Ecology and Evolutionary Biology Graduate Research Symposium
Saturday March 18th
Biological Sciences and Physics Building. Room 130
9:00 AM - 4:00 PM
The EEB Spring Symposium will be on Saturday, March 18th.
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, the submission deadlines are as follows:
Title submission deadline: Friday, March 3rd
Abstract deadline: Monday, March 13th
Please submit Abstracts to: firstname.lastname@example.org
Early submission of titles is encouraged!
Hope to see you there!
9:00-9:15 Opening Remarks By Dean Ross MacKinnon
The phylogenetic significance of a large inversion in the chloroplast genome of a lineage of mosses
Attachment in challenging environments: Functional morphology of three distinct scolex morphotypes of Acanthobothrium
Soil nutrient levels and species composition in an Old Growth Tropical Forests
Top-down control of river herring populations by striped bass: attractive myth or unanticipated consequence?
Structure and development of Nostoc strands in Leiosporoceros dussii (Anthocerotophyta): a novel symbiosis in plants.
10:30-11:00 -Morning Break
When to follow a leader: recruitment behavior in the Pavement ant, Tetramorium caespitum
Characterization, Geographical Variation and Host:Symbiont Specificity in the Green Symbiont of Anthopleura xanthogrammica, and A. elegantissima.
Social Mechanisms of Habitat Selection by the Saltmarsh Sharp-Tailed Sparrow
Comparing functional traits in native and invasive New England shrubs
Distribution of winter flounder eggs among shallow water habitats in two harbors in Long Island Sound.
Natural forest management plans in Costa Rica: a potential framework for assessing tree diversity
Evaluating models of genital evolution in male and female Phyllophaga scarab beetles.
Behavioral Interactions Among Breeding Male Bullfrogs (Rana catesbeiana) and Green Frogs (Rana clamitans) at Different Spatial Scales
Jumping Spider Mimicry in Metalmark Moth Genus Brenthia (Lepidoptera: Choreutidae)
Stand structure and species composition of tropical secondary forests
2:45-3:15 -Afternoon Break
The impact of ancient Maya home forest gardens on the modern tree species composition and biodiversity of Northwestern Belize
Diversity and distribution limits in South African Proteas
Heteropteran Endoskeleton, A Family Level Study
Natural forest management plans in Costa Rica: a potential framework for assessing tree diversity:
Protected areas are the foundation of conservation programs throughout the world; however, these areas cannot encompass all areas with significant levels of biodiversity. Development of effective, long term plans to conserve and manage biodiversity at the regional level requires understanding the distribution, diversity, and abundance of species in unprotected as well as protected areas. Natural forest management may potentially be a suitable land-use option to promote conservation of tropical biodiversity outside protected areas. In fact, a considerable amount of data on tree abundance and landscape distribution already exists in the form of natural forest management plans (NFMP) for privately owned farms throughout Costa Rica and other tropical countries. In this project I address whether NFMPs datasets can be effectively used to assess tree biodiversity by assembling a large dataset from certified (FUNDECOR/Forest Stewardship Council) and non-certified NFMP pre-harvest inventories. To test the utility of NFMP data, I will compare measures of local, landscape, and regional tree biodiversity with those of an independent set of inventories conducted in the same farms within the San Juan–La Selva Biological Corridor. The proposed research has four components: 1) tree biodiversity assessment based on natural forest management plan (NFMP) databases; 2) tree diversity assessment based on an independent, standardized biodiversity assessment methodology; 3) a comparative study of biodiversity results between NFMP data and data collected in the field; and 4) long term viability analysis of selected tree species based on the regional landscape. My research is a first step in exploring ways to integrate forest management with biodiversity assessment and conservation at the regional scale, a virtually unexplored realm.
My work addresses questions about how and why diversity arises and at what point divergence is sufficient to lead to speciation. One way to better understand diversity is by studying the process of divergence among populations isolated by natural barriers that limit dispersal and gene flow, such as those inhabiting islands. Specifically, I am interested in understanding the diversification of a clade of pseudoscorpions found on a terrestrial island system, the granite outcrops of southwestern Australia.
