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          CONTACT INFORMATION

           Michael A. Halbisen
          Environmental and Life Sciences Graduate Program
          Trent University
          1600 West Bank Drive
          Peterborough, ON, Canada K9J 7B8

          email:  michaelhalbisen@trentu.ca or michaelhalbisen@gmx.com  
          phone: 1-416-534-7488
          Citizenship: USA

          CURRICULUM VITAE  <<>> SKILLS <<>> About me

EDUCATION

Ph. D. Conservation Biology and Ecology September 2008.  Environmental and Life Sciences Graduate Program, Trent University.  Peterborough, ON, Canada. 

M.S. Biochemistry 1998.  The University of Wisconsin-Madison, Department of Biochemistry. Madison, WI.

B.S. Chemistry 1996.  Bowling Green State University, Department of Chemistry.  Bowling Green, OH. 

RESEARCH INTERESTS

Resolving ecological and genetic mechanisms that pattern phenotypic variability 

     Complex interactions between genetic and environmental factors generate an amazing degree of phenotypic diversity in nature. I seek a mechanistic understanding of how these interactions are influenced by, and influence, ecological processes at population and community levels. 

    Although many traditional approaches to resolving complex biological systems exist, newer large-scale (e.g., genomic and proteomic) and information-theoretic methodologies are becoming essential for studying these systems. I am particularly interested in integrating these approaches with traditional disciplines to address classical ecological (e.g., How do species interactions influence trait variability?) and genetic questions (e.g., To what degree does epistasis influence complex phenotypes?) about natural phenotypic variation, as well as exciting new issues in emerging fields (e.g., How does genetic variability in 'keystone' species affect community-level ecological processes? How do interspecific genetic interactions constrain genomic architectures among associated species?). Currently, I am looking for postdoctoral opportunities that will enable me to further develop these interests towards building a successful academic research program.

CURRENT PROJECTS

What factors determine whether divergent hatchery strain lake trout will successfully interbreed with natives in wild populations?

     When fish populations are disturbed by human activities they become more vulnerable to decline and eventual disappearance. Since declining populations are often stocked with non-native, cultured fish to boost production, they are exposed to further opportunities for loss of natural genetic variation through interbreeding and introgression. Contrary to some predictions, results from my thesis work indicated that stocking history, which should have been predictive of the abundance of non-native adults in the spawning population, was not a contributing factor to replacement of native genetic diversity in wild lake trout populations. This indicated that other natural and anthropogenic factors were modulating interbreeding and the reproductive success of hatchery strain lake trout.  Identification and characterization of these modulating factors will address mechanistically how the genetically divergent, non-native (i.e., primarily of Great Lakes origin) hatchery strains are less suited for long-term survival ecologically dissimilar inland lake habitats, and will also provide insight into what factors may be driving local adaptive evolutionary processes (since postglacial colonization 10,000 years ago) among isolated inland populations.

     To determine what factors modulate native and hatchery-strain interbreeding, we have undertaken a  collaborative project with Nigel Lester (OMNR) and Cindy Chu (Trent U).  We are using model-selection (AIC) on logistic and multinomial regression models to measure the relative importance of key anthropogenic, environmental, and ecological variables for introgression.  Overall, we expect that anthropogenic disturbance should be positively associated with interbreeding between natives and stocked hatchery fish, even though the historical donor populations (Great Lakes) were poorly matched to recipient populations (inland lakes) in terms of their genetic background and ecological attributes.  However, we also expect that local environmental and ecological factors will modulate the degree of interbreeding. Of the different natural factors, we predict that aquatic community attributes will strongly influence interbreeding, as they reflect ecological processes that can influence a range of biologically relevant and potentially adaptive lake trout traits.

Using information-theoretic approaches for statistical genetic analyses

This past August I was fortunate enough to attend a workshop (thanks Nigel!) given by David Anderson on the usefulness of model based inference for evaluating multiple alternative hypotheses (i.e., likelihood-based model-selection) over null-hypothesis testing (e.g., t-tests, chi-square tests, etc.).  Although I had already gained some experience with fancy likelihood-based and Bayesian statistical techniques during course of my Ph.D. research, his presentation was one of the best and most useful I've ever attended.  Several interesting case examples were provided for how an information-theoretic framework could be applied to evaluate a surprisingly broad range of mathematical models in different fields.  Given the wide applicability of this inferential framework, I am interested in determining whether it could be adapted to evaluate more complex systems, such as those encountered in studies of gene and protein interactions.  Currently I am collaborating with Brian Cox (Developmental and Stem Cell Biology Research Program, Sickkids Research Institute) to develop novel bioinformatic approaches for accomplishing this goal.

PH.D. THESIS (completed September 8th, 2008)

Does supplemental stocking alter natural patterns of genetic diversity in lake trout populations?

     When the genetic background of donor and recipient fish populations are poorly matched, supplemental stocking may be unsuccessful.  Stocked fish may not survive, or they may numerically replace naturally produced individuals without contributing to a self-sustaining, wild population.  Even in cases where supplemental stocking is successful, interbreeding between indigenous fish and non-native hatchery strains can lead to homogenization of native population genetic structure.  Ultimately these admixed populations may be less suited to changes in the natural environment than the original natives. 

     My thesis research was focused on determining how supplemental stocking had altered patterns of natural genetic diversity in lake trout (Salvelinus namaycush) populations.  I used a genetic profiling methodology to evaluate populations in three different, representative regions of natural genetic diversity in Ontario and the Great Lakes region.  I measured both mitochondrial and microsatellite DNA variation to assess the degree of interbreeding between stocked and native lake trout (see the publications section below for more details on these studies).

Some photos from the past few years...