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Ecology and Evolutionary Biology Graduate Research Symposium

Saturday March 8th
Biological Sciences and Physics Building. Room 130
8:30 AM - 4:00 PM

Schedule of Talks

(PDF schedule)

8:30-8:45 Janet Greger

Introductory Remarks

8:45-9:00 Patrick Herron, Dan Gage & Zoe Cardon

The opportunities for application of the proU-gfp transcriptional fusion as a bioreporter for water availability in the soil environment.

9:00-9:15 Ken Barber

On the gross anatomy of the spiral intestine of sharks from the Order Lamniformes.

9:15-9:30 Stacey Leicht

Life is bittersweet...the story of an invasive vine and its native congener.
The problem of invasive species is their varied effects on the landscape around us. One way in which invasive plants are problematic is in their impact on the native flora. The woody vines, C. orbiculatus and C. scandens, present a unique opportunity. These species are similar in appearance and life-history, yet one is highly invasive, while the other is on the decline in Connecticut. My research focuses on determining those factors which affect the ecological performance and success of each species.

9:30-9:45 Chris Martine

The evolution and natural history of breeding systems in sub-arid tropical Solanum of Australia.
Dioecy (sexes borne on separate plants) in Solanum is rare, having been observed in less than 1% of its ca. 1200 species. Nine of the 14 dioecious solanums inhabit the semi-arid tropics of Northwestern Australia, where they co-occur with ten andromonoecious species of the same subgenus (Leptostemonum). Phylogenetic analysis of these 19 taxa is proposed to parse out the pathway(s) taken to dioecy (and andromonoecy) in this group. One evolutionary scenario is that initially hermaphroditic ancestors first evolved andromonoecy that subsequently gave rise to dioecious species. Thus, the andromonoecious species would be evolutionarily intermediate in form. None of the evidence currently available supports this most parsimonious hypothesis. The andromonoecious and dioecious solanums of Australia offer a special opportunity to apply newer approaches in evolutionary biology to a group of species whose unusual reproductive biology and taxonomy sensu stricto is already fairly well-understood. Potential implications of the project include conservation of rare plants and habitats and the preservation of genetic diversity in the eggplant lineage.

9:45-10:15 coffee break

10:15-10:30 Maxi Polihronakis

Sexual Selection and The Genitalia of the Sacred Scarabs.
The number of reasons to study beetles parallels their astounding diversity. Examples include extensive behavioral variation (including sociality), numerous predatory defense mechanisms, and extremely broad habitat and resource utilization within individual life cycles, genera, tribes, subfamilies, etc. The diversity found within the order is also reflected in the striking morphological variation seen across many taxonomic levels. In particular, I am interested in viewing variation in male genitalia from an evolutionary perspective. The historical use of male genitalia for species-level identification suggests that they have played a role in creating patterns of adaptive radiation through selection for differentiation (Eberhard, 1986). Underlying reasons for the observed diversity of male genitalia have been debated. Hypotheses include those that invoke lock-and-key (species recognition) mechanisms, functional considerations (holdfast structures), and sexual selection via female choice. Two groups I have begun to look at in more detail are hister beetles (Histeridae), and the May/June beetles (Phyllophaga). Histerids show greater overall diversity of both habitat and morphology, while members of Phyllophaga have little morphological diversity relative to genitalic diversity. My research interests for either of these two groups include phylogenetic relationships, variation within species (genitalic shape and fertilization success), pre- and post-copulatory behavior, genitalic asymmetries, and proximate mechanisms behind the development of genitalia, focusing mainly on asymmetrical structures and plates.

10:30-10:45 Eric Mosher

Utilizing aerial photography to reconstruct and quantify land use history patterns across a heterogeneous landscape: A prelude to an investigation of the distribution of invasive plants.
Using Erdas Imagine 8.5 and historical aerial photographs, I am creating a set of geo-referenced aerial mosaics from 1934, 1951, 1970 and 1991 that cover the southern Meshomasic State Forest region of central Connecticut. This region consists of a large, intact forest block surrounded by a landscape that is heterogeneous with respect to land use. I have begun to digitize the land use features of each mosaic using ArcView 3.2 and its extension "Habitat Digitizer". My plan is to create a spatially explicit analysis of land use change across multiple time frames and then utilize the results to guide a stratified random sampling scheme for the presence/absence and abundance of Berberis thunbergii. By linking the historical data with available remote sensing and environmental data, I hope to explain as much of the variation as possible in the present distribution of B. thunbergii.

