Glacial refugia, recolonization patterns and diversification forces in Alpine-endemic Megabunus harvestmen
The Pleistocene climatic fluctuations had a huge impact on all life forms, and various hypotheses regarding the survival of organisms during glacial periods have been postulated. In the European Alps, evidence has been found in support of refugia outside the ice shield (massifs de refuge) acting as...
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| Published in | Molecular ecology Vol. 25; no. 12; pp. 2904 - 2919 |
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| Main Authors | , , , , , , |
| Format | Journal Article |
| Language | English |
| Published |
England
Blackwell Publishing Ltd
01.06.2016
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| Subjects | |
| Online Access | Get full text |
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| Summary: | The Pleistocene climatic fluctuations had a huge impact on all life forms, and various hypotheses regarding the survival of organisms during glacial periods have been postulated. In the European Alps, evidence has been found in support of refugia outside the ice shield (massifs de refuge) acting as sources for postglacial recolonization of inner‐Alpine areas. In contrast, evidence for survival on nunataks, ice‐free areas above the glacier, remains scarce. Here, we combine multivariate genetic analyses with ecological niche models (ENMs) through multiple timescales to elucidate the history of Alpine Megabunus harvestmen throughout the ice ages, a genus that comprises eight high‐altitude endemics. ENMs suggest two types of refugia throughout the last glacial maximum, inner‐Alpine survival on nunataks for four species and peripheral refugia for further four species. In some geographic regions, the patterns of genetic variation are consistent with long‐distance dispersal out of massifs de refuge, repeatedly coupled with geographic parthenogenesis. In other regions, long‐term persistence in nunataks may dominate the patterns of genetic divergence. Overall, our results suggest that glacial cycles contributed to allopatric diversification in Alpine Megabunus, both within and at the margins of the ice shield. These findings exemplify the power of ENM projections coupled with genetic analyses to identify hypotheses about the position and the number of glacial refugia and thus to evaluate the role of Pleistocene glaciations in driving species‐specific responses of recolonization or persistence that may have contributed to observed patterns of biodiversity. |
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| Bibliography: | ark:/67375/WNG-T5S7S7ZD-V ArticleID:MEC13634 University of Innsbruck - No. DEB 1118815 istex:FD4547EA68964ED1FADADAAAF6E2C602C4D98C3E Figs S1-S5 ENMs per species and projections to the present, as well as two time-periods in the past (mid-Holocene and LGM). Fig. S1 ENMs M. armatus. Fig. S2 ENMs M. lesserti. Fig. S3 ENMs M. vignai. Fig. S4 ENMs M. bergomas complex. Fig. S5 ENMs M. rhinoceros complex. Fig. S6 Areas of stability for MIROC (left) and CCSM model predictions (right) as in Fig. , but in greater detail. Sampling localities are displayed separately for species and model: A) M. armatus MIROC, B) M. armatus CCSM, C) M. lesserti MIROC, D) M. lesserti CCSM, E) M. vignai MIROC, F) M. vignai CCSM. Fig. S7 Areas of stability for MIROC (left) and CCSM model predictions (right) as in Fig. , but in greater detail. Sampling localities are displayed separately for species and model: A) M. bergomas complex MIROC, B) M. bergomas complex CCSM, C) M. rhinoceros complex MIROC, D) M. rhinoceros complex CCSM. Fig. S8 Procrustes transformation plots per species to assess association between genetic differentiation and geography (left plot) and genetic differentiation and environmental resistance (right plot). Putatively parthenogenetic populations of M. vignai and M. lesserti are labelled red. Figs S19-S13 Median-joining haplotype networks of M. armatus, M. bergomas, M. cryptobergomas, M. coelodonta, M. rhinoceros, M. lentipes, M vignai, and M. lesserti. Species are colour coded according to Fig. , populations are labelled, and the haplotype-size is proportional to the number of individuals sharing it. Putatively parthenogenetic populations of M. vignai and M. lesserti are indicated through red coloured lines. Fig. S9 Median-joining haplotype network M. armatus. Fig. S10 Median-joining haplotype networks: a) M. cryptobergomas, b) M. bergomas. Fig. S11 Median-joining haplotype networks a) M. lentipes, b) M. rhinoceros, c) M. coelodonta. Fig. S12 Median-joining haplotype network M. lesserti. Fig. S13 Median-joining haplotype network M. vignai. Fig. S14 Potential areas of long-term stability based on the CCSM model and inferred separately for each taxon (see Figs S6, S7 for individual plots). Areas were identified based on grid cells with habitat suitability scores above the 'maximum training sensitivity plus specificity' threshold throughout all three time periods (current conditions, mid-Holocene and LGM) and were not predicted to be covered by glacier in the LGM. Predictions are based on six bioclimatic variables. Note that for M. vignai, no suitable habitat above the MTSS threshold for the mid-Holocene period (Fig. S3) was predicted and in that case stability was assessed based only on current conditions and LGM. Fig. S15 Principal component analysis of the final nine-bioclimatic-variable set computed separately for the M. bergomas complex and the M. rhinoceros complex to assess environmental differences across the sampling localities. Fig. S16 Temporal framework of Megabunus diversification computed with *BEAST. The scale is in million years (Mya) and geological epochs are indicated above the x-axis. Posterior probabilities of the species tree >0.7 are indicated above nodes, and bars indicate 95% highest posterior density intervals. Table S1 Exact geographic location for the populations of the eight Megabunus species with genetic data available. Data were taken from Wachter et al. (). Table S2 Geographic position of literature records used as occurrence records in ecological niche modelling. Table S3 GenBank accession numbers for the mtDNA locus for all specimens used in this study, nuDNA sequences are available as alignments; data are taken from Wachter et al. (). Autonomous Province of South Tyrol - No. 320/138020 ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
| ISSN: | 0962-1083 1365-294X |
| DOI: | 10.1111/mec.13634 |