David S. De La Mater, III (M.S.), Biology Department, The College of William and Mary, “Biogeographic variations in common milkweed (Asclepias syriaca) functional and defensive traits, and their effect on monarch (Danaus plexippus) fitness”, Virginia.
Plants play an important role in structuring ecological communities; however, there is insufficient understanding of how infraspecific biogeographic variations in plant traits affect communities through interactions with herbivores. This research lies at the interface of biogeography, plant traits, and herbivore development, and its purpose is to elucidate the ways in which plant traits affect communities through plant-herbivore interactions. We achieve this by focusing on a model plant-herbivore system: common milkweed (Ascelpias syriaca) and the monarch butterfly (Danaus plexippus). We first quantified the variation in milkweed traits across its entire North American range through field sampling and multivariate statistical techniques. Preliminary data show statistically significant differences between populations, and suggests that as latitude increases, plant height, foliar carbon, chlorophyll, lignin, and herbivory seem to decline while cardenolide concentrations seem to increase. Root stock was harvested from each population to create a common garden of milkweed from across its range. In order to determine how observed variations in milkweed traits affect monarchs, a bioassay will be conducted in which monarch larvae will be fed on milkweed from each sampled population. Differences in monarch development and performance will provide insight into how plant trait variation affects herbivores.

S. Augusta Mccracken (Ph.D.), Anthropology Department, University of Maryland, “Ancient latitudinal diversity gradients of insect herbivory: Exploration of the Cerro del Pueblo Formation”, Mexico.
Plants and insects have an extraordinary evolutionary history, which has led to their unprecedented diversity and abundance in modern terrestrial ecosystems. The ability to predict how plant and insect communities respond to anthropogenic climate change is vital to construct appropriate management strategies. One of the best sources of information on how organisms contend with climate change is in the deep geologic past, such as during the Cretaceous, when the Earth was much hotter than today (tropical to sub-tropical). This research project focuses on the biogeography of fossil plant and insect interactions, specifically looking at how these interactions change across latitude during the Late Cretaceous of North America. The object is to understand how this latitudinal diversity gradient compares to that of today so predictions can be made of changes in plant-insect interactions in the coming decades. Museum collections provide tens of thousands of fossil specimens for this research, but the Cerro del Pueblo Formation in Coahuila, Mexico, must be further excavated in order to obtain a sufficient number of specimens for analysis of insect-damaged leaf fossils.

Enquye Wondimu Negash (Ph.D.), Center for the Advanced Study of Human Paleobiology, George Washington University, “Modelling vegetation structure in modern ecosystems: Implications for hominin landscape dynamics”, Rwanda.
Understanding parameters of vegetation structure, composition and distribution in contemporary ecosystems is crucial for interpreting past ecological conditions. As fossil soils (paleosols) are well-preserved in the fossil record and are commonly used in reconstructing past ecosystems, a detailed study and a comprehensive understanding of modern soils at a high spatial resolution is important in establishing a baseline for interpreting paleosols and their associated vegetation structure. The proposed work uses a multi-proxy approach to calibrate a model of estimating vegetation structure in modern ecosystems to apply the model produced in reconstructing vegetation proportion, distribution and woody cover from paleosols. To do this, phytolith and stable isotopic analysis of soil samples collected from national parks in eastern Africa along varying altitudinal and climatic gradients will be used. This will help better characterize the relationship of each proxy to the vegetation structure in various habitat types and offers a quantitative approach of estimating vegetation structure. The proposed work is part of a project aimed at applying the model produced from this study on paleosols from the Shungura Formation, a hominin bearing fossiliferous site in Southern Ethiopia, which will help in making more precise and accurate interpretations of hominin environments.

Brandon Semel (Ph.D.), Fish and Wildlife Conservation, Virginia Tech, “Advancing Effective Lemur Conservation in the Face of Global Change”, Madagascar.
Primates face an increasing number of threats to their survival (e.g. forest loss, hunting). Despite the mounting threat to countless other taxa, how primates will respond to climate-induced environmental change remains poorly understood. This project will assess the adaptive potential of Madagascar’s critically endangered golden-crowned sifaka (Propithecus tattersalli) in response to anticipated climate change and other proximate threats. Four objectives will be completed to meet this goal: 1) update population estimates and establish a population monitoring program, 2) relate abundance to nutritional properties in different forest types, 3) investigate genetic diversity and adaptive genetic potential across species’ range, and 4) predict land cover change, and relate back to variance in nutritional properties and genetic connectivity, in response to human use and climate change scenarios. Population estimates also will be obtained for endangered crowned (Eulemur coronatus) and Sanford’s brown (E. sanfordi) lemurs in northern Madagascar’s Daraina region. Partnering with Malagasy conservation initiatives will ensure that species monitoring continues long-term and that conservation activities are undertaken that will best promote species persistence in the face of climate change and other threats.