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Department of Biological Sciences

The Dallas lab published a new study in Biology Letters

Positive abundance-occupancy relationships - the observation that widely distributed species are also more locally abundant - is a general pattern in ecology  that has been described for many species including vertebrates, invertebrates, plants and bacteria. Occupancy can be evaluated at small or large spatial scales and is usually defined as the number or fraction of sites where a species occurs out of the full set of sampled sites. Occupancy is also estimated following the assumption that species can occupy all sampled sites. Yet, a species occurrence at a site can be affected by environmental conditions, dispersal limitation and biotic interactions. In their new study titled "Effects of occupancy estimation on abundance-occupancy relationships", graduate students Cleber Ten Caten, Lauren A. Holian and their mentor Dr. Tad Dallas  used the National Ecological Observatory Network small-mammal data to assess whether the assumption that species can occupy all sampled sites affects abundance–occupancy relationships. They estimated occupancy considering all sampled sites (traditional occupancy) and only the sites found within the species geographic range (spatial occupancy) and realized environmental niche (environmental occupancy). They found that  weaker abundance-occupancy relationships were observed when occupancy was estimated considering only sites possible for the species to colonize (spatial and environmental occupancy), demonstrating that the assumption that the species can occupy all sampled sites directly affects the assessment of abundance–occupancy relationships. Nice work!

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