**ABSTRACT NOT FOR CITATION WITHOUT AUTHOR PERMISSION. The title, authors, and abstract for this completion report are provided below. For a copy of the full completion report, please contact the author via e-mail at m.c.hale@tcu.edu or via telephone at 817-257-8707. Questions? Contact the GLFC via email at frp@glfc.org or via telephone at 734-662-3209.**
Behavioral and genetic
diversity among ecotypes of Lake Superior Brook Trout
Matthew
C. Hale1, Krista M. Nichols2, Robert McLaughlin3,
Chris Wilson4 and Robert Mackereth5
1Department
of Biology, Texas Christian University, 2800 S. University Drive, Fort Worth,
TX,
USA 76129
2Conservation
Biology Division, Northwest Fisheries Science Center, National Marine Fisheries
Service, NOAA, 2725 Montlake Blvd E,
Seattle, WA, USA 98112
3Department
of Integrative Biology, University of Guelph, Guelph, ON, Canada N1G2W1
4Aquatic
Biodiversity and Conservation Unit, Ontario Ministry of Natural Resources,
Trent
University, Peterborough, ON, Canada K9J 7B8
5Department
of Biology, Lakehead University, Thunder Bay, ON, Canada P7B 5E1
June 2017
ABSTRACT:
The main
goal of the funded project was to evaluate behavioral and genetic variability
between different ecotypes of Brook Trout from Lake Superior. This goal was
approached from different angles: 1) by determining the heritability of
behaviors such as the propensity to disperse, risk taking, general activity,
and aggressiveness, which are potentially connected to the development of
different ecotypes in Brook Trout (objective 1), and 2) by using genomic
approaches to A) identify genetic polymorphisms associated with the different
migratory types (objective 2), and B) to evaluate differential gene expression
in the brain between behavioral types (objective 3). In all objectives,
wild-caught Brook Trout in Nipigon Bay and tributaries exhibiting alternative
life histories -- either adfluvial ‘coaster’ or
residents -- were collected for our objectives. Heritability and gene expression
for behaviors were evaluated in controlled crosses made between and within life
history types, maintained at the Codrington Fisheries Research Facility for
several years. Behavioral research suggested repeatable differences in the
expression of several behaviors that can broadly be classed as “shy” and “bold”.
Several of these behaviors were found to have a strong heritable component
suggesting that there is underlying genetic variation for variation in
behavior, but our research failed to find an association between parent life
history and behaviors expressed by their offspring (objective 1). Evaluation of
gene expression in the brains of these offspring identified a small number of
genes differentially expressed between shy and bold individuals at ages 1 and 2
postfertilization; the genes differentially expressed
between these behavioral types were not genes identified a priori for an
association with behavioral diversity, but illustrate the power of a
whole-transcriptome approach in the identification of genes and biological
process underlying complex behaviors (objective 3). Finally, in wild-caught coaster
and resident Brook Trout from Nipigon Bay and tributaries, we failed to find a
consistent association in the genome with life history type (objective 2);
however, this work, leveraging samples and associated metadata collected under
prior funding, did reveal that Brook Trout captured in the Nipigon Bay were
almost exclusively from the Cypress River, among the major tributaries sampled.
The findings under these joint objectives show that there is genetic diversity
and gene expression differences underlying complex behaviors; however, parent
life history was not a significant predictor of these behaviors in a common
environment. Moreover, these results together with our association analysis in
wild-caught individuals, further suggest that life history decisions in these
Brook Trout populations are likely promoted by ecological and growth processes
operating in each tributary during development.