Center for Field Ecology Pilot Grants Program:
Each year the Center for Field Ecology awards research grants to help early career PhD students gather the pilot data required to justify more substantial external funding The grants are intended primarily for students in their first or second year of graduate studies. Proposals are solicited in the spring of each year. The 2009 deadline is 30 March and the 2009 Request for Proposals is now available (pdf).
The Center for Field Ecology defines "field ecology" broadly; however, projects must be field based and include ecological components. Research that meets these criteria may be based in or draw from behavior, ecology, evolution, epidemiology, paleontology, and related fields.
Since 2002 CFE has supported the research of 80 students in the departments of Anthropology, Ecology and Evolutionary Biology (EEB), Geology and Geophysics (G&G), Epidemiology and Public Health (EPH), and the School of Forestry and Environmental Studies (FES).
The following is a list of previous grant recipients sorted by year:
Genetic diversity within dominant species can affect ecosystem functioning and community processes. The genotypic structure of dominant species is largely unknown. In the tallgrass prairie, Andropogon gerardii is a dominant species; it structures the biotic community and accounts for the majority of productivity. This past summer I assessed the genetic structure of A. gerardii in intact prairie. I found a dominant genotype that accounted for 47% of all sampled tillers. On average there were 6 genotypes per m2 plot, with a high of 9 genotypes. It is unknown if climate change causes a loss of genetic diversity by creating conditions that favor some genotypes over others, and whether loss of genetic diversity within a dominant species impacts community and ecosystem processes. Using an on-going climate change experiment—the Rainfall Manipulation Plots at Konza Prarire, KS—I investigated the effect of more variable precipitation patterns on genotypic diversity A. gerardii. Preliminary data suggests that genotypes are more dominant in the simulated climate change treatment when compared to the ambient treatment. The increased dominance of genotypes reflects loss of overall genotypic diversity, as the majority of individual tillers represent a single genotype. This reduction of genetic diversity within the dominant species could have consequences for community level processes including diversity and productivity. What is driving changes in the genotypic structure of A. gerardii remains unknown. My research will focus on phenotypic differences between genotypes, and the interaction of A. gerardii with the mycorrhizal community for possible explanations.
Wood frogs (Rana sylvatica) have been shown to evolve rapidly in response to forest canopy-induced changes in the thermal environment of their natal wetland. Strikingly, evolutionary divergence in this system has been observed over microgeographic spatial scales on the order of tens of meters. Divergence among wetlands across such small scales is promoted in part by high rates of philopatry: approximately 85% of adult wood frogs return to breed in their natal wetland. However substantial, this philopatry is not complete. Even at low rates, dispersal by breeding adults could counteract the population genetic structuring maintained through philopatry. This begs the question as to the ultimate fate of dispersing adults. As one possibility, I hypothesized that outbreeding depression may result when adults disperse to breed in non-natal wetlands. Specifically, I predicted that the mating of one or more non-natal parents would result in less fit offspring as compared to the offspring of fully natal parents. I used my CFE Pilot Grant to test this prediction by conducting a field-based breeding and transplant experiment. I evaluated larval survivorship in the context of outbreeding by artificially breeding and rearing offspring produced by a) one pair of natal parents (fully inbred offspring), b) one natal parent mated with one dispersed parent (hybrid offspring), and c) two dispersed parents (fully outbred offspring). Preliminary results indicate these three classes of offspring differ in fitness, suggesting that outbreeding matters. The response of these offspring was shown to vary by wetland, further suggesting that the effects of outbreeding are context dependent. Future research is needed to address the mechanisms influencing alternative outcomes of outbreeding in this system. 
Widespread forest conversion and fragmentation has diminished species diversity in many regions of the tropics, producing landscapes largely dominated by pioneer species. Reforestation and restoration efforts aimed at reestablishing diverse, mixed-species forests need to consider how to reintroduce late-successional, shade tolerant tree species that are dispersal limited and show poor establishment in degraded areas. To this end, an increased understanding of the ecological regeneration niche of slower growing species is needed. My research is evaluating the regeneration ecology of seedlings in understory environments, through comparative studies of enrichment planting and assessments of natural seedling recruitment below canopies of different pioneer species. I am particularly interested in how facilitation-competition tradeoffs mediate understory establishment across an environmental gradient of increasing precipitation. This work will both improve our knowledge of understory regeneration processes, and inform silvicultural approaches for mixed species reforestation in understudied regions of the seasonally dry tropics.
An important objective of ecology has been to decipher the mechanisms that allow similar species to coexist in communities. In many cases, competition for similar resources has been implicated for niche shifts of coexisting species. Ecological niches, however, may exhibit a strong phylogenetic signal, in which closely related species tend to have very similar ecological characteristics. Therefore, instances of sympatry between closely related species provide for interesting opportunities to investigate the interaction between the evolutionary history and the realized ecological niche of an organism. Darters constitute a clade of approximately 200 freshwater fish species endemic to North America. They frequently occur in assemblages with many species– yet no comparative studies have been performed to demonstrate possible phylogenetic influences on niche shifts in these communities. My research examines patterns of co-occurrence of members of Catonotus (a sub-clade in the darter radiation), and seeks to understand the role of coexistence between populations of varying phylogenetic relatedness on niche shifts. My focus is on the trophic niche, and I will primarily use stable isotope and gut content analyses to assess shifts in resource use when species of this group occur in isolation and sympatry. Funds from the YIBS CFE Pilot Grant supported an exploratory field trip to identify suitable populations for study and also funded preliminary stable isotope sample processing.
