Long‐term within‐basin isolation patterns, different conservation units, and interspecific mitochondrial DNA introgression in an amphipod endemic to the ancient Lake Skadar system, Balkan Peninsula

Abstract

1. Investigation of biodiversity, including genetic diversity within species, is crucial for rational planning of nature conservation and species protection. Endemics or narrow-ranged taxa, sensitive to alteration of physical and chemical conditions, may serve as local bioindicators. 2.Homoeogammarus scutarensis is an endemic, cold-adapted amphipod crustacean, inhabiting fragmented spring habitats, within a relatively small area of the Lake Skadar basin. The basin is recently under heavy anthropogenic influence leading to habitat deterioration.3. Genetic diversity within H. scutarensis was investigated using the mitochondrial cytochrome c oxidase subunit I and the nuclear 28S ribosomal RNA markers.Genetic diversity within the mitochondrial (mt)DNA appeared to be surprisingly high as for the limited spatial scale. The history of within-species divergence dates back at least to the Pliocene. 4. A case of interspecific mtDNA introgression from the endemic H. scutarensis to the widespread and partly sympatric Homoeogammarus thoni was observed in one of the studied populations. Demographic analysis showed that the demography of H. scutarensis population hasbeen stable, without evidence of expansion. Thus, we believe that H. scutarensis, responsive to environmental changes, is a proper model mirroring the conditions in sensitive habitats of the Lake Skadar basin. To protect ongoing evolutionary processes, the conservation measures for this species should take into account the complex fine-scale lineage endemism patterns. This case study may also provide a hint for planning conservation strategies in other geologically old spring systems.6. Most of the localities where H. scutarensis occurs provide refugia for divergent mtDNA lineages, suggesting prolonged isolation between sites and independent evolutionary histories. We conclude that H. scutarensis is composed of two or three conservation units. One of them occupies the headwaters of the Crnojevića River and spring in its valley. The other is widespread throughout the sub-lacustrine We would like to thank

DNA barcoding of Chironomidae from the Lake Skadar region: Reference library and a comparative analysis of the European fauna

“…The Lake Skadar basin, together with its large karst spring system, is definitely ancient, having originated more than 2.5 million years ago, and having been isolated for most of that time (Grabowski et al, 2018). Some of the karst spring connections are likely to be more than 100 Ka old and to have remained in prolonged isolation, increasing the probability of the emergence of divergent and locally endemic phylogenetic lineages or even species (Jabłońska et al, 2020). Since some larvae collected in this study were not identified to the species level and their sequences were clustered in OTUs and BIN unassigned to species of BOLD, it is expected that undescribed or currently non‐barcoded species may be present within the sampled material, possibly including endemics.…”

Continental-scale patterns of hyper-cryptic diversity within the freshwater model taxon Gammarus fossarum (Crustacea, Amphipoda)

“…It might also be largely involved in the within-species biodiversity effects, increasingly acknowledged in the biodiversity-functioning relationships 85 . Generally, how many different Evolutionary Significant Units (ESU) should be considered within G. fossarum is a relevant question and a challenge as exemplified by other amphipods 35,86 . On the one hand, our results suggest that individuals of different types will barely interbreed as they belong to different Lagrue-MOTUs.…”

Successful post-glacial colonization of Europe by single lineage of freshwater amphipod from its Pannonian Plio-Pleistocene diversification hotspot

“…On one end of the spectrum, old isolated water basins (e.g. ancient lakes) can hold endemic lineages and species 31 – 33 . Recent phylogeographic studies have indicated high molecular cryptic diversity within several amphipod morphospecies, with numerous Molecular Operational Taxonomic Units (MOTUs) representing phylogenetic species of pre-Pleistocene divergence 13 , 34 .…”