June 14 2018

5:00 pm 1100 TLSB

EcoEvoPub Series

Graduate Student Presentations


Justin Keller
Department of Ecology and Evolutionary Biology, UCLA

"Functional Morphology of the Neck in Pinnipeds: The Long and Short of It"

Vertebrates have returned to aquatic environments in at least 30 distinct lineages of both extinct and extant clades, including archosaurs, lepidosaurs, and mammals. With these transitions came numerous morphological and physiological adaptations to accommodate life in water. The axial and appendicular skeleton are of particular interest in this transition due to their role in locomotion. Although several studies have focused on the limbs and thoracolumbar spine, less attention has been paid to the cervical region. In fully aquatic cetaceans, the cervical vertebrae are compressed or fused, largely because a loss of neck mobility reduces drag. We ask if this pattern of cervical evolution is present in the pinnipeds that have more recently invaded a marine habitat but retain some terrestrial habits. Here, we quantitatively compare neck morphology and function in two groups of pinnipeds with different degrees of aquatic adaptation, the Otariidae and Phocidae, as well as between pinnipeds and their terrestrial arctoid relatives \(ursids and mustelids\). Using cranial CT scans of museum specimens, we quantified the occipital surface area for neck muscle attachment and also took linear measurements of the cervical vertebrae to capture vertebral size and shape. Results show that the pinnipeds have a relatively larger occipital surface area than ursids and terrestrial mustelids. This suggests that marine carnivorans have enlarged their neck muscles to assist with stabilizing the head during swimming. Within pinnipeds, there are functional differences in cervical morphology between otariids and phocids that coincide with how aquatic the two groups are. Otariids are more specialized for terrestrial locomotion than phocids and have relatively longer cervical vertebrae centra that allow for greater neck flexibility. By contrast, phocids are more specialized for aquatic locomotion and consequently have shorter cervical vertebrae and less flexible necks. The quantitative measures used in our analysis are applicable to fossil vertebrate taxa, such as Enaliarctos or Allodesmus, and enable the tracking of progressive adaptations to life in water during the transition from land to sea.

Department of Ecology and Evolutionary Biology, UCLA

“Analysis in Los Angeles (BAILA): A novel urban biodiversity assessment framework that combines an urban habitat classification and citizen science data”

The goal of this study is to generate an urban biodiversity assessment framework that is quick and simple to implement, scientifically credible, and can be applied in urban areas across the globe. In this framework, we combine a customized urban habitat classification with modern species occurrence data generated through citizen science to produce a spatially explicit biodiversity assessment. We demonstrate this framework by using publicly accessible data in the highly urbanized Los Angeles area. We first build an urban typology using 18 ecological and anthropogenic variables to categorize lands within the Los Angeles area into nine different types. Each type has its own unique biological and anthropogenic characteristics. We then use recent, research-grade iNaturalist occurrence data collected through citizen science to examine biodiversity patterns across the Los Angeles area, and within each urban type. The integration of an urban habitat classification with species occurrence information provides insights into urban community composition, how different species use different areas within the urbanized landscape, as well as how patterns in biodiversity differ across the urban landscape. It contributes to the long-standing ecological question of how urban heterogeneity affects biodiversity, and provides useful information in urban planning and conservation management for maintaining and enhancing desirable species and ecosystem services. This framework uses publicly available and requires minimal technical expertise, and it can be widely applied to other cities and metropolitan areas pursuing biodiversity assessments, conservation planning, and urban conservation projects.

Thursday, June 14, 2018
1100 Terasaki Life Sciences Building





















































































































































































































































































































































































































































































































































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