forest fragmentation on the diversity and community dynamics of Amazonian forest regeneration are virtually unknown. The objective of my research is to evaluate whether remaining relic forest fragments will perpetuate the hyperdiverse forest community structure of intact forest, and to determine what factors influence forest compositional dynamics. My primary research question is to determine how fragment size affects the species richness and composition of tree and shrub regeneration at my research site in the Brazilian Amazon. With support from the YIBS pilot grant, I established replicate plots within forest fragments of three sizes (1,10 and 100 ha) and also within control sites in continuous forest and conducted a census of tree and shrub regeneration within these plots. Preliminary results suggest that fragment size significantly affects species diversity, with species richness in the smallest fragments approximately half that found in continuous forest. Fragment size also significantly affects community compositional dynamics. Results from this pilot work will be used to expand my experimental design to additionally determine the effect of distance from the forest edge and position within the fragment on forest regeneration dynamics, with the ultimate goal of contributing to our understanding of how potential forest diversity losses and compositional shifts resulting from forest fragmentation can be minimized
If the expression of sexually-selected traits in both males and females is condition dependent, then we may expect the expression of a trait to vary as the fitness costs and benefits associated with its expression change. The cost of expressing a trait is dependent on the resources available to an individual and its’ genetic quality (the ability to use those resources efficiently). The resources available for an individual’s use (and the fitness costs and benefits of utilizing them) will be influenced by life history trade-offs. The costs and benefits associated with trait expression may change over an individual’s reproductive lifespan, resulting in individuals that differ in genetic quality producing the same level of trait expression at different points in their reproductive lifespan. For my research I use the Threespine Stickleback (Gasterosteus aculeatus) system to investigate how the expression of condition-dependent traits varies within and between sexes, and how variation in the condition-dependent costs and benefits of a sexually selected trait in one sex affects the condition-dependent expression of a trait in the other sex. The YIBS pilot grant supported field work in British Columbia and Alaska, where I recorded variation in the expression of male mating behaviors, such as courtship and parental care, in three populations of Threespine Stickleback with different life histories.
Adaptive life-histories may be influenced by predation, maternal condition, and sexual selection, and in turn can influence population and community dynamics. My research addresses basic questions about how ecology and evolution interact to shape life-histories as well as applied questions about the consequences of life-history variation for population management. For my dissertation, I am studying how these factors interact to shape reproductive allocation patterns wild fish species. With the funds provided by the YIBS CFE Pilot Grant I looked at geographic variation in life-history characters of live-bearing fish populations in Texas and Mexico. These preliminary data allowed me to choose the best species for my research questions: the swordtail Xiphophorus birchmanni. In the future, I will continue to examine the factors influencing life-history variation in swordtails using a combination of field and lab experiments. 
A major challenge regarding secondary forest succession relies on the understanding of processes affecting species composition and species spatial distributions. Because floristic assemblages, disturbance regimes, and history of land uses vary throughout the tropics, one may hypothesize that patterns of secondary forest succession are distinct in each region. This pilot research, supported by the YIBS Center for Field Ecology, was designed to investigate what is the main pattern of secondary forest succession in southern Bahia, a center of endemism and diversity for some major groups of plants and animals in the Atlantic forest of Brazil. The overarching research goal was to investigate how structure and tree species composition of secondary forests change with succession. This was one of the first studies designed to statistically compare structure and tree species composition across a chronosequence of forest stands in the Atlantic forest of Brazil. Further research will examine how proximity to remnant forests affects life history traits of dominant tree species, and how past land use affects the rate of secondary forest succession
Most previous studies on the genetic effects of forest fragmentation have been conducted under the assumption that no significant genetic structure existed prior to fragmentation, which allows a direct interpretation of the genetic patterns observed as a result of habitat loss and isolation. However, this assumption may not hold true in regions of complex historical past. Understanding the historical past of the region and distinguishing between pre-existing genetic structure and the effects of forest fragmentation is important in formulating adequate conservation recommendations for resident taxa. My study seeks to (1) elucidate the taxonomy and the phylogeography of E. sp, a new form of the endemic rodent genus Eliurus, which was recently discovered in the highly fragmented forests of northeastern Madagascar, and (2) investigate the effects of area reduction and degree of isolation of fragments on the genetic diversity and population structure of E. sp. These goals will be achieved through a combination of field collection, habitat characterization and the use of phylogenetics systematics, population genetics, and phylogeographic approaches. Preliminary results indicate an unusually high level of genetic structure among populations from nearby forest fragments, suggesting a possible role of historical factors in the observed genetic patterns. This study is the first to investigate the effects of forest fragmentation on an endemic small mammal in Madagascar. Findings from this study will be used to formulate conservation recommendations not only for E. sp. but also for six other sympatric endemic small mammals of similar ecology, life history and dispersal behaviors. These include the necessity to build corridors among current fragments and the determination of fragment size below which a significant loss of genetic diversity is expected. 
While many explanations have been suggested for the rapid contemporary loss of amphibian populations and species, habitat degradation and fragmentation are regarded as the primary attributed causes. In addition to outright loss of suitable habitat and breeding sites, loss of upland habitat away from breeding ponds may decrease the connectivity among breeding sites, inhibiting the dispersal of individuals migrating between local pond populations. In addition to the simple loss of individuals coming into the population, this loss of gene flow may have other, less conspicuous, effects on the populations. In my research, I am investigating the effects of different types of landscape structure on local and regional amphibian population dynamics. Specifically, I am assessing how different levels of habitat connectivity influence gene flow, and how, in turn, this gene flow effects population persistence and dynamics in terms of pond occupancy, population densities, and local adaptive traits specific to each sub-population. The ultimate goal of this research will be to refine our understanding of regional amphibian population dynamics for use in strategies aimed at reversing current declines. The YIBS pilot grant has provided important funding for the initial phase of my field research, including travel costs, field equipment, and initial molecular assays of focal populations.
