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Facets of functional diversity support niche-based explanations for Australian biodiversity gradients
Journal article   Open access   Peer reviewed

Facets of functional diversity support niche-based explanations for Australian biodiversity gradients

Margaret E. Andrew, Douglas K. Bolton, Gregory J. M. Rickbeil and Nicholas C. Coops
Journal of biogeography, Vol.51(3), pp.467-482
2024
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Published (Version of Record)CC BY V4.0 Open Access

Abstract

energy environmental heterogeneity functional biogeography functional traits spatial scale species richness vegetation structure
Aim There is widespread support that species richness increases with the available energy of an ecosystem, but the mechanisms underlying this driver of biodiversity patterns remain elusive. We evaluated gradients of functional diversity to test whether the higher species richness of productive, structurally diverse environments is due to a greater range of niches being supported by the abiotic conditions present (environmental filtering), greater availability of biotic resource and habitat niches (more niches) or increasing functional similarity of species (niche packing). Location Australia. Taxon Birds and mammals. Methods We used structural equation modelling to evaluate the relative contributions of climatic harshness (actual evapotranspiration, AET) and the availability of resource (gross primary productivity, GPP) and habitat (tree height) niches on taxonomic richness and functional richness, dispersion and evenness. We performed parallel analyses within 15 bioclimatic zones and continentally to evaluate the scaling of biodiversity gradients and the shifting balance between niche-based mechanisms along environmental gradients. Results All continental diversity gradients were primarily associated with energy variables, but while species richness of both taxa and all functional diversity measures of bird assemblages increased with AET, mammal functional diversity was more strongly associated with GPP gradients. Results were more variable at the regional scale, but species richness gradients along tree height (birds and mammals) and GPP (mammals) within bioclimatic zones tended not to be paralleled by increases in functional richness or dispersion. Main Conclusions The niche-based explanations of biodiversity gradients varied in importance with scale, position on environmental gradients and taxonomic group. At the continental extent, bird biodiversity gradients were structured by environmental filtering by climatic harshness, while mammal biodiversity was related to the increasing availability of resource niches with increasing productivity. Niche packing was more prominent at the regional scale, especially in bioclimatic zones where productivity and vegetation height were less limiting, and in mammal assemblages, suggesting that biodiversity patterns scale differently for birds and mammals.

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Collaboration types
Domestic collaboration
International collaboration
Citation topics
3 Agriculture, Environment & Ecology
3.40 Forestry
3.40.195 Biodiversity Conservation
Web Of Science research areas
Ecology
Geography, Physical
ESI research areas
Environment/Ecology
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