Undergraduate Student Research
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Below you can find an example of the types of projects
undergraduate have done in my lab, in no particular order. We have a pretty
good history of publishing these projects in referred, scientific journals.
Students are included as authors if they help work on the publication.
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Sexual Dimorphism and Reproductive
Cycles in Podarcis sicula Abstract: Sexual
dimorphism with regard to body size and other morphological characteristics
in P. siculaand seasonal changes in gonadal and fat body sizes in relation to the timing of
reproductive events were investigated. Sexual dimorphism, with males being
larger than females is caused by for sexual selection. Males have (relative
to body length) significantly longer fore- and hind-limbs and both a longer
and wider head. Development of testes and epididymis were synchronous; maximum size was reached during May-July and was followed
by a period of regression until early autumn. Follicle and oviduct diameters
were largest in females between May and July. Larger females produced larger
clutches than smaller females. The frequency of females simultaneous containing yolked follicles, ovarian
eggs and corpus luteum in May-July was 37%. Second
clutches, however, were not noted. Fat body sizes coupled the breeding
season. Male breeding and courtship rituals and spermatogenesis and female vitellogenesis and oogenesis employed lipid stores.
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Food habits of a New York population
of Italian wall lizards, Podarcis sicula (Reptilia, Lacertidae) Abstract: I studied the food
habits of Italian ruin lizards, Podarcis sicula, introduced to Long Island New York 34
years ago. We recovered 436 prey items from 96 lizards. There was no
significant relationship between the percentage of lizards without any prey
items and date of capture. Diets of males and females differ in the number of
prey items per lizard, overall prey diversity and prey evenness, suggesting
important differences in foraging habits. I found remarkably high similarity
between species diversity values for the Long Island and two European
populations. There was no correlation between prey size and either head width
or snout-vent length.
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Freeze tolerance and supercooling ability in the Italian wall lizard, Podarcis sicula,
introduced to Long Island NY. Abstract: I assessed
European wall lizards, Podarcis sicula collected from populations introduced to
the U.S., for the ability to tolerate freezing temperatures. This has
implications for the future of this species currently undergoing rapid range
expansion, and allows us to make informed guesses about its over-wintering
behavior. I first determined that they could regularly survive supercooling down to -5oC (temperature
monitored by thermocouple) for at least 60 minutes. Next, individuals were
cooled to -5 oC and freezing was induced. I thawed
these lizards after 15 minutes and held them at +5o for 24 hours,
when they were checked again for life signs. All lizards frozen in this
fashion died. Thus when internal ice formation was initiated as would be
expected in a natural environment, they rapidly froze and died. This species
does not appear to be freeze tolerant, which differs from results reported by Claussen et al. for a conspecific (P. muralis). I demonstrated
that our different results are very likely due to a difference in
experimental technique. Standardization of techniques and definitions are
needed if freeze tolerance comparisons are to be made between species and
populations.
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The
Ecological Impacts of Artemisia vulgaris and Lespedeza cuneata on the Hempstead Plains Abstract : The Hempstead
Plains, a tall-grass community in Uniondale, NY, dramatically exhibits the
effects of a non-native plant invasion by Artemisia vulgaris (common mugwort) and Lespedeza cuneata. We evaluated some of the ecological impacts
of these plants in a 1.72 hectare study site in the Hempstead Plains. The
density of A. vulgaris plants was found to
have decreased overall over a four-year time interval, which is most likely
due to systematic over-estimations of percent coverage in 1995. The several
foot paths present in the Plains do not appear to be routes for A. vulgaris’s dispersal. Instead, the increased densities present in plots near the
north and south boarders suggest that A. vulgaris is utilizing adventitious runners to gradually colonize the Plains from
external areas. Soil nutrient experiments revealed significant pH increases
in soil samples removed directly from the Plains and also in controlled
growth experiments. The increase in pH may alter the abundance of
essential chemical forms of soil nutrients and minerals and thereby decrease
the ability of native plant species to compete. We determined that there was
an overall decrease in L. cuneata density,
but suspect this apparent decrease is due to errors in the earlier data.
There was a significant increase in L. cuneata densities along the perimeter of the study area, which may be due to spread
from the surrounding environment. There were also high densities on the
paths, which could be due to disturbance. Our greenhouse experiments
showed L. cuneata grows by increasing branch
number rather than height, but it does increase in weight. Soil analyses
showed that L. cuneata has no effect on %
moisture or organic matter composition, but it did cause total nitrogen to
decrease. This was not expected because L. cuneata is a legume, which typically fix nitrogen. The
most significant difference was a large increase in soil pH.
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Comparing
the number of terrapin nests on Ruler’s Bar Hassock 1999-2002 Feinberg
counted predated 1822 terrapin nests on the island of Ruler’s Bar Hassock in
1999, and observed three clear peaks of nesting activity over the nesting
season, which began 3 June and ended 23 July. This work had not been repeated
to obtain a measure of inter-annual variability. I followed the same
procedure as Feinberg in the spring summer of 2002, making weekly surveys of
terrapin nesting habitat over the areas of Ruler’s Bar Hassock used by
nesting terrapins. I counted 1837 predated nests. In 2002 nesting started on
1 June and lasted until 10 August. No peaks of nesting activity were noted.
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The
Importance of Raccoon Feces to the Nest Counts of the Diamondback Terrapin at
Jamaica Bay Wildlife Refuge Feinberg
(2000) noted differences in the pattern of raccoon predation on terrapin
nests over the nesting season. In June, the raccoons consumed only egg
contents and left eggshells behind in a pile. In July, raccoons consumed the
entire egg, and eggshells were found commonly in raccoon feces. This is
important to the terrapin nest counts. If there are no eggshells present at
the site of a hole that might be a nest, then it is usually not counted as a
nest. We are then recording lower counts of terrapin nests then there
actually are. My goal was to determine whether this was a recurrent pattern
and quantify this pattern.
Samples
of raccoon feces were collected weekly throughout the months of June and July
of 2002. The samples were dried, weighed, and ashed.
The ashed fecal samples were digested in acid into
solution and calcium analysis through EDTA titration was performed to
calculate the percent of eggshells present in each fecal sample.
Observational
results show there is in fact a mid-seasonal shift in consumption of the eggs
and eggshells. The calcium analysis through EDTA titration supported this
conclusion. With the calcium analysis results, we will now be able to adjust
the counts of terrapin nests laid to a more accurate reading.
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