EES Seminar Series 2008/2009
From EESwiki
Seminars take place on Tuesdays at 17:00h in the Biozentrum, first floor, left lecture hall.
08/09/08 Dr Jeff Jensen
University of California, Division of Biological Sciences
website: http://www-biology.ucsd.edu/labs/bachtrog/people/Jensen/jensen.html
Contact person: Wolfgang Stephan
21/10/08 Prof Dr Spencer Hall
Indiana University
Title: "Predator spreaders", "Friendly competition", and "Quality matters": three stories at the interface of food webs and disease in the plankton
website: http://www.indiana.edu/%7Ehalllab/
Contact person: Justyna Wolinska
What factors inhibit the start of disease epidemics? What then catalyzes their end? These questions continue to perplex disease ecologists and epidemiologists. We have now realized that species interactions (ecology) can profoundly influence the nature of disease in wildlife populations. I will illustrate such an ecological perspective via three examples from our recent work with lake plankton and the focal host-grazer-prey Daphnia dentifera. In the first cautionary tale ("predator spreaders"), the invertebrate predator Chaoborus likely spreads spores of the parasitic fungus Metschnikowia during times in which the physical environment otherwise would impede disease spread. This predator clearly does not "keep the herds healthy". The second act highlights the potentially important tension between the conflicting roles of competitors who act as disease diluters: competitors who are incompetent hosts remove but do not produce parasites -- but they also compete with vulnerable hosts for resources. We see this interplay between dilution and competition among Daphnia species in the "friendly competition" story. Thirdly, we argue that resource "quality matters" for epidemiology. We find that broad variation in resource quality for hosts during the time course of epidemics can actually enhance/inhibit disease via direct effects on epidemiology. Combined, these three food web modules of disease highlight the power of taking a food web perspective on wildlife epidemiology.
28/10/08 Prof Dr Susan Ptak
Max Planck Institute for Evolutionary Anthropology, Department of Evolutionary Genetics
Title: The story of FOXP2: Insights into detecting selection.
website: http://email.eva.mpg.de/~ptak/
Contact person: Pleuni Pennings
Abstract A mutation in the gene FOXP2, which encodes a transcription factor, co-segregates with a disorder in one family, in which members have severe articulation difficulties accompanied by linguistic and grammatical impairments. Indeed, FOXP2 is the only gene that is currently known to be relevant to speech and language development in humans, and as such has been studied widely by our group and others. I will discuss in detail the following three studies of FOXP2, what can be inferred from these studies and how we make such inferences. Enard et al. sequenced FOXP2 in various primates and mouse. They found two amino acid changes specific to the human lineage in an otherwise highly conserved protein, suggesting this gene has been the target of selection. They also collected polymorphism data upstream of these two amino acid changes in a world-wide sample of 20 humans, and found patterns suggesting that a selective sweep has affected this region in the past 260,000 years. The best candidates for the putative selective sweep seen in the polymorphism data are, in fact, the two amino acid substitutions that occurred on the human lineage. Krause et al. genotyped these two amino acids in two Neandertal bones and surprisingly found that these two Neandertal individuals carried the human alleles. A priori this would suggest that the mutation to the human allele occurred prior to the split of humans and Neandertals 300,000-400,000 years ago, which is in contrast to the inference based on the polymorphism data. We have now collected additional polymorphism data both upstream and downstream of these two amino acids. We find two main haplotypes that extend across these two sites, and thus alleles at SNPs upstream of these amino acids are perfectly associated with alleles at SNPs downstream of these amino acids. This is unlikely following a selective sweep. A number of possible explanations for this data will be discussed, and how in conclusion, based on all the data in these three studies, we conclude that the putative selective sweep on FOXP2 seen in polymorphism data is not likely to be associated with the two amino acid substitutions.
11/11/08 Prof Dr Hanna Kokko
University of Helsinki, Department of Biological and Environmental Science, Division of Ecology and Evolution
Title: Which sex does what, and why?
website: http://www.helsinki.fi/~hmkokko/
Contact person: Jonathan Jeschke
This talk will review the development of theory (and some data) regarding the interaction of parental costs, sex roles, and sexual selection, beginning with the seminal paper by Trivers (1972). Some verbal arguments ever-present in textbooks turn out unreliable when modelled mathematically, and we present new models that try to look at the factors promoting female or male care (e.g. expected parentage, sexual selection) in a more comprehensive way than has been possible previously.