The Cambrian radiation of animals, involving the sudden appearance of all the major groups (phyla) within ~15 million years, represents one of the most fundamental events in life history. To date, however, there has been no detailed investigation of the order of first appearances across the Precambrian-Cambrian boundary interval and consequently it has been difficult to tease out the ecological pattern of the radiation. This project involved measuring and logging stratigraphic sections from as many localities across this paleobathymetric transect as possible, and noting the fossiliferous levels. The last appearance of a fossil often does not represent its true extinction due to sampling or facies effects (the so-called ‘Signor-Lipps’ effect) and conversely the opposite problem presents itself in understanding radiations. Confidence intervals based on the relative abundance of fossiliferous horizons, similar to those used in calculating extinction horizons, will be applied to the data set for each section. The computer program CONOP9, which optimizes mis-fit of contradictory first- and last-appearances between different sections, will also be used to create composite range charts for the data from measured sections. In the summer of 2007, along with a Yale undergraduate field assistant and a postdoctoral scholar from the University of Johannesburg, I did a field season in the late Ediacaran Nama Group of southern Namibia, which represents the best exposed and dated sections of the very end of the Precambrian. The Nama Group contains fossiliferous deposits that include the enigmatic Nama-type Ediacaran fossils, as well as the first biomineralizing metazoans such as Cloudina and Namacalathus. We investigated a number of sections in the Nama Group to better understand the first appearance of the first shelly fossils in earth history. We also collected carbonate samples to investigate the effect of ocean chemistry on the advent of biomineralization, and paleomagnetic samples to look at the relationship between the Cambrian radiation and the geophysical phenomenon Inertial Interchange True Polar Wander, which has been hypothesized to occur during this time period.
The Late Miocene (12 to 5 million years ago) was a time of global climatic and environmental change, combining dropping global temperatures with the rapid spread of tropical (C4) grasses at low latitudes in much of the world. This was also a time of great diversification within the Bovidae—the group that includes living cattle and antelopes—marked by the evolution of some of the earliest representatives of the living grazing (grass-eating) clades. My thesis work focuses on the study of fossil assemblages of bovids from three main areas: southern Asia (Pakistan and India), East Africa (Ethiopia and Kenya), and the eastern Mediterranean (Turkey). This summer I visited Anatolia, Turkey, to examine newly collected bovid assemblages from two Late Miocene sites, Corakyerler and Sivas. My ongoing study of these sites highlights the great degree of endemism within Anatolia as well as within a greater biogeographic province which extended from the Aegean to Afghanistan. The fauna in this zone differs strongly from those from southern Asia and East Africa, and my work will allow for continued comparison of this phenomenon. Additionally, I have begun isotopic sampling and analysis of carbon and oxygen from bovid tooth enamel. Sample collection and analysis is already underway at Yale, and primarily includes material from the southern Asian collections. I am testing the hypothesis that large, complex-toothed bovids of the Late Miocene inhabited more open habitats and adapted to a rougher, more grassy diet than did their smaller, unspecialized relatives.
A central question in evolutionary research concerns the origin and consequences of morphological novelty. Novel structures may promote diversification – the balance of speciation and extinction – through, for example, enhanced competitive ability or the exploitation of new habitats. However, increased diversification rates may also result from the availability of new geographical and ecological opportunities. Understanding the causes of diversification provides a link between evolutionary process and current biodiversity. The Mediterranean-centered plant group Dipsacaceae (Dipsacales) is an excellent system for studying the evolution of morphological novelty and its consequences. Well known for their bizarre fruiting structures, the group is characterized by an epicalyx, a novel structure that subtends the flower and functions in ovary protection and seed dispersal. In Dipsacaceae, the epicalyx forms the dispersal apparatus, and different epicalyx phenotypes are responsible for the many dispersal syndromes found in the group. These observations have suggested to previous workers that the epicalyx is a “key innovation” that spurred the adaptive radiation of Dipsacaceae in the Mediterranean basin. I propose to resolve phylogenetic relationships within Dipsacaceae and to use the resulting tree(s) to test what effects – if any – the epicalyx has had on diversification. A finding that shifts in diversification rate have been historically correlated with the evolution of epicalyx characters would support the hypothesis that the epicalyx has been a driving factor in the evolution of these clades. If epicalyx characters are found not to be correlated with diversification shifts, then presumably other factors have been involved. In such cases biogeographic analyses may indicate that movements into new areas have played an important role in driving diversification. The YIPS pilot grant supported fieldtrips to Italy for sample collection. It provided funds for travel costs to and from field sites and field equipment (silica gel, collection bags). 
The Amur tigers, Panthera tigris altaica, the northernmost subspecies of tiger has a serious population decline during the past century, and currently are found only in very scattered populations in the Russian Far East and northeast China. The unique Far Eastern mixed deciduous-coniferous forest is known as the prime habitat for Amur tigers. Habitat loss and fragmentation caused by forest exploitation are considered as the primary threats to the tiger’s survival. With the breakup of the Soviet Union and the subsequent political and economic changes in Russia, and with the growth and spread of human populations in China, the forests have been subjected to a variety of human and natural disturbances. However, current research and conservation plans lack a quantitative analysis to demonstrate to what extent the shortage of habitat is limiting the abundance of the Amur tiger or to provide a sustainable way to solve the conflicting demands of both the Amur tiger and humans for this forest resource. I propose to reconsider the causes of the declining population of the Amur tiger from a forest dynamics perspective – a concept which recognizes that disturbance, human and natural, alters forest composition and structure. The goals of this study are to determine whether the lack of forest habitat is an important limiting factor, to determine whether the current forest structure is suitable for Amur tiger, and to determine how the tiger habitat will fluctuate over time as the forest size and structure changes. Furthermore, the result of my study would lead to suggestions for scientific forest management strategies that would incorporate both economic and ecological values into policies. In the summer of 2006, the YIBS CFE pilot grant supported me to conduct experiments and collect the forest inventory data and ground calibration data for satellite image interpretation in the forests in Northeast China. 
