February 1 2012

5:00 pm 154 BSRB

EcoEvoPub Series

Graduate Student Presentations


Dept of Ecology and Evolutionary Biology, UCLA
“Strut your stuff: Frontal sinus complexity in Bovidae and Carnivora”

Paranasal sinuses, air-filled cavities found in the skulls of many mammal species, form when nasal epithelium pneumatizes surrounding bones, including the frontal, maxilla, ethmoid, and sphenoid. Of the paranasal sinuses, the frontal sinuses are the most variable, and were acquired and lost multiple times within Mammalia. Frontal sinuses range from puny to expansive, and from relatively simple, un-strutted sinuses, to highly complex sinuses with extensive bony struts. Here we investigate frontal sinus complexity in bovids, including antelopes, sheep, goats, and relatives, and carnivores, including bears, wolves, lions, raccoons, and relatives, two clades that independently evolved frontal sinuses exhibiting great morphological disparity. We addressed two questions in this study: 1) does sinus complexity increase with sinus size?; and 2) does the presence of supra-cranial structures, such as horns, affect sinus complexity? We sampled multiple individuals of 46 species of bovids and 24 species of carnivores, and representing the morphological and taxonomic diversity within each clade. Sinus surface area and volume, proxies for sinus size and complexity, were reconstructed from CT (computed tomography) scans of each specimen. Sinus surface area and volume are strongly correlated and surface area scales with positive allometry to volume in both bovids and carnivores, suggesting that sinus complexity increases at a greater rate than sinus volume. Bovids have a higher scaling coefficient than carnivores, suggesting that supracranial structures are related to an increase in sinus complexity.

Dept of Ecology and Evolutionary Biology, UCLA
“The Temporal and Spatial Spread of a Novel Foraging Behavior Among Sperm Whales (Physeter Macrocephalus) in the Gulf of Alaska: Evidence for Cultural Transmision”

Longline fishing in the Gulf of Alaska has altered the costs and benefits of sperm whale foraging by creating novel concentrations of prey at shallow depths. Despite anecdotal observations of depredation from fisherman, National Marine Fisheries Service observers first reported anecdotal accounts of sperm whales depredating the fish from the longlines in 1997. Since 1997, this behavior has spread through the Gulf of Alaska population of sperm whales. Negative consequences on local communities have included economic loss for fishers, reduced fish stocks, and increased potential for whale entanglement . The complexity of the behavior and its spread through the Gulf of Alaska make sperm whale depredation from longlines an ideal system in which to examine cultural innovation and transmission within a wild population. I will attempt to answer the following questions: First, how did depredation of fish by sperm whales from longline fisheries become a common behavior observed in the GOA? I will test two competing hypotheses: the behavior (a) spread via cultural transmission among the whale population, or (b) arose independently among multiple individuals. Second, how do patterns of depredation vary between killer and sperm whales? Data on sperm whale depredation collected during sablefish assessment surveys conducted by National Marine Fisheries Service (NMFS) using longline gear in coastal waters off Alaska from 1998 to 2010 were analyzed by populating two types of models of cultural transmission, the diffusion curve and wave of advance, to test the hypotheses listed above.















































































































































































































































































































































































































































































































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