Natural range expansion and human-assisted introduction leave different genetic signatures in a hermaphroditic freshwater snail

Abstract

Colonization events like range expansion or biological invasions can be associated with population bottlenecks. Small population size may lead to loss of genetic diversity due to random genetic drift, to loss of heterozygosity due to increased inbreeding and should leave a signature on the genetic polymorphism and genetic structure of populations. The mating system might additionally influence the outcome of such a process. Here, we compare invasive and native populations of the hermaphroditic freshwater snail Lymnaea stagnalis. In the native range we included populations that were ice-free during the last glaciation period and populations that were glaciated and are located at the edge of the species' native distribution range. The microsatellite data show substantial loss of genetic variation in the introduced range and no signs of high propagule pressure or admixture. The expressed polymorphism was so low that mating system analysis was not possible. In the native region, all populations display strong levels of differentiation (global F ST : 0.341) independent of colonization history and exhibit no significant pattern of inbreeding. However, the populations in more recently colonized habitats show diminished genetic diversity. Overall, these results illustrate how dramatic the reduction in genetic diversity can be for hermaphroditic animals and that gene flow in the native range can be surprisingly low despite short distances.

Population genetic dynamics of an invasion reconstructed from the sediment egg bank

“…; Kopp et al . ). F IS values and selfing rates were also calculated for a separate data set excluding repeated MLGs (unique MLGs data set), to avoid a potential bias introduced by the inclusion of putatively obligate parthenogenetic genotypes.…”

Environmental versus Anthropogenic Effects on Population Adaptive Divergence in the Freshwater Snail Lymnaea stagnalis

“…The method has lower type 1 error rate and better statistical power than previous tests, and seems particularly suited when neutral differentiation is high [46], as in L. stagnalis [58],[75]. Briefly, a bootstrapping procedure is applied to compare observed values of the difference Q ST - F ST to the Q ST - F ST distribution expected under the neutral hypothesis, as derived from F ST distribution and variance components [60] and Q ST neutral distribution predicted from the Lewontin-Krakauer distribution.…”

Genetic structure and phylogeographic relationships of the Bellamya complex: A nascent aquacultural snail in the Pearl River basin, China

“…Furthermore, anthropogenic translocations, such as via food consumption and animal-mediated dispersal by waterfowl, a commonly observed phenomenon in freshwater snails (Gittenberger, 2012;Gittenberger et al, 2006;Green & Figuerola, 2005;Kopp, Wolff, & Jokela, 2012), can also influence distribution and accelerate the gene flow between populations. For example, human-and animal-mediated dispersal provide a good explanation of the current distribution of Isabellaria buresi pharsalica in Thessaly (Uit de Weerd, Schneider, & Gittenberger, 2005) and B. aeruginosa in the Yangtze River system (Gu, Husemann, et al, 2015).…”