A key question in ecology and conservation biology is whether an ecosystem can recover to its original state following a perturbation. In the case of perturbations caused by invasive species, ecosystems may have been altered such that they jump to an alternate state. Invasive species removal, then, may not be sufficient to restore ecosystems back to their original states. In such cases, active restoration of ecosystem function must be coupled with invasive species removal to successfully restore systems. I am using the many and ongoing rodent eradications on New Zealand offshore islands, and the relatively recent idea of actively restoring seabird populations following rodent removal as a study system to evaluate ecosystem resilience in the face of invasive species removal. My research season consisted of sampling 8 islands in the Marlborough Sounds region of New Zealand. Particularly, I measured vegetation and arthropod diversity, evenness, and richness on each island as well as taking soil, vegetation, and arthropod samples for stable isotopic analysis. In addition, I measured abiotic factors such as soil temperature, pH, and moisture levels. Ultimately, this project will lead to a model of ecosystem recovery following invasive species removal and encourage seabird social attraction projects as a means to speed recovery.
Using the support from the YIBS CFE pilot grant I carried out the first part of my dissertation in the Path of the Tapir Biological Corridor (PTBC) during the summer of 2006. The PTBC (82,000 ha) is a local initiative, consisting of a mosaic of land uses, 55 communities and 10,000 inhabitants. The main objective of my dissertation is to assess the effect of land use on wildlife conservation in the PTBC. I am assessing how the different components of the fragmented landscape contribute with conservation of mammal and bird species. During fifteen weeks of field work using GIS layers, cartographic maps, and a GPS unit I located all the potential areas to conduct my wildlife assessments. In addition, I carried out surveys of mammals and birds. The selected habitats were four wildlife refuges (Baru, La Merced, Rafiki, and Oro Verde) as control treatments. In addition, the other selected habitats outside these protected areas were two timber tree species, Terminalia amazonia (amarillon, native to Costa Rica) and Tectona grandis (teak, exotic), growing in pure plantations, pasture lands, riparian areas, and other fragments of forests. The PTBC is considered one of the most biodiverse regions in Central America; however, scientific research in this area is lacking. Information is needed to establish baseline ecological conditions to improve wildlife conservation in the region.
Changes in food web structure can have wide-reaching effects, impacting nutrient cycling, food web stability, and contaminant biomagnification. The restoration of anadromous alewives is a perturbation that has the potential to strongly impact food web structure and dynamics in New England lakes. These food web effects in turn have the potential to affect mercury transfer to top predators. During the summer of 2006 I conducted a comparative study of food web structure and mercury transfer in lakes with and without alewives. This study addressed two main questions: (1) What are the differences in food web structure among lakes with and without alewives? and (2) Are there differences in mercury concentrations in top fish predators that are correlated with differences in food web structure? YIBS CFE funding enabled me to collect the samples for mercury analysis. I collected phytoplankton, zooplankton, and fish from 9 lakes in Connecticut to measure mercury transfer through these food webs.
Emerging disease has been recognized as a critical challenge for environmental scientists. Urbanization and other forms of anthropogenic change have been linked with wildlife disease emergence, but the mechanisms underlying these patterns remain unknown in most cases. Recent work suggests that infection of Rana clamitans (green frogs) by echinostomes, a group of digenetic trematodes, is greater in urban as compared to rural wetlands in Northeastern Connecticut. Echinostomes are one of the most widespread macroparasites in amphibians in North America. My project is aimed at investigating the impacts of echinostomes on green frog tadpoles and improving understanding of the mechanisms by which diseases can emerge as a result of urbanization
The discovery of peaceful post-conflict interactions (PPCI) in chimpanzees, and the subsequent identification of similar behaviors in other primate and mammalian species, has raised questions concerning the relationship between PPCI in humans and other animals. Originally, PPCI in humans, especially in regards to child development, was conceptualized in terms of altruism and morality. However, the recognition of PPCI in animals suggests a biological basis for human PPCI, and thus, PPCI can be conceptualized as a selfish behavior that evolved as a result of particular ecological or social circumstances. Therefore, research on the evolution and form of PPCI in animals, especially in an ecological context, creates a starting point for an evolutionary understanding of PPCI in humans. Although PPCI (and other post-conflict behaviors) are well documented in chimpanzees, much remains to be done to understand the cost and benefits of PPCI, as well as the circumstances, social and ecological, which influence its use and expression. In the summer of 2005, I assessed the feasibility of a project concerning these ideas at the Ngogo research site in Kibale National Park, Uganda, home to the largest study community of chimpanzees. 
In recent decades, ecologists have frequently used experiments of limited spatial and temporal scale to understand factors affecting wild populations. However, their small scales make them applicable under a restricted set of conditions, and it is often unclear how experiments designed to test specific hypotheses relate to factors that can reliably predict natural history patterns that inspire experiments. For the wood frog (Rana sylvatica), experiments conducted over small time scales and spatial extents indicate that larval predation risk, habitat permanence and temperature strongly affect abundance. To evaluate the experimental results for natural populations, I developed a model based on predator density, pond depth, and temperature. I will use this model to make wood frog abundance predictions at each pond in one generation, or in two years. Data collected from 57 ponds at the 3800 ha Yale Myers Forest and historical data will be used to parameterize the model and make predictions. Predictions will be tested with abundance measurements in two years. This project will help bridge the gap between the complementary approaches of explanation and prediction in understanding ecological systems as well as aid in effective wetland conservation.
