engleski

Don’t judge book by its cover: the case of freshwater gammarids of the Periadriatic region

Background: Modern molecular studies reveal the presence of very high levels of cryptic diversity and local endemism in many freshwater taxa. The current extinction rate of freshwater species is estimated to be at least 5× higher than that of terrestrial species, mostly due to heavy anthropogenic degradation of freshwater ecosystems. This leads to the situation where the rate of extinctions in freshwater habitats will exceed the speed at which new species are identified and described. The Mediterranean, including the Periadriatic Region, is one of the most important biodiversity hotspots on the global scale. Freshwater gammarids are widely used as model organisms in ecotoxicological and biomonitoring studies. However, the majority of the studies on gammarid crustaceans of the region have focused mainly on marine species and neglected the freshwater fauna. Results: Several sampling campaigns in the years 2005– 2016 yielded a very large collection of gammarids, encompassing more than 40 000 individuals gathered from over 500 inland and insular locations in the Periadriatic region. Molecular analyses revealed an extremely high level of cryptic diversity, greatly exceeding the number of morphospecies already described from the region, i.e., 40 molecular species within the Gammarus balcanicus group, at least 12 species within Gammarus roeselii, around 10 cryptic species within Gammarus italicus, as well as 10 molecular species of Gammarus from the Peloponnese and high cryptic diversity including a few dozen species within Echinogammarus in the Apennine Peninsula. Significance: The collected data greatly aids in revealing the biogeographical affiliations and the diversification time frames of the local gammarids and will eventually help to update and revise the taxonomy within the family Gammaridae. Knowledge about the real level of biodiversity will greatly aid planning reasonable and effective strategies preventing or minimalizing the rapid loss of freshwater biodiversity, due to the extensive anthropogenic degradation of the local freshwater ecosystems.

molecular barcoding

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