A molecular phylogeography approach to biological invasions of the New World by parthenogenetic Thiarid snails

Abstract

The parthenogenetic snail Melanoides tuberculata, present in tropical fresh waters of most of the Old World before 1950, has now invaded the Neotropical area. The phylogeography of this snail was studied to evaluate the pathways and number of such invasions. Because of parthenogenetic reproduction, individuals are structured into genetical clones. Within populations from both the original and invaded areas, several morphologically distinct clones (referred to as morphs) often coexist but the amount of genetic divergence among morphs is unknown. Individuals from 27 morphs and 40 populations world-wide were sequenced at two mitochondrial genes (12S and 16S). Our phylogenetic reconstruction suggests that (i) most of the morphological variation observed in the New World predates invasion, (ii) at least six independent introductions have occurred, and (iii) invasive clones are found throughout most of the phylogenetic tree and do not come from a particular region of the area of origin. Two ideas are discussed in the light of these results. The first lies with the specificities of parthenogenesis in an invasion context. While in sexual species, independently introduced populations eventually merge into a single invasive population, in a parthenogenetic species independently introduced clones have distinct invasion dynamics and possibly exclude each other. Second, although repeated invasions in Melanoides may have an impact on indigenous molluscan faunas, their most likely effect is the world-wide homogenization of the invasive taxon itself.

Trematodes obtained from the thiarid freshwater snail Melanoides tuberculata (Müller, 1774) as vector of human infections in Thailand

“…Population dynamics and distribution of M. tuberculata were studied in many areas, where they dominated the streams, ponds, and lakes (e.g. Supian and Ikhwanuddin 2002, Eldblom and Kristensen 2003, Facon et al 2003.…”

Human-mediated transport determines the non-native distribution of the anemone Nematostella vectensis, a dispersal-limited estuarine invertebrate

“…Only a few studies have explored the role of asexual reproduction in the successful invasions of invertebrate taxa (Ting & Geller 2000, Facon et al 2003, Stadler et al 2005, and none have directly tested the hypothesis that asexuality contributes to invasiveness. It seems likely that the capacity for asexual reproduction may mitigate a number of the negative demographic and genetic effects associated with colonization (Roman & Darling 2007).…”

Out of New Zealand: molecular identification of the highly invasive freshwater mollusk Potamopyrgus antipodarum (Gray, 1843) in South America

“…Because frequently there are no obvious morphological characters to distinguish different components of invertebrate fauna, DNA barcoding and molecular phylogenetic analysis are increasingly used to identify aquatic invaders in a variety of taxa (e.g. Geller et al 1997;Facon et al 2003;Albrecht et al 2009;Duggan et al 2012;Porco et al 2013;Wetterer 2014). In 2010, an investigation of the small freshwater gastropod of the superfamily Rissooidea Gray, 1847 sensu lato of Chile was initiated by the author, sampling snails from a number of locations.…”