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

Background and Research Experience:
I was born in Seville (Spain), and received my BSc in Environmental Sciences with a specialization in National Parks Management at Cadiz University (Spain), during which time I was involved in various ecological projects (Effects of fire and periodic pruning on Mediterranean shrubby communities, Study of temporal and spatial equilibria of dioecy in a Mediterranean plant species, among others) . Then, I accomplished my MSc at Kingston University of London in Environmental Studies, where I studied the demography of a plant species with a dual demographic behavior: a pest in the UK yet an endangered species in Spain. Following, I moved to the University of Vienna, as a research assistant, where I studied the effects of various geographical variables on the modes of plant island speciation. After that I moved back to Spain, where I collaborated in a project at the University of Seville looking at the effects of habitat fragmentation in plant genetic diversity. Currently I am a PhD candidate at the Biology Department of the University of Pennsylvania, with expected graduation in 2010.

Doctoral Research Description:
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 internal physiological mechanisms, 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 phylogenetic-based literature survey, 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.

Teaching Experience:
During my time here at Penn, I have served as a teaching assistant for the introductory course on “General Biology, Animal Physiology and Evolution” 5 times, the last three as the head TA. I’ve also assisted in “Field Botany”, and been twice the TA of a field course in “Techniques in Conservation Biology” in Shenandoah NP, VA. I am the recipient of Penn Provost‘s Prize for Excellence in Teaching by Graduate Students 2007, and the Dean’s Award for Distinguished Teaching by Graduate Students 2008.

Brief List of Relevant Publications:
- Casper BB, Spindler LH & Salguero Gomez R. In review for Ecology. “Shrinkage in herbaceous perennials: a way out or the way to stay in?”.
- Stuessy TF, Jakubowsky G, Salguero Gomez R, Pfosser Martin, Philipp Schlüter, Fer T, Sun BY & Kato H. 2006. “A new anagenetic model for plant evolution in oceanic islands”. Journal of Biogeography 33: 1259-1265
- Salguero Gomez R & Garcia MB. 2005. “Dinámica poblacional comparada de Rhododendron ponticum en áreas invadidas (Islas Británicas) y relictas (Parque Natural Los Alcornocales, España). In: Special Report for the Natural Park Los Alcornocales, Spain: “Biología y estructura genética de poblaciones de árboles y arbustos de los canutos pertenecientes a la flora amenazada andaluza. Continuación: diversidad genética y factores limitantes de la regeneración”. Natural Park Los Alcornocales Press
- Salguero Gomez R. 2004. “Markov Chains applied to Rhododendron ponticum L.: ecological terminator in Great Britain… ecologically terminated in Spain?”. MSc final project. Kingston University of London Library services

Other Activities:
- Member of the Ecological Society of America (ESA), Seeds-ESA, ESA Plant Population Section, ESA Ecophysiology Section and ESA Student Section.
- Member of the Geological Society of America, the Botanical Society of America, and the Society of Conservation Biology.
- Reviewer for Ecology
- Networking & Outreach officer of the Student Section of the Ecological Society of America
- Associate member of Sigma Xi, The University of Pennsylvania chapter
- Graduate recruiting and social events officer and member of the Penn Swim Club at The University of Pennsylvania
Hobbies: watercolor painting, swimming, running, cactae and crassules preservation, traveling, knowing new cultures, languages, interacting with people.

Melanie Chang
Ecology and Evolution Student

I am a dual degree candidate in Anthropology and Biology, studying human evolution, with a primary research interest in hominin systematics. My dissertation is on Neandertal origins, which requires me to travel to many of the greater capitals of Western Europe in order to examine fossils in museum collections. There are worse places to do fieldwork. However, I do also have broader interests which include the evolution and ecology of mammals that are not extinct and not bipedal. I have also, in my time,dabbled in Palaeolithic archaeology. When I am not studying or worrying about studying, I enjoy hiking and doing things with my dogs.

The picture is of me with the Gibraltar I Neandertal cranium, at the Natural History Museum, London.

Gauri Nair
CM Student

Gauri is a student on dissertation status who hails from India. She is shown with one of her four dogs, Leia.

Congratulations to Gauri who was recently awarded the Penn Prize for Excellence in Teaching by Graduate Students! This award was established by Dr. Judith Rodin and is given to graduate students "who, through their dedication to teaching, have had a profound impact on undergraduate education at Penn." The Biology Department is proud of Gauri and her excellence in teaching.

Zongtian Tong
3rd Year CM Student

As a third year grad student in the Department of Biology, I almost finish my classes, as well as teaching requirements. Now I mainly focus on my thesis research, yeast cell biology. Saccharomyces cerevisiae is the model system we use, the one similar to what we use in baking and brewing.

Serdar Turkarslan
CM Student

The general area of investigation in our lab is c-type cytochromes (cyt). From bacteria to vertebrates, c-type cyts play important roles in vital processes. Their essentiality is also reflected in recognition of different c-type cyt maturation systems in different species. The complexity and diversity of these systems enable the organism to survive in such a broad range of environmental conditions. Therefore, studying the fine control and mechanism of c-type cyt maturation system may help to understand cellular energy metabolism. Recent advances in this field have clarified many important points but this complex and amazing process is still full of mysteries. My current studies are concentrated on the thio-oxidative and thio-reductive pathways of the c-type cyt maturation in Rhodobacter capsulatus. Our preliminary results brought us surprising evidences for the parallel functioning of thio-oxidative and thio-reductive pathways in c-type cyt assembly process. (Deshmukh et al. 2003) We are, now focused on investigating the role, interactions and mechanism of thio-redox proteins for establishing a redox homeostasis in the gram-negative periplasm for proper c-type cyt maturation. Second focus of my research highlights thiol:disulfide oxidoreductase , DsbA. Here, we investigate the respiratory growth defect of DsbA-null mutants, their Cu related phenotypes and effect of metals in general on c-type cyt maturation mutants by applying molecular, biochemical and 2D-PAGE/MS based techniques. These results may contribute to the researches in the field of thiol:disulfide oxidoreductases that are involved in processes such as oxidative stress, redox regulation of signaling proteins, protein folding and central metabolic pathways. I am also interested in computational biology especially its applications for bacterial genomics and involved in annotation of R. capsulatus genome.

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.

Ming Li
CM Student

I am working on my thesis project in Dr. Greg Bashaw's lab. The general interest of our lab is axon guidance the midline of Drosophila CNS. How axons in the developing nervous system navigate to their correct targets is a fundamental problem in neurobiology. Previous studies have shown that axonal growth cones are exposed to both attractants and repellents. The Netrin ligand and DCC receptors, and the Slit ligand and Robo receptors are two major ligand/receptor systems in both vertebrate and invertebrate nervous systems. The midline of the Drosophila CNS is an ideal system to study the signaling mechanisms downstream of attractive and repulsive guidance cues, because of the powerful genetic and molecular approaches available in Drosophila. My work is focusing on the signaling mechanism between Robo and crossGAP, a novel Rho family GTPase Activiting Protein. Recent reports show that axonal growth cones navigate their ways by regulating their actin cytoskeleton, and Rho family GTPases, Rac, Rho, and Cdc42, play important roles in axon pathfinding. As a negative regulator of Rac, crossGAP is a potential link between Slit/Robo signaling and the regulation of actin cytoskeleton.

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

last updated September 23, 2008