Chalcraft Lab

	- Chalcraft Lab - Population and Community Ecology
	Dept. of Biology	East Carolina University

Prospective Students

Chalcraft Dept. Site

Contact us:

Dept. of Biology

East Carolina University

Greenville, NC

27834

Office phone: (252) 328-2797

Lab phone: (252) 328-6062

chalcraftd@ecu.edu

Research

1) The effects of consumer diversity in temporary pond communities

	Although a great deal of work has examined how diversity loss within plant communities affects ecological systems, there has been much less work directed at examining how diversity loss of consumer species affects ecological systems. Furthermore, most studies of diversity loss often assume that species are lost at random. With the assistance of a grant from the National Science Foundation, our lab is currently focusing on how non-random patterns of diversity loss within consumer trophic levels affects ecological processes operating within temporary pond communities. The consumer species that we are focusing on include aquatic predatory insects and grazing larval frogs. To explore the effects of diversity loss within both predator and herbivore trophic levels, we are conducting a survey of temporary ponds in the coastal plain of North Carolina and conducting a series of experiments in artificial ponds.

	2) Determinants of interaction strength in food webs
	Interactions among species play an important role in controlling both community structure and the population dynamics of individual species. We have shown that variation in the identity of top predators (different species of fish and salamanders) that occur in pond food webs can alter how strongly the top predator trophic position interacts with prey species (larval frogs and toads). Furthermore, we have examined how easily identifiable characteristics (e.g., body size, traits associated with taxonomic affiliation, and microhabitat use) of a predator affects how strongly a predator species interacts with its prey. We have also evaluated how well allometric models of metabolic rate predict the impact of predator populations on their prey when the predator populations differ in abundance and average body size. Our work also examines the influence of the abiotic environment on species interactions. Previously, Chalcraft worked with Robin Andrews to demonstrate that rates of predation on lizard eggs by ants on Barro Colorado Island in Panamavaries with the amount of rainfall. Such variation in the rate of predation likely explains long-term fluctuations in the population size of the tropical lizard, Anolis limifrons. Currently, Tracy Rogers and Chalcraft have been exploring how pond hydroperiod affects the intensity of intraspecific and interspecific competitive interactions of larval squirrel (Hyla squirella) treefrogs and larval southern toads (Bufo terrestris). Jon Davenport and Chalcraft are currently studying intraguild predation between larval dragonflies and larval salamanders to explain how intermediate predators coexist with top predators.
	3) Scale dependent patterns in biodiversity
	How does productivity and nitrogen enrichment affect species diversity? Does this effect depend on the spatial scale of study? Chalcraft has worked in collaboration with a number of other scientists to address these questions by conducting meta-analytical studies of data collected in herbaceous plant communities at long-term ecological research sites. We have found that productivity has little influence on the number of species occupying small study plots but that large areas with intermdiate productivity levels have more species than large areas having either low or high productivity. The change in the pattern of how productivity affects the number of species present with an increase in spatial scale was the result of how productivity influences beta diversity; the extent of among plot variation in species composition. Specifically, regions with intermediate productivity tended to be composed of localities that were very different in their species composition while regions with low or high productivity are composed of localities that are more similar in their species composition. In a separate study, we have found that nitrogen enrichment poses a threat to diversity loss in herbaceous plant communities at both small and large spatial scales but that small scale studies may over or underestimate the extent of diversity loss at larger spatial scales if they fail to consider how nitrogen enrichment affects beta diversity. Specifically, we found that nitrogen enrichment causes localities that occur in less productive areas to become more dissimilar in their species composition while nitrogen enrichment causes localities that occur in more productive areas to become less dissimilar in their species composition. Consequently, we found many instances where the increase in beta diversity following nitrogen enrichment can minimize the extent of species loss at large spatial scales despite reductions in the number of species that occur in small localities. Currently, Chalcraft is investigating how species diversity affects the stability of herbaceous plant communities.