Standing geographic variation in eclosion time and the genomics of host race formation in fruit flies.

Taxa harboring high levels of standing variation may be more likely to adapt to rapid environmental shifts and experience ecological speciation. Here, we characterize geographic and host-related differentiation for 10,241 single nucleotide polymorphisms in fruit flies to infer whether standing genetic variation in adult eclosion time in the ancestral hawthorn ( spp.)-infesting host race, as opposed to new mutations, contributed substantially to its recent shift to earlier fruiting apple ().

Genomic Differentiation during Speciation-with-Gene-Flow: Comparing Geographic and Host-Related Variation in Divergent Life History Adaptation in .

A major goal of evolutionary biology is to understand how variation within populations gets partitioned into differences between reproductively isolated species. Here, we examine the degree to which diapause life history timing, a critical adaptation promoting population divergence, explains geographic and host-related genetic variation in ancestral hawthorn and recently derived apple-infesting races of . Our strategy involved combining experiments on two different aspects of diapause (initial diapause intensity and adult eclosion time) with a geographic survey of genomic variation across four sites where apple and hawthorn flies co-occur from north to south in the Midwestern USA.