Phylogeography and Postglacial Dispersal of Brook Trout in Labrador
One position is available for a graduate student interested in brook trout genetics, evolutionary history, or environmental biology. A brief description of the project goals and student requirements are provided below. This project is in collaboration with Robert Perry of the Department of Environment and Conservation.
Background: The Department of Environment and Conservation has been conducting a ten-year monitoring program of lakes along phase II and III of a newly developed highway in Labrador. We are in the third sampling year of this bi-annual program. The purpose of this work is to establish an inventory of fish populations that are in proximity to the new highway. The inventory will provide baseline data for the management of these fish populations.
To date, 21 lakes have been surveyed and 1200 brook trout sampled. Preliminary analysis revealed that brook trout located in lakes of the Eagle River watershed have distinct morphological differences from brook trout sampled from neighboring watersheds. In the past, work done with species composition and distribution has suggested that brook trout in the southeastern region originated from two glacial refugia. The first group moved across Quebec and arrived in the Churchill drainage basin via a distribution originating from the Mississippi refugium. The second colonized the coastal watersheds, moving up the eastern seaboard into Labrador from the Atlantic refugium. Little information exists to determine the extent to which these two groups have dispersed and/or mixed in Labrador.
The province is interested in determining whether brook trout sampled from the various watersheds came from a single common refugium or whether they are a mixture from both. With particular reference to fish sampled from the Eagle River watershed, we would like to determine whether they originated from the Mississippi refugium or the Atlantic refugium.
Proposed Methodology: The Wildlife Division is seeking one graduate student to design an experimental methodology and perform genetic analysis on archived fin clip samples taken during the previous two years of sampling. The goal is to ascertain the refugial origin of the various stocks of brook trout in southeastern Labrador, and to identify those stocks where mixing between refugial groups may have occurred.
Brook trout genetics (mtDNA and SSRs) have been examined throughout much of their range in eastern North America. The mitochondrial work suggests that lineages restricted to each putative glacial refugium are present in the northern glaciated zone, but that fish outside southern Ontario are primarily of a single lineage present in both putative refugial populations. In the current study we will first identify the mitochondrial lineage composition in the southeastern Labrador region and compare it to the lineage distribution in the broader range. Finer-scale assessment of admixture within specific populations will then be performed with the more variable SSR loci.
The student will have the opportunity to accompany provincial biologists and technicians in the field to collect samples during the summer of 2007, and will be expected to identify data deficiencies (inadequate sampling of a particular watershed) so that arrangements can be made for sampling in the summer of 2008 or 2009. The results of the student’s work will be disseminated in both a Master's thesis and peer-reviewed publications.
