Lecture 32

Question 1

If we are trying to find genes involved in adaptive shifts:

Answer 1

• Clinical shifts provide an ideal system

- Candidates from microarray/gene expression, physiological/biochemical studies, mutant studied, spatial patters

Question 2

A pathway to determining the adaptive capability of a trait

Answer 2

• Field patterns for traits
• Genetic basis
• Adaptation or population process?
• Allele association, lab selection studies, QTL mapping microarray etc

Question 3

How many polymorphisms are there for trait variation?

Answer 3

• Different organisms have different numbers of genes
• Each gene has a certain number of bp
• But..
• There is a limited number of genetic changes with phenotypic effects (nucleotide changes, deletions, duplications, insertions)

Question 4

Candidate gene identification:

Answer 4

• Knock out the gene
• Increase the expression of the gene
• Engineer strains with the same background but different alleles
• Understand biochemical and physiological interactions between traits and genes

Question 5

Dca polymorphism:

Answer 5

• Dca gene on the right arm of chr3 of Dros. Has three common alleles in the promoter region.
• Alleles show clinical patterns
• 237 alleles decrease size, increase towards tropics, increase expression of dca
• Over expression decreases size
• Dca is likely to influence expression of insulin pathway

Question 6

After Dca was studied for clinical size variation and maintained in the lab it was shown to be adaptive (repeatable, stronger than patterns for neutral markers)

Answer 6

• Associated with alleles on 3RP
• Lab studies indicate size increases at cold temperatures
• Mapping/association shows tight association with 2 peaks on 3RP, and the Dca gene

Question 7

Conservation: what do we conserve to ensure potential for adaptation?

Answer 7

• Genetic variation collapses when populations are small
• Heritability for physiological traits can be high in model systems
• High heritability is thought to be maintained by mutation-stabilising selection balance

Question 8

What will happen to specialist species?

Answer 8

• Restricted distributions may reflect evolutionary limits
• Limits may indicate lack of genetic variation in key traits
• Limits make extinction much more likely than previously through, particularly in reservers