engleski

Micro-Scale Vicariance and Diversification of Western Balkan Caddisflies Linked to Karstification

The karst areas in the Dinaric region of the Western Balkan Peninsula are a hotspot of freshwater biodiversity. Many studies have examined the diversification of the subterranean freshwater fauna in these karst systems. However, the diversification of surface water fauna remains largely unexplored. We assess local and regional scale diversification of surface water species in karst systems and explicitly examine if patterns of population differentiation can be explained by dispersal-diversification processes or allopatric diversification following karst-related micro-scale vicariance. We analysed mtCOI sequence data of four caddisfly species (genus Drusus) in a phylogeographic framework to assess local and regional population genetic structure and Pliocene/Pleistocene history. Using BEAST we assessed the timing of intraspecific diversification of the target species. We compared climate envelopes of the study species and projected climatically suitable areas during the last glacial maximum (LGM) to assess differences in the species climatic niches and infer potential LGM refugia. The haplotype distribution of the four species (324 individuals from 32 populations) is characterized by strong genetic differentiation with few haplotypes shared among populations (16%) and deep divergence among populations of the three endemic species, even at local scales. Divergence among local populations of the endemics often exceeds the divergence among regional and continental clades of the widespread D. discolor. Major divergences among regional populations date to 2.0-0.5 Mya. SDM projections and genetic structure suggest that the endemic species persisted in situ and diversified locally throughout multiple Pleistocene climate cycles. The pattern for D. discolor is different and consistent with multiple invasions into the region. Main conclusions: The patterns of population genetic structure and diversification are similar for the three regional endemic Drusus species and consistent with micro-scale vicariance after the onset of intensified karstification in the Dinaric region of the Western Balkans. Our study shows that karstification may induce micro-scale vicariance of running surface water habitats and likely promotes allopatric fragmentation of stream insects at small spatial scales.

allopatric diversification; comparative phylogeography; endemism; species distribution modeling; stream insects; Trichoptera; biodiversity

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