Cryptic and Complex Nesting in the Yellow-Spotted Monitor,<i>Varanus panoptes</i>

Doody, J. Sean; James, H. G.; Ellis, Ryan J.; Gibson, Noula; Raven, Mitchell; Mahony, Stephen V.; Hamilton, David G.; Rhind, David; Clulow, Simon; McHenry, Colin R.

doi:10.1670/13-006

Cited by 34 publications

(44 citation statements)

References 32 publications

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“…Savannah‐burrower consists of large, widely foraging, savannah monitors who burrow extensively in soil (Doody, James, et al., 2014). These species are rarely found in trees, and include Varanus gouldii and Varanus panoptes (Christian, 2004b; Thompson, 1995).…”

Section: Methodsmentioning

confidence: 99%

“…Guild members are characterized as generalist, opportunistic predators possessing a degree of dietary overlap (Losos & Greene, 1988; Shine, 1986). The spread of the invasive cane toad ( Rhinella marinas ) has decreased populations of many varanid species across northern Australia (Doody et al., 2009; Doody, James, et al., 2014; Doody, Mayes, et al., 2014; Doody et al., 2017; Doody, Soanes, et al., 2015; Shine, 2010), potentially changing the nature of these guilds.…”

Section: Introductionmentioning

confidence: 99%

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Claw morphometrics in monitor lizards: Variable substrate and habitat use correlate to shape diversity within a predator guild

D’Amore

Clulow

Doody

et al. 2018

Ecology and Evolution

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Numerous studies investigate morphology in the context of habitat, and lizards have received particular attention. Substrate usage is often reflected in the morphology of characters associated with locomotion, and, as a result, claws have become well‐studied ecomorphological traits linking the two. The Kimberley predator guild of Western Australia consists of 10 sympatric varanid species. The purpose of this study was to quantify claw size and shape in the guild using geometric morphometrics, and determine whether these features correlated with substrate use and habitat. Each species was assigned a Habitat/substrate group based on the substrate their claws interact with in their respective habitat. Claw morphometrics were derived for both wild caught and preserved specimens from museum collections, using a 2D semilandmark analysis. Claw shape significantly separated based on Habitat/substrate group. Varanus gouldii and Varanus panoptes claws were associated with sprinting and extensive digging. Varanus mertensi claws were for shallow excavation. The remaining species’ claws reflected specialization for some form of climbing, and differed based on substrate compliance. Varanus glauerti was best adapted for climbing rough sandstone, whereas Varanus scalaris and Varanus tristis had claws ideal for puncturing wood. Phylogenetic signal also significantly influenced claw shape, with Habitat/substrate group limited to certain clades. Positive size allometry allowed for claws to cope with mass increases, and shape allometry reflected a potential size limit on climbing. Claw morphology may facilitate niche separation within this trophic guild, especially when considered with body size. As these varanids are generalist predators, morphological traits associated with locomotion may be more reliable candidates for detecting niche partitioning than those associated directly with diet.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Claw morphometrics in monitor lizards: Variable substrate and habitat use correlate to shape diversity within a predator guild

D’Amore

Clulow

Doody

et al. 2018

Ecology and Evolution

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“…In accord, females select nest sites carefully and may dig a number of pilot nests before they oviposit (Warner and Shine, ). Nests are typically in or on the ground and range from shallow in tropical rain forests (Andrews, ) to as much as a meter below the soil surface in arid environments (Cohn, ; Sherbrooke, ; Andrews et al, ; Doody et al, ). Eggs are also placed in humus, rotten logs, tree holes, piles of compost, and termite mounds (e.g., King and Green, ; Löwenborg et al, ).…”

