DOI: 10.5061/dryad.1dr748t
title: Data from: Reduced competition may allow generalist species to benefit from habitat homogenization

description: 1. Complex environments support high biodiversity and diverse microhabitat
 availability, which may reduce the intensity of competition among species.
 Both natural and anthropogenic disturbances reduce the structural
 complexity of habitats, leading to homogenization. High abundances of
 common, generalist species in disturbed habitats may be driven by reduced
 competition from specialists in similar habitats. 2. We quantified habitat
 availability for and utilization of three co-occurring arboreal geckos
 (Australian native house geckos [Gehyra dubia], northern velvet geckos
 [Oedura castelnaui], and eastern spiny-tailed geckos [Strophurus
 williamsi]) in four replicated grazing regimes in an experimental grazing
 trial in northeast Queensland, Australia. 3. Native house geckos were most
 abundant in heavily grazed habitats, whereas the two other species rarely
 co-occurred (either with each other or with native house geckos). Geckos
 displayed resource partitioning of habitat features, such as tree species
 and structural characteristics. 4. We found evidence of interspecific
 competition among gecko species, in which native house geckos shifted
 their habitat selection in the presence of velvet geckos. In the absence
 of other geckos, native house geckos preferred rough, peeling bark and
 dead trees; yet in the presence of velvet geckos, native house geckos
 shifted away from dead trees, and used more structurally complex trees,
 probably due to high niche overlap with velvet geckos. 5. Native house
 geckos were more resistant to the negative effects of livestock grazing
 than either velvet or spiny-tailed geckos. In the absence of other
 species, native house geckos used a wider range of microhabitats. 6.
 Synthesis and applications. Species assemblages are often the result of
 multiple or complex factors, such as predation pressure, habitat
 availability, or competitive interactions. The homogenizing effects on
 habitat structure caused by livestock grazing reduced diversity and
 suitability for microhabitat specialists. Reduced competition, therefore,
 apparently promoted the abundance of microhabitat generalist species (G.
 dubia), suggesting that livestock grazing was a mechanism leading to
 homogenization and simplification of habitat structure, which ultimately
 led to changes in the species composition through reduced competition.
 Understanding species responses to disturbance, and more broadly, habitat
 complexity, is crucial for our ability to maintain or increase biological
 diversity in anthropogenically modified landscapes.
description: gecko
 abundanceAbundance (mean &
 SE) of geckosnew.gecko.abund.fig.csvCDA data - grazing treatment and habitat featuresContains data for CDA on grazing regime and habitat featurescda.grazing.habitat.fig.data.csvniche breadth and grazing regimeAdjusted niche breadth by grazing regime for each gecko speciesniche grazing regression.1.csvniche shiftNiche shift (or lack of) in geckos in the presence (or absence) of other speciesniche.pca.data.1.new.2.csvRDA tree characteristicsRDA data for tree characteristicspca.data.only.tree.characteristics.csvRDA tree speciesRDA data for tree speciespca.data.tree.species.2.csvNordberg and Schwarzkopf Homogenization r codeR code for analyses and figures