Biological Sciences Faculty Publications

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Increasing evidence suggests that altered environmental conditions within cities (e.g. temperature) can have strong effects on the biology and ecology of animals. Moreover, multiple abiotic (e.g. soil moisture, distributions of water bodies) and biotic factors (e.g. plant and animal communities) may be more similar among cities in distinct climate regions as compared to outside cities. But the mechanisms behind these patterns are unclear. We suggest that animal physiological condition responds to urbanization and may become more similar with urbanization among cities. As a first attempt at assessing this possibility, we measured hydration (water content) of field-collected arthropods, across variation in urbanization (impervious surface), in three US cities with distinct climate. We found that seasonal variation, regional context and impervious surface are strongly associated with arthropod hydration. Moreover, mean arthropod hydration decreases with urbanization in a moist city with moderate temperatures (Raleigh, NC), while increasing with urbanization in cities in hot regions (Phoenix, AZ and Orlando, FL) during certain seasons, leading to greater similarity in mean hydration among cities with increasing urbanization (convergence). However, variance in hydration was greater among cities vs. undeveloped areas in some seasons, contrary to expectations. Impervious surface, region and season were better predictors of arthropod hydration than measured soil moisture, humidity, or temperature—suggesting landscape management may influence effects of climate on arthropod hydration. To understand the mechanisms behind these patterns and the implications for urban ecosystems, will require additional testing. But we offer the first evidence that animal water balance may be influenced by urbanization.

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This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( licenses/by-nc/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact

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Publication Title

Journal of Urban Ecology


Oxford University Press