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January 28, 2021

5:00pm Zoom

EcoEvoPub Seminar Series
Department of Ecology and Evolutionary Biology, UCLA

" Graduate Student Presentations "

Nick Russo
Department of Ecology and Evolutionary Biology, UCLA, Smith Lab

Movement ecology of hornbills and spatial patterns of seed dispersal in rainforests of Cameroon

Animals decide where to move based on the structure of their environment, but also engineer vegetation structure in myriad ways, such as dispersing seeds. In tropical forests, up to 90% of tree species rely on vertebrates to disperse their seeds. Black-casqued (Ceratogymna atrata) and white-thighed hornbills (Bycanistes albotibialis) disperse the seeds of more than 50 tree species in Central Africa and move among rainforest fragments during seasonal long-distance movements. I used GPS location data from eight hornbills to investigate the role of landscape structure and phenology as predictors of their movement decisions. Canopy height was the best predictor of hornbill movements, indicating that both species select for taller canopies as they move through a fragmented Congo Basin landscape. I will also share a prototype of a seed shadow model that incorporates habitat selection by a hornbill and gut passage time of seeds. Finally, I will share some of my experiences conducting fieldwork in the Dja Faunal Reserve of southern Cameroon and prospects for future research.


Alayna Mead

Department of Ecology and Evolutionary Biology, UCLA, Sork Lab

Convergent evolution shapes drought adaptation in oaks

Oak (Quercus) species have adapted to a wide range of climates, and in many cases different lineages have adapted to the same climates in parallel. To investigate the genomic basis of adaptation to drought stress, we compared the transcriptomic response to drought and drought-related functional and ecophysiological traits among six California oak species. Species pairs were selected from the three sections of oaks present in California and from contrasting mesic and xeric climates to test the extent to which their responses were due to phylogenetic history or the climate niche of the species. We measured drought traits, plastic gene expression responses, and non-plastic gene expression divergence in these six oak species. We find that distantly-related species with similar drought tolerance also share similarities in other characteristics, including the amount of plasticity in gene expression and evolutionary divergence in gene expression levels consistent with positive selection. These results show that there may be some amount of parallel evolution in drought-related gene expression. However, the relatively low levels of parallelism in the gene expression response even among similar species suggests that there are multiple mechanisms through which drought response can evolve. The range of genes that these oak species use to respond to drying stress may have allowed species within different sections to adapt to similar climates independently.

Authors: Alayna Mead, Camila Medeiros, Lawren Sack, Victoria Sork