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
8:30-8:45 Janet Greger
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
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
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
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.
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
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
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: