Parturition in the Sleepy Lizard, Tiliqua rugosa

Bull, C. Michael; Pamula, Y.; Schulze, L.

doi:10.2307/1564848

Cited by 50 publications

(48 citation statements)

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“…Similar patterns of infection were observed in other long-lived reptiles: the sleepy lizard (Tiliqua rugosa), which may live up to 50 yr (Bull 1995), and the water python (Liasis fuscus), which lives .15 yr (Madsen et al, 2005). In both species, infection levels are lowest among larger (older) adults, either because resistance to infection increases with exposure to infection and age, or because only fit and resistant individuals survive to reach an old age (Smallridge and Bull, 2000;Madsen et al, 2005).…”

Section: Summary and Implications For Conservation Managementsupporting

confidence: 60%

Ecology and Dynamics of the Blood Parasite, Hepatozoon Tuatarae (Apicomplexa), in Tuatara (Sphenodon Punctatus) on Stephens Island, New Zealand

Godfrey

Nelson

Bull

2011

Journal of Wildlife Diseases

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ABSTRACT:We explored infection patterns and temporal dynamics of the protozoan blood parasite Hepatozoon tuatarae (Apicomplexa) infecting the tuatara (Sphenodon punctatus), a protected reptile living on Stephens Island, New Zealand. In March 2006, we surveyed tuatara in five study sites to examine spatial variation in infection prevalence, and four times, from May 2005 to November 2006, we recaptured marked individuals within three study sites to examine the temporal dynamics of infection. We also examined how blood-parasite infection patterns were influenced by host sex, body size, and host infestation with ticks (Amblyomma sphenodonti) and mites (Neotrombicula spp.), which are potential vectors of the blood parasite. Infection prevalence (16.9-24% infected) and intensity (,0.01-0.1% blood cells infected) were low in all samples. Infection intensity varied among the five sampled sites in March 2006, but prevalence did not. Neither infection prevalence nor intensity varied with time, and infections were detected in consecutive samples from recaptured individuals for up to 18 mo. Neither survey showed an influence of host sex on infection, but both surveys showed infection intensity declined with increasing host body size, as did infection prevalence in the spatial survey. In the temporal survey, we found a positive relationship between the tick numbers on hosts and blood-parasite infection intensity, which were stronger in two of the sampling periods and among larger hosts. These data suggest that exposure and susceptibility to infection decreases with host size and that ticks, but not mites, are probably the vectors in this ancient host-parasite association of a long-lived (.50 yr) host.

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Section: Summary and Implications For Conservation Managementsupporting

confidence: 60%

Ecology and Dynamics of the Blood Parasite, Hepatozoon Tuatarae (Apicomplexa), in Tuatara (Sphenodon Punctatus) on Stephens Island, New Zealand

Godfrey

Nelson

Bull

2011

Journal of Wildlife Diseases

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“…False-negative assessment of gestation is possible if animals are not fasted, as the gut may obscure embryonic structures. False-positive assessment of gestation may occur, as some viviparous lizards retain infertile yolks for the full duration of gestation [Bull et al, 1993] (Edwards and Jones, unpublished data). Our accuracy and ability to identify other structures, such as the gut, improved markedly with experience.…”

Section: Discussionmentioning

confidence: 99%

“…Blue-tongued skinks (such as Tiliqua nigrolutea, T. rugosa, and T. scincoides) are large (snout-vent length up to 370 mm), placid, viviparous lizards that are commonly kept for display purposes, and are also the subjects of research in Australia [Fergusson and Bradshaw, 1992;Bull et al, 1993;Edwards, 1999;Zuri and Bull, 2000;Edwards and Jones, 2001a, b;Atkins et al, 2002] and the United States [Graves and Halpern, 1991;Cooper, 2000]. Currently, the reproductive physiology and endocrinology of T. nigrolutea is being researched [Edwards, 1999;Edwards and Jones, 2001a, b;Atkins et al, 2002].…”

Section: Introductionmentioning

confidence: 99%

Comparison of noninvasive methods for the evaluation of female reproductive condition in a large viviparous lizard, Tiliqua nigrolutea

et al. 2002

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We compared the diagnostic value of three noninvasive methods (radiography, ultrasound, and palpation) of evaluating reproductive status in females of a large viviparous skink, the blotched blue-tongued lizard (Tiliqua nigrolutea). Radiography could be used to identify postovulatory females during the periovulatory period. However, in early to mid-gestation, radiography did not allow differentiation of the relatively homogenous structures within the abdomen. In late gestation, once calcification of the embryonic skeleton had occurred, gestation could be diagnosed and embryos counted. Ultrasound allowed differentiation between preovulatory, postovulatory, and nonreproductive females during the periovulatory period. Ultrasound also allowed visualisation of follicles during the early and middle stages of gestation. However, the level of operator experience, and the misdiagnosis of artefacts limited the accuracy of diagnosis. In the later stages of gestation, ultrasound did allow the detection of identifiable features of the developing foetal unit (fluid-filled foetal membranes, independent movement of the embryo, and visualisation of the heartbeat). Colour Doppler imaging could be used to visualise embryonic blood flow. Ultrasonography was not useful in detecting the number of embryos present. Palpation during the periovulatory period could be used to detect follicles and determine whether ovulation had occurred. However, during the remainder of the gestation period, palpation was unable to differentiate reproductive condition. This study provides a basis for the diagnosis of reproductive condition and problems in viviparous reptiles. Each of the diagnostic techniques is useful at different stages of gestation, and the use of a combined approach will give the most information throughout the reproductive cycle.

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“…Tyre (1999) calculated Jolly-Seber estimates of lizard density near Mt. Mary, South Australia (SA) from random capture data described in Bull (1995). Assuming that the random capture transect is sampling lizards from a 400 m wide strip (based on 200 m diameter home ranges on either side of the transect), lizard density ranges from 15 to 420 lizards/km 2 .…”

Section: Individual Based Spatially Explicit Modelmentioning

confidence: 99%

“…A flat 10% of all lizards are chosen at random and killed at the end of each season. Empirical observations place annual adult survival at around 90% (Bull, 1995). Any ticks on the killed lizards are likewise killed.…”

Section: Between Season Processesmentioning

confidence: 99%