DOI: 10.5061/dryad.pn090
title: Data from: Density-dependent habitat selection predicts fitness and abundance in a small lizard

description: Density-dependent habitat selection has been used to predict and explain
 patterns of abundance of species between habitats. Thermal quality, a
 density-independent component of habitat suitability, is often the most
 important factor for habitat selection in ectotherms which comprise the
 vast majority of animal species. Ectotherms may reach high densities such
 that individual fitness is reduced in a habitat due to increased
 competition for finite resources. Therefore, density and thermal quality
 may present conflicting information about which habitat will provide the
 highest fitness reward and ectotherm habitat selection may be
 density-independent. Using ornate tree lizards Urosaurus ornatus at 10
 sites each straddling two adjacent habitats (wash and upland), we tested
 the hypothesis that habitat selection is density-dependent even when
 thermal quality differs between habitats. We first tested that fitness
 proxies decline with density in each habitat, indicating density-dependent
 effects on habitat suitability. We also confirmed that the two habitats
 vary in suitability (quantified by food abundance and thermal quality).
 Next, we tested the predictions that habitat selection depends on density
 with isodar analyses and that fitness proxies are equal in the two
 habitats within a site. We found that monthly survival rates decreased
 with density, and that the wash habitat had more prey and higher thermal
 quality than the upland habitat. Lizards preferred the habitat with more
 food and higher thermal quality, lizard densities in the two habitats were
 positively correlated, and fitness proxies of lizards did not differ
 between habitats. These patterns are consistent with density-dependent
 habitat selection, despite differences in thermal quality between
 habitats. We expect that density-dependent habitat selection is widespread
 in terrestrial ectotherms when densities are high and temperatures are
 close to their optimal performance range. In areas where thermal quality
 is low, however, we expect that depletable resources, such as food, become
 less limiting because assimilating resources is more difficult.
description: treelizardcapturehistoriesMark-recapture history of ornate tree lizards (Urosaurus ornatus) at 10 sites and their growth rates. id: numeric identifier for lizards ch: capture histories of lizards (1 = detected, 0 = undetected at a capture event) sex: sex of each lizard (M = male, F = female) hab: character identifying whether the lizard’s mean coordinates were in the upland (u) or wash (w) gr: growth rate (cm/day) of each lizard using the first and last capture measurements of snout-vent-length. Only lizards captured more than once in their first breeding season have values for growth rates.weathersummaryWeather summary data for detection covariate in mark-recapture models in paper. site: number (1:10) identifying the site columns labeled 1:13 contain the PC1 values from climate station data on the day of a capture event. The column label refers to the capture event for a site (eg. column labelled 1 contains PC1 of climate data for the first capture event at each site).arthropodpitfalldataArthropod prey abundance at study sites in two habitats. arthropods: number of arthropod prey caught in each pitfall trap (over 24 hours) month: number identifying month the trap was set site: number (1:10) identifying the site where the trap was set hab: character identifying whether the trap was set in the upland (u) or wash (w)thermalqualitydataThe thermal quality in study sites. time.tset: number of hours the thermal model was between 32.2 C and 26.0 C (preferred temperature range of ornate tree lizards) for each julian day a model recorded data site: number (1:10) identifying the site hab: character identifying whether the thermal model was in the upland (u) or wash (w) month: number identifying the month