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Non-tree like speciation: Examples for California herps
Date: 1/10/2008, 4:10 - 5 p.m.
Location: Kraus Natural Science auditorium
Host department: Ecology and Evolutionary Biology
Dr. Elizabeth Jockusch, Associate Professor, Ecology and Evolutionary Biology, University of Connecticut
Abstract
Classic views of speciation suggest that it is tree-like: species have only a single origin and diverge following isolation, eventually evolving complete reproductive isolation. The complex geological history of California makes it a good laboratory for studying the consequences of secondary contact between independently evolved lineages. I will present results of my lab’s work on the evolutionary history of two groups that are widely distributed in California, slender salamanders of the genus Batrachoseps and skinks of the genus Plestiodon. In slender salamanders, gene flow between differentiated lineages is common, and at least one species has likely originated by hybridization between two parental species. In skinks, the parallel evolution of large body size in three separate lineages has led to reproductive compatibility between distantly related lineages and reproductive incompatibility between more closely related lineages, rather than the typical pattern in which reproductive compatibility and evolutionary relatedness are correlated.
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Diversification, convergence and key innovations in Agaricomycetidae (mushrooms)
Date: 1/24/2008, 4:10 - 5
Location: Kraus Natural Science auditorium
Host department: Ecology and Evolutionary Biology
Dr. Manfred Binder, Postdoctoral Fellow, Clark University
Abstract
The Agaricomycetidae (ca. 10,000 species) is a terminal clade of Basidiomycota that includes the well-known Agaricales and Boletales, which are dominated by mushroom-forming fungi, and the more obscure Atheliales, which is a relatively small groupof resupinate (crust-like) taxa. These fungi pursue diverse life styles, including ectomycorrhizal symbioses, parasitism, and distinct saprotrophic modes. One detailed example from the Boletales using ancestral state reconstructions illustrates the historical patterns of morphological evolution and ecology, which involve multiple transitions from free-living forms to symbionts and multiple transformations from resupinate to pileate-stipitate fungi. In addition, a six-gene nuclear dataset (nuc-ssu, nuc-lsu, 5.8S, rpb1, rpb2, tef1) has been developed, with taxon sampling focused on resupinate forms that may be related to the Agaricomycetidae. The analyses of multilocus data corroborate the view that Boletales evolved from athelioid forms. The analyses have also resolved an additional early-branching clade within the Agaricomycetidae that is composed primarily of resupinate forms. This clade (< 100 spp.), which is tentatively called the "Anomoporiales", is the sister group of the Agaricales. Collectively, the results suggest that the largest radiation of pileate-stipitate mushrooms resulted from the elaboration of resupinate ancestors. Preliminary results of “key innovation” tests performed on a subset of these data suggest that evolution of the ectomycorrhizal life style has promoted the diversification of Boletales.
Current challenges in fungal systematics: Defining natural groups in the Ascomycota
Date: 1/28/2008, 4:10 - 5 p.m.
Location: Kraus Natural Science auditorium
Host department: Ecology and Evolutionary Biology
Dr. Priscila Chaverri, Assistant Professor, Department of Biology, Howard University
Abstract
Defining genera and species in fungi, especially in the Ascomycota, is a constant challenge. The Ascomycota is an especially difficult group because its members are generally very small, and have asexual stages (anamorph) that are completely different from their sexual forms (teleomorph). In addition, most species grow and reproduce asexually for most of their lives. Because precise taxon identification is necessary for other research and applied areas (e.g. biodiversity surveys, ecological studies, plant pathology, bioterrorism, etc.), delimiting genera and species is a basic and essential task for mycologists.
