The Better To Eat You With: The Comparative Feeding Morphology And Evolution Of Feeding Strategies In Phocid Seals (Pinnipedia, Phocidae)

摘要: OF THE THESIS The Better to Eat You With: Comparative Feeding Morphology and Evolution of Strategies in Phocid Seals (Pinnipedia, Phocidae) by Sarah Elizabeth Stachura Kienle Master Science Biology San Diego State University, 2014 During the transition from land water, phocids (seals) evolved adaptations that allowed them efficiently obtain prey an aquatic habitat. Phocids are most diverse pinniped (seals, sea lions, walruses) lineage with eighteen extant species a rich fossil record. Previous qualitative research hypothesized existence four feeding strategies phocids: filter, grip tear, pierce, suction feeding. Most classified as generalists, employing pierce or Grip tear filter specialized used only Hydrurga leptonyx Lobodon carcinophaga, respectively. No quantitative morphological study has been conducted date. first objective this was determine whether original were supported data then phocid species. Three dimensional landmark collected for all taxa. Principal Component Analysis Canonical Variate performed summarize cranial mandibular variation. Prey type facial musculature dissections included provide comprehensive description each strategy. results found evidence three previously strategies: There no being distinct category. Instead, generalist feeders, using biting opportunistically capture prey. derived require specific adaptations; these unique have carcinophaga exploit novel niches types. This is Cystophora cristata, Mirounga angustirostris, leonina. These framework understanding evolution adaptability employed second calculate standardized diet compositions focus on endangered deficient investigate relationship between quality quantity. Standardized calculated based published dietary studies. items divided into nineteen categories taxonomic class. Average energy densities (kilojoules per gram) species’ diet. composition revealed specialists, consuming actinopterygians, cephalopods, malacostracans. v malacostracans positively correlated composition. average relative density 4.76 kJ/g. findings confirm apex predators marine ecosystem trophic levels similar other predators, including mammals, rays, sharks. information future studies interspecific variation diet, well indicated need more in-depth investigations especially limited data. third pinnipedimorphs, test evolutionary hypotheses understand strategy, conduct comparative phylogenetic analyses Phocidae. Three-dimensional pinnipedimorphs phocids. describe major axes dataset. OUCH method six hypotheses. ancestral state strategy reconstructed maximum parsimony Bayesian methods. generalist, pinnipeds. Stem consume prey, suggesting may be shape driven multiple factors, specifically phylogeny, type. likely ancestor extinct pinnipedimorphs. Knowledge fundamental pinnipeds reinvade ecosystem.