The regional species richness and genetic diversity of Arctic vegetation reflect both past glaciations and current climate

Abstract

Aim The Arctic has experienced marked climatic differences between glacial and interglacial periods and is now subject to a rapidly warming climate. Knowledge of the effects of historical processes on current patterns of diversity may aid predictions of the responses of vegetation to future climate change. We aim to test whether plant species and genetic diversity patterns are correlated with time since deglaciation at regional and local scales. We also investigate whether species richness is correlated with genetic diversity in vascular plants.Location Circumarctic. MethodsWe investigated species richness of the vascular plant flora of 21 floristic provinces and examined local species richness in 6215 vegetation plots distributed across the Arctic. We assessed levels of genetic diversity inferred from amplified fragment length polymorphism variation across populations of 23 common Arctic species. Correlations between diversity measures and landscape age (time since deglaciation) as well as variables characterizing current climate were analysed using spatially explicit simultaneous autoregressive models. ResultsRegional species richness of vascular plants and genetic diversity were correlated with each other, and both showed a positive relationship with landscape age. Plot species richness showed differing responses for vascular plants, bryophytes and lichens. At this finer scale, the richness of vascular plants was not significantly related to landscape age, which had a small effect size compared to the models of bryophyte and lichen richness. Main conclusionOur study suggests that imprints of past glaciations in Arctic vegetation diversity patterns at the regional scale are still detectable today. Since Arctic vegetation is still limited by post-glacial migration lag, it will most probably also exhibit lags in response to current and future climate change. Our results also suggest that local species richness at the plot scale is more determined by local habitat factors.

Flower‐visitor communities of an arcto‐alpine plant—Global patterns in species richness, phylogenetic diversity and ecological functioning

“…The positive association between faunistic and floristic similarities (Figure , Supplemental information) suggests that the two communities have been moulded by the same biogeographical processes, in particular by similar refugial and post‐glacial history (a pattern robust to controls for confounding patterns; Table , Supplemental information). To evaluate whether this interpretation holds true, we compared our results to the distribution of genetic diversity and the borders for gene flow found in vascular plants (Eidesen et al., ; Stewart et al., ). In both studies, plant genetic diversity was found to be highest in “Beringia” (Hultén, ), that is, the area around the Bering Strait, a region that was never glaciated during the Pleistocene (Dyke ).…”

Future directions and priorities for Arctic bryophyte research

“…We discuss the utility of museum collections, providing a brief discussion of digitally accessible specimen data, in conjunction with molecular data to understand how species richness, based on morphological species concepts, reflects genetic diversity. Genetic diversity and species richness are positively correlated for Arctic vascular plants (Stewart et al 2016), but this hypothesis remains untested for Arctic bryophytes, as data for bryophyte genetic diversity are limited at both taxonomic and spatial scales ).…”

“…Here we use refugium to describe an area that was ice free and may have allowed for the survival of bryophytes during the LGM. Refugia are predicted to now harbor a higher diversity in terms of species richness and allelic diversity relative to surrounding areas (Hewitt 1996;Stewart et al 2016). High relative diversity may also be attributed to contact zones for populations with high dispersal potential (Kyrkjeeide et al 2014); however, refugial populations are expected to have more rare alleles (Comps et al 2001;Petit et al 2003).…”

“…Correlation between landscape age and bryophyte species diversity at a fine scale suggests that there may be postglacial migration lag, and traces of the Pleistocene glaciations may still be apparent in the genetic diversity of the flora (Stewart et al 2016). We can predict, then, that the bryophyte floras of formerly glaciated areas should be more species poor (and exhibit lower genetic diversity) compared to refugial areas.…”

The Greenland vascular plant herbarium of the University of Copenhagen

“…We have contributed to Walker et al 2005) and Arctic Vegetation Archive (Walker et al 2013) plus Conservation of Arctic Flora and Fauna (Aronsson et al, in preparation;Talbot et al 1999). Stewart et al (2016) used the results of many of the vegetation studies for modelling the regional vegetation richness on plot and landscape scales and related it to past glaciations and current climate.…”