My research in the past focused in defining genus and species concepts in two economically important genera in the Hypocreales: Hypocrea (anamorph Trichoderma) and Hypocrella (anamorph Aschersonia). Both studies analyzed a combination of multiple characters, morphological and molecular (3-4 genes), to elucidate phylogenetic relationships and define genera and species. Hypocrea/Trichoderma is mostly fungicolous and thus contains the most widely used biocontrol agents (T. virens and T. harzianum). Hypocrea/Trichoderma includes species with green and colorless ascospores. In the past, the genus Creopus was segregated from Hypocrea to include only species with green ascospores. In addition, the anamorphic forms are more common than the teleomorphs and are generally morphologically indistinguishable between species. This research resulted in the rejection of Creopus based on the polyphyletic nature of species with green ascospores. In addition, correlation of a combination of multiple morphological characters to DNA sequence-based monophyletic groups was used to define a species concept. Fifteen new species were described based on this concept.
Species of Hypocrella/Aschersonia sensu lato are entomopathogenic on scale insects and whiteflies and are mostly found in the Tropics. The morphology of this group is highly variable in both anamorphic and teleomophic stages. Based on the results from this study, three genera were segregated from Hypocrella/Aschersonia sensu lato and that correspond to discrete and easy-to-identify morphological characters. One new genus and thirteen new species were described based on the genus and species concepts defined in this study.
My current research focuses on the systematics of another economically important family in the Hypocreales (Nectriaceae) and in defining and identifying species that are endophytes of the rubber tree (Hevea brasiliensis) in its “center of origin” in the Amazon and in areas were it has been introduced for commercial plantations. Preliminary results from these studies will be presented.
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One, if by land, and two, if by sea
Date: 1/31/2008, 4:10 - 5 p.m.
Location: Kraus Natural Science auditorium
Host department: Ecology and Evolutionary Biology
Dr. Diarmaid Ó Foighil, Associate Professor of Ecology and Evolutionary Biology and Curator, Museum of Zoology, University of Michigan
Abstract
Marine and terrestrial invertebrates typically experience very different population genetic settings. Pelagic larval development routinely scatters marine propagules over 10s-100s of km/generation and is presumed to promote genetic coherence across geographically extensive ranges, e.g., the Caribbean. Dispersal in terrestrial invertebrates is often restricted to meters/generation and can result in fine scale genetic structuring and cladogenesis, e.g.,the presumed monophyletic land snail radiations of individual Pacific Islands. Over the past six years, Taehwan Lee and I have developed qualitatively new biodiversification paradigms for both marine (Caribbean mussel Brachidontes exustus) and terrestrial (critically endangered Society Island Partula) species complexes. Caribbean Brachidontes populations consist of multiple cryptic species whose distributional limits are set by post-recruitment ecological factors rather than by insufficient scales of larval dispersal. Society Island partulid faunas stem from multiple independent founding events and a rational conservation program requires a multi-island perspective.
Sex and the single nucleus: evolutionary investigations into how mushroom fungi find their mates and keep them
Date: 2/4/2008, 4:10 - 5
Location: Kraus Natural Science auditorium
Host department: Ecology and Evolutionary Biology
Dr. Timothy James, Research Associate, Department of Biology, McMaster University, Hamilton, Ontario
Abstract
Mating in mushroom-forming fungi results in the formation of a heterokaryon or a stable union of two or more nuclei per cell. The formation and maintenance of the heterokaryotic state requires communication between nuclei through the mating-type loci (transcription factors and pheromone signaling components). This talk addresses the role that genetic changes to the mating-type loci could have on the interaction between nuclei in a common mycelium and attempts to address the independence of individual nuclei following cell fusion and heterokaryon formation.
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Signaling in social groups: Connections between mate choice, immunity, and dominance in sparrows
Date: 2/7/2008, 4:10 - 5 p.m.
Location: Kraus Natural Science auditorium
Host department: Ecology and Evolutionary Biology
Dr. David Westneat, University of Kentucky
Abstract
Plumage ornaments of male birds are often thought to serve as a signal of some underlying attribute of the male. Such signals could function either in contests between males or through female preference. The black throat patch (bib) of male house sparrows does not fit these alternatives neatly and has complex effects on social interactions. Data do not support a simple female preference, but evidence exists that learning through contests may be involved. Some experimental evidence suggests the bib signals resource holding potential, but it has some odd effects on winter-time dominance interactions. Moreover, the underlying attribute being signaled is also confusing. In a series of diet experiments, we have found evidence of condition-dependence of melanin deposition in the bib as well as on immunocompetence. However, these are insufficient to explain the bib's signal function, and emerging data suggest a role of social interactions prior to signal development. Socially-mediated development has the potential for explaining a number of niggling details about how plumage traits act as signals.
