Data from: Maintaining genetic diversity and population panmixia through dispersal and not gene flow in a holocyclic heteroecious aphid species

Heteroecious holocyclic aphids exhibit both sexual and asexual
reproduction and alternate among primary and secondary hosts. Most of
these aphids can feed on several related hosts, and invasions to new
habitats may limit the number of suitable hosts. For example, the aphid
specialist Aphis glycines survives only on the primary host buckthorn
(Rhamnus spp.) and the secondary host soybean (Glycine max) in North
America where it is invasive. Owing to this specialization and sparse
primary host distribution, host colonization events could be localized and
involve founder effects, impacting genetic diversity, population structure
and adaptation. We characterized changes in the genetic diversity and
structure across time among A. glycines populations. Populations were
sampled from secondary hosts twice in the same geographical location: once
after secondary colonization (early season), and again immediately before
primary host colonization (late season). We tested for evidence of founder
effects and genetic isolation in early season populations, and whether or
not late-season dispersal restored genetic diversity and reduced
fragmentation. A total of 24 single-nucleotide polymorphisms and 6
microsatellites were used for population genetic statistics. We found
significantly lower levels of genotypic diversity and more genetic
isolation among early season collections, indicating secondary host
colonization occurred locally and involved founder effects. Pairwise FST
decreased from 0.046 to 0.017 in early and late collections, respectively,
and while genetic relatedness significantly decreased with geographical
distance in early season collections, no spatial structure was observed in
late-season collections. Thus, late-season dispersal counteracts the
secondary host colonization through homogenization and increases genetic
diversity before primary host colonization.