Isolated Populations

Question 1

What are the causes of a sixth mass extinction?

Answer 1

Habitat destruction, Fragmentation, poaching, hunting

Question 2

Why is habitat destruction such a massive threat?

Answer 2

causes populations to become small and genetically isolated. Genetic drift and inbreeding will then affect patterns of genetic variation

Question 3

What is genetic drift?

Answer 3

the process of losing genetic variation by chance, governed by population size. Loss of genetic variation is faster in small population

Question 4

How do elephant seals show loss of genetic variation?

Answer 4

Common in the North and south, hunted to nearly extinction in the north, Heterozygosity much lower in the north, led to decline in variation - population today arose from small populatoin

Question 5

What is the problem with having little genetic variation?

Answer 5

Less capable of evolving in response to new challenges, higher extinction rate

Question 6

What are the reasons the Glanille fritillary went extinct in some populations?

Answer 6

Popula4on size, degree of isola4on, flower abundance, patch size,
heterozygosity, presence of ca]le

Question 7

What is another example of low population genetics?

Answer 7

Mauritus kestrels

Question 8

What factors contribute to extinction risk?

Answer 8

environmental and genetic factors

Question 9

How do the world conservation society list their endangered species?

Answer 9

Compare the genetic variation in a species that is taxonomically close, but non threatened, If genetic factors are important, then threatened species should have lower heterozygosity in >50% of paired comparisons

Question 10

What is inbreeding?

Answer 10

Mating of close relatives

Question 11

Why is inbreeding more common in a small population?

Answer 11

Less potential mates, so probability of mating with a relative increases

Question 12

What is wrights inbreeding coefficient?

Answer 12

Standard measure of the degree of interbreeding in an individual, the probability that an individual is IBD for the gene in question. Larger value means more inbred

Question 13

What is identical by descent?

Answer 13

Two alleles are identical by descent if they trace their ancestry back to a common ancestor

Question 14

What are the consequences of inbreeding?

Answer 14

Inbred progeny have higher f values, if IBD must be homozygous at the locus, homozygosity is more normal in inbred populations, so no benefits come from heterozygosity

Question 15

What are small isolated populations particularly vulnerable to?

Answer 15

Loss of genetic variation by genetic drift
Inbreeding depression
Leads to lower evolutionary potential, compromises fitness and elevates extinction risk

Question 16

What is a captive breeding programme?

Answer 16

Endangered species reared in captivity, some inbreeding unavoidable, so need to be monitored

Question 17

What problems were encountered by breeding condors in captivity?

Answer 17

Prevalance of the homozygous recessive allele, which kills the offspring, so had to ensure that heterozygous individual didn’t mate to pass on the allele

Question 18

How do incidents of disease vary between populations?

Answer 18

Due to a combination of selection and drift, some populations have high occurrence of genetic diseases, lots of autosomal recessive diseases arise

Question 19

What is the aim of conservation genetics?

Answer 19

Reduce the loss of genetic variation and avoid inbreeding