Inbreeding

Question 1

implications of inbreeding (2)

Answer 1

• all of us carry deleterious recessive alleles and close relatives likely carry some of the same bad alleles
• mating with close relatives gives these alleles a good chance to pair up into homozygotes

Question 2

inbreeding consequences

Answer 2

• inbreeding depression

Question 3

inbreeding depression

Answer 3

• increased homozygosity of the entire genome, may result in reduced fitness

Question 4

what causes inbreeding depression (2)

Answer 4

• expression of deleterious recessive alleles

- loss of heterosis

Question 5

• when does inbreeding increase

Answer 5

• with closeness of inbreeding

Question 6

examples of inbreeding depression (3)

Answer 6

• corn inbreeding resulted in lower smaller corns due to loss of heterosis
• more birds eggs fail as inbreeding in creases
• mortality rate of offspring is greater of first cousins than of unrelated parents

Question 7

inbreeding depression formula

Answer 7

inbreeding depression = 1 - (Winbred/Woutbred)

Question 8

what are Winbred and Woutbred measures of

Answer 8

• measures of traits that correlate with fitness

Question 9

inbreeding avoidance mechanisms (4)

Answer 9

• mate choice (kin recognition)
• dispersal
• differences in maturation times between brothers and sisters
• morphological adaptations

Question 10

morphological adaptations to avoid inbreeding (4)

Answer 10

• plants with separate sexes
• male/female structures in separate flowers
• heterostyly
• pollen self incompatibility

Question 11

permanently inbred species (3)

Answer 11

• fig wasps
• naked mole-rats
• social spiders

Question 12

how are social spiders inbred (4)

Answer 12

1. in an established colony, a females with egg-sacs will leave to form a new colony
2. offspring mature and mate
3. colony size increases
4. offspring mature and mate again and colony size increases to become an established colony

Question 13

when is inbreeding depression expected to be a problem (2)

Answer 13

• when an outbred species switches to inbreeding

- social spiders are though to have originated from outbred subsocial species

Question 14

outbred spiders (4)

Answer 14

• single female with egg-sac
• spiderlings grow
• spiders disperse as subadults
• spiders mate

Question 15

when should inbreeding be tolerated (2)

Answer 15

• when costs of avoiding inbreeding exceed costs of inbreeding depression
• graph costs of avoiding depression against inbreeding depression

Question 16

cost of avoiding inbreeding (3)

Answer 16

1. due to dispersal as subadults
2. due to solitary living as adults
   - costs: finding mates, predation, etc

Question 17

long term effects of inbreeding (2)

Answer 17

• purging of recessive deleterious alleles

- high homozygosity and low variability