Climate and geochemistry as drivers of eucalypt diversification in Australia

Bui, E.N., Thornhill, A.H., González-Orozco, C.E., Knerr, N., and Miller, J.T. (2017) Climate and geochemistry as drivers of eucalypt diversification in Australia. Geobiology, 15 (3). pp. 427-440.

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Abstract

Eucalypts cover most of Australia. Here, we investigate the relative contribution of climate and geochemistry to the distribution and diversity of eucalypts. Using geostatistics, we estimate major element concentrations, pH, and electrical conductivity at sites where eucalypts have been recorded. We compare the median predicted geochemistry and reported substrate for individual species that appear associated with extreme conditions; this provides a partial evaluation of the predictions. We generate a site-by-species matrix by aggregating observations to the centroids of 100-km-wide grid cells, calculate diversity indices, and use numerical ecology methods (ordination, variation partitioning) to investigate the ecology of eucalypts and their response to climatic and geochemical gradients. We find that β-diversity coincides with variations in climatic and geochemical patterns. Climate and geochemistry together account for less than half of the variation in eucalypt species assemblages across Australia but for greater than 80% in areas of high species richness. Climate is more important than geochemistry in explaining eucalypts species distribution and change in assemblages across Australia as a whole but there are correlations between the two sets of environmental variables. Many individual eucalypt species and entire taxonomic sections (Aromatica, Longistylus of subgenus Eucalyptus, Dumaria, and Liberivalvae of subgenus Symphyomyrtus) have distributions affected strongly by geochemistry. We conclude that eucalypt diversity is driven by steep geochemical gradients that have arisen as climate patterns have fluctuated over Australia over the Cenozoic, generally aridifying since the Miocene. The diversification of eucalypts across Australia is thus an excellent example of co-evolution of landscapes and biota in space and time and challenges accepted notions of macroecology.

Item ID: 52059
Item Type: Article (Research - C1)
ISSN: 1472-4669
Keywords: climate; geochemistry; eucalypt diversification; distribution;
Date Deposited: 26 Feb 2018 05:46
FoR Codes: 06 BIOLOGICAL SCIENCES > 0603 Evolutionary Biology > 060303 Biological Adaptation @ 50%
06 BIOLOGICAL SCIENCES > 0603 Evolutionary Biology > 060306 Evolutionary Impacts of Climate Change @ 50%
SEO Codes: 96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960805 Flora, Fauna and Biodiversity at Regional or Larger Scales @ 40%
97 EXPANDING KNOWLEDGE > 970105 Expanding Knowledge in the Environmental Sciences @ 40%
96 ENVIRONMENT > 9603 Climate and Climate Change > 960305 Ecosystem Adaptation to Climate Change @ 20%
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