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Two New Hybrid Dendroica Warblers and New Methodology for Inferring Parental Species
Vol. 111, No. 2 (Apr., 1994), pp. 441-449
Published by: American Ornithological Society
Stable URL: http://www.jstor.org/stable/4088607
Page Count: 9
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A phenotypic hybrid between Dendroica townsendi × D. nigrescens is described from coastal British Columbia. It carried the mitochondrial-DNA (mtDNA) haplotype of nigrescens, indicating a nigrescens mother in the original cross that led to this hybrid. This specimen is used to demonstrate the special value of "contradictory characters" in refuting alternate hypotheses of parentage for hybrids. Contradictory characters exist when a potential hybrid exhibits character states more extreme than those found in both of a possible pair of parents. While intermediate characters can suggest a hybrid ancestry, intermediate character states may also be consistent with a variety of potential pairs of species as parents, a point I demonstrate using this townsendi × nigrescens hybrid. Phenotypically, the second specimen is a typical townsendi, but its mtDNA haplotype was that of virens. An extensive survey of townsendi haplotypes revealed no other polymorphism for the virens haplotype; furthermore, at least four mutations would be required to move from a townsendi to a virens haplotype. Together these observations suggest that this specimen is a highly backcrossed descendent of a townsendi × virens cross, a hypothesis consistent with the fact that this specimen was collected where the ranges of townsendi and virens very nearly make contact in the Rocky Mountains of British Columbia.
The Auk © 1994 American Ornithologists' Union