University of Michigan
Department of Ecology and Evolutionary Biology

Ian M. Hamilton, Assistant Professor, Evolution, Ecology, and Organismal Biology, The Ohio State University

Abstract
Individual phenotypes may be influenced by the social environment, which is itself a function of the phenotypes of a set of socially-interacting individuals.  We have been using theoretical models and experiments with a cooperatively-breeding African cichlid fish, Neolamprologus pulcher, to examine social behavior, and selection on social behavior, in the context of interacting phenotypes.  I will present results from two sets of studies. In the first, we tested the general hypotheses that, in N pulcher groups, there is conflict between the dominant male and female over the presence and behavior of subordinate “helpers” that provide care for all group offspring but may be reproductive competitors, and that, as a consequence, the behavior of subordinate helpers in the group depends, in part, on the resolution of conflict between the dominant pair. We also examined whether individual variation in subordinate male behavior (or subordinate ‘personality’) indirectly influenced conflict between the dominant pair.  We found that consistently helpful subordinate males were associated with reduced conflict between dominant males and females. In a second set of studies, we used evolutionary dynamic models to investigate the role of partner control on the phenotypic make-up of groups and selection on behavior that is costly to social partners. We find that, when individual variation in behavior exists or when behavior is plastic with respect to the social environment, strategies of partner control can result in non-random association between costliness and willingness to engage in partner control. This non-random association results in social selection for increased investment in partner control and reduced costliness relative to a well-mixed model.

Photo credit: Michael Taborsky

Host: Elizabeth Tibbetts

Coffee and cookies will be served at 4 p.m.

Andrew J. Eckert, Assistant Professor, Department of Biology, Virginia Commonwealth University

Abstract
The recognition that incomplete lineage sorting is a common and expected pattern in comparative DNA sequence data has revolutionized the theory and practice of phylogenetics. This recognition was fueled in part by the realization that replicated sampling within lineages is necessary to fully describe evolutionary relationships and in part by the further realization that different genomic regions are expected to yield different gene trees despite the same underlying divergence history. As such, most empirical studies, especially those interested in the relationships among closely related species, use multiple individuals per lineage in combination with multiple loci to make inferences about evolutionary histories. As these multilocus data sets increase coverage of the focal genomes, however, they are likely to include non-neutral regions. I examined the extent of this problem for inference of evolutionary relationships among 11 species of soft pines (Pinus subgenus Strobus) using a 167 nuclear gene data set. First, patterns of non-neutral evolution were examined using standard tests of neutrality based on the site-frequency spectrum and polymorphism-to-divergence ratios. Second, species-level phylogenies were inferred using standard approaches based on the reconciliation of gene and species trees. Finally, effects of non-neutral evolution on the inference of species trees were examined empirically and through simulation. The results to date are consistent with the idea that non-neutral evolution impacts inference of species-level phylogenies and that the recalcitrancy of this clade to phylogenetic resolution is due partially to signals of natural selection. Future phylogenetic studies, therefore, need to consider carefully the effect of increased genomic sampling.

Host: Professor L. Lacey Knowles

Coffee and cookies will be served at 4 p.m.

Fred Adler, Professor of Biology and Mathematics, The University of Utah

Abstract

In the great experiment humans that are conducting on the biosphere, urban areas are the "preliminary data," where everything from biogeochemical cycles to evolutionary processes have been rapidly and profoundly transformed. These changes are the endpoints of long chains of unintended consequences initiated by human actions designed, in almost every case, for an unrelated purpose. In the pristine world of the mind, theoretical ecologists seek to deduce how processes at one level (generally one deemed less interesting like the spatial distribution of habitats) alter results at another (usually one thought to be more interesting like species richness and abundance). Urban areas challenge ecologists to develop a more unified view of the field and ecological theory plays a central role in this unification. Through models of urban biodiversity, invasive species, trophic dynamics, diseases, physiology, evolution and human health, I will seek to illustrate this unified view.

Given that current urban environments are windows into the future of the entire planet, this unified view can provide the framework for better understanding the results of the great experiment.

Host: Professor Annette Ostling

Coffee and cookies will be served at 4 p.m.

Professor Scott Barolo, University of Michigan Medical School, Cell and Developmental Biology

Abstract

A handful of ancient developmental signals, such as Hedgehog, Notch, Wnt, and RTK/MAPK, control cell fate by activating transcription factors (TFs), which bind to specific sites in animal genomes to turn genes on and off.  These pathways and TFs are highly pleiotropic: they are involved in many developmental fate decisions in diverse organs, tissue types, and stem cell systems.  How does one signal have different effects on gene expression in different types of cells, and how do genomic DNA sequences evolve in response to that signal?  I will present results from our investigations of specific cis-regulatory sequences (aka enhancers) and the developmental and evolutionary forces that shape them, at the level of individual TF binding sites.

