Historical contingency, niche conservatism and the tendency for some taxa to be more diverse towards the poles
- Published
- Accepted
- Subject Areas
- Biodiversity, Biogeography, Ecology, Climate Change Biology, Spatial and Geographic Information Science
- Keywords
- Biotic exchange, niche conservatism, time-for-speciation effect, species richness, reversed diversity gradients, diversification, Bering land bridge, latitudinal diversity gradient, mammals
- Copyright
- © 2018 Morales-Castilla et al.
- Licence
- This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ Preprints) and either DOI or URL of the article must be cited.
- Cite this article
- 2018. Historical contingency, niche conservatism and the tendency for some taxa to be more diverse towards the poles. PeerJ Preprints 6:e26440v1 https://doi.org/10.7287/peerj.preprints.26440v1
Abstract
Successful explanations for diversity gradients should account for both the generalized tendency towards a higher tropical diversity and its exceptions. Moreover, identifying exceptions to general trends, such as the latitudinal diversity gradient can give insight into the mechanistic explanations responsible for structuring them. The Cenozoic biotic exchange of mammals across the Bering land-bridge provides an illuminating case-study. It allows comparing the diversity of clades that participated in the exchange (colonizers), whose ancestors withstood the Beringian cold temperatures, with that of the clades that did not participate (sedentaries). We find that assemblages of colonizers are more diverse towards higher latitudes, opposing the traditional latitudinal diversity gradient which is followed by sedentaries. Despite the long passage of time since this major dispersal event, the geographic distribution of colonizers is more strongly correlated to the distributions of other colonizers inhabiting a different continent than by the distribution of sedentary species. These results highlight the importance of historical migrations and dispersal in configuring present-day diversity gradients. Importantly, we also suggest that colonizers may be particularly vulnerable to projected climate change because of the predicted decrease in climate space in the extra-tropical realm where they are currently most diverse.
Author Comment
This is a preprint submission to PeerJ Preprints.
Supplemental Information
Supplemental files including Appendices S1-S7
Appendix S1 Species list and classification.
Appendix S2 Detailed results from MEMs.
Appendix S3 Model verification.
Appendix S4 Moran’s I spatial autocorrelation analyses.
Appendix S5 Phylogenetic analyses of variation in richness-temperature slopes.
Appendix S6 Cross-predictions among phylogenetic models of climatic tolerances.
Appendix S7 Diversification analyses for the subsets of colonizers and sedentary mammal species.