Molecular data suggest multiple origins and diversification times of freshwater gammarids on the Aegean archipelago

Abstract

Our main aim was to investigate the diversity, origin and biogeographical affiliations of freshwater gammarids inhabiting the Aegean Islands by analysing their mtDNA and nDNA polymorphism, thereby providing the first insight into the phylogeography of the Aegean freshwater gammarid fauna. The study material was collected from Samothraki, Lesbos, Skyros, Evia, Andros, Tinos and Serifos islands as well as from mainland Greece. The DNA extracted was used for amplification of two mitochondrial (COI and 16S) and two nuclear markers (28S and EF1-alpha). The multimarker time-calibrated phylogeny supports multiple origins and different diversification times for the studied taxa. Three of the sampled insular populations most probably represent new, distinct species as supported by all the delimitation methods used in our study. Our results show that the evolution of freshwater taxa is associated with the geological history of the Aegean Basin. The biogeographic affiliations of the studied insular taxa indicate its continental origin, as well as the importance of the land fragmentation and the historical land connections of the islands. Based on the findings, we highlight the importance of studying insular freshwater biota to better understand diversification mechanisms in fresh waters as well as the origin of studied Aegean freshwater taxa.

A new freshwater amphipod (Amphipoda, Gammaridae), Gammarus tumaf sp. nov. from the Gökgöl Cave, Türkiye

“…DNA barcoding studies, first introduced by Arnot et al (1993) and later gained popularity with the work of Hebert et al (2003), have allowed speedy, reliable and cost-effective species identification, based on specific nucleotide sequences on the genome. Some mitochondrial (such as COI, Cytb, 16S, 12S) and nuclear DNA (such as 18S, 28S, ITS, EF1-alpha) genes are powerful markers for deducing evolutionary relationships at the species, genera, family and higher levels (Johns and Avise 1998;Englisch and Koenemann 2001;Cristescu and Hebert 2005;Kartavtsev and Lee 2006;Witt et al 2006;Hou et al 2007Hou et al , 2011Costa et al 2009;Hupało et al 2020;Morhun et al 2022). Studies to date have confirmed that molecular techniques are a powerful tool for the discovery of cryptic species, as well as revealing speciation and population diversity within the genus Gammarus (Meyran et al 1997;Meyran and Taberlet 1998;Müller 2000;Hou et al 2007;Lagrue et al 2014;Mamos et al 2014;Weiss et al 2014;Wysocka et al 2014;Copilaş-Ciocianu et al 2018;Copilaș-Ciocianu et al 2019).…”

Widespread infection, diversification and old host associations of Nosema Microsporidia in European freshwater gammarids (Amphipoda)

“…17 MYA) in the central Balkans, and for which cryptic lineages are locally endemic due to paleo-habitat fragmentation and a complex phylogeographic history [36,38]. Furthermore, the recent biogeographical study of the pan-European morphospecies Gammarus pulex [41][42][43] and Gammarus fossarum [44] show high levels of cryptic lineages diversity, with diversification starting some >10 MYA. The crown age of the genus Gammarus itself has been estimated at 65 MYA [41].…”

Fuzzy Species Borders of Glacial Survivalists Revealed Using a Multimarker Approach - A Case Study of Amphipod Crustaceans in the Carpathian Biodiversity Hotspot

“…Since that time, however, more than a dozen of new species were described from inland waters of Europe and adjacent regions (e.g., Jażdżewski 1975a; Jażdżewski & Konopacka 1989 Mamos et al 2016). Also, recent phylogeographic studies on several geographically widespread Gammarus morphospecies pointed out to, formerly unforeseen, outstanding cryptic and pseudo-cryptic diversity with an ancient divergence between phylogenetic lineages (e.g., Mamos et al 2014Mamos et al , 2016Grabowski et al 2017a,b;Copilaș-Ciocianu et al 2017Hupało et al 2020;Wattier et al 2020).…”