Host: Professor Patricia Wittkopp

Coffee and cookies will be served at 4 p.m.

Stuart McDaniel, Assistant Professor of Biology, University of Florida

Abstract

The evolution of separate sexes (dioecy) has occurred numerous times across the tree of life. Nevertheless, the evolutionary forces that promote and maintain dioecy remain elusive. Here we found evidence for at least 133 transitions between sexual systems in mosses, representing an extremely high level of sexual lability. In sharp contrast to predictions, the transition rate from hermaphroditism to dioecy was twice as high as the reverse transition. These results have important implications for understanding the genomic and macroevolutionary consequences of hermaphroditism and dioecy.

Host: Professor Yin-Long Qiu

Coffee and cookies will be served at 4 p.m.

Richard Kobe, Chair and Professor, Department of Forestry, Michigan State University

Abstract
The composition and relative abundances of tree species in forest communities are fundamental attributes, but rarely have multiple processes causing these community-level patterns been considered together.  I will report on mechanisms that govern these community properties in wet tropical forest in Costa Rica as well as northern hardwood forest in northwestern lower Michigan. In wet tropical forest, seedling limitation does not constrain the recruitment of more common species. There also is little evidence to support that more common species are more susceptible to density dependent natural enemies. However, across species, there is strong covariance in seedling mortality responses to local conspecific density and shading, suggesting density-dependent natural enemies could exaggerate species differences in low-light seedling survival.  Nevertheless, species that survive poorly under low light and that are susceptible to density-dependence also are more growth responsive to soil nutrients (N, P, and base cations), even in the shaded understory. In Michigan northern hardwood forests, dramatic variation in species composition across glacial landforms can be explained by an interspecific trade-off between growth under high soil resources and survival under low soil resources. The species that survive well under low soil resources likely are excluded from higher fertility sites because of increasing competition for irradiance. Overall, these studies support that the multiple mechanisms governing forest community dynamics can be understood from the perspective of individual seedling / tree responses to resources and interactions with neighboring individuals.

Hosts: Inés Ibáñez and Annette Ostling

Coffee and cookies will be served at 4 p.m.

Professor Christopher Dick, Ecology and Evolutionary Biology, Associate Curator, U-M Herbarium, University of Michigan

Abstract
Rain forest has been a persistent feature in South America for ≥55 million years. However, climate-envelope models predict that future air temperature increases will cause pervasive tree species extinction, and some biosphere models predict  widespread Amazon forest die-off. We used a phylogeographic analysis to estimate the age of 12 widespread Amazon tree species to determine if they have persisted though times when air temperatures were similar to predicted levels over the coming decades. Nine of the 12 study species originated >2.6 Ma ago when air temperatures were warmer than today, and may have been similar to 2100 projections under mid-range anthropogenic emissions  scenarios. Our results suggest that, all else being  equal, near-term high temperature induced Amazon tree species extinction is unlikely.

Coffee and cookies will be served at 4 p.m.

Benjamin Prud'homme, Principal Investigator, Developmental Biology Institute of Marseille-Luminy, France

Abstract
The typical pattern of morphological evolution associated with the radiation of a group of related species is the emergence of a novel trait and its subsequent diversification. From butterfly eyespots and their various colorful rings to the diversity of shapes assumed by vertebrate teeth, seashells or horn beetles, this pattern of emergence-diversification holds for countless characters across most animal groups. Yet, the genetic mechanisms associated with these two evolutionary steps are poorly characterised. We have characterized some of the genetic changes underlying the evolution and the diversification of a wing pigmentation pattern in some Drosophila species. Our results show how a primitive spot of dark pigment on fly wings has first evolved from the assembly of a novel gene regulatory module whereby pigmentation genes fell under the regulation of a common transcriptional activator. The primitive wing spot pattern subsequently diversified through the sole changes in spatial distribution of this activator. These results suggest that the genetic changes underlying the emergence and the diversification of the wing pigmentation patterns are partitioned within genetic networks. More generally, this two-step model accounts at the gene regulatory level for the general pattern observed in animals and plants where morphological diversification mostly results from occasional novelties and infinite variations on these new themes.

Host: Professor Patricia Wittkopp

Coffee and cookies will be served at 4 p.m.

Christy McCain, Assistant Professor and Curator of Vertebrates, University of Colorado Boulder

Abstract
to come

Coffee and cookies will be served at 4 p.m.