Deep Communal Nesting by Yellow-Spotted Monitors in a Desert Ecosystem: Indirect Evidence for a Response to Extreme Dry Conditions

Doody, J. Sean; McHenry, Colin R.; Durkin, Louise K.; Brown, Mike; Simms, Angela; Coleman, Lizzy; Phizacklea, Charlotte; Jones, Hayes; Phizacklea, Oliver; Clulow, Simon

doi:10.1655/herpetologica-d-18-00004.1

Cited by 3 publications

(10 citation statements)

References 18 publications

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“…4 in 39 ). We can think of no other reason why nest depth would vary significantly and consistently with wet season rainfall, and our interpretation is supported by the species nesting deeper in more arid locations across a rainfall gradient 39,41,42 (and T. Madsen, unpubl. data).…”

Section: Discussionmentioning

confidence: 58%

“…Although information on the timing of oviposition in this species is scarce, V. panoptes lays eggs in the late wet season/early dry season, with hatching occurring in the following wet season 47,48 . It excavates nesting burrows communally in warrens, depositing its eggs deeper (up to 4 m) than any other vertebrate, except perhaps its closest relative, V. gouldii 39,41,42 .…”

Section: Methodsmentioning

confidence: 99%

“…The recent revelation of exceptionally deep nesting in two large monitor lizards in the wet-dry tropics and deserts of Australia underscored the potential for the hydric environment in shaping the evolution of nest site choice. The yellow-spotted monitor ( V. panoptes ) and Gould’s monitor ( V. gouldii ) excavate deeper nests than any other ground-nesting vertebrate, depositing their eggs up to 4 m below the surface in communal nesting warrens 39 – 42 . Deep nesting in these species appears to be a response to hydric conditions: embryos require very long (~ 8 months) developmental periods that must span the long, harsh dry season, and nesting at shallower depths would likely result in the desiccation of embryos 39 , 41 , 42 .…”

Section: Introductionmentioning

confidence: 99%

“…The yellow-spotted monitor ( V. panoptes ) and Gould’s monitor ( V. gouldii ) excavate deeper nests than any other ground-nesting vertebrate, depositing their eggs up to 4 m below the surface in communal nesting warrens 39 – 42 . Deep nesting in these species appears to be a response to hydric conditions: embryos require very long (~ 8 months) developmental periods that must span the long, harsh dry season, and nesting at shallower depths would likely result in the desiccation of embryos 39 , 41 , 42 . In support, mean and variance in soil temperatures in warrens were very similar among depths in the 1–4 m range 39 , and nest depth was inversely proportionate to annual wet season rainfall across a rainfall gradient 42 .…”

Section: Introductionmentioning

confidence: 99%

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Plasticity in nest site choice behavior in response to hydric conditions in a reptile

Doody

McGlashan

Fryer

et al. 2020

Sci Rep

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Natural selection is expected to select for and maintain maternal behaviors associated with choosing a nest site that promotes successful hatching of offspring, especially in animals that do not exhibit parental care such as reptiles. In contrast to temperature effects, we know little about how soil moisture contributes to successful hatching and particularly how it shapes nest site choice behavior in nature. The recent revelation of exceptionally deep nesting in lizards under extreme dry conditions underscored the potential for the hydric environment in shaping the evolution of nest site choice. But if deep nesting is an adaptation to dry conditions, is there a plastic component such that mothers would excavate deeper nests in drier years? We tested this hypothesis by excavating communal warrens of a large, deep-nesting monitor lizard (Varanus panoptes), taking advantage of four wet seasons with contrasting rainfall amounts. We found 75 nests during two excavations, including 45 nests after a 4-year period with larger wet season rainfall and 30 nests after a 4-year period with smaller wet season rainfall. Mothers nested significantly deeper in years associated with drier nesting seasons, a finding best explained as a plastic response to soil moisture, because differences in both the mean and variance in soil temperatures between 1 and 4 m deep are negligible. Our data are novel for reptiles in demonstrating plasticity in maternal behavior in response to hydric conditions during the time of nesting. The absence of evidence for other ground-nesting reptile mothers adjusting nest depth in response to a hydric-depth gradient is likely due to the tradeoff between moisture and temperature with changing depth; most ground-nesting reptile eggs are deposited at depths of ~ 2–25 cm—nesting deeper within or outside of that range of depths to achieve higher soil moisture would also generally create cooler conditions for embryos that need adequate heat for successful development. In contrast, extreme deep nesting in V. panoptes allowed us to disentangle temperature and moisture. Broadly, our data suggest that ground-nesting reptiles can assess soil moisture and respond by adjusting the depth of the nest, but may not, due to the cooling effect of nesting deeper. Our results, within the context of previous work, provide a more complete picture of how mothers can promote hatching success through adjustments in nest site choice behavior.

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Section: Discussionmentioning

confidence: 58%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Plasticity in nest site choice behavior in response to hydric conditions in a reptile

Doody

McGlashan

Fryer

et al. 2020

Sci Rep

Self Cite

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show abstract

“…Third, Gould’s monitor lizard, V. gouldii , the smaller, sister species to the yellow‐spotted monitor, exhibited the same deep, communal nesting, with helices and separate hatchling escape burrows (Fig. 1B; Doody et al 2018b). The Gould’s monitor lizard is more widespread and is a major mesopredator in both tropical savannahs and desert ecosystems, falling prey to yellow‐spotted monitor and a few other top predators.…”

Section: Figmentioning

confidence: 96%

Ecosystem engineering by deep‐nesting monitor lizards

Doody

Soennichsen

James

et al. 2021

Ecology

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Australian lizards are outstanding models for reproductive biology research

et al. 2021

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Australian lizards are a diverse group distributed across the continent and inhabiting a wide range of environments. Together, they exhibit a remarkable diversity of reproductive morphologies, physiologies, and behaviours that is broadly representative of vertebrates in general. Many reproductive traits exhibited by Australian lizards have evolved independently in multiple lizard lineages, including sociality, complex signalling and mating systems, viviparity, and temperature-dependent sex determination. Australian lizards are thus outstanding model organisms for testing hypotheses about how reproductive traits function and evolve, and they provide an important basis of comparison with other animals that exhibit similar traits. We review how research on Australian lizard reproduction has contributed to answering broader evolutionary and ecological questions that apply to animals in general. We focus on reproductive traits, processes, and strategies that are important areas of current research, including behaviours and signalling involved in courtship; mechanisms involved in mating, egg production, and sperm competition; nesting and gestation; sex determination; and finally, birth in viviparous species. We use our review to identify important questions that emerge from an understanding of this body of research when considered holistically. Finally, we identify additional research questions within each topic that Australian lizards are well suited for reproductive biologists to address.

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Deep Communal Nesting by Yellow-Spotted Monitors in a Desert Ecosystem: Indirect Evidence for a Response to Extreme Dry Conditions

Cited by 3 publications

References 18 publications

Plasticity in nest site choice behavior in response to hydric conditions in a reptile

Plasticity in nest site choice behavior in response to hydric conditions in a reptile

Ecosystem engineering by deep‐nesting monitor lizards

Australian lizards are outstanding models for reproductive biology research

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