LECTURE 18 (inbreeding PG 3)

Question 1

what’s the result of inbreeding?

Answer 1

deficit in heterozygous and increase in homozygotes

Question 2

what are the main consequences of inbreeding?

Answer 2

1. alters genotype freq but not phenotype freq

2. reduces recombination

Question 3

what are the 4 types of inbreeding and which is the most severe?

Answer 3

• selfing
• full siblings
• backcross with parents
  the most severe is selfing bc it’s the fastest way by which hetero disappear from a population.

Question 4

what’s an autozygous genotype?

Answer 4

when two alleles come from the same imdv by inbreeding (non random mating)
autozygous homozyogus: the same allele come from the same common ancestor

Question 5

what’s an allozygous genotype?

Answer 5

when two alleles come from different imdv an allozygous homozygote has two alleles that are the same but come from different parents

Question 6

does recombination occur in inbred individuals?

Answer 6

yes it does however recombination is not causing variation when there’s recombination bt two homozygotes.

Question 7

What are the benefits of inbreeding (4)

Answer 7

1. reproductive assurance if you can mate with yourself;
   e. g flower comes to an island and will able to create a population if it can mate with itself
   e. g haplodiploidy insects, a female bee comes to an island and creates males from unfertilized eggs, then it’ll be able to mate with these eggs and form a population with daughters and sons.
2. different forms of gene transmission
   e.g in plants if they’re self compatible have 3 ways of forming zygotes; self crossing, ovaries and out crossing
   if in contrast they’re not compatible there’re only two ways of producing offspring. (Fisher)
3. reduction of the cost of sexual adaptations
   e. g Viola has flowers that don’t close to ensure reproductive assurance
4. sex ratio
   a bias sex ratio can potentially produce more offspring
   e.g fig wasps mother allows offspring to reproduce before they disperse
   e.g mites leave pregnant daughters inside the clutch and are born already pregnant

Question 8

what are the costs of inbreeding

Answer 8

reduction in effective recombination because although there’s recombination the recombination of homozygous alleles produces no variation

inbreeding depression
example of clutch birds that there’s higher mortality in those by inbreeding
example of drosophila which become extinct after several generations of inbreeding

Question 9

how does inbreeding depression occur?

Answer 9

• due to the unmask of deleterious alleles that were in the heterozygous form
• due to the over dominance hypothesis, getting rid of hetero that were good e.g sickle cell anemia

Question 10

ways of being outbreeding.

Answer 10

card.

Question 11

costs of outbreeding?

Answer 11

outbreeding depression & bad results from genetic admixture

Question 12

what’s genetic admixture?is it good or bad?

Answer 12

when crossing native individuals with immigrants and ned genetic lineages are introduced, this can be bad bc for example too much outbreeding can lead to the lost of of a local adaptation that was already there.

Question 13

when can genetic admixture occur?

Answer 13

it can occur when there’s an introduction of invasive spp for example by removing an isthmus