
Injury

Question 9

6 Hypotheses to explain the evolution of sex

Answer 9

1. Repair of damaged DNA
2. Sibling competition
3. Muller’s ratchet: Eliminating Genetic Load
4. Avoiding synergetic negative epistasis among mutations
5. Adaptation to fluctuating environments
6. Enhanced adaptation under directional selection

Question 10

Two potential advantages to sex evolution

Answer 10

1. It brings beneficial mutations together, creating novel genotypes
2. It purges the genome of harmful mutations

Question 11

1. Repair of Damaged DNA

Answer 11

New DNA acquired via sexual reproduction provides a good copy to use to repair mistakes/errors

Question 12

2. Reduce Sibling Competition

Answer 12

Variable siblings are less likely to compete than clonal offspring

Question 13

3. Preventing Mutational Deterioration: “Muller’s Ratchet”

Answer 13

Sexual reproduction and recombination provide a way to purge the accumulation of mutations. Linkage equilibrium: a random association among alleles and chromosomes. Linkage disequilibrium: non-random disassociation among alleles and chromosomes.

Question 14

4. Sexual Reproduction Reduces Negative Epistatic Interactions Among Deleterious Mutations

Answer 14

Epistasis: when the effect of two genes is greater or less than their additive effects. Positive or negative synergistic effect.

Question 15

5. Sexual Reproduction Promotes Adaptation to Fluctuating Environments

Answer 15

Faster evolution

Question 16

6. Enhanced Adaptation Under Directional Selection

Answer 16

The Red Queen Hypothesis: running to stand still. Sexual reproduction provides a way for hosts to keep up with evolving parasite populations.