Using the support of the YIBS Center for Field Ecology Pilot Grants Program, I conducted field research during the summer of 2005. During that summer, I measured and collected samples from fifteen stratigraphic sections, and I collected fossil plants from approximately twenty localities. Based on this field research, I was able to construct a lithostratigraphic section for the first ~ 4 million years of the Paleocene in the Williston Basin of North Dakota. Subsequently, I have analyzed the samples that I collected in the field and have been able to construct a magnetostratigraphic section for the lowermost Paleocene section from C29r to C27r and to determine sediment accumulation rates for the entire section as well as within each subchron. Based on the average sediment accumulation rates of ~38.5 m/myr, I have calculated the duration of the section to be ~4 myr. Furthermore, these data have allowed me to calibrate the two tongues of the marine Cannonball Member to within C28r and C27r respectively, correlate pollen biostratigraphic zone P1 to C29r-C28n and zone P2 to C28n-C27r, and identified a major change in the composition and dominant taxa in the megafloral record at the end of C28n at ~63 Ma. One potential implication of this result is the temporal restriction of the Puercan-Torrejonian 1 NALMA by nearly a factor of two, from previous estimates of ~2 Myr to ~1 Myr. This in turn suggests that post-extinction mammal speciation occurred twice as fast as previously supposed.
Newfoundland's Avalon peninsula famously exposes ~570 million year-old sedimentary rocks preserving wildly unusual fossil organisms called the Ediacara biota. To this day, it is not clear whether many members of this group were animals, plants, colonial microbiota, or a separate, extinct form of life of similar stature. Several sedimentary kilometers beneath the very first Avalonian Ediacara, boulder conglomerates associated with an unusual carbonate layer document a million-year long glaciation. Since other Precambrian glaciations appear to have encased the whole Earth like a "Snowball," I set out to measure new stratigraphic sections of the Avalonian end-glacial interval and collect paleomagnetic samples with which to determine a paleolatitude. If the Avalonian glaciation occurred at low latitude and were a Snowball Earth, Ediacara organisms, whatever they were, would seem to have evolved soon afterwards, perhaps as a direct consequence of postglacial ocean chemistry. The kilometers of rock between the older glaciation and the younger Ediacara are poorly exposed and have not been exhaustively searched for the very earliest Ediacara fossil. Along with Geology and Geophysics colleagues David Evans, Erik Sperling, and Catherine Izard, I examined the immediately postglacial interval for possible earliest signs of Edacara life. Paleomagnetic and paleontological results are in-progress.
Rain-induced soil CO2 pulses have been observed by many field studies. However, effects of rainfall on soil respiration via rapid change in soil moisture are not well understood as a result of both difficulties in measuring during rainfall and episodic sampling strategies by most field studies. Better understanding of response dynamics of soil respiration during rain events is important to accurately estimate net ecosystem production (NEP) and to better predict impacts on carbon cycling from a projected increase in precipitation variability due to global climate change. Rain simulation field experiment was carried out at Harvard Forest, Petersham, MA, throughout the growing season of 2005. Soil CO2 flux, soil moisture at different depths and soil temperature were measured before, during and after rain simulation. Preliminary results include: (1) Soil CO2 flux increased rapidly in plots with O horizon right after the onset of rain simulation and dropped back gradually to the pre-rain rate after rain stopped. The rapid and immediate response might well be overlooked if measurements were not made during rainfall. The pulse-like CO2 flux during rainfall is likely to result from the enhanced decomposition of carbon compounds in soil organic matter. (2) Temporal variation in soil CO2 flux enhancement showed a strong negative correlation to soil moisture of O horizon, indicating that water was not limiting at Harvard Forest during the growing season in 2005. For plots with O horizon removed, flux enhancement showed a clear trend to decrease with increasing soil moisture at 15 cm depth at Harvard Forest. (3) Repeated wetting at Harvard Forest did not show significant impacts on soil respiration.
Studies of female choice in chimpanzees have tested traditional interpretations of sexual selection theory, expecting to find females who are exceptionally choosy at the time of ovulation and males who are largely indiscriminate. However, the mixed and ambiguous results of these studies show a need for further investigation and consideration of alternative hypotheses concerning female mate choice, male sexual coercion and sexual conflict. I am investigating these questions in an extraordinarily large group of chimpanzees (Pan troglodytes schweinfurthii) at Ngogo, Kibale National Park, Uganda. I am doing this in two ways: 1) I address female mate choice by determining whether females behave proceptively toward some males while avoiding others, and 2) I examine the effects of male coercive behavior on male reproductive success and investigating what effect male coercion has on females’ ability to exercise mate choice. I am also considering whether male coercion and female mate choice are expressed differently during the periovulatory and the non-periovulatory periods of estrus.
I used the YIBS grant to conduct fieldwork at a number of sites in the eastern U.S. and Canada. In order to produce accurate hypotheses about the roles of cospeciation, life history, and host specificity in the evolution of the cedar apple rusts, I needed to collect specimens of over 50 species in this group. These species have many different geographic ranges and habitats, so I needed to visit many locations to collect them. Using YIBS funding, I visited Ontario, Florida, Georgia, New Jersey, New Hampshire, Pennsylvania, Massachusetts, and New York. In addition, the YIBS grant helped me to attend the 2004 meeting of the Mycological Society of America in Asheville, North Carolina.
