New preprint: mtDNA-based reconstructions of change in effective population sizes of Holarctic birds do not agree with their reconstructed range sizes based on paleoclimates

European robin (Erithacus rubecula), picture by Michela Leonardi
European robin (Erithacus rubecula), one of the species analysed in the study.
Picture by Michela Leonardi

A new preprint to which I collaborated was just submitted to BioRxiv: mtDNA-based reconstructions of change in effective population sizes of Holarctic birds do not agree with their reconstructed range sizes based on paleoclimates. The work is led by Eleanor Miller, and was performed under the supervision of Andrea Manica and Bill Amos (University of Cambridge).  

Eleanor F. Miller, Rhys E. Green, Andrew Balmford, Robert Beyer, Marius Somveille, Michela Leonardi, William Amos, Andrea Manica

mtDNA-based reconstructions of change in effective population sizes of Holarctic birds do not agree with their reconstructed range sizes based on paleoclimates

During the Quaternary, large climate oscillations had profound impacts on the distribution, demography and diversity of species globally. Birds offer a special opportunity for studying these impacts because surveys of geographical distributions, publicly-available genetic sequence data, and the existence of species with adaptations to life in structurally different habitats, permit large-scale comparative analyses. We use Bayesian Skyline Plot (BSP) analysis of mitochondrial DNA to reconstruct profiles depicting how effective population size (Ne) may have changed over time, focussing on variation in the effect of the last deglaciation among 102 Holarctic species. Only 3 species showed a decline in Ne since the Last Glacial Maximum (LGM) and 7 showed no sizeable change, whilst 92 profiles revealed an increase in Ne. Using bioclimatic Species Distribution Models (SDMs), we also estimated changes in species potential range extent since the LGM. Whilst most modelled ranges also increased, we found no correlation across species between the magnitude of change in range size and change in Ne. The lack of correlation between SDM and BSP reconstructions could not be reconciled even when range shifts were considered. We suggest the lack of agreement between these measures might be linked to changes in population densities which can be independent of range changes. We caution that interpreting either SDM or BSPs independently is problematic and potentially misleading. Additionally, we found that Ne of wetland species tended to increase later than species from terrestrial habitats, possibly reflecting a delayed increase in the extent of this habitat type after the LGM.

bioRxiv 2019.12.13.870410; doi: https://doi.org/10.1101/2019.12.13.870410

New paper: Late Quaternary horses in Eurasia in the face of climate and vegetation change

Horses in Camargue, France. Photo by Michela Leonardi
Horses in Camargue, France. Photo by Michela Leonardi

It just came out in Science Advances our paper “Late Quaternary horses in Eurasia in the face of climate and vegetation change“, done in collaboration with Ludovic Orlando (Copenhagen/Toulouse), David Nogues-Bravo (Copenhagen), Andrea Manica (Cambridge), Francesco Boschin and Paolo Boscato (Siena), and many other excellent scientists!

This study represents the most ambitious effort so far to reconstruct the palaeoecology of the horse in Eurasia through more than 40 thousand years to gain a better understanding of their population dynamics through space and time. Our results suggest that European and Asian horses show different climatic adaptations;  allow a better understanding of the progressive reduction in European horse remains during the Holocene, and shed new light on potential domestication centres.

Michela Leonardi, Francesco Boschin, Konstantinos Giampoudakis, Robert M. Beyer, Mario Krapp, Robin Bendrey, Robert Sommer, Paolo Boscato, Andrea Manica, David Nogues-Bravo and Ludovic Orlando

Late Quaternary horses in Eurasia in the face of climate and vegetation change

Wild horses thrived across Eurasia until the Last Glacial Maximum to collapse after the beginning of the Holocene. The interplay of climate change, species adaptability to different environments, and human domestication in horse history is still lacking coherent continental-scale analysis integrating different lines of evidence. We assembled temporal and geographical information on 3070 horse occurrences across Eurasia, frequency data for 1120 archeological layers in Europe, and matched them to paleoclimatic and paleoenvironmental simulations for the Late Quaternary. Climate controlled the distribution of horses, and they inhabited regions in Europe and Asia with different climates and ecosystem productivity, suggesting plasticity to populate different environments. Their decline in Europe during the Holocene appears associated with an increasing loss and fragmentation of open habitats. Europe was the most likely source for the spread of horses toward more temperate regions, and we propose both Iberia and central Asia as potential centers of domestication.

Science Advances, Vol. 4, no. 7, eaar5589