October 23 2014

5:00 pm 154 BSRB

EcoEvoPub Series

Graduate Student Presentations


Department of Ecology and Evolutionary Biology

Character Displacement in Body Size and Craniodental Adaptations Among North American Fossil Dogs

Among extant taxa, competition between ecologically similar species can lead to character displacement: a divergence in characters, such as body size and skull shape, that relates directly to the way in which the species compete. Character displacement likely acts also at longer time scales, leading to double-wedge diversity patterns in the fossil record of carnivorous mammals, such as dogs (Carnivora: Canidae). Body-size estimates and craniodental metrics of dogs from the Oligocene to middle Miocene (34 - 15 million years ago) were recorded to a) quantify the degree of morphological specialization for feeding abilities such as hypercarnivory, b) determine the timing of, and potential temporal overlap among, morphological specializations, and c) examine differences in diversity and disparity among time intervals. A morphospace of extant carnivorans was generated using a principal component analysis of 38 linear measurements of the skull and dentition, against which component scores of fossil canids from five time intervals were superimposed. Time intervals of high canid species richness showed high disparity in body size and craniodental adaptations, suggesting that divergence in resource use enabled fossil canids to minimize interspecific competition and exist at high richness. High disparity resulted in significant part from the iterative appearance of hypercarnivorous morphologies. However, while discriminant function analysis classified 10 of these canids as hypercarnivores, it could not assign the remainder of the sample to a category more specific than "omnivore", necessitating a more refined method for determining the exact diet of Oligo-Miocene canids.

La Kretz Center for California Conservation
Institute of the Environment and Sustainability, UCLA
Santa Monica Mountains National Recreation Area, National Park Service

Hybridization Dynamics between Wolves and Coyotes in Ontario, Canada

Eastern wolves (Canis lycaon) have hybridized extensively with coyotes (C. latrans) and gray wolves (C. lupus) in Ontario but little is known about the mechanisms underlying Canis hybridization. We combined genetic analysis with an intensive field study to investigate the genetic, morphologic, demographic, and behavioral consequences of hybridization between wolves and coyotes. We documented 3 genetically distinct Canis types that also differed morphologically, corresponding to putative gray wolves, eastern wolves, and eastern coyotes in a hybrid zone that overlapped a large protected area (Algonquin Provincial Park, APP) and adjacent areas in central Ontario. There were also a substantial number of hybrids (36%) that exhibited intermediate morphology relative to parental types. The eastern wolf, a species of special concern in Canada, was the numerically dominant canid within APP but was rare and patchily distributed in adjacent, unprotected areas where it was associated with specific environmental conditions. Survival was poor for eastern wolves outside of APP, presumably due to their naiveté regarding human-caused mortality risk outside the protected area. Contrary to all previous studies of sympatric wolves and coyotes, home range overlap was negligible between neighboring canid packs in the hybrid zone regardless of their genetic ancestry. Thus, interspecific spatial relationships between canids appear to be fundamentally different within the hybrid zone relative to areas where wolves and coyotes are reproductively isolated. We also compared kill rates of wolves, coyotes, and hybrids on deer and moose to evaluate the influence of the different canid predators on ungulate populations. Coyotes and hybrids were effective deer predators and occasionally killed moose, but likely serve a different ecological function than wolves. High rates of harvest mortality and hybridization, as well as strong Canis territoriality in human-altered landscapes mean that significant expansion of genetically distinct eastern wolves outside of APP is unlikely under current environmental conditions and harvest regulations. More broadly, our results show that protected areas can strongly influence the structure of hybrid zones and dynamics between interbreeding species.















































































































































































































































































































































































































































































































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