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

- Clinical shifts provide an ideal system
- Candidates from microarray/gene expression, physiological/biochemical studies, mutant studied, spatial patters


A pathway to determining the adaptive capability of a trait

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


How many polymorphisms are there for trait variation?

- 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)


Candidate gene identification:

- 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


Dca polymorphism:

- 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


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)

- 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


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

- 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


What will happen to specialist species?

- 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