Diversity and evolution of the freshwater fishes of North America

Louis Bernatchez (Supervisor)
Robert Hanner (Co-Supervisor)

To protect biodiversity efficiently, I believe it is important to be able to identify the components of biodiversity and to know the spatial distribution of these entities. Furthermore, since nature is dynamic, it is also important to preserve the evolutionary processes that allow species to diversify.

In this context, my research project will aim to:

1. Develop a molecular identification tool for all species of freshwater fish in North America. This tool was develop in order to differentiate morphologically similar species, identify species regardless of life stage (e.g. egg and larvae) and identify degraded (e.g. stomach content) or transformed (e.g. fish fillets) specimens. The approach is based on the principle of DNA barcode; i.e. a standardized data base of mitochondrial DNA sequences freely available on the Internet and associated with a collection of specimens. This project is conducted in association with CCDB (Canadian Center for DNA Barcoding) and FISHBOL (Fish Barcode of Life Initiative). See April et al. (2011) for results of this study.

2. Improve our understanding of the evolutionary mechanisms shaping the global latitudinal gradient in biodiversity. More precisely, I specifically tested the hypothesis that both temporal habitat stability associated with historical climatic fluctuation, as well as metabolic rate associated with thermal regime and influencing mutation rate, have dually contributed in shaping global patterns of biodiversity among North American freshwater fishes. Using our DNA barcode database (April et al. 2011) of the nearly all North American freshwater fishes, I analysed levels of sequence divergence between both intraspecific phylogroups and nearest neighbour species using various phylogenetic and generalized linear mixed models. Results of this study have recently been submitted to a scientific journal (see April et al., Submitted).

3. Investigate the possible role of the Pleistocene glacial cycles in acting as an allopatric speciation pump for North Eastern American freshwater fish. To do that, I first compared the mitochondrial phylogeography of 10 freshwater fish species having apparently been isolated in the same two glacial refugia (Atlantic and Mississippian). In a second step, I verified the existence of reproductive isolation between the Atlantic and Mississippian glacial lineages in 4 freshwater fish using AFLP markers. I am presently writing the manuscript presenting the results of this study (see April et al. in prep).

Publications:

Julien April, Robert Hanner and Louis Bernatchez. (In preparation). Glacial cycles act as an allopatric speciation pump in North Eastern American freshwater fish.

Julien April, Richard L. Mayden, Robert Hanner and Louis Bernatchez. (Submitted). Metabolic rate and climatic fluctuations shape continental wide patterns of genetic diversity and species richness in fishes.

Julien April, Richard L. Mayden, Robert Hanner and Louis Bernatchez. 2011. Genetic Calibration of Species Diversity among North America's Freshwater Fishes. Proceedings of the National Academy of Sciences of the United States of America. Volume 108, 10602–10607.

Nicolas Hubert, Robert Hanner, Erling Holm, Nicholas E. Mandrak, Eric Taylor, Mary Burridge, Douglas Watkinson, Pierre Dumont, Allen Curry, Paul Bentzen, Junbin Zhang, Julien April and Louis Bernatchez. 2008. Identifying Canadian Freshwater Fishes through DNA Barcodes. PLOS ONE. Volume 3, e2490.

Julien April and Julie Turgeon. 2006. Phylogeography of the banded killifish (Fundulus diaphanus): glacial races and secondary contact. Journal of Fish Biology. Volume 69, 212-228.