Diversity and distribution of genetic variation in gammarids: Comparing patterns between invasive and non‐invasive species

Abstract

Biological invasions are worldwide phenomena that have reached alarming levels among aquatic species. There are key challenges to understand the factors behind invasion propensity of non‐native populations in invasion biology. Interestingly, interpretations cannot be expanded to higher taxonomic levels due to the fact that in the same genus, there are species that are notorious invaders and those that never spread outside their native range. Such variation in invasion propensity offers the possibility to explore, at fine‐scale taxonomic level, the existence of specific characteristics that might predict the variability in invasion success. In this work, we explored this possibility from a molecular perspective. The objective was to provide a better understanding of the genetic diversity distribution in the native range of species that exhibit contrasting invasive propensities. For this purpose, we used a total of 784 sequences of the cytochrome c oxidase subunit I of mitochondrial DNA (mtDNA‐COI) collected from seven Gammaroidea, a superfamily of Amphipoda that includes species that are both successful invaders (Gammarus tigrinus, Pontogammarus maeoticus, and Obesogammarus crassus) and strictly restricted to their native regions (Gammarus locusta, Gammarus salinus, Gammarus zaddachi, and Gammarus oceanicus). Despite that genetic diversity did not differ between invasive and non‐invasive species, we observed that populations of non‐invasive species showed a higher degree of genetic differentiation. Furthermore, we found that both geographic and evolutionary distances might explain genetic differentiation in both non‐native and native ranges. This suggests that the lack of population genetic structure may facilitate the distribution of mutations that despite arising in the native range may be beneficial in invasive ranges. The fact that evolutionary distances explained genetic differentiation more often than geographic distances points toward that deep lineage divergence holds an important role in the distribution of neutral genetic diversity.

First true brackish-water nudibranch mollusc provides new insights for phylogeny and biogeography and reveals paedomorphosis-driven evolution

“…There are several brackish water invertebrates which are common in Scandinavian fjords and particularly in the Swedish Idefjord, including cnidarian hydroid polyp Cordylophora caspia (Pallas, 1771), nemertean Cyanophthalma obscura (Schultze, 1851), polychaete Hediste diversicolor (O.F. Müller, 1776), crustaceans Neomysis integer (Leach, 1814), Gammarus zaddachi Sexton, 1912, Gammarus duebeni Lilljeborg, 1852 and Palaemon varians Leach, 1813 [ 53 – 60 ] and the bryozoan Einhornia crustulenta (Pallas, 1766) [ 61 ]. Some invasive brackish-water species present in the inner part of the Idefjord are the gastropod mollusc Potamopyrgus antipodarum (Gray, 1843) [ 62 ] and the polychaete Marenzelleria viridis (Verrill, 1873) [ 63 ].…”

Is salinity an obstacle for biological invasions?

“…Two sequences were added to act as outgroups to the overall dataset (i.e., Crangonix pseudogracilis) and within genus (i.e., Hou & Sket, 2016). Accession numbers can be found in Appendix S1 (Baltazar-Soares, Paiva, Chen, Zhan, & Briski, 2017). Sequences were aligned and manually trimmed to a standard fragment size in BioEdit v7.0.4.1 (Hall, 1999).…”

Sea freshening may drive the ecological impacts of emerging and existing invasive non‐native species

“…Amphipods are major drivers of disturbance through predation, herbivory, competition for substrate and modification of sediment (Conlan, 1994), and their invasions have lead to major changes in the faunal make‐up of the systems in which they establish (Dick & Platvoet, 2000; Jazdzewski et al., 2004; Kelly et al., 2006). Predicting the likely identities of future INNS and recipient areas at risk are major goals of invasion ecology (Gallardo et al., 2016; Lucy et al., 2020; Peyton et al., 2019; Roy et al., 2014) and one Ponto‐Caspian amphipod expected to spread through Europe in the near future is Pontogammarus maeoticus (Baltazar‐Soares et al., 2017). Endemic to the Caspian, Black and Azov Seas (Stock et al., 1998), this species has a limited documented invasion history, with only some reports from Turkey and Ukraine in recent decades (Ahmet et al., 2003; Alexandrov et al., 2007).…”