Graduate Research Symposium 2007
Biological Sciences and Physics Building. Room 1309:00 AM - 4:00 PM
The EEB Spring Symposium will be on Saturday, March 31st. This is an all day event where graduate students get a chance to present their research to other graduates and faculty in the department. Regardless of your research level, this symposium provides an opportunity to present project ideas and/or results in a low-stress atmosphere, and obtain valuable feedback from grads and faculty. Because this is an all day event, lunch and snacks will be provided by funds requested from the GSS by our graduate student GSS senators. Grads, please consider giving a talk.
Please submit titles to: firstname.lastname@example.org Early submission of titles is encouraged!
- 8:15-9:00 Breakfast
- 9:00-9:15 Tsitsi McPherson
- Transboundary Protected Areas: potential for the Guiana Shield Corridor
- 9:15-9:30 Suegene Noh
- Testing for preference of song characters in Chrysoperla lucasina
- 9:30-9:45 Kristiina Hurme
- Tadpole schooling and parental care in an aquatic-breeding tropical frog, Leptodactylus insularum
- 9:45-10:00 Nicholas Tippery
- Expanding the phylogenetic utility of the internal transcribed spacer (ITS) region using predicted secondary structure.
- 10:15-10:30 Beth Jacobsen
- Gene flow between multiple species in the New Zealand cicada genus Kikihia
- 10:30-11:00 Break
- 11:00-11:15 J. Pablo Arroyo
- Natural Forest Management Plans: A framework for assessing tree diversity
in Costa Rica.
- 11:15-11:30 Susan Z. Herrick
- Spatial Interactions of Breeding Male Green Frogs (Rana clamitans) and Bullfrogs (Rana catesbeiana)
- 11:30-11:45 Krissa Skogen
- Does atmospheric nitrogen deposition contribute to the decline of a native nitrogen-fixing species, Desmodium cuspidatum?
- 11:45-12:00 Jang K. Kim
- Are Intertidal Seaweeds More Efficient at Nutrient Absorption?
- 12:00-12:15 Adam Wilson
- The Fire-Weather relationship in the South African Fynbos: Implications under Climate Change
- 12:15-12:30 Roberta Engel
- Origins of pseudoscorpion lineages endemic to the outcrops of southwestern Australia
- 12:30-1:45 Lunch
- 1:45-2:00 Susan Letcher
- Methods for evaluating ecological similarity in large multivariate data sets: an example using forest succession data from northeastern Costa Rica
- 2:00-2:15 Carrie Fyler
- Erection of a new genus: A total evidence approach to tapeworm systematics
- 2:15-2:30 Karolina Fucikova
- New Algal Species Records for the Great Smoky Mountains National Park, U.S.A.
- 2:45-3:00 Diego Sustaita
- Prey processing in predatory birds: food for thought
Transboundary Protected Areas: potential for the Guiana Shield Corridor
Recognizing that species ranges extend beyond the political boundaries of individual countries, there is increasing advocacy for the creation of protected areas, or networks, extending into two or more countries. These transboundary conservation areas serve to protect species at a landscape scale approach. Conflicts over existing international boundaries between neighbouring countries are a hindrance to such conservation efforts. The countries of the Guiana Shield clearly illustrate why conservation must focus on a transboundary approach. Occupying a unique geological region, many of the countries on the Guiana Shield have contested borders with neighbouring countries. It is proposed that the focus of conservation along the Shield should be on the maintenance of systems that provide local, regional, and global goods for the public and private sectors. The potential for a transboundary biological corridor across the Guiana Shield, as a method for the continued provision of public goods, is discussed for Guyana relative to its neighbours, Venezuela on the west and Suriname on the east.
