DOI: 10.5061/dryad.j0zpc86f6
title: Natural and anthropogenic sources of habitat variation influence exploration behaviour, stress response, and brain morphology in a coastal fish

description: 1. Evolutionary ecology aims to better understand how ecologically
 important traits respond to environmental heterogeneity. Environments vary
 both naturally and as a result of human activities, and investigations
 that simultaneously consider how natural and human-induced environmental
 variation affect diverse trait types grow increasingly important as human
 activities drive species endangerment. 2. Here, we examine how habitat
 fragmentation and structural habitat complexity, affect disparate trait
 types in Bahamas mosquitofish (Gambusia hubbsi) inhabiting tidal creeks.
 We tested a priori predictions for how these factors might influence
 exploratory behaviour, stress reactivity, and brain anatomy. 3. We
 examined approximately 350 adult Bahamas mosquitofish from seven tidal
 creek populations across Andros Island, The Bahamas that varied in both
 human-caused fragmentation (three fragmented, four unfragmented) and
 natural habitat complexity (e.g. 5-fold variation in rock habitat). 4.
 Populations that had experienced severe human-induced fragmentation, and
 thus restriction of tidal exchange from the ocean, exhibited greater
 exploration of a novel environment, stronger physiological stress
 responses to a mildly stressful event, and smaller telencephala (relative
 to body size). These changes matched adaptive predictions based mostly on
 1) reduced chronic predation risk and 2) decreased demands for navigating
 tidally dynamic habitats. Populations from sites with greater structural
 habitat complexity showed a higher propensity for exploration and a
 relatively larger optic tectum and cerebellum. These patterns matched
 adaptive predictions related to increased demands for navigating complex
 environments. 5. Our findings demonstrate environmental variation,
 including recent anthropogenic impacts (&lt;50 years), can
 significantly affect complex, ecologically important traits. Yet
 trait-specific patterns may not be easily predicted, as we found strong
 support for only six of 12 predictions. Our results further highlight the
 utility of simultaneously quantifying multiple environmental factors—e.g.
 had we failed to account for habitat complexity, we would not have
 detected effects of fragmentation on exploratory behaviours. These
 responses, and their ecological consequences, may be complex: rapid and
 adaptive phenotypic responses to anthropogenic impacts can facilitate
 persistence in human-altered environments, but may come at a cost of
 population vulnerability if ecological restoration were to occur without
 consideration of the altered traits. 
description: All methodological details are provided in the article. Briefly,
 digital videos and photographs were taken in the field and analyzed to
 quantify exploration behaviour, ventilation frequency, and brain
 morphology.
description: The first sheet of the Excel file provides information for
 labels/terms. A small number of individuals have missing data for at least
 one of the three phenotypic categories owing to problems encountered in
 the field (e.g. video recording error).