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confidence: 99%

Rigid shells enhance survival of gekkotan eggs

Andrews

2015

J. Exp. Zool.

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The majority of lizards and snakes produce permeable parchment-shelled eggs that require high moisture conditions for successful embryonic development. One clade of gekkotan lizards is an exception; females produce relatively impermeable rigid-shelled eggs that normally incubate successfully under low moisture conditions. I tested the hypothesis that the rigid-shell increases egg survival during incubation, but only under low moisture conditions. To test this hypothesis, I incubated rigid-shelled eggs of Chondrodactylus turneri under low and under high moisture conditions. Eggs were incubated with parchment-shelled eggs of Eublepharis macularius to insure that incubation conditions were suitable for parchment-shelled eggs. Chondrodactylus turneri eggs had very high survival (>90%) when they were incubated under low moisture conditions. In contrast, eggs incubated under high moisture conditions had low survival overall, and lower survival than those of the parchment-shelled eggs of E. macularius. Mortality of C. turneri and E. macularius eggs incubated under high moisture conditions was the result of fungal infection, a common source of egg mortality for squamates under laboratory and field conditions. These observations document high survival of rigid-shelled eggs under low moisture conditions because eggs escape from fungal infection. Highly mineralized rigid shells also make egg survival independent of moisture availability and may also provide protection from small invertebrates in nature. Enhanced egg survival could thus compensate for the low reproductive output of gekkotans that produce rigid-shelled eggs.

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“…During periods of dry and hot climatic conditions, typical of semi‐arid regions, high desiccation rates, thermal stress and limited moisture availability restrict cane toads to moist microhabitats such as sites with standing water or underground shelter sites (Reynolds & Christian ; Brown, Kelehear & Shine ; Doody et al . ). To combat dehydration, toads living in the study area forage at night and frequently visit dams to rehydrate during the day or night (Letnic et al .…”

Section: Methodsmentioning

confidence: 97%

Restricting access to invasion hubs enables sustained control of an invasive vertebrate

Letnic

Webb

Jessop

et al. 2015

Journal of Applied Ecology

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Summary1. Biological invasions often occur through expansion of satellite populations that become established at 'invasion hubs'. Invasion hubs can result from random dispersal events, but frequently arise when invading individuals actively choose habitats using cues that signify highquality environments where the fitness consequences are positive. Theoretical studies suggest that targeted control at invasion hubs can effectively suppress the populations and impacts of invaders. 2. In arid Australia, small dams that provide water for livestock function as invasion hubs by providing an invasive vertebrate, the cane toad Rhinella marina, with refuge from extreme aridity during the annual dry season. Toads are attracted to dams and use them as stepping stone habitats from which they disperse during rainy periods. Here, we ask whether sustained control of this invasive vertebrate can be achieved by converting invasion hubs into ecological traps. We did this by manipulating invasion hub habitats to induce a mismatch between toads' habitat preference and the fitness consequences of their habitat choice to cause high mortality. 3. We constructed fences to exclude toads from dams and maintained these fences for 1 year. This period encompassed periods of dry and wet seasonal climatic conditions. Our manipulation did not alter the attractive cues for invading toads which died en masse while attempting to settle at fenced dams that prevented toads from reaching water. Toad populations at the fenced dams were suppressed by 1-2 orders of magnitude compared to unfenced controls and procedural controls. Toad populations remained suppressed for a year after exclusion. 4. By excluding toads from dams, we converted invasion hubs into ecological traps and effectively thwarted the reinvasion of cane toads. Our research suggests that water exclusion devices could be used to prevent toad invasion or to control cane toad populations in arid landscapes colonized by toads. 5. Synthesis and applications. Our study demonstrates that sustained control of invader populations can be achieved by restricting their access to invasion hubs. Control of invasive species via elimination of invasion hubs could be conducted reactively, to control established populations of invaders, or conducted strategically, by rendering invasion hubs unsuitable for colonization ahead of the invasion front to prevent further population spread.

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Cryptic and Complex Nesting in the Yellow-Spotted Monitor,Varanus panoptes

Cited by 34 publications

References 32 publications

Claw morphometrics in monitor lizards: Variable substrate and habitat use correlate to shape diversity within a predator guild

Claw morphometrics in monitor lizards: Variable substrate and habitat use correlate to shape diversity within a predator guild

Rigid shells enhance survival of gekkotan eggs

Restricting access to invasion hubs enables sustained control of an invasive vertebrate

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