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Full-Text Articles in Life Sciences
Mexican Jay (Aphelocoma Ultramarina), John Mccormack, L. Brown
Mexican Jay (Aphelocoma Ultramarina), John Mccormack, L. Brown
John E. McCormack
No abstract provided.
Niche Expansion Leads To Small-Scale Adaptive Divergence Along An Elevation Gradient In A Medium-Sized Passerine Bird, John Mccormack, Thomas Smith
Niche Expansion Leads To Small-Scale Adaptive Divergence Along An Elevation Gradient In A Medium-Sized Passerine Bird, John Mccormack, Thomas Smith
John E. McCormack
Niche expansion can lead to adaptive differentiation and speciation, but there are few examples from contemporary niche expansions about how this process is initiated. We assess the consequences of a niche expansion by Mexican jays (Aphelocoma ultramarina) along an elevation gradient. We predicted that jays at high elevation would have straighter bills adapted to feeding on pine cones, whereas jays at low elevation would have hooked bills adapted to feeding on acorns. We measured morphological and genetic variation of 95 adult jays and found significant differences in hook length between elevations in accordance with predictions, a pattern corroborated by analysis …
Integrating Paleoecology And Genetics Of Bird Populations In Two Sky Island Archipelagos, John Mccormack, Bonnie Bowen, Thomas Smith
Integrating Paleoecology And Genetics Of Bird Populations In Two Sky Island Archipelagos, John Mccormack, Bonnie Bowen, Thomas Smith
John E. McCormack
Background: Genetic tests of paleoecological hypotheses have been rare, partly because recent genetic divergence is difficult to detect and time. According to fossil plant data, continuous woodland in the southwestern USA and northern Mexico became fragmented during the last 10,000 years, as warming caused cool-adapted species to retreat to high elevations. Most genetic studies of resulting 'sky islands' have either failed to detect recent divergence or have found discordant evidence for ancient divergence. We test this paleoecological hypothesis for the region with intraspecific mitochondrial DNA and microsatellite data from sky-island populations of a sedentary bird, the Mexican jay (Aphelocoma ultramarina). …
Speciation In The Highlands Of Mexico: Genetic And Phenotypic Divergence In The Mexican Jay (Aphelocoma Ultramarina), John Mccormack, A. Peterson, E. Bonaccorso, Thomas Smith
Speciation In The Highlands Of Mexico: Genetic And Phenotypic Divergence In The Mexican Jay (Aphelocoma Ultramarina), John Mccormack, A. Peterson, E. Bonaccorso, Thomas Smith
John E. McCormack
The pine-oak woodlands of the Mexican highlands harbour significant biological diversity, yet little is known about the evolutionary history of organisms inhabiting this region. We assessed genetic and phenotypic differentiation in 482 individuals representing 27 populations of the Mexican jay (Aphelocoma ultramarina) — a widespread bird species of the Mexican highlands — to test whether populations in the central and northern Mexican sierras display discrete breaks between groups, which would be consistent with a role for the different mountain chains in divergence and speciation. We found abrupt breaks in mitochondrial DNA (mtDNA; ND2 and control region) delineating four major genetic …