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Evolution of fern chloroplast genomes
Date: 2/14/2008, 4:10 - 5 p.m.
Location: Kraus Natural Science auditorium
Host department: Ecology and Evolutionary Biology
Dr. Paul Wolf, Professor of Biology, Utah State University
Abstract
I will provide a brief overview of past and current research in my lab. These studies focus on the plastid genome of ferns, its structural evolution, how changes in gene order can affect gene function, and an examination of RNA editing of plastid genes.
DNA sequences from highly conserved genes provide useful phylogenetic data in many groups of taxa. However, as one goes back in time the resolution of nucleotide sequence data diminishes with the effects of saturation of substitutions. It has been proposed that genomic rearrangements can potentially provide more useful data for deep phylogenetic branches because such structural changes are rare and unlikely to be as susceptible to parallel and reverse evolution as are nucleotide substitutions. My lab is testing this assumption with an analysis of gene order changes in fern plastid genomes for taxa for which we have what we believe is a robust phylogenetic hypothesis. Rather than sequence many complete plastid genomes we design universal primers in areas that appear to be rearranged so that we can determine structural patterns.
We have detected several large-scale inversions, one of which occurred in the ancestor to most (not all) leptosporangiate ferns, approximately 265 MYA. This inversion disrupted a tRNA gene and an intron flanking the matK gene which encodes a protein implicated in intron-splicing. We estimated the ratios of non-synonymous to synonymous substitutions to investigate whether loss of the intron is associated with a detectable change in function of matK.
Finally I report on levels of RNA editing, which appears to be high in fern plastid genomes. I will also speculate on how this unusual molecular phenomenon may have evolved.
Acute infectious disease dynamics in space and time
Date: 2/21/2008, 4:10 - 5 p.m.
Location: Kraus Natural Science auditorium
Host department: Ecology and Evolutionary Biology
Dr. Bryan Grenfell, Penn State
Professor of Biology
Abstract
We discuss how nonlinearity arising from herd immunity, stochastic and seasonal forcing conspire to determine the spread, predictability and control of acute infectious diseases. We then explore how immune escape due to evolution.
Evolutionary genomics of the fungi: Connecting phylogenomics and morphology
Date: 3/3/2008, 12:10 - 1 p.m.
Location: Room 1230 Undergraduate Science Building
Host department: Ecology and Evolutionary Biology
Dr. Jason Stajich, Posdoctoral Fellow, Department of Plant and Microbial Biology, University of California, Berkeley
Candidate for the faculty position in fungal systematics and evolution
Abstract
The complex morphologies of extant fungi evolved from a single-celled ancestor of the fungi and animals. What evolutionary steps occurred to facilitate these changes? Comparative genomic analyses provide a means of assessment of genome content change and a phylogenetic approach enables mapping of the relative timing and order of changes. Major transitions in the fungal kingdom include the flagellated aquatic form of the early branching Chytrids, introduction of polarized growth in the form of hyphae, and multicellular forms including mushrooms and other elaborate structures. The fungal phylogeny also has many examples of independent reversions to reduced repertoire of cell-types like a single-celled yeast form.
I will describe my work studying several morphological changes in the context of comparative genomic analyses to understand patterns of fungal genome evolution. This includes comparing genomes from the early branches in the fungal tree starting with a flagellated Chytrid fungus, Batrachochytrium dendrobatidis. I have used the more than 50 available fungal genomes to reconstruct the ancestral fungus by identifying gene gains and losses in a phylogenetic context. I find patterns of change in gene families related to cell wall biosynthesis and structure that correlate with changes in morphology and cellular biology. I will also introduce experimental and comparative approaches to identify potential regulators of gene expression in the model mushroom Coprinopsis cinerea and the model filamentous ascomycete Neurospora crassa.
