June 1 2017

5:00 pm 1100 TLSB

EcoEvoPub Series

Graduate Student Presentations


Ian McFadden
Department of Ecology and Evolutionary Biology, UCLA

"Drought tolerance and dispersal limitation jointly shape community structure in an aseasonal Amazonian forest"

Establishment and survival mediated by the abiotic environment or environmental filtering and variation in the distribution of seeds due to dispersal limitation are two key processes hypothesized to maintain diversity in plant communities. Environmental filtering can promote coexistence via stabilizing niche differences, while dispersal limitation can slow competitive exclusion and maintain diversity at the landscape scale by increasing intraspecific aggregation. Unfortunately, these processes are often studied separately within distinct theoretical frameworks. Progress in the study of community assembly therefore requires frameworks of analysis that allow for the simultaneous consideration of both processes. Here, I use spatial point pattern modeling to infer the relative importance of both environmental filtering and dispersal limitation as drivers of community structure and diversity in a highly-diverse Amazonian forest in Ecuador. In addition, I tested if a suite of field-collected physiological and morphological traits are correlated with metrics related to each process.

Zack Gold
Department of Ecology and Evolutionary Biology

"Spatial and Temporal Variation of Environmental DNA in Kelp Forest Ecosystems"

Accurate monitoring and assessment of ecosystem function and biodiversity is critical for assessing anthropogenic impacts on marine ecosystems. However, current methods for evaluating marine biodiversity require taxonomic expertise, are costly and labor intensive, and difficult to repeat. New environmental DNA (eDNA) techniques offer rapid, affordable, and accurate tools for monitoring marine biodiversity. Recent studies have demonstrated eDNA as an accurate and highly sensitive species detection tool, out performing all traditional fish survey methods including observer transect surveys and trawling. Thus eDNA has the capacity to revolutionize biodiversity monitoring and fisheries science by facilitating large scale comparisons of marine biodiversity across environmental gradients, anthropogenic stressors, and marine management practices. However, little is known of the variability of eDNA signals in marine ecosystems. Understanding the variability of marine eDNA methods is critical for determining the sampling biases and underlying mechanisms that effect the accuracy and repeatability of this new biodiversity monitoring technique. Thus to better understand the temporal and spatial variability of eDNA in marine systems we conducted 140m repeated transects in high and low current velocity rocky subtidal kelp forest reefs. Five samples were taken a 0m, 20m, 40m, 90m, 140m and transects were repeated at 0, 6, 12, 24, 48, 120 hours. We generated eDNA sequence data using PCR primers that targeted the mitochondrial 12S rRNA and CO1 genes of marine teleost, elasmobranch, and invertebrate species. This project provides much needed insights into the spatial and temporal patterns of marine eDNA and the role of ocean currents in effecting eDNA patterns in kelp forest ecosystems. Importantly this research will inform effective eDNA sampling strategies to rigorously compare kelp forest communities both inside and outside of marine protected areas and across urbanization gradients.











































































































































































































































































































































































































































































































































































































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