Abstract
Topographic change shapes the evolution of biodiversity by influencing both habitat connectivity and habitat diversity as well as abiotic factors like climate. However, its role in creating global biodiversity gradients remains poorly characterized because geology, climate and evolutionary data have rarely been integrated across concordant timescales. Here we show that topographic uplift over the last 3 million years explains more spatial variation in the speciation of all mammals and birds than do the direct effects of palaeoclimate change and both present-day elevation and present-day temperature. By contrast, the effects of topographic changes are much smaller than those of present-day temperatures in eroded areas. Together, our results stress that historical geological processes rather than traditionally studied macroecological gradients may ultimately generate much of the world’s biodiversity. More broadly, as the Earth’s surface continues to rise and fall, topography will remain an important driver of evolutionary change and novelty.
Highlights
Topographic change shapes the evolution of biodiversity by influencing both habitat connectivity and habitat diversity as well as abiotic factors like climate
Speciation rates increased by a mean of 11% (95% confidence interval (CI): 9 to 13%) and 10% in mammals and birds, respectively, for a 1 standard deviation (s.d.) gain in elevation of 195 m above the mean change in uplift cells of 144 m
We found that historical elevation uplift explained more spatial variation in speciation of two large vertebrate classes than did the direct effects of present-day environmental conditions
Summary
Topographic change shapes the evolution of biodiversity by influencing both habitat connectivity and habitat diversity as well as abiotic factors like climate. Ecological opportunity linked to the Andean uplift has been shown to drive the fast radiation of endemic lupines[7] Together, these two mechanisms may explain why global species richness increases with topographic relief[8] and why high-elevation bird lineages speciate at faster rates than low-lying relatives[9]. Greater climatic instability arising from topographic change may have promoted rapid and repeated ecological speciation by creating novel niches and increased ecological opportunity[16,23] This relationship between climatic instability and speciation may, be non-linear, as higher speciation rates have been linked with areas of high climatic stability like Pleistocene refugia[24]. The complex interactions between climate and geology have not to our knowledge been explicitly modelled when attempting to explain patterns of biodiversity at large scales
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