Kin, Genes, and Sex ratio stuff

Question 1

sexual vs. asexual reproduction

Answer 1

sexual
- fusion of gametes
- meiosis
asexual
- w/o sex
- clones
- mitosis

Question 2

what is sex

Answer 2

genetic recombination

Question 3

costs of sex

Answer 3

1. The costs of males - could produce twice as many females
2. The costs of meiosis - recombination breaks up favorable gene combos
3. Finding a mate takes time and energy

Question 4

benefits of sex

Answer 4

1. genetic variation
2. prevents Muller’s Ratchet - a process which, in the absence of recombination (especially in an asexual population), results in an accumulation of irreversible deleterious mutations.
3. Novel gene combos created
   - Red Queen Hypothesis: need to create new gene combos to combat pathogen evolution
   - provide short term benefits

Question 5

host sexuality and parasitism

Answer 5

snail example
- as the frequency of males increases so does the rate of infection in the snail colony
- some snails are sexual and asexual

Question 6

sex determination

Answer 6

Types
- genetic (chromosomal/genetic)
- environmental
- social
influences the degree to which a female can alter the sex ratio of her offspring

Question 7

haplodiploidy

Answer 7

mechanism where males develop from unfertilized eggs and diploid females develop from fertilized eggs
- all hymenoptera (insects like bees)

Question 8

Environmental Sex Determinism
(turtles, lizzards, and gators)

Answer 8

example for incubation of turtles, lizards, and gators
- Turtles as temp rises number of males decreases
- Lizards as temp rises number of males increases
- Gators as temp rises males increase and then decrese

Question 9

Lacerta Vivipara

Answer 9

a lizard that use oviparity, viviparity or both based on environment and evolution

Question 10

social sex determinism (fish)

Answer 10

many fish can undergo sex reversal
depends on mating system
- protogeny (born female) largest in group switches first
- protandry (born male) split off into pairs

Question 11

sex allocation ratio: Null Model

Answer 11

Proposed by R. A. Fisher: parental strategies should evolve toward equal investment in offspring of the two sexes.
- If sex ratio falls below 50% then increased production of rare sex is favored
- Why? assuming random mating, rare sex will experience greater reproductive success
frequency dependent selection (frequency of males+females) lead to 1:1 stable sex ratio

Question 12

Trivers-Willard Effect

Answer 12

When population sex ration is 1:1 but individuals sex allocation depends on condition of parents
- females in good condition transfer competitive ability to sons
- dominant individuals have more offspring and then, produce more sons than daughters
- females in poor conditions produce more daughters to replace themselves in their community

EX. dependent sex allocation in Yellow Baboons where social rank of females and number of sons had have a positive correlation

Question 13

Adaptive sex ratio Bias (things that effect it)

Answer 13

• maternal condition influences offspring investment (Trivers-Willard Effect)
• local mate competition
• local resource competition
• local resource enhancement (more likely to mate with male with many resources)

Question 14

local mate competition

Answer 14

• mating between siblings happens near hatching site
• brothers compete to mate
• Solution: Produce fewer sons!
  Ex. fig wasps adjust sex ratio based on where eggs are laid

Question 15

local resource competition

Answer 15

• some offspring stay home and compete with parents to resources while others move out
• solution: produce more of the dispersing sex
  EX. Galagos (bush baby lamers) produce more males

Question 16

local resource enhancement

Answer 16

in some species, offspring of one sex delay dispersal to assist parents in raising siblings (often where there is little habitat opportunity) (not competing)
ex. red-cockeyed woodpecker groups are male-based
- males help feed young
- available nesting spots are scarce
(Seychelles warblers - higher quality territory, fewer males)