Predators, prey or temperature? Mechanisms driving niche use of a foundation plant species by specialist lizards.

Kristian J Bell,Tim S Doherty,Don A Driscoll

doi:10.1098/rspb.2020.2633

Kristian J Bell, Tim S Doherty + Show 1 more

Open Access

https://doi.org/10.1098/rspb.2020.2633

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Abstract

Foundation species interact strongly with other species to profoundly influence communities, such as by providing food, refuge from predators or beneficial microclimates. We tested relative support for these mechanisms using spinifex grass (Triodia spp.), which is a foundation species of arid Australia that provides habitat for diverse lizard communities. We first compared the attributes of live and dead spinifex, bare ground and a structurally similar plant (Lomandra effusa), and then tested the relative strength of association of two spinifex specialist lizard species (Ctenophorus spinodomus and Ctenotus atlas) with spinifex using a mesocosm experiment. Temperatures were coolest within spinifex compared to bare ground and Lomandra. Invertebrate abundance and the threat of predation were indistinguishable between treatments, suggesting temperature attenuation may be a more important driver. Overall, the dragon C. spinodomus preferred live over dead spinifex, while the skink C. atlas preferred dead spinifex, particularly at warmer air temperatures. However, both species displayed individual variability in their use of available microhabitats, with some individuals rarely using spinifex. Our results provide an example of temperature attenuation by a foundation species driving niche use by ectothermic animals.

Highlights

Niche theory underpins almost every aspect of ecology [1], with the concept describing the complex and dynamic interaction of organisms with environmental variables, constrained by resource limitations, competition and predation [2]
There was a weak interaction between temperature and treatment (χ2 = 6.154, p = 0.104), with C. spinodomus increasing use of live spinifex compared to bare ground (−0.072, p = 0.037) and dead spinifex (−0.106, p = 0.030) at higher temperatures
We tested the functional environment of a foundation species for two putative spinifex specialist lizard species

Summary

Introduction

Niche theory underpins almost every aspect of ecology [1], with the concept describing the complex and dynamic interaction of organisms with environmental variables, constrained by resource limitations, competition and predation [2]. The attenuation of temperatures by foundation species, often with favourable outcomes for associated biota, has been recorded across numerous systems, including marine (macroalgae [16]), temperate forest (eastern hemlock [17]) and alpine environments (cushion plant [18]) In addition to these well-established abiotic impacts, foundation species can affect biotic processes such as species interactions and resource acquisition [19,20], often through their impact on the physical structure of the environment.

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