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

Abstract

SUMMARY1. How species reach and persist in isolated habitats remains an open question in many cases, especially for rapidly spreading invasive species. This is particularly true for temporary freshwater ponds, which can be remote and may dry out annually, but may still harbour high biodiversity. Persistence in such habitats depends on recurrent colonisation or species survival capacity, and ponds therefore provide an ideal system to investigate dispersal and connectivity. 2. Here, we test the hypothesis that the wide distributions and invasive potential of aquatic snails is due to their ability to exploit several dispersal vectors in different landscapes. We explored the population structure of Physa acuta (recent synonyms: Haitia acuta, Physella acuta, Pulmonata: Gastropoda), an invasive aquatic snail originating from North America, but established in temporary ponds in Doñ ana National Park, southern Spain. In this area, snails face land barriers when attempting to colonise other suitable habitat. 3. Genetic analyses using six microsatellite loci from 271 snails in 21 sites indicated that (i) geographically and hydrologically isolated snail populations in the park were genetically similar to a large snail population in rice fields more than 15 km away; (ii) these isolated ponds showed an isolation-by-distance pattern. This pattern broke down, however, for those ponds visited frequently by large mammals such as cattle, deer and wild boar; (iii) snail populations were panmictic in flooded and hydrologically connected rice fields. 4. These results support the notion that aquatic snails disperse readily by direct water connections in the flooded rice fields, can be carried by waterbirds flying between the rice fields and the park and may disperse between ponds within the park by attaching to large mammals. 5. The potential for aquatic snails such as Physa acuta to exploit several dispersal vectors may contribute to their wide distribution on various continents and their success as invasive species. We suggest that the interaction between different dispersal vectors, their relation to specific habitats and consequences at different geographic scales should be considered both when attempting to control invasive freshwater species and when protecting endangered species.

How do freshwater organisms cross the “dry ocean”? A review on passive dispersal and colonization processes with a special focus on temporary ponds

“…Although papers documenting passive dispersal of adult microcrustaceans, water mites and plants are available in the literature (Dahms, 1995;Di Sabatino et al, 2004;Allen, 2007;Frisch & Green, 2007;van Leeuwen et al, 2013;Bruckerhoff et al, 2014), passive dispersal mechanisms more generally require the production of resting stages able to survive unfavourable environmental conditions and to act as dispersal propagules, functionally performing as plant seeds (see Van Damme & Sinev, 2013). Resting stages are the most important propagules for many aquatic taxa (Rundle et al, 2002) and are easily transported by different physical and biological vectors (Fig.…”

“…The arrow from Spain to French Aquitaine was added on the basis of the results by Cellamare et al (2010) 2008a; Meier & Soininen, 2014) and dispersal by surface waters (hydrochory) like that occurring in floodplains or during the rice-fields inundation (e.g. Frisch et al, 2005;Akasaka & Takamura, 2012;Van Leeuwen et al, 2013, and references therein) can also be important. However, this mechanism is not treated here in detail because its action is quite obvious.…”

“…Short-distance dispersal can be favoured by several other vertebrates such as cattle, rats, rabbits, amphibians and fish (e.g. Zedler & Black, 1992;Bohonak & Whiteman, 1999;Beladjal et al, 2007;Van Leeuwen et al, 2013 and literature therein) as well as by invertebrates (Duthie, 1929); in particular, crayfish (Pérez-Bote et al, 2005) and flying insects (van de Meutter et al, 2008;Beladjal & Mertens, 2009) are documented vectors for the dispersal of resting stages and seeds among temporary waters, and water mites are known to be phoretic on insect larvae and adults (Di Sabatino et al, 2004;Bohonak et al, 2004).…”

What can aquatic gastropods tell us about phenotypic plasticity? A review and meta-analysis

“…However, the capacity for dispersal may not reflect how the organism experiences environmental variability. For example, freshwater gastropods may lack a planktonic stage, but they can be dispersed as juveniles or adults by water birds and mammals (Wesselingh et al, 1999, Figuerola and Green, 2002, Van Leeuwen, 2012Van Leeuwen et al, 2013). Further, marine species with benthic development may disperse widely via rafting on seaweeds (Highsmith, 1985;Martel and Chia, 1991;Donald et al, 2011).…”

Scientific Opinion on the assessment of the potential establishment of the apple snail in the EU

“…During flooding of large areas, snails can move actively or can be carried passively and might connect with other snail populations in the wetlands of the flooded area ( Van de Meutter et al, 2006). Snails in annually flooded rice fields, for instance, form one large population (Van Leeuwen et al, 2013).…”