The classification of reproductive isolating barriers laid out by Dobzhansky and Mayr has
motivated and structured decades of research on speciation. We argue, however, that this …

The most common classification of modes of speciation begins with the spatial context in
which divergence occurs: sympatric, parapatric or allopatric. This classification is …

The outcome of natural hybridization is highly variable and depends on the nonexclusive
effects of both pre‐and post‐mating reproductive barriers. The objective of this study was to …

One of the longest debates in biology has been over the relative importance of different
isolating barriers in speciation. However, for most species, there are few data evaluating …

Alpine biotas are paradigmatic of the countervailing roles of geographical isolation and
dispersal during diversification. In temperate regions, repeated distributional shifts driven by …

Hybrid zone theory provides a powerful theoretical framework for measuring and testing
gene flow and selection. The Senecio aethnensis and Senecio chrysanthemifolius hybrid …

The climate is often evoked to explain broad‐scale clines of body size, yet its involvement in
the processes that generate size inequality in the two sexes (sexual size dimorphism) …

The grasshoppers Chorthippus brunneus and Chorthippus jacobsi are highly differentiated
for male mating signals, and form a mosaic hybrid zone in northern Spain. At some sites …

In recently diverged species, ancestral polymorphism and introgression can cause
incongruence between gene and species trees. In the face of hybridization, few genomic …

When lineages diverge in allopatry and come into secondary contact, we have a unique
opportunity to examine the degree to which they have become reproductively isolated from …