Attachment in challenging environments: Functional morphology of three distinct scolex morphotypes of Acanthobothrium
Acanthobothrium is a species rich and globally distributed genus of host specific cestodes that parasitizes a diversity of elasmobranchs and whose phylogenetic relationships remain unknown. Several conspicuous morphological characters distinguish Acanthobothrium from other tetraphyllidean genera but the morphological diversity within the genus is also extensive. One of the most remarkable differences among species of Acanthobothrium is related to scolex shape; each species falls into one of three distinct categories referred to here as the robust, classic and cloverleaf morphotypes. This study attempts to understand the underlying structural differences among these scolex types. Whole mounts and histological sections were prepared according to conventional methods for multiple species of Acanthobothrium. The scolex proper of all species of each morphotype was found to have the same complex of muscle fibers. The bothridial muscles however, differed dramatically among scolex forms. The robust morphotype possessed thick bothridial muscles that were completely attached to the scolex proper on their proximal surface; the musculature was composed of densely interwoven fibers. The cloverleaf forms had long slender bothridia with 25-33% of the musculature attached to the scolex proper; the bothridial margins were reinforced with thicker musculature. The classic form had long slender bothridia but unlike the cloverleaf 60-70% of the musculature was attached to the scolex proper. Bothridial morphology appears to be intimately associated with mode of attachment. Species with the robust and classic scolex morphotypes were found with their scolices embedded deep in the host’s intestinal musoca. The cloverleaf forms however, were found attached superficially to the intestinal surfaces, which may be facilitated by their flat sucker-like bothridia. At this time it remains unclear if the variation in scolex morphotypes is of phylogenetic or functional significance.
Comparing functional traits in native and invasive New England shrubs:
Because of increasing concern about the detrimental effects of invasive species on native ecosystems, the importance of understanding invasives is more and more obvious. Shrubs are abundant in the New England landscape and of the 123 species listed on the Invasive Plant Atlas of New England website, 22 of them are shrubs: nearly 18%. Shrubs are an interesting study group for many reasons, one of which is their development of secondary xylem tissue called wood. Not only does wood allow for study of yearly differences in growth in temperate zones due to rings, it plays an important role in plant function, especially water relations. Because wood is the pipeline through which shrubs move water from the roots through the plant body toward the leaves, its structure influences the flow of water and essentially photosynthesis. Carbon gain through photosynthesis depends partly on the structure of the leaves, including their specific leaf area. I am interested in comparing how invasive and native shrubs build their various structures, specifically by looking at specific leaf area and the density of wood. I hope to use these two traits as well as measurements for hydraulic conductivity and leaf pressure potential to gain some insight into how natives and invasive compare in their photosynthetic and hydraulic function. If invasives are able to use less carbon when building their structures by developing less dense wood and leaves with a higher specific leaf area, that could help to explain how they are able to have additional resources available for greater reproductive output and increased vegetative growth.
Behavioral Interactions Among Breeding Male Bullfrogs (Rana catesbeiana) and Green Frogs (Rana clamitans) at Different Spatial Scales:
North American bullfrogs and green frogs are syntopic, broadly sympatric and have very similar breeding ecology. The effects of competition and predation on larval interactions have been well studied, but interspecific behavioral and ecological interactions of adults have largely been ignored. Fieldwork in 2005 revealed some microhabitat partitioning in these species. Green frogs prefer calling sites in shallow water near shore, with dense cover overhead, whereas bullfrogs often are found in deeper water farther from shore, with little or no cover overhead. We found evidence of some spatial separation in the pond, but there also were instances of bullfrogs using space very close to green frogs and of green frogs using abandoned bullfrog territories. This type of behavioral adjustment in a natural setting has not been quantified for these species but may be important to our understanding of how native anurans are influenced by introduced bullfrogs. This research will expand our knowledge of the influences these two sympatric and syntopic species have on each other and add another layer to our understanding of anuran behavioral ecology.
Diversity and distribution limits in South African Proteas:
Extraordinarily high plant diversity in South Africa's Cape Floristic Region is linked to high endemism, and to restriction of many species to particular subregions. Closely related species tend to have non-overlapping distributions, resulting in high species turnover. The CFR thus ranks as a global biodiversity hotspot in large part because of the distribution limits on its plant species. Do these distribution limits arise from local ecological processes (species cannot grow elsewhere), or from regional level processes (species cannot migrate)? Through reciprocal transplant experiments on a group of closely related shrubs in genus Protea (Proteaceae), we tested the hypothesis that species distributions are limited primarily by 1) ecophysiological factors or 2) by competition. Seeds and transplants of species were grown in common garden plots within the distributions of each species, and along an altitudinal gradient. Each species performed best (germination, growth and/or mortality) when planted within its own distribution. But each species also performed well in at least one site outside its current distribution, suggesting that early life stages do not place hard limits on existing distributions. Interspecific competition also appears not to impose limits, since plants generally performed better in mixtures than in monocultures. It appears that localized distributions of these species are restricted primarily by regional migration limitation rather than by habitat diversity and local adaptation.
Stand structure and species composition of tropical secondary forests:
Tropical secondary forests play an increasingly important role in today’s fragmented landscape. I examined the species composition and structure of fifteen forest stands, ranging from 14 yrs to old growth. Species accumulation and stem density were influenced by forest age, and by the intensity of land use prior to regeneration. Species composition varied widely, with the highest similarity values among old growth stands and the lowest for secondary-old growth comparisons. There was a weak negative correlation between tree basal area and the percent of basal area composed of lianas (woody vines). The structure and composition of regenerating forests depend on a complex interplay of factors.
