November 16 2017

5:00 pm 1100 TLSB

EcoEvoPub Series

Graduate Student Presentations


Daniel Chavez
Department of Ecology and Evolutionary Biology, UCLA

"Comparative genomics reveal genetic signatures of African wild dogs (Lycaon pictus) remarkable adaptations"

Within the family Canidae, African wild dogs (Lycaon pictus) stand out due to several distinct adaptations. Through a comparative genomics approach, we investigate the genetic underpinnings of several of their remarkable adaptations using 13 genomes from 10 canid species. Wild dogs are cursorial hunters, adapted for running down prey, with only four digits on their forefeet. They are hypercanivorous with blade-like premolar teeth, a characteristic shared with distantly related bush dogs (Spheotus venaticus) and dhole (Cuon alpinus). They are also the only canid species with a distinct mottled color pattern that may be important for individual recognition and camouflage. Like gray wolves (Canis lupus), dholes, and bush dogs, wild dogs hunt in packs, taking prey larger than themselves. We identify wild dog-specific signals of positive selection relevant to digit loss, tooth morphology and pigmentation. We find that genes under selection were enriched in primary cilium, an antenna-like structures projecting from the surface of the cell with sensory receptors for sonic hedgehog that provides instruction for digit and tooth development, which is remarkably concordant with previous genomic studies of other tetrapods. Genes relevant to the blade-like premolar were different for wild dog and Dhole, which suggest that convergence in tooth morphology may occurred through different genetic loci. Regarding signals of selection shared among pack-hunting species, these were relevant to respiration and skeletal muscle development, which may be important¬¬¬¬ for running down preys. These findings offer insights into the genetic mechanisms underlying African wild dog adaptions and pack-hunting in Canids.

Christine Jaquemetton
Department of Ecology and Evolutionary Biology, UCLA

"Overcoming the Incline: The kinematics of Echidna nebulosa on wet pebble substrate"

One of the major morphological changes in the water to land transition is the development of limb-like fins. However, many extant species of fish lacking fins manage to move across a variety of terrestrial substrates. These species are generally described as highly elongate, relying on axial based locomotion to advance their bodies on land. Aquatic animals must overcome an elevation gradient which is inherent to the water to land transition.. Echidna nebulosa, the snowflake moray, is an eel which occupies both coral reefs and intertidal reef flats. Snowflake morays are known to make terrestrial forays to feed on invertebrates such as crabs. For this study, we tested the hypothesis that incline has an affect on the kinematics of locomotion of E. nebulosa when moving across wet pebble substrate. We tested individual eels at two different inclines, 5 and 10 degrees. A level pebble substrate, 0 degrees served as our control. We measured two kinematic variables to determine terrestrial locomotion efficiency: distance ratio, and velocity. We also measured wavelength, and amplitude across the body. Distance ratio and velocity were gathered by tracking three body points (head, center of mass, and tail). When faced with either incline, E. nebulosa demonstrated a consistent reduction in velocity and distance ratio while moving across a terrestrial substrate compared to a flat (0 degree) treatment. Differences in kinematic variables between the two incline treatments (5 and 10 degrees) were not significant. Our results show that movement on land for an elongate fish is possible but the real challenge is overcoming the incline to transition from water to land.
















































































































































































































































































































































































































































































































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