Emma Aronson
Ecology and Evolutionary Biology Student

I find it fascinating that microbial and cellular level processes can scale up to have global-scale atmospheric effects. I study microorganisms that live in soil everywhere and cycle two important greenhouse gases, methane and carbon dioxide. There is one set of microbes that produces methane as a byproduct, which are often found in bogs or other wetlands. The other set of microbes uses methane as a carbon and energy source, through oxidation, and produces carbon dioxide, which is a far less powerful greenhouse gas than methane. The environmental conditions of soil, type of soil and vegetation all play a role in what amount of greenhouse contribution the soil is making, and some soils are overall greenhouse gas sinks, while others are sources. I am trying to better understand how the environment affects these two groups of microbes using various field and lab experiments. I measure the affects of treatments on methane flux and on the diversity and abundance of the microbes themselves.

I love living in Philadelphia! I lived here growing up and then went away for University. I was thrilled when I was accepted to Penn, because I hated being away. This city, West Philly where Penn is located in particular, is filled with beautiful architecture and great restaurants. The Penn Biology Department allows you to build upon a basic structure to create a course schedule that is right for you and what you want to study.

Roberto Salguero-Gomez
Ecology and Evolutionary Biology Student

Size is arguably one of the best predictors of plant fitness. Much is known about the requirements that must be fulfilled in order for plants to grow (e.g., cell elongation relies on internal hydrostatic pressures, hormonal control, etc), as well as for the maximum size that a plant individual may attained based on physiological limitations of xylem architecture, plant height and soil water potential. Surprisingly, plant size decrease (aka shrinkage), a crucial factor of maximum size, has not received much attention. My area of research focuses on the how's, when's and why's of plant shrinkage. How: I am studying one of the many the internal physiological mechanisms that the plant itself may actively be able to regulate to get rid of modules: hydraulic sectoriality. When and why: I am also exploring the frequency and ecological relevance of perennial plant species shrinkage; in order to understand how plant shrinkage may affect the fitness of individuals plants and to discern the importance of this phenomenon across taxa across different habitats and taxonomic families, I am using a wide range of approaches including ecophysiological field-based techniques, senescence theory, matrix based demography, a literature survey, phylogenetic independent contrast analyses and simulation modeling.

I spend most of my summer in the Great Basin Desert, in Utah, running several ecophysiological and demographic field experiments on my study species, Cryptantha flava L. (Boraginaceae), an during the rest of the year I analyze field-collected data and continue working on my computer-based projects at the University of Pennsylvania. The teaching requirement for Penn biology graduate students is two semesters. In my case, not having TAed before, TAing has become a surprisingly rewarding activity. Penn undergrads are extremely motivated and very intelligent and it's fun to interact with them!

As for Philadelphia, I love it! It's full of beautiful places to hang out, art galleries and great coffee-shops. I'd define Philly as a very vibrant, international city. I spend my free time helping to organize extra-academic activities. I am the co-organizer of the Biology Movie Nights, the graduate recruiting officer of the Swim Club of UPenn, and vice chair of the Student Section of the Ecological Society of America. I love cactae, swimming, running, reading, water-color painting and being exposed to people from different cultures.

Chantal Francis
Computational Biology Student

Mammalian behavior is extremely heterogeneous: spanning from complex language, social or sexual behaviors to very simple stimulus responses. What is the neurological basis for such variety of behavioral traits in mammals? A classical answer would relate the complexity of an organism’s behavior to the complexity of its nervous system. Indeed, Brain size and the increased structural complexity of the cerebral cortex is one of the hallmarks of mammalian’s evolution. At both the functional and biochemical level all nerve cells have similar signaling properties. However, the pattern of functional interconnections between neurons, known as synaptic plasticity, which is the main neurochemical bases of learning and memory, is unique. We can speculate that animals with different behavior might differ in their molecular neurophysiology. I am interested in elucidating many questions related to the mechanisms controlling neuronal gene expression and its evolution: Are the molecular programs controlling and regulating gene expression in neurons conserved between and/or within species? What role does the potential differences play in evolutionary diversification of brain function? I am combining both computational and experimental biology in order to investigate the above questions.

Philadelphia, the more time I spend in this city the more I love it! You can find activities and attractions for all tastes and all ages! I enjoy visiting its museums, theaters, outdoor concerts as well as eating in its various restaurants and bars. Another Key feature that I particularly love in Philadelphia area is its numerous parks, biking/hiking trails. Whenever I have free time, I enjoy the outdoors with my husband and one year old son. On top of all that, Philadelphia has a well connected international airport and is in the heart of the northeast: a short drive to Manhattan, Baltimore and Washington D.C.

Jennifer Pastore
Plant Biology Student

I use the model organism Arabidopsis thaliana to study plant development. Plants undergo distinct developmental phases throughout their life cycle. I’m interested in understanding how plants go from a vegetative developmental program, with cells of the shoot apical meristem specified to produce leaves, to a reproductive program with cells specified to produce flowers. This developmental switch, known as the meristem identity transition, is not only vital for species survival but it is also important for our economic and agricultural resources.

A robust transcriptional network regulates the meristem identity transition in Arabidopsis. In my thesis lab we are trying to determine the components that make up this network using a number of approaches including genomics (expression array and global binding studies) and genetics. In my research, I use molecular, genetic and cellular biological tools to elucidate the function of a MYB transcription factor that is a central component of the regulatory network involved in this transition.

As a graduate student, the Penn Biology department is a wonderful place to learn and teach science. The department offers a number of different areas of research. This diversity has given me the opportunity to learn different disciplines and experimental techniques through my lab rotations, classes and departmental seminars. The biology department is also a great place to teach. I loved the time I spent as a teaching assistant and still enjoy interacting with and mentoring undergraduates who are actively working in my research lab.

Annalise Bloss Paaby
Ecology and Evolutionary Biology Student

My work investigates the question of life-span control in Drosophila melanogaster from an evolutionary perspective: What are the principal genes regulating life-span in D. melanogaster, and under what selection pressures do they fall? Work in the fly and other model systems has elucidated important features of hormone mediation on life-span, specifically in terms of signal transduction. Work done by my advisor, Paul Schmidt, has implicated reproductive diapause as a key character in understanding life history tradeoffs. We see here important interactions among mechanisms of hormone control and the environmental selection pressures which maintain various life-history strategies. My approach is to combine what we know about hormone pathways and phenotypic tradeoffs to uncover the genetic mechanisms. I look for variation among aging characters in natural populations, and the functional significance of this variation under natural selection. I hypothesize that temporally and spatially varying selection on diapause ability may be imposing pleiotropic regulation on multiple life history variables, including life-span. This type of evolutionary approach can help us to understand why aging occurs.

Graduate Program
Department of Biology
School of Arts and Sciences
University of Pennsylvania

last updated December 3, 2008