Vulnerability to climate change for two endemic high-elevation, low-dispersive Annitella species (Trichoptera) in Sierra Nevada, the southernmost high mountain in Europe

Abstract

Climate change is predicted to progressively shift habitat characteristics that will alter the distribution and eco-physiological responses of organisms. High-elevation stream insects without extensive dispersal are expected to be highly vulnerable if they are unable to track predicted shifts. Understanding dispersal is therefore crucial to implement practical solutions in conservation. The evolutionary history of the Palaearctic genus Annitella (Trichoptera), the population dynamics and habitat distribution (present and future) of two endemic species (A. esparraguera and A. iglesiasi) confined to Baetic Mountains (SE-Iberian Peninsula) were assessed to gain fundamental insights into species responses to climate warming and to identify populations at risk. Diversification of Annitella was dated to the Pleistocene and was likely associated with southern and extra-Mediterranean refugia located across Europe. The two endemic species belong to distant lineages that preferred similar cold headwater pristine habitats. The range of A. esparraguera was larger than that of A. iglesiasi. Both species showed low genetic diversity in cox1, but only A. esparraguera exhibit locally unique haplotypes, indicating limited gene flow. For A. esparraguera, modelled future habitat suitability showed 88.4% range contraction by 2050 (RCP scenario 8.5) and a displacement of 41.5% of the current potential distribution to higher elevations. Populations of A. esparraguera are predicted to be lost because of the reduction of optimal habitat and limited propensity for tracking future suitable conditions. Beyond the preservation of their current habitat, their conservation might require proactive measures (translocations). Similar predictions may apply to other Mediterranean endemic headwater specialist restricted to isolated high-elevation streams.