18/11/08 Prof Dr Jody Hey
Rutgers University , Department of Genetics, Nelson Biological Laboratories
Title: New Methods and Applications in Divergence Population Genetics
Divergence population genetics is the use of population genetic data and models to reveal how and when populations and closely related species have diverged. With new statistical methods it is possible to analyze data to reveal complex histories that include changes in population sizes, population splitting times, and gene exchange between populations. The latest methods, that include methods for more than two populations, will be described together with applications to chimpanzees and other organisms.
website: http://lifesci.rutgers.edu/~heylab/
Contact person: Wolfgang Stephan
25/11/08 Prof Dr Nico Michiels
University of Tuebingen, Division of Animal Evolutionary Ecology
Title: Red fluorescence in reef fish: a novel communication mechanism?
At depths below 10 m, reefs are dominated by blue-green light because seawater selectively absorbs the longer, ‘red’ wavelengths beyond 600 nm from the downwelling sunlight. Consequently, the visual pigments of many reef fish are matched to shorter wavelengths, which are transmitted better by water. Combining the typically poor long-wavelength sensitivity of fish eyes with the presumed lack of ambient red light, red light is currently considered irrelevant for reef fish. Contrary to this expectation, we discovered that at least 32 reef fishes from 16 genera and 5 families show pronounced red fluorescence under natural, daytime conditions at depths where downwelling red light is virtually absent. Fluorescence was confirmed by spectrometry. In most cases peak emission was around 600 nm and fluorescence was associated with guanine crystals. Our data indicate that red fluorescence may function in a context of intraspecific communication: Fluorescence patterns were typically associated with the eyes or the head, varying substantially even between species of the same genus. Moreover red fluorescence was particularly strong in fins that are involved in intraspecific signalling. Finally, microspectrometry in one fluorescent goby, Eviota pellucida, showed a long-wave sensitivity that overlapped with its own red fluorescence, indicating that this species is capable of seeing its own fluorescence. We propose that red fluorescence is used as a private communication mechanism in small, benthic, pair- or group-living fishes. Many of these species show quite cryptic colouration in other parts of the visible spectrum. Our findings challenge the notion that red light is of no importance to marine fish, calling for a reassessment of its role in fish visual ecology in subsurface marine environments.
website: http://www.uni-tuebingen.de/evoeco/html/people/michiels_nico.htm
Contact person: Christian Laforsch
09/12/08 Prof Dr Luc de Meester
Katholieke Universiteit Leuven, Division of Aquatic Ecology and Evolutionary Biology
website: http://www.kuleuven.be/cv/u0008482.htm
Contact person: Christian Laforsch
20/01/09 Prof Dr Wolfgang Schroeder
The Yellowstone wolf reintroduction: a large scale experiment
In 1995 and 1996 a founder population of 31 wolves in Yellowstone National Park (YNP) was declared a "nonessential experimental Population" - not with an ecological experiment in mind. This definition was a legal condition to get the project of the ground. However he YNP wolf reintroduction turned out to be one of the most productive ecological experiments involving large carnivores. A set of hypotheses could be tested, including impact on prey populations, wolf population regulation and trophic cascades. This presentation will focus on wolf and elk (Cervus elaphus) behavior and the "ecology of fear". The wolf reintroduction project has met recovery objectives beyond expectations.
Contact person = Volker Witte
03/02/09 Prof Dr Gregor Fussmann
McGill University, Biology Department
website: http://biology.mcgill.ca/faculty/fussmann/
Contact person: Volker Witte
Population and community dynamics – how important is contemporary evolution?
The last three decades have seen an accumulation of studies demonstrating that evolutionary change in ecologically important organismal traits often takes place at the same time and pace as ecological dynamics. I will present three experimental examples of population dynamics that differ in complexity and in the degree to which evolutionary processes play a role in them. Example 1 is a phytoplankton monoculture that displays cyclical population oscillations caused by cell cycle dynamics. Example 2 is a rotifer-algal predator-prey system that could be maintained in a cyclical mode for several hundred generations. Example 3 uses the same system but introduces genetic and phenotypic diversity in the prey population, which crucially alters the community dynamics. A major conclusion from these experiments is that “details matter” for understanding community dynamics. Such “details” can be a population’s inherent potential for evolution due to its genetic diversity but also the specific nature of the prey uptake by the predator (form of functional response, predator-dependence, prey switching), the internal structure of the interacting populations (age or stage), the existence of additional non-trophic interactions (inducible defenses, swarming, vertical migration) and the spatial structure of the environment.
See also EES_seminars_0708
