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Geographic Variability in Elevation and Topographic Constraints on the Distribution of Native and Nonnative Trout in the Great Basin

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Title Geographic Variability in Elevation and Topographic Constraints on the Distribution of Native and Nonnative Trout in the Great Basin
Names Warren, Dana R. (creator)
Dunham, Jason B. (creator)
Hockman-Wert, David (creator)
Date Issued 2014-01-01 (iso8601)
Note To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The article is copyrighted by the American Fisheries Society and published by Taylor & Francis. It can be found at: http://www.tandfonline.com/toc/utaf20/current#.UyiHN_Pn-Hs.
Abstract Understanding local and geographic factors influencing species distributions is a prerequisite for conservation
planning. Our objective in this study was to model local and geographic variability in elevations occupied by native
and nonnative trout in the northwestern Great Basin, USA. To this end, we analyzed a large existing data set of
trout presence (5,156 observations) to evaluate two fundamental factors influencing occupied elevations: climate-related
gradients in geography and local constraints imposed by topography. We applied quantile regression to model
upstream and downstream distribution elevation limits for each trout species commonly found in the region (two
native and two nonnative species). With these models in hand, we simulated an upstream shift in elevation limits
of trout distributions to evaluate potential consequences of habitat loss. Downstream elevation limits were inversely
associated with latitude, reflecting regional gradients in temperature. Upstream limits were positively related to
maximum stream elevation as expected. Downstream elevation limits were constrained topographically by valley
bottom elevations in northern streams but not in southern streams, where limits began well above valley bottoms.
Elevation limits were similar among species. Upstream shifts in elevation limits for trout would lead to more habitat
loss in the north than in the south, a result attributable to differences in topography. Because downstream distributions
of trout in the north extend into valley bottoms with reduced topographic relief, trout in more northerly latitudes are
more likely to experience habitat loss associated with an upstream shift in lower elevation limits. By applying quantile
regression to relatively simple information (species presence, elevation, geography, topography), we were able to
identify elevation limits for trout in the Great Basin and explore the effects of potential shifts in these limits that could
occur in response to changing climate conditions that alter streams directly (e.g., through changes in temperature
and precipitation) or indirectly (e.g., through changing water use).
Genre Article
Identifier Warren, D. R., Dunham, J. B., & Hockman-Wert, D. (2014). Geographic Variability in Elevation and Topographic Constraints on the Distribution of Native and Nonnative Trout in the Great Basin. Transactions of the American Fisheries Society, 143(1), 205-218. doi:10.1080/00028487.2013.833551

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