Adaptive phenotypic plasticity in a clonal invader

Abstract

Organisms featuring wide trait variability and occurring in a wide range of habitats, such as the ovoviviparous New Zealand freshwater snail Potamopyrgus antipodarum, are ideal models to study adaptation. Since the mid‐19th century, P. antipodarum, characterized by extremely variable shell morphology, has successfully invaded aquatic areas on four continents. Because these obligately and wholly asexual invasive populations harbor low genetic diversity compared to mixed sexual/asexual populations in the native range, we hypothesized that (1) this phenotypic variation in the invasive range might be adaptive with respect to colonization of novel habitats, and (2) that at least some of the variation might be caused by phenotypic plasticity. We surveyed 425 snails from 21 localities across northwest Europe to attempt to disentangle genetic and environmental effects on shell morphology. We analyzed brood size as proxy for fitness and shell geometric morphometrics, while controlling for genetic background. Our survey revealed 10 SNP genotypes nested into two mtDNA haplotypes and indicated that mainly lineage drove variation in shell shape but not size. Physicochemical parameters affected both shell shape and size and the interaction of these traits with brood size. In particular, stronger stream flow rates were associated with larger shells. Our measurements of brood size suggested that relatively larger slender snails with relatively large apertures were better adapted to strong flow than counterparts with broader shells and relatively small apertures. In conclusion, the apparent potential to modify shell morphology plays likely a key role in the invasive success of P. antipodarum; the two main components of shell morphology, namely shape and size, being differentially controlled, the former mainly genetically and the latter predominantly by phenotypic plasticity.

A layover in Europe: Reconstructing the invasion route of asexual lineages of a New Zealand snail to North America

“…In particular, Dybdahl and Drown (2011) showed that two lineages (US1 and US2; defined via a combination of mitochondrial and nuclear markers) predominated in the western and eastern parts of the United States, respectively. The mtDNA haplotypes of lineages US1 and US2 are identical to haplotypes (22 and 37 in Neiman & Lively, 2004, respectively) that are also found across Europe (Städler et al., 2005; Verhaegen, McElroy, et al., 2018) and in New Zealand (Verhaegen, Neiman, et al., 2018). The other two lineages defined by Dybdahl and Drown (2011), US1a and US3, have genotypes that have to date only been found in the western United States (Dybdahl & Drown, 2011).…”

“…The genetic background of these invasive P. antipodarum populations has been characterized with mitochondrial DNA (mtDNA) markers, revealing that, as for many other invasive taxa (Estoup et al., 2016), the invasive populations harbour very little diversity relative to the native range (Dybdahl & Drown, 2011; Neiman & Lively, 2004; Verhaegen, Neiman, & Haase, 2018). These mtDNA data also indicate that the European invasion is primarily composed of two distinct lineages with haplotypes identical to haplotypes found in New Zealand (Städler, Frye, Neiman, & Lively, 2005; Verhaegen, McElroy, et al., 2018). Dybdahl and Drown (2011) demonstrated that the picture is broadly similar with respect to the North American invasion and emphasized that this lack of diversity is surprising in light of how rapidly the North American invasive populations have successfully established throughout a wide range of environments.…”

“…We included a total of 1617 snails from three continents: 1,016 snails (51 sites) from the native range in New Zealand, 445 snails (25 sites) from the invaded range in Europe, and 156 snails from 13 invaded sites in North America (Table 1). All our sampling locations were freshwater sites with the exception of the European brackish water site DEBIN (Verhaegen, McElroy, et al., 2018). The genetic data from the New Zealand snails and most of the European ( N = 421, 94.6%) snails were generated in Verhaegen, McElroy, et al.…”

The genus Mercuria Boeters, 1971 in Morocco: first molecular phylogeny of the genus and description of two new species (Caenogastropoda, Truncatelloidea, Hydrobiidae)

“…This has been recently shown for the freshwater gastropod species Potamopyrgusantipodarum (Gray, 1843) (Kistner and Dybdahl 2014; Verhaegen et al 2018). Thus, given that M.tensiftensis sp.…”

“…n. were found in a wide spectrum of habitat types, variation in shell shape and size within these species could be a response to variable conditions. A potential adaptive value of morphological variation within Mercuria species should be better evaluated in further common garden studies (see, for instance, Verhaegen et al 2018). Lengths of the penis and the penial appendix were shown, however, to vary within Mercuria species according to the sexual maturity of the individuals, regardless of shell size.…”