In a continuation of research initiated in May 2003, I studied the feeding ecology and habitat characteristics of two communities of chimpanzees in Kibale National Park, Uganda. The distribution of chimpanzees in Kibale is markedly aggregated in the center of the park, with lower densities found in the northern and southern sectors. I was interested in determining the potential relationships between variations in feeding ecology of distinct chimpanzee communities inhabiting the park (as well as inter-site floristic variation) and these notable patterns of distribution and abundance. I studied the feeding behaviors of chimpanzees at two sites within Kibale: Ngogo (with a size of 150 chimpanzees) and Kanywara (with 50 chimpanzees). I found that chimpanzees from the large, high-density community (Ngogo) traveled a shorter distance between successive instances of feeding, and that individuals tended to feed in a greater number of distinct patches per day and for shorter lengths of time on average than did the chimpanzees from the small, low-density community (Kanyawara). This research has provided important data regarding the interplay between habitat heterogeneity within Kibale and spatial variability in the population density of Kibale chimpanzees.
In collaboration with the Centre National de Recherche et de Formation sur le Paludisme in Burkina Faso, West Africa, I identified natural predators of larval Anopheles gambiae mosquitoes and developed a PCR-based assay to detect predation on larval mosquitoes. Although understanding of larval mortality is critical to our understanding of mosquito population structure, little is known about the survival of larval mosquitoes in natural habitats. PCR allows us to distinguish between the morphologically identical members of the A. gambiae complex, which is responsible for the majority of malaria transmission in Africa. The assay that we developed allows us to test for the presence of A. gambiae DNA in the DNA extracted from potential mosquito predators. A positive result indicates predation on A. gambiae. Development of this assay is a first step toward field studies of predation on mosquito larvae. YIBS funding assisted with plane fare, housing in Burkina Faso, and field and laboratory supplies.
This study established stable carbon isotopic records of Paleogene-age higher-plant organic matter (e.g. coal, charcoal) collected from marginal marine sediments of the Bracklesham and Solent Groups exposed on Isle of Wight, UK. The purpose of this study was to determine average stable carbon isotopic values of Paleogene C3-plant organic matter (d13CC3plant) plant values were used to estimate the carbon isotopic composition of n-alkanes derived from C3-epicuticular leaf waxes (d13CC3n-alk) as well as constrain the d13C value of atmospheric carbon dioxide by using established values for the isotopic fractionation between bulk plant organic carbon, leaf waxes, and atmospheric CO2. From this, percent abundance of Paleogene C4 plants across similar latitudes were quantified by measuring n-alkane carbon isotope ratios (d13CC3n-alk) determined from marine sediments and applying a linear mixing model using the C3-end member d13CC3n-alk values determined from the Isle of Wight and theoretical C4-end member n-alkane carbon isotope ratios (d13CC4n-alk) determined from modern data. Using this approach, late Eocene d13CCn-alk records for Atlantic Ocean suggest that C4 plant material input was ~0-20% of total terrestrial plant material delivery. These C4 plant input estimates are coherent with late to middle Eocene high pCO2 conditions that would select for the C3 photosynthetic pathway rather than a C4 pathway.
The YIBS CFE Pilot Grant has funded my research on the effects of varying oxygen levels on vertebrate development and evolution. It has mainly contributed to the field portion of my research which is carried out at the Rockefeller Wildlife Refuge in southwestern Louisiana in collaboration with Ruth Elsey, a wildlife biologist at the refuge. While there, I travel into the surrounding swampland in fan boats to Alligator mississippiensis (the American alligator) nests to collect eggs and bring them back to Yale University. Back in the lab, I raise the eggs under varying partial pressures of oxygen to monitor the effects on their development. The results of this work show an effect of both hyper- and hypoxia on growth patterns, development rate, the timing and extent of bone development, its chemical composition, and the mortality of the developing eggs. I then apply this work to the fossil record during hypothesized times of high and low oxygen in the past to look for similar patterns. Overall, I have shown that oxygen has a large effect on modern vertebrate development, as well as the evolution of several vertebrate lineages.
In aquatic ecosystems, dam construction and the diversion of water for consumptive use have substantially altered the natural hydrology of streams, and climate change is likely to further affect hydrological regimes. My project explores the effect of lowered flow on stream community structure and ecosystem functioning by conducting reach-scale manipulations of flow through the use of diversion structures. Flow is one of the key drivers in stream ecosystems; it can affect the abundance, distribution, and behavior of stream organisms through its effects on key ecological processes such as dispersal, habitat use, resource acquisition, and competition. The goal of my study is to link the effect of an altered stream hydrological regime with ecological interactions and ecosystem processes by sampling the fish, crayfish, and aquatic insect communities, examining grazing and predation by aquatic insects, and measuring ecosystem level variables such as respiration, productivity, and decomposition in my experimentally manipulated stream reaches. The YBS CFE pilot grant supported the purchase of waders, aquatic insect sampling equipment, coolers, and water level loggers.
The Yale Institute for Biospheric Studies (YIBS) supported pre dissertation work in one of my three study sites: the Klamath Siskiyou Ecoregion of northern California/southern Oregon. The pre-dissertation scoping allowed me to make contacts with locally based nonprofits and meet with professors and students at local universities. The following year, I hired eight of those students as research assistants to help conduct a large scale, general public survey. Moreover, the pre-dissertation visit helped immensely in clarifying my understanding of the environmental forces at work in the Klamath Siskiyou—an ecoregion where residents are deeply divided over many critical conservation issues. Based on the work I was able to complete with YIBS funding, I returned to that field site the following year for six months, during which time I conducted more than 35 in-depth interviews with ecoregional residents and managed the administration of nearly 500 surveys.