Testing for preference of song characters in Chrysoperla lucasina
Enter Abstract Here
Tadpole schooling and parental care in an aquatic-breeding tropical frog, Leptodactylus insularum
Group-living is a widespread phenomenon among animals that increases survival through increased predator detection and dilution of risk. Parental care is also widespread; parents may increase offspring survival through predator defense, food provisioning or nest building. Despite high levels of predation in aquatic environments, parental care of tadpoles is rare, probably because most adult anurans are terrestrial whereas tadpoles are aquatic. Within the Neotropical genus Leptodactylus, research has revealed an adaptive tendency towards tadpole schooling and female care and the novel use of stereotyped signals in female-offspring communication. Leptodactylus insularum tadpoles form dense aggregations that experience intense predation from terrestrial and aquatic invertebrates. Females attend the eggs and aggregations of tadpoles, and lead these schools to different microhabitats in temporary ponds. I will address multiple hypotheses about the effect of group size on predation risk and oxygen availability in tadpole schools, the biology of parental care, and the genetic composition of female-tadpole groups in Leptodactylus insularum. Additionally, I will discuss current research on growth rates and lung development in tadpoles, the effect of variation in female attendance on offspring growth and survival, and parent-offspring communication.
Expanding the phylogenetic utility of the internal transcribed spacer (ITS) region using predicted secondary structure.
Molecular phylogenetic methods often are based purely on the linear sequence of nucleotides for the region of interest. Methods that explore additional facets of sequence data include models of codon evolution for protein coding regions and doublet models that account for covarying sites. I have developed a method that extracts further phylogenetically-informative data from the nuclear internal transcribed spacer (ITS) region, based on predicted models of ITS secondary structure. Like their flanking ribosomal genes, the ITS regions (ITS-1 and ITS-2) have secondary structures ('stems' and 'loops') that are conserved across taxonomic groups as divergent as algae and angiosperms. In the method presented, seven conserved structural regions of ITS (three from ITS-1 and four from ITS-2) were encoded for their nucleotide composition and pairwise alignment type (match or mismatch). Data for different taxa were aligned to each other under the primary criterion of structural similarity, which differed from the traditional, phenetic alignment. Rather than incurring costs simply for changes in nucleotide identity, the method penalizes changes that disrupt secondary structure. Thus, by aligning sequences based on structure and assigning costs to structural changes, the method generates phylogenetic data that are nearly independent from the simple nucleotide sequences on which they were based. In an application from the family Menyanthaceae, the method substantially improved support for nodes that were ambiguous under analysis of traditionally aligned sequences.
Gene flow between multiple species in the New Zealand cicada genus Kikihia
The Kikihia genus of New Zealand cicadas has 20-30 species that extend over the entire country. There are over twenty contact zones between recently diverged Kikihia species and subspecies and hybridaztion has been found to occur between some of them. I propose to use microsatellite data to ascertain to what extent gene flow is occuring, between what species, and what effect on genetic differences gene flow is having.
J. Pablo Arroyo
Natural Forest Management Plans: A framework for assessing tree diversity in Costa Rica.
Enter Abstract Here
Susan Z. Herrick
Spatial Interactions of Breeding Male Green Frogs (Rana clamitans) and Bullfrogs (Rana catesbeiana)
Many anurans breed in mixed-species assemblages, and in some cases, breeding males engage in interspecific aggressive interactions. North American bullfrogs (Rana catesbeiana) and green frogs (Rana clamitans) are broadly sympatric, often are found together in permanent or semi-permanent breeding ponds throughout the summer months, and have very similar mating systems. Males defend territories that offer appropriate vegetation for egg-laying, and they have similar vocal repertoires used in territorial interactions and in attracting females. This similarity in breeding ecology creates a potential for interspecific competition among breeding males, but very few studies have focused on interspecific adult interactions. I used ArcView to study the movements and spatial interactions of individually marked bullfrogs and green frogs in a pond in Connecticut. Calling and oviposition sites of each individual were characterized by measuring water depth, distance from shore, water temperature, and amount of overhead cover. I found that in the presence of bullfrogs, green frogs occupy sites that are closer to shore, in shallower water, and with abundant cover overhead, although some green frog territories were adjacent to those of bullfrogs. Green frogs also were more likely to use artificial shelters as territory sites than were bullfrogs. When bullfrog numbers declined late in the breeding season, some green frogs move into sites previously occupied by bullfrogs and sites that were farther from shore and with less cover. Large males of both species showed strong fidelity to particular territories, but smaller individuals often moved between territories or behaved as satellite males in the territories of larger frogs.
