| interspecific variability of prevalence in blood parasites of adult passerine birds during the breeding season in alaska. | blood parasite prevalence based on microscopic examination of stained blood smears was determined in adults of 11 passerine bird species sampled during their breeding season (may and june 1997-98) in interior alaska (usa). these species included primarily nearctic migratory species such as the dark-eyed junco (junco hyemalis) and neotropical migratory species such as the blackpoll warbler (dendroica striata), alder flycatcher (empidonax alnorum), swainson's thrush (catharus ustulatus), northern ... | 2001 | 11272501 |
| 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 |
| cultural isolation is greater than genetic isolation across an avian hybrid zone. | elucidating the relationship between genetic and cultural evolution is important in understanding speciation, as learned premating barriers might be involved in maintaining species differences. here, we test this relationship by examining a widely recognized premating barrier, bird song, in a hybrid zone between black-throated green (setophaga virens) and townsend's warblers (s. townsendi). we use song analysis, genomic techniques and playback experiments to characterize the cultural and genetic ... | 2017 | 27732753 |
| 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 |