 Developmental constraints in offspring shape
the evolution of mammalian parental behavior
Date: 3/6/2008, 4:10 - 5 p.m.
Location: Kraus Natural Science auditorium
Host department: Ecology and Evolutionary Biology
Dr. Kay Holekamp, Michigan State
University
Abstract
Spotted hyenas are highly unusual in that a number of sexually dimorphic traits are reversed from mammalian norms. For example, females are larger and more aggressive than males, and socially dominant to them. Although inter-specific feeding competition has often been invoked as the explanation for these role-reversed sex differences, I point out why competition alone cannot account for them. Instead, I suggest that any viable explanation must consider the phylogenetic history of these animals as well as their current socio-ecological conditions. Specifically, spotted hyenas recently descended from carrion-feeding ancestors, and the massive feeding apparatus of adult hyenas allows them to crack open large bones. I hypothesize that the ontogenetic development of this robust feeding apparatus is constrained such that youngsters are handicapped in competing for food with adults until long after weaning, even though weaning occurs very late in hyenas relative to other carnivores. I further suggest that constrained development of the feeding apparatus has favored the evolution of large, aggressive females able to assist their cubs during competitive interactions with conspecifics both before and after weaning. I enumerate predictions derived from these hypotheses and explain how we are currently testing them. I conclude that derived traits associated with bone-cracking in adult hyenas may indeed constrain the evolution of developmental rates in young, selecting for extreme and prolonged maternal care.
Evolution of morphological and functional disparity in fishes
Date: 3/13/2008, 12:10 - 1 p.m.
Location: 1640 Chemistry
Host department: Ecology and Evolutionary Biology
Dr. David Collar, Research Fellow, Department of Organismic and Evolutionary Biology, Harvard University
Candidate for the faculty position in functional organismal biology
Abstract
Diversity in form is unevenly distributed throughout the tree of life. Although some clades display a spectacular variety of shapes and sizes, others show surprising conservation of form. My research examines the factors that make some groups more morphologically diverse than others by integrating functional morphology and phylogenetic comparative methods.
Specifically, I investigated how time, feeding ecology, and the intrinsic relationship between form and function interact to produce disparate cranial forms in the Centrarchidae, a trophically diverse radiation of freshwater fishes endemic to North America. I used a molecular phylogeny with fossil-calibrated divergence time estimates to demonstrate that the rate of character evolution—the time-independent variance parameter of the Brownian motion model— is the appropriate metric for comparing phenotypic diversity between clades because it accounts for the confounding effects of time and phylogeny on the accumulation of variation. I applied rates comparisons to test the hypothesis that an adaptive peak for piscivory has constrained functional and morphological diversification in the centrarchid clade, Micropterus. As this hypothesis predicts, origin of a highly piscivorous diet in Micropterus coincides with a decrease in the rate of suction performance evolution relative to the other centrarchid lineages. However, the reduction in rate of performance evolution in this clade is not translated into a slow down in the rate of evolution of the underlying morphology because the map of cranial form to suction mechanics is many-to-one—multiple morphologies produce equivalent functional capacity. This result demonstrated that many-to-one mapping of form to function promotes morphological diversification in spite of conservation of function. My current and future research will investigate the generality of these and additional diversifying mechanisms.
 Multi-scale forecasts of potential distributions of invasive plant species
Date: 3/13/2008, 4:10 - 5 p.m.
