| ongoing movement of the hermit warbler x townsend's warbler hybrid zone. | movements of hybrid zones - areas of overlap and interbreeding between species - are difficult to document empirically. this is true because moving hybrid zones are expected to be rare, and because movement may proceed too slowly to be measured directly. townsend's warblers (dendroica townsendi) hybridize with hermit warblers (d. occidentalis) where their ranges overlap in washington and oregon. previous morphological, behavioral, and genetic studies of this hybrid zone suggest that it has been ... | 2010 | 21152406 |
| a 2000 km genetic wake yields evidence for northern glacial refugia and hybrid zone movement in a pair of songbirds. | hybrid zones are natural experiments that expose the forces maintaining species differences. but for cases where a trait of one of the hybridizing pair appears shifted into the range of the other, the underlying mechanism can be difficult to infer. for example, hybridization between hermit warbler (dendroica occidentalis) and townsend's warbler (dendroica townsendi) is restricted to narrow hybrid zones in washington and oregon, yet hermit mtdna can be found in phenotypically pure townsend's popu ... | 2009 | 18986973 |
| androgens, interspecific competition and species replacement in hybridizing warblers. | the steroid hormone testosterone regulates aggressive behaviour in many vertebrates and is important for territorial defence among males of the same species. however, its role in mediating interspecific competition, and ultimately species distributions, is unknown. we show that testosterone may influence the geographical replacement of one species by another. townsend's warblers (dendroica townsendi) have replaced hermit warblers (d. occidentalis) over a vast portion of their historical range, p ... | 2004 | 15801615 |
| plumage and mitochondrial dna haplotype variation across a moving hybrid zone. | we analyze variation in phenotypes and mitochondrial dna (mtdna) haplotypes over the breeding ranges of hermit and townsend's warblers and across two of their three hybrid zones. within these two hybrid zones, we demonstrate that the placement, shape, and width of transitions in seven plumage characters are remarkably similar, suggesting that a balance between dispersal and sexual selection keeps these hybrid zones narrow. a consistent asymmetry in these character transition curves suggests that ... | 2001 | 11308096 |
| mitochondrial restriction fragment length polymorphism (rflp) and sequence variation among closely related avian species and the genetic characterization of hybrid dendroica warblers. | to address several interconnected goals, we used mitochondrial dna (mtdna) sequences to explore evolutionary relationships among four potentially hybridizing taxa in a north american avian superspecies (dendroica occidentalis, d. townsendi, d. virens, and d. nigrescens). we first compared the results of a previous restriction fragment length polymorphism (rflp)-based study with 1453 nucleotides from the mitochondrial cytochrome oxidase subunit i (coi), atp-synthase 6 (atpase 6), and atp-synthase ... | 1999 | 10564448 |
| cross-decades stability of an avian hybrid zone. | hybrid zones are particularly valuable for understanding the evolution of partial reproductive isolation between differentiated populations. an increasing number of hybrid zones have been inferred to move over time, but in most such cases zone movement has not been tested with long-term genomic data. the hybrid zone between townsend's warblers (setophaga townsendi) and hermit warblers (s. occidentalis) in the washington cascades was previously inferred to be moving from northern s. townsendi sou ... | 2019 | 31430391 |