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Abstract Pleistocene diversity was much higher than today, for example there were three distinct wolf morphotypes (dire, gray, Beringian) in North America versus one today (gray). Previous fossil evidence suggested that these three groups overlapped ecologically, but split the landscape geographically. The Natural Trap Cave (NTC) fossil site in Wyoming,USAis an ideally placed late Pleistocene site to study the geographical movement of species from northern to middle North America before, during, and after the last glacial maximum. Until now, it has been unclear what type of wolf was present atNTC. We analyzed morphometrics of three wolf groups (dire, extant North American gray, Alaskan Beringian) to determine which wolves were present atNTCand what this indicates about wolf diversity and migration in Pleistocene North America. Results showNTCwolves group with Alaskan Beringian wolves. This provides the first morphological evidence for Beringian wolves in mid‐continental North America. Their location atNTCand their radiocarbon ages suggest that they followed a temporary channel through the glaciers. Results suggest high levels of competition and diversity in Pleistocene North American wolves. The presence of mid‐continental Beringian morphotypes adds important data for untangling the history of immigration and evolution ofCanisin North America.
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Can large carnivores change streams via a trophic cascade?
Abstract Large carnivores were persecuted in Yellowstone National Park, WY, USA, during the late 1800s and early 1900s, leading to extirpation of grey wolves (Canis lupus) and cougars (Puma concolor). Soon thereafter increased herbivory of riparian plant communities by Rocky Mountain Elk (Cervus elaphus) became widespread in the park's northern ungulate winter range or “northern range.” Wolves were reintroduced in 1995–1996, again completing the park's large carnivore guild. In 2004 and 2017, we sampled Geyer willow (Salix geyeriana), a commonly occurring tall willow, along the West and East Forks of Blacktail Deer Creek in the central portion of the northern range. Results indicated high levels of elk herbivory in the 1990s, as in previous decades, not only continued to keep willows short, generally ≤52 cm in height, but also resulted in stream widening and incision, leading to “oversized” channel cross‐sections and a drastically reduced frequency of overbank flows. However, by 2017, willow heights ≥200 cm ( = 310 cm) were prevalent, and canopy cover over the stream, essentially absent in 1995, had increased to 43% and 93% along the West Fork and East Fork, respectively. These recent increases in tall willow heights, greater canopy cover, well‐vegetated streambanks, and the recent development of an inset floodplain all pointed towards a riparian/aquatic ecosystem beginning to recover. Overall, results were consistent with a landscape‐scale trophic cascade, whereby reintroduced wolves, operating in concert with other large carnivores, appear to have sufficiently reduced elk herbivory in riparian areas to initiate the recovery of Blacktail Deer Creek's riparian plant communities and stream channels.
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- PAR ID:
- 10079327
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Ecohydrology
- Volume:
- 12
- Issue:
- 1
- ISSN:
- 1936-0584
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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