Lecture 32 Flashcards Preview

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Flashcards in Lecture 32 Deck (8)
1

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

2

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

3

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)

4

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

5

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

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)

- 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

7

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

8

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