Niche expansion can lead to adaptive differentiation and speciation, but there are few
examples from contemporary niche expansions about how this process is initiated. We …

Low-elevation regions harbour the majority of the world's species diversity compared to high-
elevation areas. This global gradient suggests that lowland species have had more time to …

Adaptation to local environmental conditions and the range dynamics of populations can
influence evolutionary divergence along environmental gradients. Thus, it is important to …

Discerning the relative roles of adaptive and nonadaptive processes in generating
differences among populations and species, as well as how these processes interact, is a …

Variation in species richness across environmental gradients may be associated with an
expanded volume or increased packing of ecological niche space. However, the relative …

Physical barriers to gene flow were once viewed as prerequisites for adaptive evolutionary
divergence. However, a growing body of theoretical and empirical work suggests that …

The capacity of species to track changing environmental conditions is a key component of
population and range changes in response to environmental change. High levels of local …

Elucidating forces capable of driving species diversification in the face of gene flow remains
a key goal in evolutionary biology. Song sparrows, Melospiza melodia, occur as 25 …

Correlations between species richness and climate suggest non-random occupation of
environmental space and niche evolution through time. However, the evolutionary …

Understanding geographic variation in the species richness and lineage composition of
regional biotas is a long-standing goal in ecology. Why do some evolutionary lineages …