Characterization, Geographical Variation and Host/Symbiont Specificity in the Green Symbiont of Anthopleura xanthogrammica, and A. elegantissima:
To understand ecological interactions and diversity in complex systems, it is important to understand symbiotic relationships. Two species of Anthopleura in the temperate Pacific intertidal, Anthopleura xanthogrammica (Brandt 1835), and A. elegantissima (Brandt 1835) can form symbioses with two photosynthetic protists, a green alga (Chlorophyta), and a dinophyte belonging to the genus Symbiodinium (Freudenthal, 1962). By testing the variability, coevolution and geographic distribution of the green alga symbiont in two temperate Pacific Anthopleura species we hope to gain a better understand the energy resources available to these anemones. There are four main areas of investigation I am proposing to further our knowledge of these interactions. The first objective of this project is to determine the phylogenetic relationship of the zoochlorellae to other symbiotic and free-living green algae for which published sequences or cultured algae are available. If the zoochlorella of these anemones is determined to be a distinct taxon, it will be taxonomically described. The second objective of this project is to compare the Anthopleura zoochlorellae to other green symbionts of marine invertebrates to determine if there is a distinct clade of Chlorophyta that have produced invertebrate symbionts. The third objective of this project is to compare the geographic variation and host specificity of the Anthopleura zoochlorellae, with what is known about the Symbiodinium systems in the Anthopleura anemones. The fourth objective is to determine if symbiont distribution in and between A. elegantissima clonal aggregations is linked to clone relationships or microhabitat distribution along temperature or irradiance gradients.
Soil nutrient levels and species composition in an Old Growth Tropical Forests:
Attempts to understand the drivers of biodiversity have engaged the attention of ecologists for centuries with a myriad of hypotheses proposed including soil and topographic variation. We analyzed data from 18 plots of the CARBONO project at La Selva , Costa Rica; two edaphic and topographic categories thought to discriminate among the plots. The 5261 stems, representing 294 species, and soil nutrients at 5cm and 75 cm, were used to examine floristic characteristics among these plots. Species were classified using importance values, then related statistically to soil nutrients and topographic slope. Assessment of soil fertility showed significant statistical differences among the 18 plots at both depths, a nutrient continuum rather than discrete categories. Multivariate analysis of dominant, intermediate and rare species, as groups, showed an inverse association among nutrients for dominant and intermediate species. Further reseach is needed to improve our understanding of species interactions, both interspecific, considered in this study, and intraspecific as a means of understanding the dynamic processes interacting in tropical forests.
Distribution of winter flounder eggs among shallow water habitats in two harbors in Long Island Sound:
Winter flounder (Pseudopleuronectes americanus) is an important commercial and recreational species providing both a valuable catch for commercial fisherman and an incentive for recreational fisherman to spend money in their pursuit. Winter flounder eggs are at risk of burial during maintenance dredging efforts in harbors. This impact can be minimized if the time and location of egg deposition can be pinpointed. Here we report results of fine-scale sampling for eggs and concurrent substrate characterization using an acoustic system. Benthic sled samples (N = 185), stratified by depth and location, were taken in Milford and New Haven Harbor in February, March and April 2004. The benthic sled samples yielded a total of 164 winter flounder eggs and 122 winter flounder larvae. These occurred in both inner and outer harbor regions. Multivariate analysis on acoustic data was conducted to identify bottom types that were sampled. This analysis identified an unexpected use of fine mud habitats by spawning flounder.
When to follow a leader: recruitment behavior in the Pavement ant, Tetramorium caespitum:
Colonies of the Pavement ant, Tetramorium caespitum, have extended territorial disputes every spring and summer. One component which may affect the spatio-temporal dynamics and outcome of these battles, is the ability of each colony to recruit nestmates to the "battle zone" where dyads of ants are fighting. This presentation will introduce an ongoing study of the recruitment patterns in T. caespitum
Heteropteran Endoskeleton, A Family Level Study:
A sweeping study of endskeletal structures in Heteroptera. 50% of families were examined resulting in over 50 drawings and nearly 600 SEM micrographs. 26 newly named structures have been identified, along with 107 characters and over 400 states. These independently observed characters have been phylogenetically analyzed with interesting results.