Location: Kraus Natural Science auditorium
Host department: Ecology and Evolutionary Biology
Dr. Ines Ibañez, School of Natural Resources and Environment
Abstract
The fact that plant invasions are an ongoing process makes generalizations of invasive spread extraordinarily challenging. This is particularly true given the idiosyncratic nature of invasions, where both historical and local conditions affect establishment success and hinder our ability to generate guidelines for early detection and eradication of invasive species. To overcome these limitations we have implemented a comprehensive approach that examined plant invasions at three spatial scales: the regional, landscape and local levels. And at each scale, in combination with the others, we have evaluated the role of key environmental variables, such as climate, landscape structure, habitat type, and canopy closure in the spread of three commonly found invasive woody plant species in New England, Berberis thunbergii, Celastrus orbiculatus and Euonymus alatus. We developed a spatially explicit hierarchical Bayesian model that allowed us to take into account the ongoing nature of the spread of invasive species and to incorporate presence/absence data from the species native ranges as well as from the invaded regions. Comparisons between predictions from climate-only models with those from the multi-scale forecasts emphasize the importance of including landscape structure into our models of invasive species potential distributions. In addition predictions generated by using native range data only performed substantially worse than those which incorporated data from the invasive range, this points out important limitations in extrapolating distributional ranges from one region to another.
Paradigm shifts in modern morphology: Addressing today's challenges with computational thinking
Date: 3/17/2008, 4:10 - 5 p.m.
Location: 1300 Chemistry
Host department: Ecology and Evolutionary Biology
Dr. Anne Maglia, Assistant Professor, Missouri University of Science and Technology
Candidate for the faculty position in functional organismal biology
Abstract
With the onset of the genomic era, and the ensuing embrace of reductionism, the field of comparative morphology was relegated by many to the backwaters of science. However, as researchers realize that an integrative and holistic approach to biology requires an understanding of form and function, there is a resurgence of interest in studying morphology. Moreover, new technological advances in the areas of scientific visualization, mathematical modeling and analysis, and information retrieval are helping morphologists overcome many of the obstacles that previously have limited the acquisition of knowledge. In light of these new advancements, the 21st Century has been deemed a new “Golden Age of Morphology.”
In this presentation I will outline three projects that embrace the new paradigm of comparative morphology: 1) a study of skeletal morphogenesis and miniaturization, 2) an examination of vertebral column development and malformation, and 3) an investigation of the origins of the anuran nasal capsule. I also will introduce two projects, MorphologyNet and the Amphibian Anatomical Ontology, which are helping to modernize comparative morphology by allowing rapid data capture, novel methods of data analysis and visualization, and the means to integrate large data sources.
 Natural and sexual selection on function: An integrative look at phenotypic evolution
Date: 3/19/2008, 4:10 - 5 p.m.
Location: 1400 Chemistry
Host department: Ecology and Evolutionary Biology
Dr. Jerry Husak, Research Fellow, Department of Biology, University of Massachusetts,
Department of Biological Sciences, Virginia Tech University
Candidate for the faculty position in functional organismal biology
Abstract
Recent advances in evolutionary biology suggest that selection operates on the functional properties of morphological traits (i.e., performance). Accordingly, a few recent studies have demonstrated a fitness advantage to better performers in the form of enhanced survival probability. However, the possibility that sexual selection can also shape performance capacity remains largely unexplored. Using collared lizards as a model, I discovered that older individuals do not use their maximal locomotor performance capacity while escaping predators or foraging in nature, whereas younger lizards use a high proportion of their maximal abilities in those same contexts. Accordingly, I found selection for adults to be merely ‘adequate’ at escaping predators in nature, whereas hatchlings experience strong directional selection for high maximal running speed. However, using genetic analysis, I found that faster adult males do have a fitness advantage in a sexual selection context; faster males were better territory defenders, which, in turn, granted them significantly higher reproductive success. Thus, I confirmed that both natural and sexual selection can operate on the functional properties of morphological traits. I complement my field-based microevolutionary studies of the adaptive significance of performance traits with examinations of proximate mechanisms that govern those traits. For example, bite-force performance also is important for dominance and territory acquisition in male lizards, and I am exploring how variation in bite force can be explained, in part, by testosterone levels in several lizard species. My approach to studying the functional properties of morphological traits has the goal of integrating physiological measures of the phenotype, typically measured in a laboratory, with an appropriate ecological context. Further, this approach is not restricted to one taxonomic group and is broadly applicable to a variety of questions about the strength of natural and sexual selection in nature.
Asymmetric information and the evolution of mutualism
Date: 3/20/2008, 4:10 - 5 p.m.
