Minnesota Project: Ecological and genetic characteristics of slimy sculpin in s...

Minnesota Project

Ecological and genetic characteristics of slimy sculpin in s...

July 2005 - June 2009

Personnel

Participating Agencies

Cargill Fellowship
Minnesota Department of Natural Resources

The Departments of Natural Resources in Iowa, Minnesota, and Wisconsin have implemented “reintroduction” programs for sculpin Cottus spp. in streams in the Driftless Area Ecoregion of each state. The goal of these projects is to increase the distribution of sculpin by re-establishing viable, self-sustaining populations in trout streams where native populations are presumed to have been present historically, but were extirpated and unable to recolonize (http://www.dnr.state.mn.us/areas/fisheries/lanesboro/management.html). This effort will potentially restore an ecologically important species to these coldwater streams and provide an additional prey component for wild trout populations. Sculpin were successfully reintroduced to a southwest Wisconsin stream in the 1970s. However, the reintroduction programs were instituted with limited information about the ecological suitability of the streams selected for reintroduction. This study will investigate genetic characteristics, survival, prey availability, diet of slimy sculpin, and habitat of donor and recipient streams. Our goal is to determine characteristics of streams most amenable to establishing reintroduced populations and examine ecological exchangeability of the sculpin.

Research Publications

Research Publications	Publication Date
Huff, D. D., L. M. Miller, and B. Vondracek. 2010. Patterns of ancestry and genetic diversity in reintroduced populations of the slimy sculpin: Implications for conservation. Conservation Genetics DOI 10.1007/s10592-010-0124-6. \| Abstract	December 2010	Reintroductions are a common approach for preserving intraspecific biodiversity in fragmented landscapes. However, they may exacerbate the reduction in genetic diversity initially caused by population fragmentation because the effective population size of reintroduced populations is often smaller and reintroduced populations also tend to be more geographically isolated than native populations. Mixing genetically divergent sources for reintroduction purposes is a practice intended to increase genetic diversity. We documented the outcome of reintroductions from three mixed sources on the ancestral composition and genetic variation of a North American fish, the slimy sculpin (Cottus cognatus). We used microsatellite markers to evaluate allelic richness and heterozygosity in the reintroduced populations relative to computer simulated expectations. Sculpins in reintroduced populations exhibited higher levels of heterozygosity and allelic richness than any single source, but only slightly higher than the single most genetically diverse source population. Simulations intended to mimic an ideal scenario for maximizing genetic variation in the reintroduced populations also predicted increases, but they were only moderately greater than the most variable source population. We found that a single source contributed more than the other two sources at most reintroduction sites. We urge caution when choosing whether to mix source populations in reintroduction programs. Genetic characteristics of candidate source populations should be evaluated prior to reintroduction if feasible. When combined with knowledge of the degree of genetic distinction among sources, simulations may allow the genetic diversity benefits of mixing populations to be weighed against the risks of outbreeding depression in reintroduced and nearby populations.
Huff, D. D., L. M. Miller, C. J. Chiziniski, and B. Vondracek. 2011. Mixed-source reintroductions lead to outbreeding depression in the second-generation descendents of a native North American fish. Molecular Ecology 20:4246–4258. \| Abstract	October 2011	Reintroductions are commonly employed to preserve intraspecific biodiversity in fragmented landscapes. However, reintroduced populations are frequently smaller and more geographically isolated than native populations. Mixing genetically, divergent sources are often proposed to attenuate potentially low genetic diversity in reintroduced populations that may result from small effective population sizes. However, a possible negative tradeoff for mixing sources is outbreeding depression in hybrid offspring. We examined the consequences of mixed-source reintroductions on several fitness surrogates at nine slimy sculpin (Cottus cognatus) reintroduction sites in south-east Minnesota. We inferred the relative fitness of each crosstype in the reintroduced populations by comparing their growth rate, length, weight, body condition and persistence in reintroduced populations. Pure strain descendents from a single source population persisted in a greater proportion than expected in the reintroduced populations, whereas all other crosstypes occurred in a lesser proportion. Length, weight and growth rate were lower for second-generation intra-population hybrid descendents than for pure strain and first-generation hybrids. In the predominant pure strain, young-of the-year size was significantly greater than any other crosstype. Our results suggested that differences in fitness surrogates among crosstypes were consistent with disrupted co-adapted gene complexes associated with beneficial adaptations in these reintroduced populations. Future reintroductions may be improved by evaluating the potential for local adaptation in source populations or by avoiding the use of mixed sources by default when information on local adaptations or other genetic characteristics is lacking.

Theses and Dissertations

Theses and Dissertations	Publication Date
Huff, D. D. 2010. Examining genetic diversity, outbreeding depression, and local adaptation in a native fish reintroduction program. PhD Dissertation, University of Minnesota, St. Paul, Minnesota.	April 2010

Cooperative Fish and Wildlife Research Units Program: Minnesota Education, Research and Technical Assistance for Managing Our Natural Resources