Christy M. McCain

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The diversity of life is ultimately generated by evolution, and much attention has focused on the rapid evolution of ecological traits. Yet, the tendency for many ecological traits to instead remain similar over time [niche conservatism (NC)] has many consequences for the fundamental patterns and processes studied in ecology and conservation biology. Here,(More)
A latitudinal gradient in biodiversity has existed since before the time of the dinosaurs, yet how and why this gradient arose remains unresolved. Here we review two major hypotheses for the origin of the latitudinal diversity gradient. The time and area hypothesis holds that tropical climates are older and historically larger, allowing more opportunity for(More)
The striking ecological changes that occur along elevational gradients drew the attention of early researchers, such as Darwin (1839, 1859), von Humboldt (1849), Wallace (1876, 1878) and Merriam (1890). Although latitudinal gradients in species richness have received more attention, elevational patterns have been addressed in the literature recently for(More)
A global analysis of elevational diversity trends for nonvolant small mammals revealed a clear pattern of mid-elevational peaks in species richness. Fifty-six data sets were used to test the predictions of a null model (the mid-domain effect) and climatic hypotheses. Very few data sets fit entirely within the predictions of the null model, and the average(More)
Aim A global meta-analysis was used to elucidate a mechanistic understanding of elevational species richness patterns of bats by examining both regional and local climatic factors, spatial constraints, sampling and interpolation. Based on these results, I propose the first climatic model for elevational gradients in species richness, and test it using(More)
Aim Elevational gradients distributed across the globe are a powerful test system for understanding biodiversity. Here I use a comprehensive set of bird elevational gradients to test the main drivers of diversity, including sampling, area, mid-domain effect, temperature, temperature and water availability, and hypotheses of evolutionary history. Location(More)
Elevational gradients hold enormous potential for understanding general properties of biodiversity. Like latitudinal gradients, the hypotheses for diversity patterns can be grouped into historical explanations, climatic drivers, and spatial hypotheses. The spatial hypotheses include the species-area effect and spatial constraint (mid-domain effect null(More)
The elevational gradient in plant and animal diversity is one of the most widely documented patterns in ecology and, although no consensus explanation exists, many hypotheses have been proposed over the past century to explain these patterns. Historically, research on elevational diversity gradients has focused almost exclusively on plant and animal taxa.(More)
In 1967, Daniel Janzen proposed the influential, but largely untested hypothesis, that tropical mountain passes are physiologically higher than temperate mountains. I test his key prediction, the one upon which all the others rely: namely, that elevational range sizes of organisms get larger on mountains at increasing latitudes. My analyses use 170 montane(More)