February 28 2013

5:00 pm BSRB 154

EcoEvoPub Series

Graduate Student Presentations


Christine Scoffoni
Department of Ecology and Evolutionary Biology

"Evolution of leaf hydraulics in Viburnum"

Abstract: Leaf hydraulic conductance (Kleaf) varies greatly across species and plays a major role in determining how plants function and adapt to their environments. The genus Viburnum is a clade of about 140 species of trees and shrubs with a wide geographical distribution. With collaboration with Drs. Erika Edwards (Brown University) and Michael Donoghue (Yale University) the complete phylogeny for Viburnum was obtained. This permit us to look at the evolution of leaf hydraulics within this genus really diverse in leaf shape, size and venation architecture.

Venation architecture varies greatly among species and provides water and support to the leaf. We quantified all venation and hydraulic traits (Kmax) for 30 species of Viburnum grown in a common garden at the Harvard arboretum. We measured hydraulic conductance through the petiole, midrib, secondary and tertiary vein orders, and through the minor veins of fully hydrated leaves using the High Pressure Flow Method (HPFM) for a subsample of 17 species. From the Kmax values obtained from the evaporative flux method (EFM) and total conductance through the leaf xylem (Kx), we calculated Kox for those 17 species to look at the partitioning of the resistance throughout the leaf. Our aim is to determine which traits or trait combinations drive diversity in Kleaf and the relative rates of evolution of traits and trait clusters.

Samantha Cheng
Department of Ecology and Evolutionary Biology

Examining Diversity within the Big Fin Reef Squid (Sepioteuthis lessoniana) Species Complex

Abstract: The big fin reef squid (Sepioteuthis lessoniana) is a vital component of inshore commercial and artisanal fisheries throughout the Pacific and Indian Oceans. There is significant recognition that S. lessoniana is not one, but many species. However, despite its crucial importance for local economies and food security, there is still little known about how many species exist, where they occur and how they differ. Lack of this information on species identification and occurrence cripples conservation and management efforts. My research focuses on discovering a) phylogenetic, geographic, morphological, and ecological differences between these species and b) understanding the evolutionary and ecological processes that gave rise to and maintain these differences in order to provide both pattern and process data for management of harvested reef squid. Today, I will present preliminary findings of the characteristics of S. lessoniana collected from the Indo-West Pacific region using genetic, morphometric and geographic data. Using coalescent-based approaches, I estimate divergence times and effective population sizes between divergent lineages to examine the history of this species complex. Evidence suggests that three genetic lineages of S. lessoniana exist within this region, however with little corresponding morphometric or coloration differences. Furthermore, these lineages appear to occur sympatrically, providing an interesting avenue to explore mechanisms driving sympatric co-occurence in marine systems. Further research is being conducted to obtain more in-depth analyses of genetic, morphological/morphometric and ecological differences between putative species.

THURSDAY, February 28, 2013











































































































































































































































































































































































































































































































































































































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