Evolutionary genomics I (DONE) Flashcards
What is the focus of evolutionary genomics?
Understanding the genetic basis of phenotypic variation & how genetic variation shapes adaptation, speciation & evolution
What are the main processes shaping genomic variation?
Selection, gene flow & recombination
What are genome-wide association studies (GWAS)?
GWAS identify genetic variants associated w phenotypic traits across the genome
How do Manhattan plots help in GWAS?
They visualise the strength of association between genetic variants & phenotypic traits
What is the genetic basis of phenotypic variation in Darwin’s finches?
Variants influencing blunt vs pointed beaks, potentially linked to ancient alleles
What does “standing variation” mean?
Pre-existing genetic variation in a population that selection can act upon
What is a selective sweep?
A process where beneficial mutation rapidly increases in freq –> reducing genetic diversity near the locus
How do hard & soft selective sweeps differ?
Hard sweeps = involve new mutations
Soft sweeps = act on existing variation
What genomic signature indicated a selective sweep?
- Reduced genetic diversity
- Inc linkage disequilibrium
- Higher differentiation from other pops
What study demonstrated habitat-driven genetic selection?
Deer mice (Peromyscus maniculatus) showing coat colour adaptation to their environment
What is genetic drift?
Random changes in allele frees, significant in small pops
What is gene flow?
Exchange of genetic material between pops, introducing variation
What is adaptive introgression?
Transfer of beneficial alleles between species through hybridisation
Give an example of adaptive introgression?
Snowshoe hares acquiring winter coat colour adaptation thru gene flow
What role does recombination play in genomic variation?
It reshuffles genetic material, breaking linkage disequilibrium & shaping genetic diversity
How does recombination influence gene flow?
It breaks down blocks of introgressed ancestry over time, facilitating adaptation
Why are high recombination regions significant?
They often show greater introgression due to reduced linkage disequilibrium
What did Cutter & Payseur (2013) conclude about recombination?
Recombination limits the extent of selection’s influence on genetic variants
What confounds genomic data interpretation?
- Overlapping influences of selection
- Gene flow
- Recombination
- Environmental factors
Why is it important to integrate genomic & ecological data?
To accurately identify drivers of adaptation & evolution
What example links genomic data to phenotypic traits in birds?
Great tits: variants in COL4A5 are linked to bill length & reproductive success
What does a genome scan reveal?
Genomic regions under selection & their associations w phenotypic traits
What is phenotypic variation?
Observable differences in traits among individuals of a species
Why are Mendelian traits easier to study than complex traits?
They are controlled by single genes, simplifying genetic associations
What role do ancient alleles play in evolution?
They can be reused across pops, contributing to standing variation
How does natural selection affect genetic diversity?
It reduces diversity near selected loci while favouring beneficial mutations
What is linkage disequilibrium?
The non-random association of alleles at different loci in a population
What is a key challenge in genomic studies?
Distinguishing the effects of selection from neutral evolutionary process
What is the importance of gene flow in adaptation?
It introduces novel genetic variation that can enhance survival in changing environments
What is the evolutionary significance of genomic tools?
They allow precise identification of genetic drivers of adaptation, speciation & biodiversity