Does atmospheric nitrogen deposition contribute to the decline of a native nitrogen-fixing species, Desmodium cuspidatum?
Nitrogen (N) deposition is one of three anthropogenic factors most likely to cause biodiversity changes in the future. Increased N deposition may have an especially large impact on temperate forests, which are highly N limited and occur in regions with the highest levels of atmospheric N deposition. Legumes growing in temperate forests may be especially sensitive. N2-fixing plants, including legumes, often have a competitive advantage in areas of N limitation, but they may be outcompeted by other species when N deposition increases. The influence of N fertilization on agricultural species and on community-level properties has been extensively documented, but only recently have plant conservationists begun to consider the possible role of N deposition in species declines. This project investigates whether N deposition in the northeastern United States has contributed to the loss of a N2-fixing species, Desmodium cuspidatum (Fabaceae). Desmodium cuspidatum disappeared from suitable habitat in New England in the last 30-40 years. A greenhouse experiment tested whether D. cuspidatum competition with Solidago sp. is influenced by levels of applied N. To control for density effects, plants were grown alone, with another D. cuspidatum, or with Solidago sp. Five N treatments – no N, three simulated N deposition rates, and half-strength Hoagland’s solution - were applied weekly for 10 weeks. Measures of plant size were collected weekly. At harvest, aboveground and belowground biomass, number of nodules and delta 15N stable isotope ratios were measured. Delta 15N signatures identify the source of N used by each plant. The relationship between applied N, nodulation, and delta 15N and the implications of these results for D. cuspidatum population dynamics will be discussed.
Jang K. Kim
Are Intertidal Seaweeds More Efficient at Nutrient Absorption?
Desiccation stress can determine the upper distribution limits and could enhance the uptake of nitrate and ammonium of intertidal algal species. Emersion following desiccation might stimulate several aspects of metabolism. Upper shore species may exhibit greater stimulation of N uptake following desiccation and achieve maximum uptake at higher desiccation levels. The objective of this study was to determine whether Porphyra species from different vertical elevations respond differently to the desiccation stress, in terms of nitrate uptake and growth. The intertidal species (Porphyra umbilicalis) and subtidal species (P. amplissima) were utilized in this study. Both species were cultivated at 100–150 umol m-2 s-1 light intensities, 500 uM nitrate concentration and 10 C (P. umbilicalis). Porphyra amplissima was cultivated at 15 C for three days, and P. umbilicalis was cultivated at 10 C for three weeks at a photoperiod of 12:12h L:D. Samples were exposed to air for 0, 30 min (30-50% water loss) and 2 hrs (90% water loss), 4 hrs after light exposure each day. Desiccation was more stressful to the subtidal species, P. amplissima, than to the intertidal species, P. umbilicalis. When tissues were exposed for 2 hrs daily, P. amplissima lost weight and pigments, while the growth rate of P. umbilicalis dropped by only 30% compared with that of continually submerged blades. Nitrate uptake rate of subtidal P. amplissima was only 73% (30-50% water loss) and 62% (90% water loss) of that of continually submerged tissue. Nitrate uptake rates of P. umbilicalis were not significantly different in each treatment. These results suggest that species in the intertidal zone, which have longer exposure times, may have higher time-use efficiency than the subtidal species in terms of nitrate uptake. This indicates a possible correlation between nitrate uptake and observed vertical distribution patterns.
The Fire-Weather relationship in the South African Fynbos: Implications under Climate Change
Fire is a defining component of the fynbos ecosystem in the Cape Floristic Region (CFR) of South Africa. Many ecologically important species require fire for reproduction and the frequency of fire is a primary determinant of species composition. It has been hypothesized that climate change will increase fire frequency by raising temperature and reducing the reliability of rainfall. However, little work has been done to quantify the relationship between fire occurrence and climate factors. I am currently working on spatio-temporal statistical models to explain the monthly variability of fire frequency in mountain fynbos regions from 1980-2000. Preliminary results suggest a clear relationship between temperature, precipitation, and fire events, with more and larger fires occurring in hotter, drier months and years. These findings have important ramifications for conservation and management of fynbos. If climate change leads to higher temperatures or lower rainfall, our models imply that fire frequency will increase. Increased fire frequency will favor re-sprouters and other species that reproduce quickly over plants with slower reproduction cycles. Thus, if the fire regime changes, the community composition of the fynbos could change.
