Browsing by Author "Lovell, Scott Foley"

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    Vocal, morphological, and molecular interactions between vireo taxa in Alberta
    (2010) Lovell, Scott Foley; Lein, M. Ross
    During the Pleistocene glaciations split the ranges of many North American species into disjunct populations that survived within ice-free refugia. These populations subsequently diverged genetically and phenotypically. After the glaciers receded many of these sister populations came into secondary contact and show distinct eastern and western forms (taxa). Such populations demonstrate various stages of speciation with some having reached partial, but not complete, reproductive isolation. One such example is provided by two subspecies of the Warbling Vireo (Vireo gilvus). The Eastern Warbling Vireo (Vireo g. gilvus) and the Western Warbling Vireo (V g. swainsoni) come into secondary contact in central Alberta. A previous study found differences in mitochondrial DNA (mtDNA) between the two taxa, and antidotal accounts suggest differences in song, morphology, and plumage coloration as well. My objectives were to analyze whether patterns of variation in mtDNA (Cyt b), song, morphometrics, and plumage are sufficiently distinct between the taxa to warrant their recognition as separate biological species, and to infer the level of hybridization occurring in the contact zone. My results indicate that the two taxa of Warbling Vireo are distinct in all of the characters examined. The two taxa come into contact in a very narrow ( < 50 km) area in Barrhead County northwest of Edmonton, Alberta. They show few signs of extensive hybridization. The distinct differences are maintained in the contact zone, where individuals of the two taxa were found occupying neighboring territories. These results lead me to conclude that they two taxa represent two distinct cryptic species: an eastern form, Vireo gilvus, and a western form, Vireo swainsoni. My findings add to the list of cryptic species discovered in the last 10 years, using DNA along with more traditional taxonomic characters (morphology and plumage). My results further our understanding the selective forces that maintain narrow contact zones, and gives insight into the evolutionary history shaping the biota of Alberta.