Graduate Research Symposium 2010
Saturday, March 27, 2010
The EEB Graduate Student Symposium is an all day event where graduate students present their research to other graduate students and faculty. Any EEB graduate student can present: BSMS, masters, PhD, old and new students. New graduate students usually present research ideas or preliminary data, while those more ‘seasoned’ students present their most recent results, often in preparation for upcoming spring and summer meetings.
|8:30-9:00||Coffee & Tea (drinks only)|
|9:00-9:15||Debra Kendall||Welcome address by the associate dean for life sciences and for research and graduate education|
|9:15-9:30||Alejandro Rico||Hummingbird feeding mechanics|
|9:30-9:45||Elizabeth Wade||Microsatellite and gene discovery using 454 sequencing in the cicada genus Kikihia|
|9:45-10:00||Jessica Budke||Examining the gametophytic calyptra and its role in sporophyte development using the cord moss (Funaria hygrometrica).|
|10:30-11:00||Morning Break - Drinks and Fruit|
|11:00-11:15||Susan Herrick||Temporal patterns in calling behavior of syntopic anurans.|
|11:15-11:30||Tobias Landberg||Something something salamanders|
|11:45-12:00||Kristiina Hurme||Antipredator behavior in schooling tadpoles|
|12:00-1:30||Lunch - Sandwiches and Salad|
|1:30-2:00||Lori Hosaka LaPlante||Keynote Address: TBA|
Temporal patterns in calling behavior of syntopic anurans
Phenotypically similar species are hypothesized to adjust their behavior when they coexist to decrease competition. Pond-breeding frogs constitute an ideal system to address this hypothesis because multiple species may compete for noise-free periods to call for mates. American bullfrogs (Rana catesbeiana) and green frogs (R. clamitans) commonly co-occur in breeding ponds. Males of both species vocalize to defend territories and attract females. However, bullfrogs call more aggressively than green frogs and are expected to control access to the limiting acoustic resources. I predicted that green frogs increase chorusing activity in periods of bullfrog inactivity and that these patterns can be detected at both diel and seasonal scales. I used automated acoustic software to identify bullfrog and green frog vocalizations through two breeding seasons. Temporal partitioning occurs on a seasonal time scale. Bullfrog and green frog calling rates are both high early in the season in late May but then diverge. Bullfrog calling rate peaks in mid-June and drops sharply thereafter. In contrast, green frog calling falls to low levels in June but then rebounds when bullfrog calling declines, so that green frog calling reaches a second peak in late June and tapers off thereafter, ceasing in early August. There is no evident temporal partitioning on shorter time scales. Both species call most from midnight until 0600. However, the diel timing of bullfrog calling is predictable, whereas green frog calling is more variable. These results suggest green frogs are responding to reduced bullfrog activity by adjusting their calling effort.
Hummingbird feeding mechanics
Modulation of feeding behavior in hummingbirds, the most important vertebrate pollinators, has been demonstrated to affect the persistence of many kinds and number of plants, and subsequently the interactions and services provided by entire ecosystems. Similarly, composition and concentration of floral nectars has been shown to influence which flowers hummingbirds feed at, and their rate of movement among flowers. To date, our understanding of feeding behavior in hummingbirds is based on the theory that they use capillarity in order to feed on nectar. It is widely accepted as fact that hummingbirds feed by moving nectar up their tongues in the same way that water moves up a tiny capillary glass tube. Our entire understanding of the nature of the interaction of hummingbirds and plants has been based on this concept of the mechanics of feeding. My previous work on the structure of the hummingbird tongue suggests that the capillarity model of feeding in hummingbirds may be wrong. Preliminary results point to a novel and radically different nectar trapping mechanism; if true, our ideas about how external factors affect the rate at which hummingbirds gain nectar from flowers would change. In this presentation I document the process of nectar uptake using high-speed video and microscopy capabilities describing the fluid mechanics of tongue loading, discussing the implications of this new perspective at several different levels ranging from biophysics to ecology and evolution.
Examining the gametophytic calyptra and its role in sporophyte development using the cord moss (Funaria hygrometrica).
In bryophytes (mosses, liverworts and hornworts) the diploid sporophyte is small, unbranched, and physically attached to the maternal haploid gametophyte. One of the major maternal influences in moss plants is a cap of gametophyte tissue (the calyptra) that covers the sporophyte’s apex during early developmental stages. Previous studies indicate that the calyptra functions mechanically to influence sporophyte development and is necessary for spore formation. Sporophytes without their calyptra wilt at the apex; they survive only when placed in a high humidity chamber. These observations stimulated the hypothesis that the maternally derived calyptra functions as a waterproof cap, preventing desiccation of the developing sporophyte’s apex. In plants the cuticle, an external layer of lipids and waxes, maintains internal hydration. To explore this hypothesis, I am using scanning and transmission electron microscopy to examine cuticle morphology and development of both the calyptra and sporophyte in the moss Funaria hygrometrica. Results for this species indicate that the calyptra’s cuticle is thicker and more complex than other gametophyte tissues; the cuticle is also present on the calyptra throughout sporophyte development. These observations support the calyptra as a specialized maternal gametophyte structure and provide a mechanism by which the calyptra prevents harmful water loss during critical sporophyte developmental stages. Sporophyte development is directly related to reproductive output and thus evolutionary fitness in mosses. The maternal care provided by the calyptra and its cuticle may have been a critical innovation for the evolutionary success of the ~12,500 moss species worldwide.