Post‐glacial determinants of regional species pools in alpine grasslands

Abstract

Aim Alpine habitats support unique biodiversity confined to high‐elevation areas in the current interglacial. Plant diversity in these habitats may respond to area, environment, connectivity and isolation, yet these factors have been rarely evaluated in concert. Here we investigate major determinants of regional species pools in alpine grasslands, and the responses of their constituent species groups. Location European mountains below 50° N. Time period Between 1928 and 2019. Major taxa studied Vascular plants. Methods We compiled species pools from alpine grasslands in 23 regions, including 794 alpine species and 2,094 non‐alpines. We used species–area relationships to test the influence of the extent of alpine areas on regional richness, and mixed‐effects models to compare the effects of 12 spatial and environmental predictors. Variation in species composition was addressed by generalized dissimilarity models and by a coefficient of dispersal direction to assess historical links among regions. Results Pool sizes were partially explained by current alpine areas, but the other predictors largely contributed to regional differences. The number of alpine species was influenced by area, calcareous bedrock, topographic heterogeneity and regional isolation, while non‐alpines responded better to connectivity and climate. Regional dissimilarity of alpine species was explained by isolation and precipitation, but non‐alpines only responded to isolation. Past dispersal routes were correlated with latitude, with alpine species showing stronger connections among regions. Main conclusions Besides area effects, edaphic, topographic and spatio‐temporal determinants are important to understand the organization of regional species pools in alpine habitats. The number of alpine species is especially linked to refugia and isolation, but their composition is explained by past dispersal and post‐glacial environmental filtering, while non‐alpines are generally influenced by regional floras. New research on the dynamics of alpine biodiversity should contextualize the determinants of regional species pools and the responses of species with different ecological profiles.

Checklist of the vascular plants of the Cantabrian Mountains

“…Mountains of León are expected given their geographic proximity . Indeed, the two mountain systems have been recently considered as a single biogeographical unit (Fernández-Prieto et al, 2020) and a single refugia for alpine species in Europe (Jiménez-Alfaro et al, 2021). From cold alpine (1) to cool subalpine (3), submontane (5), warm lowland (7) and warmest (9) temperatures.…”

Global functional variation in alpine vegetation

“…Global alpine areas can be grouped according to their macroclimate (Testolin et al, 2020), and they are linked to different vegetation zones (Walter & Box, 1976) and biomes characterised by their distinct evolutionary history and own species pools (Mucina, 2019). Indeed, present-day alpine floras are the result of upward shifts of species undergoing regional radiations and long-distance migrations associated with the displacement of cold-climate biomes, such as during the Pleistocene glacial cycles (Billings, 1974;Horandl & Emadzade, 2011;Jiménez-Alfaro et al, 2021). The historical legacy of ancestral species, which may have belonged to different vegetation zones and biogeographic realms, together with the environmental filtering of the current macroclimate, have determined the diversity of alpine trait pools, i.e.…”

Why Is the Alpine Flora Comparatively Robust against Climatic Warming?

“…The 'drama' of glaciation and deglaciation of alpine terrain recurred 8-10 times during the last 1 million years, meaning that all but some rock flora on so-called nunatak outcrops [48] that protruded the ice shield became locally eradicated and pushed into refugia at the low elevation edges of the ice shield [49]. Since these refugia were often not connected, the fingerprints of genetic differentiation into clusters of greater similarity within species can still be found in the current alpine flora [4,[50][51][52]. The different routes of re-colonisation added to such patterns [53].…”