Abstract
AbstractTerrestrial reptiles are particularly vulnerable to climate change. Their highest density and diversity can be found in hot drylands, ecosystems which demonstrate extreme climatic conditions. However, reptiles are not isolated systems but part of a large species assemblage with many trophic dependencies. While direct relations among climatic conditions, invertebrates, vegetation, or reptiles have already been explored, to our knowledge, species’ responses to direct and indirect pathways of multiple climatic and biotic factors and their interactions have rarely been examined comprehensively. We investigated direct and indirect effects of climatic and biotic parameters on the individual (body condition) and population level (occupancy) of eight abundant lizard species with different functional traits in an arid Australian lizard community using a 30‐yr multi‐trophic monitoring study. We used structural equation modeling to disentangle single and interactive effects. We then assessed whether species could be grouped into functional groups according to their functional traits and their responses to different parameters. We found that lizard species differed strongly in how they responded to climatic and biotic factors. However, the factors to which they responded seemed to be determined by their functional traits. While responses on body condition were determined by habitat, activity time, and prey, responses on occupancy were determined by habitat specialization, body size, and longevity. Our findings highlight the importance of indirect pathways through climatic and biotic interactions, which should be included into predictive models to increase accuracy when predicting species’ responses to climate change. Since one might never obtain all mechanistic pathways at the species level, we propose an approach of identifying relevant species traits that help grouping species into functional groups at different ecological levels, which could then be used for predictive modeling.
Highlights
In a world driven by climate change (IPCC 2014), it is an urgent need to understand how species might respond
Structural equation modeling Based on previous studies and our own expertise, we developed a conceptual network between the climatic and biotic factor groups that could potentially influence the eight focal lizard species at either individual or population level (Fig. 1, Table 2; see Appendix S1 for a detailed network description)
Occupancy was high for G. variegata and M. boulengeri (~0.5) and did not vary much but spanned the whole range between 0 and 1 for the remaining species
Summary
In a world driven by climate change (IPCC 2014), it is an urgent need to understand how species might respond. Lizards are strongly dependent on food availability (Ballinger 1977, Pianka 1986) and vegetation cover (Kearney et al 2009, Grimm-Seyfarth et al 2017). Desert invertebrates, which are both the most common food of arid-zone lizards (Pianka 1986) and potential predators (Henle 1990a), depend on water, temperature, and vegetation abundance and composition (Read 1995, Kwok et al 2016), with the latter being related to rainfall (Shmida et al 1986, Robertson 1988) or to standing water in flooded anabranches (Shmida et al 1986)
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