10:45-11:00 Robynn Shannon

The Nettlesome Questions of Gender Determination and Breeding System Evolution in Urtica dioica.
The herbaceous perennial Urtica dioica is one of only a few angiosperm species to exhibit both monoecy and dioecy. There is some evidence of gender lability among monoecious plants, and also evidence of limited monoecy occurring in dioecious populations. My goal is to understand breeding system evolution in Urtica dioica through a combination of population biology and molecular and Mendelian genetics. I am also conducting investigations into the genetics of gender determination in this species.

11:00-11:15 late morning break

11:15-11:30 Hilary A. McManus and Louise A. Lewis

Phylogenetic relationships among the freshwater green algae, Pediastrum spp. and Hydrodictyon spp.
Within the class Chlorophyceae, the family Hydrodictyaceae (order Sphaeropleales) consists of taxa that form flat or net-like coenobia and reproduce asexually by way of biflagellated zoospores. Two taxa within this family, Pediastrum and Hydrodictyon, share many features during development, especially the manner of daughter colony formation. The colonies of Pediastrum differ from Hydrodictyon in that growth is planar resulting in two-dimensional colonies, while three-dimensional nets are formed in Hydrodictyon. Studies of the Chlorophyceae using morphological and ultrastructural data, as well as molecular sequence data, have supported the close relationship of Pediastrum and Hydrodictyon. However, in these studies only single species of Pediastrum (P. duplex) and Hydrodictyon (H. reticulatum) were included, therefore the exact relationship of these two taxa could not be explored. Preliminary molecular data from a second species of Pediastrum, P. boryanum, indicate that Hydrodictyon may be derived from Pediastrum. In this previous analysis, H. reticulatum resolves as sister taxon to P. duplex with P. boryanum the ancestral taxon. Further molecular studies of the family Hydrodictyaceae allow exploration of the relationships between Pediastrum spp. and Hydrodictyon spp., and assist in determining whether they are monophyletic. Phylogenetic analyses that include three species of Hydrodictyon and twelve sequences of Pediastrum indicate that Hydrodictyon forms a monophyletic clade nested within the genus Pediastrum. With this better understanding of the phylogenetic relationships among the species of Pediastrum and Hydrodictyon, a more complete comparison of colony formation is possible.

11:30-11:45 Pat Owen

The significance of small frequency changes in the aggressive calls of the green frog, Rana clamitans.
The green frog, Rana clamitans, has a graded call system. As the perceived distance of an intruder decreases, some males progressively decrease the dominant frequency of their aggressive calls. I performed playback experiments to determine whether males can perceive small differences in dominant frequency independent of call intensity. Males were presented with size-matched synthetic calls. In the control trial, the dominant frequency of synthetic calls remained constant. In the experimental trial, the dominant frequency of synthetic calls was decreased in 10 Hz increments. Calls given in response to the experimental trial were lower in average dominant frequency than calls given in response to the control trial. These results suggest that green frogs perceive and respond to small changes in dominant frequency. Small graded changes in the dominant frequency of aggressive calls seem to signal changes in aggressive intent.

11:45-12:00 Uzay Sezen

Parentage analysis of an abundant neotropical palm.

12:00-1:00 lunch

1:00-1:15 Michael Wall

Trend spotting in taxonomy: from the beehive to the mullet.

1:15-1:30 Lori Hosaka LaPlante

SRF (single red female) seeks attractive DM (dominant male): advertising availability in the fish world.
Showy male displays are a familiar result of sexual selection in conventional mating systems. In these systems, males compete for females and females play the role of chooser. Theory predicts that females show nuptial displays in mating systems that are sex-role reversed or under certain conditions associated with bi- or uniparental care. Nonetheless, female nuptial displays have been observed in several conventional species and across a wide range of taxa, but little is known about the mechanisms driving the evolution of these displays. The pink-belly wrasse, Halichoeres margaritaceus is a polygynous marine fish and broadcast spawner (i.e. no parental care). Females are cryptic in coloration and develop ephemeral red belly coloration. I studied a population of H. margaritaceus on the shallow reef flats of Okinawa, Japan, in order to examine whether female belly coloration played a role in intersexual communication. Bellies of females developed from white to red (with an intermediate pink stage), and expression of the latter increased as spawning approached. Red belly coloration was displayed more often while females performed courtship activities compared to other social or non-social activities, and males were observed to direct significantly more courtship behavior towards females displaying red bellies than females displaying either white- or pink bellies. Results from this study suggest that red belly coloration is a nuptial signal displayed by females indicating their readiness to spawn. The study is significant for two reasons: i) it is the first to examine potential mechanisms favoring female nuptial displays in a conventional species with no parental care; and ii) it provides evidence for female nuptial displays under natural social conditions.