Location: Kraus Natural Science auditorium
Host department: Ecology and Evolutionary Biology
Dr. Doug Yu
University of East Anglia
Abstract
Cooperative behavior is ubiquitous at all levels of biological organization, occurring both within and between species. Cooperation between species, or mutualism, poses a special challenge because kin selection cannot apply, because partners are often horizontally transmitted between generations, and because reciprocity would seem to require a degree of individual recognition that is rarely achieved. Nonetheless, over the years, evolutionary biology has built up and successfully tested a set of mechanisms that can maintain cooperation between species. I will draw on some simple concepts from microeconomics to present a way of thinking about mutualisms that is different from the standard set of explanations and that promises to give us a richer set of tools and questions with which to investigate the evolution of cooperation between species.
Linking evolutionary hypotheses and endocrine mechanisms
Date: 3/24/2008, 4:10 - 5 p.m.
Location: 1300 Chemistry
Host department: Ecology and Evolutionary Biology
Dr. Robert Cox, Research Fellow, Department of Biological Sciences, Dartmouth College
Candidate for the faculty position in functional organismal biology
Abstract
Evolutionary biologists dating back to Darwin have sought to understand why females are the larger sex in some species, yet males are larger in others. I use this ubiquitous phenomenon of sexual size dimorphism (SSD) to illustrate how such
“ultimate” questions are best approached with an integrative research program that simultaneously investigates the “proximate” physiological mechanisms regulating sexspecific development. I begin at the macro-evolutionary level with phylogenetic comparative analyses showing that, across ca. 300 lizard species, the evolution of SSD is correlated with changes in the intensity of both sexual selection for large male size and fecundity selection for large female size. At the population level, my current research on the highly dimorphic Bahamian brown anole (Anolis sagrei) quantifies sexually
antagonistic selection on body size that generates intra-locus sexual conflict. The resolution to this conflict may involve several proximate mechanisms, including sex linkage, reductions in inter-sexual genetic correlations, cryptic mate choice, and sexspecific epigenetic modifiers. As an example of the last mechanism, I discuss a series of studies on the endocrinology of sex-specific growth regulation in Sceloporus lizards.
Using a comparative experimental approach, I show that SSD in both male- and female-larger Sceloporus species results from sexual differences in growth rate, and that key ontogenetic stages of growth divergence correlate with peaks in male testosterone levels. I then provide the first empirical evidence that testosterone serves as a “bipotential”
growth regulator by inhibiting growth in species where females are the larger sex and stimulating growth in congeners where males are the larger sex. Collectively, these studies span levels of biological complexity ranging from broad evolutionary patterns to precise physiological mechanisms to offer new insight into how sexual dimorphism
develops and why it evolves.
 Convergence as a model for studying novelty: Case studies in elongate ectothermic vertebrates
Date: 3/26/2008, 4:10 - 5 p.m.
Location: 1210 Chemistry
Host department: Ecology and Evolutionary Biology
Dr. Rita Mehta, Postdoctoral Researcher, Section of Evolution and Ecology, University of California, Davis
Candidate for the faculty position in functional organismal biology
Abstract
I am interested in novelty, innovation, and diversity in organismal design. I study the evolution of novel feeding behaviors in ectothermic vertebrates from a hierarchy of levels -- behavior, function, physiology, and morphology. In this seminar, I will discuss major insights that I have gained into these issues during my research on snakes and moray eels, organisms that have converged on an elongate body plan.
The elongate, limb-reduced body plan is an extreme phenotype that has evolved multiple times across ectothermic lineages. Moray eels and snakes not only share a serpentine body plan but also a similar trophic ecology. Using tools from functional morphology, comparative animal behavior, and ecological physiology, I have shown how these highly successful vertebrate predators overcome gape constraints imposed by this body plan. My studies investigate the novel prey capture strategies of morays and snakes and further reveal how both groups of organisms have evolved convergent prey transport mechanisms for consuming large prey whole. Innovations in the transport system of both snakes and morays stem from subtle modifications of the jaws that result in significant functional novelties. The discovery of an alternative mechanism to hydraulic prey transport in morays demonstrates how striking functional novelties may be driven by the interaction between body plan and feeding ecology. These case studies provide us with a new perspective on the origins of innovation in organismal design and shed insight on the predictability of novelties associated with particular feeding habits and body plans.