Origins of pseudoscorpion lineages endemic to the outcrops of southwestern Australia
Enter Abstract Here
Methods for evaluating ecological similarity in large multivariate data sets: an example using forest succession data from northeastern Costa Rica
Since species abundance data sets are often massively multivariate, extracting useful axes of variation is a challenge. Here, I present a data set of woody plant abundance from 30 sites along a forest succession gradient in northeastern Costa Rica, comprising 8914 individuals of 477 species. I summarize the state-of-the-art methods for examining similarity in species composition between sites, performing an ordination based on the similarity matrix, and examining the validity of a priori groupings in the data set. This analysis reveals significant changes in the species composition of sites along a chronosequence.
Erection of a new genus: A total evidence approach to tapeworm systematics
New tapeworm species are continually being discovered and described from a variety of vertebrate hosts. Traditionally, all taxonomic assessments have been based on morphology alone. Recently an increase in tapeworm molecular sequence data has made it possible to construct molecular phylogenies to confirm morphological hypotheses and thus incorporate a total evidence approach to tapeworm systematics. In the current study the elasmobranch host Pristis clavata Garman, 1906 (dwarf sawfish) was examined for a unique tapeworm complex suspected to be a genus new to science. Traditional morphological techniques were used to erect the new genus and to describe three new species. Molecular sequence data from the nuclear ribosomal subunit 28S were generated for at least two individuals of each putative new species. Bayesian inference and maximum parsimony were used to analyze the dataset within a much larger phylogenetic framework. The morphological results led to the erection of a new genus and three new species. The molecular results confirmed the presence of three species. Each hypothesized morphological species formed a clade distinct from the other two species. The molecular results however did not support the placement of all three species in a single genus. In both parsimony and Bayesian analyses species A and B formed a clade phylogenetically distinct from the most closely related genera, however species C was always sister taxon to the genus Acanthobothrium. The results of these molecular analyses suggest that the cestode species parasitizing sawfish are some of the most basal lineages of a very interesting clade including Acanthobothrium (parasites of elasmobranches), Proteocephalidea (parasites of fresh water teleosts) and Potomotrygonocestus (parasites of fresh water rays in South America). This is a very diverse group of parasites in which each genus has at least some affinities to freshwater. This is in contrast to their closest relatives, which are found entirely parasitizing elasmobranchs in marine environments. These new species may be the key to understanding the origin and diversification of the group.
New Algal Species Records for the Great Smoky Mountains National Park, U.S.A.
The Great Smoky Mountains National Park harbors a remarkable biodiversity. Within the All Taxa Biodiversity Inventory (ATBI), a project that has been in progress in the park since 1997, 976 algal taxa have been reported to this day. This number includes a few old historical records from the 1940s, as well as hundreds of taxa reported by the algal Taxonomic Working Group (TWiG) of the ATBI. From the total of 976 taxa, 392 have been added since the last published species record list (2004). Ranges of several algal taxa have been extended as a result of this work. In addition, some new species of diatoms (Bacillariophyta), blue-green algae (Cyanobacteria), green algae (Chlorophyta), and conjugating green algae (Charophyta) have been described. Even more taxa, ca. 50, have not been identified to species level with certainty, and are therefore putative new species as well.
Prey processing in predatory birds: food for thought
Prey processing generally refers to the act of manipulating prey to facilitate its passage through the alimentary tract. Naturally, there is tremendous variation in the way different groups of birds go about this. In predatory birds for instance, this process begins with capturing and killing prey, followed by further processing prior to consumption. Here I discuss my endeavor to study the biomechanics of prey processing and feeding in a predatory songbird – the Loggerhead Shrike – through an intraspecific, ecomorphological approach. Given their morphological and behavioral adaptations for processing vertebrate prey, unique impaling behavior, broad geographic distribution, and omnivorous food habits, shrikes form a particularly interesting system for examining functional trade-offs, and the mechanistic basis to patterns of phenotypic variation.