The impact of ancient Maya home forest gardens on the modern tree species composition and biodiversity of Northwestern Belize:
I test the hypotheses that, 1) due to centuries of intensive management, home forest gardens built by the ancient Maya altered the tree species composition of the forests and these effects can still be detected today, and 2) despite the high population density of the Maya, the tree diversity was maintained by the extensive use of these gardens. In the forest around the ancient Maya urban center of El Pilar, Belize I compare the species compositions of high and low ancient settlement density areas of similar forest type including comparing the abundances of 20 indicator species known to have been used by the ancient Maya. Preliminary data from 2005 showed a significantly higher abundance of 9 indicator species in the high settlement density area (G-value= 38.700 , df= 8, p<0.0001). The maintenance of a visible pattern of ancient Maya silviculture would argue for a sustainable method of agroforestry that works within the ecology of the system and can be used as a model for future land use decisions in the New World tropics.
Jumping Spider Mimicry in Metalmark Moth Genus Brenthia (Lepidoptera: Choreutidae): Jumping spiders are visual predators that prey on other arthropods. They are very territorial and through territorial displays they signal to other jumping spiders that happen to cross into their territory. Such displays usually end with the newcomer’s leaving. It appears that metalmark moths in the genus Brenthia evolved mimicry of jumping spiders as a means of protection from their predation. Through a series of laboratory trials, I show that Brenthia have higher survival rates than other moths and that jumping spiders respond to them as to other jumping spiders, not as potential prey.
Social Mechanisms of Habitat Selection by the Saltmarsh Sharp-Tailed Sparrow:
Understanding habitat selection mechanisms is critical to understanding species distributions at local and regional scales. Selection of breeding habitat, in particular, has immediate effects on individual fitness, and is therefore under strong selection pressure. Habitat selection, thus, has important consequences for species demography, ecology and evolution. The saltmarsh sharp-tailed sparrow (Ammodramus caudacutus) is a non-territorial, socially polygamous species that breeds in the coastal saltmarshes of the northeastern United Sates. Several lines of evidence suggest that these sparrows may combine social information with their assessment of the physical environment in order to select nesting habitat, yet the way in which birds integrate these disparate types of information has not been well studied. To resolve this uncertainty I will investigate how social interactions and cues obtained from conspecifics influence breeding habitat selection in the saltmarsh sharp-tailed sparrow. Using experimental methods, I will test the role of conspecific attraction by manipulating social cues to determine whether birds preferentially settle and nest where conspecifics appear to be present. I will also track nest placement, settlement order and nest fate in established populations in order to explore the underlying social structure of saltmarsh sparrow populations, as well as determine the potential benefits of aggregated breeding.
Structure and development of Nostoc strands in Leiosporoceros dussii (Anthocerotophyta) a novel symbiosis in plants:
The presence of Nostoc in longitudinally-oriented schizogenous canals is a feature that separates Leiosporoceros from all other hornworts and represents a novel symbiotic arrangement in land plants. All other hornworts develop discrete globose colonies with a continuous production of mucilage clefts as avenues for multiple invasions and independent colonies within a single thallus. To elucidate the anatomy and development of Nostoc strands, we examined sporeling development in culture and the structure of strands in field-collected plants using light and electron microscopy. In Leiosporoceros, rosette-like sporelings have mucilage clefts located in proximity to swollen apices. All field specimens were strap-shaped, contained Nostoc and lacked mucilage clefts. In surface view, Nostoc canals are visible as elongated, dichotomously-branched blue-green strands. These strands are located in the center of the thallus and develop behind the apical cell by dissolution of the middle lamella between apical derivatives. Strands elongate and branch in synchrony with apical growth and only a single invasion of each thallus is required for its development. Two distinct ultrastructural morphotypes between collections suggest non-specificity of Nostoc. We speculate that Nostoc enters the thallus in the sporeling stage through the mucilage clefts and once a colony is established, clefts cease to be produced.
The phylogenetic significance of a large inversion in the chloroplast genome of a lineage of mosses:
The Funariales is an order of mosses whose phylogenetic position is critical to our understanding of the evolution of the arthrodontous peristome (jointed teeth lining the opening of the sporangium that aid in spore dispersal), but within which the relationships remain unresolved. Variability in the peristome, which can be reduced or lost entirely, as well as the poorly differentiated gametophytes have led to difficulty in determining the relationships between the three families: Funariaceae, Disceliaceae, Gigaspermaceae and the closely related order Encalyptales. Previous studies have suggested that the Funariales is paraphyletic, with the Gigaspermaceae forming a sister-group relationship with the other families and the Encalyptales, though this hypothesis was not supported. Recently, the chloroplast genome of Physcomitrella patens (Funariaceae) was sequenced revealing the loss of the rpoA gene and a 71-kilobase inversion in the large single copy region. We sequenced both ends of the inverted region for exemplars from the Funariales, Encalyptales, and other mosses and determined that the inversion is present in the Funariaceae, Disceliaceae and Encalyptales, but not in the Gigaspermaceae or more distantly related mosses. These results support the hypothesis that the Encalyptales is nested within a paraphyletic Funariales.
2006 Symposium committee: