Weight watching in burrows: variation in body condition in pygmy bluetongue lizards

Author version made available in accordance with the publisher's policyThe pygmy bluetongue lizard, Tiliqua adelaidensis, is an endangered scincid lizard which occurs in remnants of natural grasslands in the mid-north of South Australia. We assessed the factors affecting body condition of male and female lizards, using body size residuals as an index, over five sampling years. We included sex, phenotypic (patterned or plain morphs), temporal (sampling year and activity period within year), and climatic factors in our analyses. The results indicated that sampling year and activity period within the year were the two most important factors influencing variation in body condition of both male and female lizards over the period of the study. There were similar trends when we considered females separately in each of three stages of their reproductive cycle (pre-partum, gravid, post-partum). None of the analyses showed any significant effect of phenotype on body condition. Winter-spring rainfall was positively correlated with body condition of females in the pre-partum period, but showed no significant effect on mean body condition of any other grouping of adult lizards, nor a consistent direction of correlation among the different subsets of adult lizards that we considered. The substantial annual variations in the body condition of lizards, although of uncertain cause, provide important information for conservation managers who monitor persisting populations of this endangered species

Variation in size and condition of neonate pygmy bluetongue lizards, Tiliqua adelaidensis

This is an Accepted Manuscript of an article published by Taylor & Francis in TRANSACTIONS OF THE ROYAL SOCIETY OF SOUTH AUSTRALIA on 9 June 2015, available online: http://www.tandfonline.com/10.1080/03721426.2015.1045312. This item is under embargo for a period of 12 months from the date of publicationPhenotypic variation among offspring of individual animals is an important life-history trait. In viviparous lizards, it could result from genetic variation of individuals and also differences in environments experienced by mothers during gestation. We investigated variation in phenotype and survival of neonate pygmy bluetongue lizards, Tiliqua adelaidensis, over three sampling years. We explored changes in body condition, using body size residuals as an index, and body size (snout-vent length (SVL) and mass) of neonates. For litters that were captured with their mothers, we hypothesised that body condition and size of offspring are influenced by the condition and size of their mothers, presence of mothers in the burrow and litter size. We found that there were significant variations in body condition and mass of neonates among years. There was no significant relationship between neonate body condition, mass and SVL and post-partum body condition of their mothers. Results revealed that females with higher SVL produced larger litters. None of the analyses showed any effect of mother’s presence on neonate body condition, SVL or mass. Neither was there any effect of observed litter size on these parameters. Our findings have important conservation implications for this endangered species, given that the aim of conservation managers is to encourage conditions that promote optimum body condition and fitness in offspring in order to maximise their survival in fragmented habitats

Image Asymmetry Measurement for the Study of Endangered Pygmy Bluetongue Lizard

Author version made available in accordance with the publisher's policyAbstract—There are applications for the measurement of body asymmetry as some studies have shown a correlation between asymmetry and fitness for some species. In our study of the endangered Pygmy Bluetongue Lizard, the asymmetry of its head is being investigated to see whether this has a correlation with its health and chance of survival in the wild. As there are restrictions on handling the endangered lizards, their digital photos must be taken in the field and therefore it is difficult to impose restrictions on the conditions under which the digital images are acquired. In this paper, we propose a novel automatic technique that is invariant to rotation, size, illumination and tilt, for the measurement of lizard symmetry based on its digital imagery and the resulting symmetry index is used to infer the lizard’s asymmetry. The conventional manual methods being used by biologists for fluctuating asymmetry measurement have a number of disadvantages including human errors, and their methods of measurement are based on counting the number of scales and length measurement that do not often agree well with visual assessment. Our proposed image processing technique is non-invasive, robust in a way that will give a similar symmetric index for different images of the same lizard, and more importantly based on the actual image scale pattern of the lizards. Hence our proposed method will also give a better agreement with visual assessment