Under threat: Land use change, distribution and conservation of poorly-known endemic microsnails from the coast of Chile

Abstract

Mollusks are among the most affected groups in the current extinction crisis, with rates surpassing those of other taxa combined. This is compounded by limited knowledge of many groups and a high proportion of endemic species restricted to small geographic areas. We assessed the vulnerability of six Chilean terrestrial punctoid microsnails by combining species distribution maps with land use, ecosystem, and protected area layers, and by developing semi-quantitative and quantitative vulnerability indices integrating these data with information on habitat, current distributions, and potential future scenarios of climate change and human pressures. We tested the hypothesis that endemic microsnail from the Chilean coast are threatened by the overlap of their distributions with areas of intense anthropogenic pressure, expected to expand under future climate change. Conservation status of species was evaluated using IUCN Red List and NatureServe criteria. Results show significant variation in habitat conditions and threats across species' biogeographical regions. Primary threats encompass habitat loss and fragmentation, wildfires, droughts, and land use changes from urban expansion, agriculture, and forestry, collectively limiting dispersal and increasing vulnerability. Although both climate and composite vulnerability indices vary among species, the former forecasts future exposure to drought and warming, while the latter reflects current ecological traits, anthropogenic pressures, and protection gaps, revealing additional risks and facilitating targeted conservation efforts. Under IUCN criteria, five species qualify as Critically Endangered and one as Endangered. All species are categorized as Critically Imperiled by NatureServe. This assessment underscores the need for habitat protection and sustainable land use in conservation.