Chapter 16

Question 1

Environmental unpredictability model, why does it favor sexual reproduction?

Answer 1

Sexual reproduction should be seen more often in rapidly changing environment; offers great deal of variation allowing for better adaptability to unpredictable environments

Question 2

Number of niches, why does it favor sexual reproduction?

Answer 2

S.R. will be favored in niche-rich environments because of the potential for large numbers of new genotypes capable of colonizing new niches
-lakes have greater # of eco-niches

Question 3

Red Queen Hypothesis

Answer 3

Frequency of S.R. will be related to the level of PARASITIC infection. Sexual reproduction creates a moving target for parasites= parasite resistant genotypes may result

Question 4

Asexual reproduction

Answer 4

Production of offspring from unfertilized gametes from a single female parent

Question 5

Apomixis

Answer 5

Unfertilized gamete undergoes a single mitosis-like cell division, producing two “daughter cells”. Each daughter cell has an UNREDUCED number of chromosomes and is genetically identical to its mother

Question 6

Automixis

Answer 6

Haploid gametes produced via MEIOSIS but diploidy is usually restored by the fusion of haploid nuclei from the same meiosis. Offspring is genetically different from parent and siblings, but MUCH LESS than sexual reproduction.

Question 7

Sexual reproduction

Answer 7

The joining together of genetic material from 2 parents to produce an offspring that has genes from each parent

Question 8

Amphimixis

Answer 8

characterizes sexual reproduction; but with alternating phases of meiosis and gamete fusion

Question 9

Syngamy

Answer 9

alternating phases of meiosis and gamete fusion

Question 10

Recombination

Answer 10

The crossover between homologous chromosomes, which produce new chomosomal events

Question 11

Gametes production

Answer 11

The production of haploid gametes by diploid individuals via reductive meiotic division

Question 12

Gamete fusion

Answer 12

The gametic exchange between (usually) UNRELATED individuals, in which haploid gametes fuse to produce a diploid offspring

Question 13

Does genetic exchange in bacteria constitute as sexual reproduction?

Answer 13

NO

Question 14

How do you distinguish between sexual and asexual reproduction?

Answer 14

Observing genetics (presence/ absence of reproductive genes like homologs) &
Comparing phylogenetic trees (asexual will have a more congruent tree when comparing nuclear and mt genes)

Question 15

Asexual reproducing species tend to go extinct more quickly or less quickly than sexual species?

Answer 15

More quickly!

Question 16

Are there a lot of taxa (genus or higher) that are entirely composed of Asexual species?

Answer 16

Almost none.

Question 17

Where have all asexual species thought to have evolved from?

Answer 17

Sexually reproducing ancestors

Question 18

What is the genetic cost of asexual reproduction?

Answer 18

Asexual females are twice as genetically related to their offspring as are sexual females

Question 19

What is the advantage of asexual repro?

Answer 19

Population in ASR increases twice as quick, as a consequence of anisogamy

Question 20

Anisogamy

Answer 20

When female produces TWO LARGE gametes & males reproduce a lot of small sperm. (male’s effort is basically wasted)

Question 21

Isogamy

Answer 21

Each parent produces mid-sized gametes

Question 22

How is asexual more “expensive”

Answer 22

Twofold cost of sex (cost of males)

Question 23

How can sexual reproduction come at a cost?

Answer 23

Can break up favorable gene combinations (recombination)

Question 24

Benefits of sexual reproduction (3)?

Answer 24

• Can purge deleterious mutations
• Generates genetic variation that is favored by natural selection
• Combination of both

Question 25

Muller's ratchet

Answer 25

Number of deleterious mutations will INCREASE; not equivalent to a deleterious mutation becoming fixed *sexual reproduction reverses ratchet*

Question 26

Two facts on Y chromosome

Answer 26

- Doesn't undergo recombination | - Has been degenerating and accumulating deleterious mutations

Question 27

Epistasis

Answer 27

Interactions between the effects of alleles at different loci

Question 28

Synergistic mutations

Answer 28

Two mutations occurring together have more of a detrimental effect

Question 29

Fisher-Muller Hypothesis

Answer 29

Recombination allows natural selection to operate at a quicker rate than is possible in asexual species

Question 30

Linkage disequilibrium

Answer 30

If two genes are in linkage disequilibrium, it means that certain alleles of each gene are inherited together more often than would be expected by chance. (This may be due to actual genetic linkage--that is the genes are closely located on the same chromosome.) *sex breaks down link-disequi.*

Question 31

What is the evidence that sex accelerates adaptive evolution?

Answer 31

Yeast and green algae; in a harsh environment, sexual strains increase in fitness faster than do asexual strains

Question 32

"bet hedging"

Answer 32

Increases the chance that at least one of an individual's offspring will be a good match to the environment.

Question 33

Cyclical parthogenesis

Answer 33

Usually reproduce asexually, but occasionally reproduce sexually

Question 34

What is the hypothesis on the origin for sexual reproduction?

Answer 34

Means for transposable genetic elements to spread from cell to cell. Also, mechanism for DNA repair

Question 35

transposable genetic elements

Answer 35

is a DNA sequence that can change its position within the genome, sometimes creating or reversing mutations and altering the cell's genome size