A grant from the YIBS Center for Field Ecology has enabled me to conduct a one-month field trip to East Africa to check the feasibility of my project on the ecology of trypanosomes, the parasites causing African sleeping sickness. During this month I visited research institutes and field sites in Uganda, Kenya, and in the Serengeti National Park, Tanzania. I trapped several thousand tsetse flies, the disease vector, in all three countries. The funding from YIBS has enabled a field experience that was of crucial importance for the development of my thesis. The trip made me realize several short-comings in my initial project plan while at the same time guiding me to more realistic questions. It has been more instructive than the many months of work at my desk before, removed from the realities of the field. It has also enabled me to discuss my PhD project with many leading researchers in my field of research and build up connections that greatly facilitate my research now.
The money I received from the YIBS Center for Field Ecology was immensely helpful in facilitating access to fossil collections that are pertinent to my dissertation research. My research involves the compilation of a large database of measurements of felid skulls, especially extinct groups. To obtain these measurements, I must travel and visit many different collections. One of these important collections is in the Museum of Natural History in Addis Ababa. I used the money to help fund travel to Ethiopia, where I joined Dr. Tim White (University of California at Berkeley) and Berhani Asfaw (Rift Valley Research Service) for a field season. In assisting with the field season, I was granted access to collections at the museum in Addis Ababa. While I cannot discuss particulars regarding that collection, I can state that several of the specimens there will factor very heavily in the analyses I plan to perform. The money supplied to me by the YIBS Center for Field Ecology paid for my Ethiopian visa, a preliminary trip to UC Berkeley to meet several of the paleontologists involved in this expedition, and part of the airfare to Ethiopia. The trip to UC Berkeley is the only aspect of my travels that was completely funded by the YIBS Center for Field Ecology, and I would not have been able to make that trip without that money. This trip afforded me the opportunity to meet with Dr. White and discuss various legal and logistical aspects of the expedition. I am quite certain that without this face-to-face meeting, Dr. White would have been less inclined to include me in his expedition, and therefore less inclined to offer me access to his collections.
YIBS funding greatly assisted in pilot paleontological field work at 4.42 Ma early hominin sites in the Tugen Hills, Kenya. My 2003 summer fieldwork focused on recovering paleoenvironmentally diagnostic mammalian fossils. Small-bodied or rare fossil species (e.g. rodents, primates, carnivorans, etc.) can be important paleoenvironmental indicators, but are often subject to collector bias. To facilitate recovery of these diagnostic taxa my field investigations utilized a “total collection” fossil recovery method. Work in preparation demonstrates that “total collection” yields taxa and specimens poorly represented in traditional survey-collected assemblages. During six weeks in the field I directed a crew of ~30 individuals. The primary objective was to completely sweep and sieve the fossiliferous exposures and gullies and recover identifiable specimens. Notable finds include four primate species, one of which may represent an early member of the primate genus Theropithecus. In addition, we recovered multiple in situ specimens, including a relatively complete cercopithecid cranium (see photo). Recovered vertebrate fossils are being used in paleocommunity analyses to indicate the paleoenvironmental context(s) of early Pliocene hominins in the Tugen Hills. Microstratigraphic and sedimentologic studies of the sites help contextualize paleoenvironmental interpretations and identify taphonomic agents potentially affecting the assemblage. The results of this study will be compared and contrasted with paleoenvironmental interpretations from penecontemporaneous Ethiopian hominin sites, ultimately providing a better understanding of variation in early hominin paleoenvironments.
Daphnia, the water flea, is an integral component of the lake ecosystem. Many aspects of Daphnia biology are well characterized, including the role of food quality constraints on growth and reproduction, the dynamics of predator-prey interactions, and the complete genome sequence, making it an ideal model organism for an integrated examination of the chemical, environmental, and molecular components of ecology. Incorporating controlled lab experiments and field manipulations to understand the relative importance of “bottom-up” and “top-down” forces, my research investigates the effect of food quality and predation on Daphnia life history, including growth rate and reproductive output, and elemental composition. The results obtained increase awareness of the importance of elemental ratios in the environment and the impact on organismal composition and ecosystem function. The broader objective of the project is to provide a more complete understanding of the complexity of the aquatic ecosystem. By incorporating chemical, physiological, and molecular approaches to understand ecosystem dynamics, the impact of human-induced environmental change, particularly the eutrophication of lakes via phosphorus enrichment, can be predicted at the molecular, individual, and food web levels. The YIBS CFE pilot grant facilitated the collection and analysis of initial field data that helped shape the design and the approach I used to address these questions.
My dissertation research, funded in part by the Center for Field Ecology, looks at the causes and consequences of the evolution of a landlocked life history in a typically anadromous fish species, the alewife (Alosa pseudoharengus). This work focuses on understanding how selection for different traits has influenced anadromous and landlocked populations with respect to morphology and zooplankton prey selectivity and investigating how these evolved differences feedback to influence the ecological dynamics of the lakes in which the different populations reside for either all or part of their life cycle. My work in this system has revealed that anadromous and landlocked alewives have diverged in gape size and gill raker spacing, traits that are important for prey size-selection. Using a mesocosm experiment, I asked whether evolved differences have important consequences for zooplankton dynamics. Data from this experiment preliminarily indicate that differences in size-selectivity do indeed change zooplankton dynamics. This research addresses the reciprocal influences of ecological interactions and contemporary evolution in natural communities, an important emerging area of ecological and evolutionary research, and will provide important insights into the effects of ongoing anadromous alewife restoration efforts.
