topic 5

Question 1

Assortative mating

Answer 1

Any type of mating where mate choice is based on phenotype

-phenotype based matings that have a higher or lower frequency than expected by chance in a randomly mating population

Question 2

Positive assortative mating

Answer 2

individuals mate with others who are phentopically similar to them

-in NA, this occurs for height, weight, IQ scores, socieconomic variables

Question 3

Negative assortative mating

Answer 3

indiv choose mates that are phenotypically different than them

-relatively rare, result in more diversity

Question 4

Consequences of assortatice mating

Answer 4

Result in H-W disequilibrium, but ONLY for those genes associated with the traits involved

Question 5

Parallel evolution

Answer 5

independent evolution of similar traits, starting from a similar ancestral condition.

Ex. 3 spined stickle back which evolved via positive assortative mating and speciation,evolution of some traits was seen in 3 separate lakes

Question 6

Inbreeding

Answer 6

Mating between relatives

• effect: increases homozygosity at ALL loci
• on its own, not a mechanism of evolution (does not change allele frequencies, though it changes genotype frinbredding
• self fertilization: strongest form of inbreeding (this is not a form of asexual mating)
• increases homozygosity and autozygosity
• retard the rate of gametic disequ’m (in double het’s)

Question 7

IBD (Identical by decent)

Answer 7

2 alleles are identical by descent if they arose by replication from the same copy of an allele in an ancestral population

Question 8

Autozygous

Answer 8

an individual that possesses two alleles at locus identical by descent (can only be homozygous)

Question 9

Allozygous

Answer 9

An individual that possesses two alleles at a locus that are not identical by descent (could be heterozygous or homozygous)

Question 10

Inbreeding coefficient (F)

Answer 10

-Fractional reduction in heterozygosity in comparison in heterozygosity in comparison to a randomly mating population

• F gives the probability that an individual in pop’s is autozygous (if no other forces are playing)
• also gives probability that any two randomly chosen alleles from a pop’n are identical by decent (if no other forces are playing)

Question 11

Inbreeding Depression

Answer 11

-inbreeding increases probability that a deleterious recessive allele occur in a homozygous form

Question 12

Genetic Rescue Effect

Answer 12

An increase in the average population fitness as a result of a reintroduction of genetic diversity (from another population)

Question 13

Outbreeding

Answer 13

• opposite of inbreeding
• increases heterozygosity (excess) at all loci
• negative value of F
• Outbreeding coefficient= -F (same formula)

Question 14

Outbreeding depression

Answer 14

sometimes translocation of individuals from one pop’n to another can a reduction in fitness; this can occur is the pop’ns have local adaption (so heterozygotes are not adapted to either environment)
-ex: Garter snakes (colour patterns and escap mechanisms - stripes: keep moving and not seen and blotches: dart and stop) Mix b/w the two had higher mortality than either.

-key: local adaptation is impaired