Density and genetic diversity of grizzly bears at the northern edge of their distribution ...
Species at the periphery of their range are typically limited in density by lower habitat quality. As a result, the Central-Marginal Hypothesis (CMH) predicts a decline in genetic diversity of populations towards the periphery of a species’ range. Grizzly bears (Ursus arctos) once ranged throughout...
| Main Authors: | , , , |
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| Format: | Dataset |
| Language: | English |
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Dryad
2023
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| Subjects: | |
| Online Access: | https://dx.doi.org/10.5061/dryad.p8cz8w9vz https://datadryad.org/stash/dataset/doi:10.5061/dryad.p8cz8w9vz |
| Summary: | Species at the periphery of their range are typically limited in density by lower habitat quality. As a result, the Central-Marginal Hypothesis (CMH) predicts a decline in genetic diversity of populations towards the periphery of a species’ range. Grizzly bears (Ursus arctos) once ranged throughout most of North America but have been extirpated from nearly half of their former range, mainly in the south. They are considered a species at risk even in Canada’s remote North, where they occupy the northernmost edge of the species’ continental distribution in a low-productivity tundra environment. With climate change, one of their main food items in the tundra (caribou), which has always shown yearly fluctuations, is declining, but simultaneously, grizzlies appear to be expanding their range northward, in tundra environment. Yet, a lack of population density estimates across the North is hindering effective conservation action. The CMH has implications for the viability of peripheral populations, and the links ... : Study area The 30,000km2 study area, centred at N 64.2°, W 110.0°, was located in the Southern Arctic (Coppermine River Upland Ecoregion, CRU) and Taiga Shield (Takijuq Lake Upland Ecoregion, TLU) Ecozones (Figure 1) (Ecological Stratification Working Group Canada 1995). Its northern limit extended to the border of NT and Nunavut, and its southern limit to the tree line. The mean annual temperature of the CRU ecoregion was -7.5 ˚C, and -10.5 ˚C for the TLU ecoregion (Ecological Stratification Working Group Canada 1995). Average temperatures at the time of the study were likely higher than those cited above, due to a changing climate (Post et al. 2009). The tundra area is considered semi-arid, with mean annual precipitation ranging from 200-300 mm, with mostly continuous permafrost characterized by a rolling landscape of uplands, lowlands, and plateaus (Ecological Stratification Working Group Canada 1995). Eskers, created through glaciation and composed of stratified sand and gravel, are found throughout the ... |
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