In Summer 2003, I received the YIBS CFE pilot grant to conduct pre-dissertation research in Mexico on the capacity of agroforestry systems (i.e., shade coffee plantations) to enhance the quality and diversity of agricultural landscape mosaics, and to reduce the effects of fragmentation on remnant montane cloud forests in their vicinity. Funding from YIBS was primarily used for field reconnaissance. During June and July, I spent four two-week periods in: Morelia (State of Michoacán), Xalapa (State of Veracruz), Oaxaca (State of Oaxaca), and Mexico City. I visited universities and research institutes; established contacts with Mexican researchers; acquired maps, books, journal articles, and recently completed theses and dissertations unavailable through the Yale University library system; visited several possible study regions and study sites; sought out institutional support for the research; and forged relationships with potential collaborators. Funding from YIBS enabled me to select a study region, and almost three years later, I am now conducting my dissertation research in collaboration with investigators at the Institute of Ecology, A.C., in Xalapa, Veracruz.
Predicting species interactions across diverse spatial scales represents an important objective for ecology and conservation. Interspecific interactions, such as predation, often depend on scale-dependent variation in environments and genotypes. In particular, the relative importance of current environmental selection and past evolutionary history on interspecific responses is expected to change according to the scale of analysis. I used my Center for Field Ecology pilot grant to evaluate when space matters for predicting the outcome of predator-prey interactions in pond-breeding spotted salamanders (Ambystoma maculatum) across local (~100 m), regional (2 km) and geographic (180 km) spatial extents. Funds made possible the completion of a field enclosure experiment, predator selection trials and biweekly field samples in 36 populations. Research demonstrated that A. maculatum populations not only adapted to variable predation risks at coarser regional and geographic scales, but also adapted to the local assemblage of predators in ponds separated by mean distances of less than 100 m. Results suggest that predicting interspecific interactions may require a more localized understanding about community selection than previously expected.
...Studies of biological organization have focused on solitary organisms while almost completely neglecting colonial structure. In the case of animals, the range of organizational properties known to exist in colonies presents an opportunity to investigate many of the evolutionary patterns that motivate current research on solitary taxa. These include trends in functional specialization and the evolution of buffered, stereotypic developmental processes. These two topics are well suited to an investigation of the siphonophores, a group of pelagic colonial Hydrozoa. 
...Commonly, plants living in arid environments build tissues that successfully operate at very low water potentials, a situation that presents a diverse array of challenges to basic plant metabolism. In xylem tissue, low water potentials will provoke xylem cavitation, a process that results in the formation of air embolisms within the plant’s water-conducting cells. Embolisms are critically dangerous to a transpiring plant, as they disrupt the continuous water column within the xylem and prevent the replenishment of water to dehydrating leaves.
...Lignin is a highly complex and variable polymer with ether and aromatic components that can only be degraded by the white rot Basidiomycetes. Five to thirty percent of the dry mass of a plant consists of lignin thereby giving this polymer the distinction of being the third most common plant polymer behind cellulose and hemicelluose. Hence, lignin degradation plays an important part of the cycling of carbon in both terrestrial and coastal systems. Due to the complex nature of lignin, the enzymes responsible for its destruction have both a high redox potential and a non-specific radical-based mode of action. Thus, they are of interest to biotechnologists where pulp bleaching and xenobiotic pollutant degradation are targets.
...Population genetics models and laboratory studies have shown that levels and patterns of relatedness among individuals can affect the growth and evolution of a population through such things as inclusive fitness, inbreeding depression and disease. However, the ecological importance of such kin level structure and variation is still obscure because of the difficulty or impossibility of identifying individuals and their relations in the wild using traditional techniques. That has now changed. Recently developed molecular techniques such as microsatellite analysis now make it possible to identify individual organisms and infer relatedness.
...More than 20 theories have been proposed to explain how sexual reproduction could provide both long-term and short-term fitness advantages over asexual reproduction (Barton and Charlesworth 1998). There are several species of adelgids (e.g. hemlock woolly adelgid, Adelges tsugae) that undergo both sexual and asexual reproduction in their native ranges, but lack the necessary host plants to support the sexual cycle in their introduced ranges. These circumstances offer unique opportunities to examine the costs and benefits of sexual vs. asexual reproduction in an ecological context. Before this can be accomplished, reconstruction of adelgid phylogeny is necessary to examine the evolutionary patterns of sexual reproduction within this group.
...There are two proximate goals for the research discussed here. First, I wish to establish the prevalence of intestinal parasites among the Ngogo chimpanzees. The data collected on parasitic prevalence will provide an index of the health of the population and serve as an important reference point for formulating hypotheses in future studies as to the ecological, physiological, and behavioral determinants of parasite infection in natural populations of primates.
...Landscapes throughout Central America are undergoing rapid degradation and abandonment as uncertain cattle markets, unsustainable land use practices, soil erosion, declining fertility, and declining rural populations have led smallholders to abandon their farms. The inclusion of arboreal elements in cattle production systems may offer one means of integrating products with more stable markets into these systems while also providing high conservation and biodiversity values. Instead of abandoning their land, farmers may instead seek to reforest their property or to add economically valuable trees to their cattle pasture system. This study will assess the potential economic value of trees that are regenerating in pastures. Natural regeneration may be a low-cost and effective way to increase the number of trees in a pasture if small-holders exclude fire from their system and leave forest fragments. Thus, I will work with the smallholders in the area to explore the feasibility and practicality of reforesting and protecting the land from fire and/or increasing the number of trees in a pasture.
...In general, there is an extensive literature on the social relationships of male chimpanzees in the wild and extensive comparative research on female social relationships in many other nonhuman primate species, but female chimpanzees have received relatively little attention from field researchers. Increased knowledge of free-living female chimpanzee behavior will improve the overall understanding of the species. Also, better information on the social behavior of female chimpanzees will contribute much to efforts to reconstruct the behavioral ecology of early hominins (humans and their ancestors) and to models of the evolution of modern human social behavior.