Abstract
Species richness and genetic diversity are the two most fundamental products of evolution. Both are important conservation targets—species richness contributes to ecosystem functioning and human wellbeing, while genetic diversity allows those species to respond to changes in their environment and persist in the long-term. Biogeographic patterns of species richness are well-described, but we know little about patterns of genome-wide genetic diversity at similar spatial scales. Further, despite considerable attention to latitudinal trends in species richness, we still do not have a solid empirical understanding of the various processes that produce them, how they interact, or how they affect genetic diversity. Here we show that genome-wide genetic diversity and species richness share spatial structure, however, species richness hotspots tend to harbor low levels of within-species genetic variation. A single model encompassing eco-evolutionary processes related to environmental energy availability, niche availability, and proximity to humans explained 75% of variation in gene diversity and 90% of the variation in species richness. Our empirical model of both levels of biodiversity supports theory and demonstrates the importance of carrying capacity and ecological opportunity at individual and species levels for generating continent-wide genetic and species diversity gradients.
Competing Interest Statement
The authors have declared no competing interest.