1:30-1:45 Gregor Yanega and Margaret Rubega

Bending Bones and Hummingbird Lips.
During the course of studies with Ruby-throated hummingbirds in 2002, we discovered a novel mode of mandibular flexion in birds attempting to catch fruit flies. The evolution of a mandibular articulation in tetrapods can be traced back to early archosaurs (225 mya), though the direction of flexion and application of the feature are different than those we have observed in other birds or inferred for their ancestors. In addition to this unexpected form of kinesis, we found hummingbirds capable of typical avian cranial kinesis (bending of the upper jaw) and documented its use during prey capture and transport. Cranial kinesis is known primarily from museum specimens (dead birds) and its documentation in living birds is a rare and important step in determining the functional consequences of this trait for birds. The coupling of two kinds of kinesis, as is found in hummingbirds, is extremely rare, and understanding the reasons for patterns of kinesis in avian lineages is contingent on our understanding of the functions and costs of these traits.

1:45-2:00 Krissa Skogen

Exploring causes of decline in rare plant species better known as: Why walruses don't live in North Dakota even though they want to.

2:00-2:15 afternoon break

2:15-2:30 Tracy Gartner

Where are the neighbors? How layering of leaves on the forest floor influences decomposition.
Leaf litters do not segregate neatly in forests. Rather, composition of litter mixes and the stratification of leaf types on the forest floor depend on community structure and timing of leaf release. In northeastern forests, sugar maple and red oak often co-occur. Both are deciduous and drop their leaves primarily in the autumn, but peak leaffall for these two species can be separated in time from 1 to 3 weeks, depending on the year, with maples always dropping their leaves earlier than oaks. Variation in timing of leafdrop occurs between species (as is the case between sugar maple and red oak) but even within a single species, separation between early and late leaffall influences the leaf layering pattern on the forest floor. How extensively can vertical distribution of fresh litters within the forest floor (created by these differences in timing of leaf release) affect litter mass loss and nutrient dynamics? Effects of layering and litter mixing on decomposition of sugar maple and red oak were examined using outdoor microcosms and litterbags. Within each species, decay significantly differed between layers; bottom layers lost less mass and retained more nitrogen than leaves of the same species in top layers. Changes induced by the identity and location of neighboring leaves released by key tree species may be essential to understanding decomposition of mixes of leaves on the forest floor as a whole.

2:30-2:45 Jonathan Richmond

Two Skinks Walk into a Bar and One says to the other. . .

2:45-3:00 Dan Vanderpool

Estimating Divergence Times within Cicadettini (Homoptera:Cicadidae:Tibicininae): A Bayesian Approach
The Cicada tribe Cicadettini has a distribution that spans five continents and multiple Island groups in the South Pacific. However the tribe is disproportionately represented in Australia and New Zealand, with these two countries accounting for nearly 65% of the group at the generic level. There exists a number of different hypotheses that explain this type of biogeographic pattern, where a group is over-represented in a particular area. Knowing the phylogeny and time of diversification for a group of taxa helps one make informed decisions about competing hypotheses. Here I propose to use a Bayesian method that can be applied to molecular sequence data in order date divergences among Cicadettini genera. Can this pattern be explained by some ancient adaptive radiation event? Are Australian cicadettines now occupying a niche left vacant by a tiny, xylem sucking dinosaur that went extinct when an asteroid collided with Earth some 65 million years ago? This study hopes to answer these questions and more.

3:00-3:15 Pablo Arroyo

Changes in landscape structure and composition for the Chorotega region, Costa Rica from 1960 to 2000.

3:15-3:30 afternoon break

3:30-3:45 Andrew Latimer

Assembling Diversity by Patchwork: reframing the question of fynbos hyperdiversity.
The fynbos of South Africa's Cape Floral Region (CFR), while recognized as a global plant diversity hotspot, has no higher point diversity than other Mediterranean systems such as California's chaparral. An exceptional rate of turnover among sites, across scales of 101 to 102 kilometers, drives the plant species density up to New World tropical moist forest levels. Surveys of vascular plants at fynbos sites across the region illustrate the high turnover rates and provide a striking contrast to patterns of diversity reported from some Amazonian sites. In the Amazonian sites, even relatively rare species tend to be geographically widely dispersed, so that high local diversity represents a sampling from a huge regional flora. In the CFR, by contrast, species provincialism appears to dominate the constitution of local assemblages. Much research in the CFR has focused in classical community ecology fashion on explaining local coexistence of species. Yet the diversity patterns in the CFR appear to require a rather different set of explanations: species turnover rather than coexistence is the norm, and replacement or mutual exclusion rather than coexistence is the real conundrum. Dispersal limitation in connection with nutrient poverty is proposed as a core mechanism in generating divergent diversity patterns and as a focus for further research.

2003 Symposium committee:

Norm Wickett
Rob Dunn
David Lubertazzi

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