Competing for crevices: interspecific conflict influences retreat-site selection in montane lizards

Abstract

Direct interference competition between sympatric taxa affects habitat use and shelter-site selection in species within most major vertebrate lineages. However, studies on interspecific social interference in reptiles largely have been confined to research on interactions between non-native (invasive) species and native fauna. Does interspecific interference also influence habitat use within natural assemblages of reptiles? We studied five broadly sympatric species of viviparous montane skinks within the genera Egernia and Eulamprus in southeastern Australia. Previous work has shown strong interspecific overlap in abiotic attributes of shelter-sites for these taxa, but no joint occupancy of retreats. Laboratory trials in which we manipulated the identity of co-occurring lizards revealed frequent displacement from "preferred" (hotter) shelters, with interspecific interactions more intense than intraspecific conflicts. The five species displayed a linear interspecific dominance hierarchy, with larger species displacing smaller taxa. Field manipulations confirmed that interspecific interactions between these species affect shelter-site use. We conclude that direct agonistic encounters between individuals of different species strongly influence habitat use by lizards within this assemblage.

How much stress do researchers inflict on their study animals? A case study using a scincid lizard, Eulamprus heatwolei

“…All species (three within the genus Egernia and two within Eulamprus) are diurnally active heliotherms that inhabit rocky outcrops among the eucalypt forest at this site. They occupy refuges that are similar in most abiotic characteristics (Langkilde et al, 2003), with strong, highly aggressive competition among these species for the warmest refuge sites (Langkilde and Shine, 2004). The current study focuses on one of these species, Eulamprus heatwolei (Wells & Wellington, Scincidae).…”

“…The current study focuses on one of these species, Eulamprus heatwolei (Wells & Wellington, Scincidae). As one of the smallest of the five taxa (approximately 85·mm snout-vent length SVL) (Cogger, 2000), E. heatwolei is often excluded from preferred refuges by more dominant species (Langkilde and Shine, 2004). Eulamprus heatwolei is insectivorous, and females give birth to a litter of one to eight offspring per year in late summer (Greer, 1989).…”

“…(x) Exposure to heterospecific lizard -the lizard was transferred to an unfamiliar enclosure (as described above) containing a potentially aggressive heterospecific lizard, E. saxatilis (Langkilde and Shine, 2004), for 1·h.…”

Squeezed at the top: Interspecific aggression may constrain elevational ranges in tropical birds

“…The influence of interspecific competition on the spatial arrangement of species in sympatry has been suggested for many taxa, including fish (Bay et al 2001), amphibians (Cunningham et al 2009), reptiles (Langkilde and Shine 2004), and mammals (Brown 1971). In birds, such interactions can determine local habitat selection (Martin and Martin 2001), settlement patterns of migrants arriving to breeding grounds (Fletcher 2007), and spatial partitioning of closely related species along successional gradients (Robinson and Terborgh 1995).…”

Abiotic and biotic influences on the dispersal behavior of metamorph cane toads (Bufo marinus) in tropical Australia

“…Indeed, mechanistic models of the distribution of ectotherms include the physiology-temperature interaction as a matter of course (Huey and Stevenson,'79;Hutchison and Maness,'79). Furthermore, ectotherms must trade off the benefits of precise thermoregulation against other fitness-determining issues such as avoidance of predators and competitors and the need to obtain food (Downes and Shine, '98;Downes, 2001;Langkilde and Shine, 2004;Langkilde et al, 2005;Herczeg et al, 2006).…”