The ecological consequences of winter in freshwater systems are an understudied but rapidly emerging research area. Here, we argue that winter periods of reduced temperature and light (and potentially oxygen and resources) could play an underappreciated role in mediating the coexistence of species. This may be especially true for temperate and subarctic lakes, where seasonal changes in the thermal environment might fundamental...

In hybrid zones in which two divergent taxa come into secondary contact and interbreed, selection can maintain phenotypic diversity despite widespread genetic introgression. Red‐breasted ( Sphyrapicus ruber ) and red‐naped ( S. nuchalis ) sapsuckers meet and hybridize along a narrow contact zone that stretches from northern California to southern British Columbia. We found strong evidence for changes in the structure of this h...

Although theoretical models predict that the structure of a hybrid zone can change under a variety of scenarios, only a few empirical studies of hybrid zones have unequivocally demonstrated zone movement. These studies are rare because few data sets exist that include repeated, temporally spaced, samples of the same hybrid zone. We analysed mitochondrial DNA haplotype data from samples separated by 40–45 years from across the...

Sex‐chromosomes are thought to play an important role in speciation, but few studies of non‐model organisms have investigated the relative influence of multiple sex‐linked markers on reproductive isolation. We collected 222 individuals along a geographical transect spanning the hybrid zone between Passerina amoena and P. cyanea (Aves: Cardinalidae). Using maximum‐likelihood cline fitting methods, we estimated locus‐specific in...