Evolutionary genomics II (DONE) Flashcards
What is speciation with gene flow?
Speciation that occurs while populations continue exchanging genetic material
What is parapatry?
Speciation across adjacent populations w non-overlapping ranges & some gene flow
What does Fst measure?
The proportions of genetic diversity due to allele freq differences among populations
Why can high Fst values be misleading?
Peaks may result from reduced diversity within populations rather than the true divergence
What occurs in stage 1 of speciation?
Divergence at one of few loci under strong disruptive selection
How does divergence spread in later speciation stages?
Selection & reduced recombination spread divergence across the genome
What are islands of divergence?
Genomic regions showing high differentiation, often due to selection
What us hybridisation’s role in evolution?
It:
- Introduces genetic variation
- Fuels adaptive radiation
- Promotes phenotypic exchange
What is adaptive introgression?
Gene flow that transfers beneficial alleles between species
What do ABBA/BABA tests detect?
Patterns of introgression in hybridising pops
How do Dobzhansky-Muller incompatibilities arise?
Thru negative interactions between genes from diff species
Give an example of a genetic incompatibility in hybrid species?
Caudal melanoma in swordtail fishes (Xiphophorus melinche & X. birchmanni
Why are species considered fluid?
Gene flow blurs boundaries & facilitates phenotypic exchange
What does recombination do in genomic divergence?
It reshuffles alleles, reducing linkage disequilibrium & influencing selection
How does gene flow influence speciation?
It promotes adaptive variation while maintaining some species identity
What are the challenges of interpreting Fst?
Differentiating true selection from recombination or within population diversity
Why is hybrid vigor?
Enhanced fitness in hybrids due to gene flow & genetic variation
Why are subspecies important in early divergence?
They represent pops at stage I of speciation w localised genetic differences
How does selection within pops resemble divergence between pops?
Selection reduces genetic variation, creating patterns similar to divergence
What role does recombination play in hybrid genomes?
It breaks down blocks of introgressed ancestry over time, shaping adaptation
How does gene flow facilitate adaptive radiation?
By introducing genetic diversity that allows rapid ecological specialisation
Why is hybridisation more common than previously though?
Many species exch genetic material w/o losing their identities
What is the impact of disruptive selection on speciation?
It drives divergence by favouring extreme phenotypes over intermediates
How can gene flow maintain species identity?
By balancing the exchange of adaptive traits w reproductive barriers
Why might islands of divergence be illusionary?
They can result from transient processes like gene flow rather than permanent barriers
How do incomaptibilities contribute to speciation?
They create reproductive barriers that reinforce genetic divergence
What is the significance of genomic scans in speciation studies?
They identify regions under selection that contribute to divergence
What is the role of selection in genome evolution?
It promoted beneficial alleles while reducing neutral of deleterious variation
How do polyphyletic species challenge traditional taxonomy?
They exchange useful genes across species, complicating boundaries
What processes interact to change genomic patterns in speciation?
- Selection
- Gene flow
- Recombination
- Genetic drift
