Distributional pattern of cold-adapted plants and arthropods in a peripheral mountain range: cold- and warm-stage refugia should be considered

The geographical isolation due to the ice-sheets expansion in cold-climatic stages (e.g. Last Glacial Maximum, LGM) has been traditionally involved to explain the present patchy distribution of some cold-adapted plant and arthropod species on peripheral mountain ranges; more recently, the areal contraction during warm-climatic stages (e.g. Holocene Climate Optimum) was also called into question. Recent studies ontheInner Alps demonstrated the role of ice-relatedlandforms (glaciers and rock glaciers) as habitat for cold-adaptedspecies. Since such landformmay represent potentialwarm-stage refugia, the comparison of their occurrence, that of cold-stagerefugia and that of cold-adapted species may shed light on the events driving present species distribution.In this work we aimed to explain the present distribution of cold-adapted plant and animal species on a peripheral mountain range(Orobian Alps: Italy). We focused on ten species: 5 plants (Viola comollia, Androsace alpina, Artemisia genipi, Ranunculus glacialisand Saxifraga oppositifolia); 3 ground beetles(Oreonebria castanea, O. lombardaandO. soror tresignore) and2 spiders (Coelotes pickardi tirolensisand Drassodes heeri) living on debris-featured landforms above 2000 m a.s.l.Some of these species are endemic while others show wide distribution, but they share the same main ecological requirements.We compared by GIS-approach 574 records of plants and arthropods (379 plants, 54 ground beetles and 141 spiders) with the distribution of cold-stage refugia (summits emerging from the LGM ice-sheet)and potential warm-stage refugia (highest summits and 80 glaciers and 27 intactrock glaciers). The results highlighted two rather different distributional patterns: 1) plant species seems more linked to warm-stage refugia,beingmainly distributed where highest peaks occur and around glaciers and intact rock glaciers, and absent even at favorable altitude where the overall elevation of the chain is lower; 2) arthropod species seem linkedto cold-stage refugia, being widely distributed in most of the summit emerging from the LGM ice-sheet.Our study suggests the potential role of both cold-and warm-stage refugia on the current distribution of cold-adapted plants and arthropods on peripheral mountain ranges. This result could help to a better interpretation of the results obtained by phylogeographicalstudies performed on taxa with distribution limited to peripheral mountain range.