Spatial variation in water loss predicts terrestrial salamander distribution and population dynamics

Abstract

25Many patterns observed in ecology, such as species richness, life history variation, 26 habitat use, and distribution have physiological underpinnings For many ectothermic 27 organisms temperature relations shape these patterns, but for terrestrial amphibians, 28 water balance may supersede temperature as the most critical physiologically-limiting 29 factor. Many amphibian species have little resistance to water loss, which restricts 30 them to moist microhabitats and may significantly affect foraging, dispersal, and 31 courtship. Using plaster models as surrogates for terrestrial plethodontid salamanders, 32we measured water loss under ecologically-relevant field conditions to estimate the 33 duration of surface activity time across the landscape. Surface activity time was 34 significantly affected by topography, solar exposure, canopy cover, maximum air 35 temperature, and time since rain. Spatially, surface activity times were highest in 36 ravine habitats and lowest on ridges. Surface activity time was a significant predictor 37 of salamander abundance, as well as a predictor of successful recruitment; the 38 probability of a juvenile salamander occupying an area with high surface activity time 39 was two times greater than an area with limited predicted surface activity. Our results 40 suggest that survival, recruitment, or both are demographic processes that are affected 41 by water loss and the ability of salamanders to be surface active. Results from our 42 study extend our understanding of plethodontid salamander ecology, emphasize the 43 limitations imposed by their unique physiology, and highlight the importance of water 44 loss to spatial population dynamics. These findings are timely to understanding the 45 effects that fluctuating temperature and moisture conditions predicted for future 46 climates will have on plethodontid salamanders. 47

Comparative landscape genetics reveals the evolution of viviparity reduces genetic connectivity in fire salamanders

“…Amphibians are susceptible to dehydration (Hillyard, ), and wind is one factor increasing rates of evaporative water loss. Amphibians, including S. salamandra , tend to reduce terrestrial activity under windy conditions to maintain hydric balance (Andreone, Clima, & De Michelis, ; Peterman & Semlitsch, ; Velo‐Antón & Buckley, ). This suggests dispersal rates are limited across terrains highly exposed to the wind.…”

Prescribed fire and timber harvest effects on terrestrial salamander abundance, detectability, and microhabitat use

“…Salamander responses to forest management practices are greatly influenced by their unique life‐history characteristics. Terrestrial salamanders respire cutaneously, which makes them dependent on moisture (Spotila , Gatz et al 1975, Kleeberger and Werner , Feder ) and limits their surface activity (Jaeger , O'Donnell et al , Peterman and Semlitsch ). Terrestrial salamanders have small home ranges—typically just a few square meters—because of their limited movement capacity and high site fidelity (Kleeberger and Werner , Ousterhout and Liebgold ).…”

State of the World's Amphibians

“…The frequency of exceptional droughts is already increasing in some regions. High water loss may affect survival and recruitment in populations of terrestrial amphibians (141). The integration of spatially explicit data relating body temperature, water balance, seasonality, and activity times will improve our ability to formulate scenarios for amphibian populations impacted by climate change.…”