This was expected with these two AOU meeting abstracts:
CRAIG W. BENKMAN, Dept. Zool. & Physiol., Univ. Wyoming, Laramie, WY, THOMAS L. PARCHMAN, JULIE W. SMITH, Dept. Biol., New Mexico State Univ., Las Cruces, NM, LISA K. SNOWBERG, Dept. Zool. & Physiol., Univ. Wyoming.
Ecological speciation in the Great Basin: divergence and reproductive isolation in the South Hill Crossbill.
Divergent natural selection for resource specialization has been implicated as underlying the evolution and maintenance of Red Crossbill (Loxia curvirostra complex) diversity despite wide-ranging nomadism and widespread sympatry of the different taxa. Here we will discuss evidence that the South Hills Crossbill, which is endemic to two small mountain ranges in the Great Basin, is speciating from other related and sympatric Red Crossbill call types. The South Hills Crossbill experiences divergent selection relative to other crossbills because it is in a coevolutionary arms race with lodgepole pine. This divergent selection leads to differences in ecology between call types, which in turn leads to temporal reproductive isolation, and directly and indirectly leads to assortative mating. Although we lack such detailed evidence of reproductive isolation between the other call types, the observed genetic differentiation (AFLP markers) between the different call types suggests restricted gene flow between them consistent with the early stages of ecological speciation.
One Hundred and Twenty-Third Stated Meeting of the American Ornithologists' Union
23 - 27 August 2005 at The University of California Santa Barbara, CA
LEONARD SANTISTEBAN, Dept. Biol., New Mexico State Univ., Las Cruces, NM, CRAIG W. BENKMAN and PATRICK C. KEENAN, Dept. Zool. & Physiol., Univ. Wyoming, Laramie, WY.
Life history strategies of a resident crossbill (Loxia curvirostra complex).
Life history theory is central to understanding biological processes such as selection, adaptation, evolution, and more specifically ecological speciation. During ecological speciation the processes of local adaptation and reproductive isolation are linked to adaptive changes in the life history of the organism undergoing speciation. The objective of this study is to describe the life history of a resident crossbill population, the South Hills crossbill (Loxia curvirostra complex). We also explored the hypothesis that exceedingly stable pine cone production in the South Hills drives the evolution of a life history that differs from nomadic crossbills. Consistent with a stable food resource, the density of crossbills (ca. 188 birds/km ) has remained relatively stable over the last several years, and, based on mark-recapture efforts from 1998 - 2006, there is little evidence to suggest significant annual variation in adult survival rates. Clutch size (3 eggs) does not differ between this resident population and nomadic crossbills. Results suggest that the South Hills crossbill exhibits a life history that has evolved in a stable environment with predictable food resources.
One Hundred and Twenty-Fifth Stated Meeting of the American Ornithologists' Union
9 - 11 August 2007 at The University of Wyoming, Laramie, WY
