Populations of the European freshwater pulmonate Physa acuta are not reproductively isolated from American Physa heterostropha or Physa integra

Abstract

Abstract. It has long been speculated that Physa acuta, a pulmonate snail widespread and invasive in fresh waters of the old world, may have originated in North America. But the identification of a new‐world cognate has been complicated by the confused systematics and taxonomy of the Physidae in America. More than 40 species of physids are currently recognized in the United States, many with variable and overlapping morphology. We have previously established that premating reproductive isolation is negligible among physid snails. Here we report the results from no‐choice crosses each involving 2 populations of the widespread American species Physa heterostropha and Physa integra, both with each other and with P. acuta, designed to compare measures of reproductive success between species and between populations within species. Samples of P. acuta were collected from France and Ireland, P. heterostropha from eastern Pennsylvania and South Carolina, and P. integra from southern Indiana and northern Michigan. The 6 intrapopulation controls varied quite significantly in their survival, age at first reproduction, parental fecundity, F1 viability, and F1 fertility under our culture conditions. Measures of survival and reproduction in the 6 interpopulation crosses were generally intermediate, but in no case significantly worse than the more poorly performing control. Thus we were unable to detect evidence of reproductive isolation among our 6 populations of snails from 2 continents. All should be referred to the oldest available nomen, P. acuta.

Partial selfing, ecological disturbance and reproductive assurance in an invasive freshwater snail

“…As a consequence, population size is likely to vary dramatically through time because of drying out events or floods (reviewed in Städler and Jarne, 1997). Second, P. acuta is the commonest species in isolated habitats (ie ponds) of the area studied here (reviewed in Henry, 2002), in accordance with its invasive status (Dillon et al, 2002;Bousset and Jarne, unpublished data). As colonization has been shown to be associated with founding events in freshwater snails (Charbonnel et al, 2002;Meunier et al, 2004), this opens opportunities for selfing as a RA strategy.…”

“…Those events might have indeed been the ecological factors maintaining selfing as a RA mechanism. Founding events very likely occur in P. acuta since this species displays high dispersal abilities (reviewed in Henry, 2002) and is the most successful worldwide invasive freshwater snail (Dillon et al, 2002;Bousset and Jarne, unpublished data). Such founding events might be scarce in the studied area, since neither demographic, nor genetic signatures were detected (Henry, 2002;Bousset et al, 2004).…”

Diel activity cycles of freshwater gastropods under natural light: Patterns and ecological implications

“…For example, P. acuta is considered a poor competitor (Brown, 1982;Perrin, 1986;Jokinen, 1987) despite its high grazing effectiveness (e.g., Lowe and Hunter, 1988;Lombardo, 2001; but see Wojdak and Mittelbach, 2007) and success in productive habitats at both local/regional (e.g., Girod et al, 1980, and authors' personal observations) and global scale (Dillon et al, 2002). P. acuta's high activity and quick response to food may translate into a high potential to exploit food, which may be exacerbated by its fast way of moving around (thus increasing access to food patches: Lombardo and Cooke, 2004).…”

“…All species are herbivorous on periphyton and/or detritus (Brown, 2001;Lombardo and Cooke, 2002;Mouthon and Daufresne, 2008); bithyniids and valvatiids may also filter-feed on suspended particles (Kabat and Hershler, 1993;Mouthon and Daufresne, 2008). Nomenclature follows Dillon et al (2002) for Physa (= Physella) acuta and Bank (2007) for all other species.…”

How did this snail get here? Several dispersal vectors inferred for an aquatic invasive species

“…Here, we investigated the dispersal vectors used by a small invasive snail, Physa (Costatella) acuta Draparnaud, 1805 (recent synonyms: Haitia acuta, Physella acuta) (Gastropoda; Pulmonata; Physidae). Other synonyms for this species are Physa heterostropha and Physa integra, as previous work has indicated that these all belong to a single widespread species (Dillon et al, 2002). Described as P. acuta from Europe, it was discovered that this species originates from North America and was probably introduced via the aquarium trade or by the intentional introduction of water plants.…”