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| The endemic hummingbirds Trochilus polytmus and T. scitulus
hybridize in a narrow zone of secondary contact in eastern Jamaica. The cline
in bill width across the hybrid zone represents the steepest morphological
gradient documented thus far in avian biology. Hindlimb size and skeletal
proxies for core body size, however, exhibit incongruent patterns of variation
across the same transect. Significant correlation between bill width and skull
width indicates that genetic loci that affect bill width have pleiotropic effects
on cranial morphology posterior of the craniofacial hinge. This study is the
first direct examination of skeletal size variation across an avian hybrid zone. | |
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