Plant-fungal interactions in a changing environment:
Linking functional diversity of fungal communities to soil carbon dynamics
Date: 3/27/2008, 12:10 - 1 p.m.
Location: 1640 Chemistry
Host department: Ecology and Evolutionary Biology
Dr. Jeri Parrent
National Science Foundation Postdoctoral Fellow, Department of Integrative Biology, University of Guelph, Canada
Abstract
Plant-fungal symbioses are ecologically diverse, ranging from mutually beneficial to asymmetrically antagonistic associations. Plant-associated fungi are also ubiquitous; most living plant tissue is either covered or infiltrated by symbiotic fungi that acquire their carbon (C) nutrition directly from living plant hosts. Thus, symbiotic fungi have a large influence on the movement of C between plants, soil and the atmosphere. Ecological guilds of symbiotic fungi are both speciose and phylogenetically diverse. What is not well understood is whether there are also functional differences among taxa within guilds that explain and maintain community diversity, and whether such differences may translate into meaningful variation for host-symbiont interactions.
In this seminar I will discuss two projects that explore the functional diversity within guilds of symbiotic fungi, and the consequences for symbiotic C and nutrient exchange. In the first study, I have taken advantage of an ecosystem where the “symbiotic currency” of the mycorrhizal mutualism has been experimentally altered through increasing atmospheric CO2 concentrations to ask: (1) are mycorrhizal communities shaped by changes in supply and demand of plant C and nitrogen? (2) Do mycorrhizal fungi differ in functional traits related to C demand and distribution? In the second study, I examine the distribution and abundance of genes involved in symbiotic C exchange to determine the degree of variation that exists both within and between fungal ecological guilds in the ability to acquire plant C. In both instances I find evidence for large differences in traits between guilds but also a greater degree of variation within symbiotic fungal guilds in the demand for, allocation of and mechanisms for acquiring plant C than have previously been appreciated. These findings suggest that changes in symbiotic fungal communities have a large impact on soil carbon dynamics and storage.
 Behavioral variation in primate populations: Implications for conservation and the comparative method
Date: 3/27/2008, 4:10 - 5 p.m.
Location: Kraus Natural Science auditorium
Host department: Ecology and Evolutionary Biology
Dr. Karen Strier
University of Wisconsin
Abstract
Efforts to understand primate behavioral diversity have tended to emphasize phylogeny and ecology at the expense of demography. This emphasis has been fueled, in part, by the widespread application of comparative methods that focus on analyses of species or higher taxonomic units instead of on populations, where demographic fluctuations and their effects on behavior are most apparent. Long-term field data from one population of the critically endangered northern muriqui (Brachyteles hypoxanthus) provide insights into the extent to which demographic conditions can change over individual lifetimes, as well as into the ways in which behavioral responses to demographic changes affect life histories and ultimately, population viability. Extending these examples to include other primates provides a method for characterizing and integrating intraspecific behavioral variation and demography into comparative models, and for identifying the potential risks of evolutionary traps that can lead to population extinctions.
The genetics of speciation in Drosophila
Date: 4/3/2008, 4:10 - 5 p.m.
Location: Kraus Natural Science auditorium
Host department: Ecology and Evolutionary Biology
Dr. H. Allen Orr
University Professor and Shirley Cox Kearns Chair of Biology, University of Rochester
Abstract
Genetic studies of speciation have focused on the evolution of hybrid sterility and inviability. In the last five years, my laboratory and others have attempted to connect speciation with the study of molecular evolution, an effort that obviously requires identifying "speciation genes" at the DNA sequence level. I will review these efforts, describing two recently-characterized genes that cause hybrid sterility in Drosophila. This work points to an important role for natural selection, perhaps involving genetic conflict, in speciation.
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