RAPD Analysis for Genetic Diversity of Varanus salvator

[Objective] The aim was to carry out RAPD analysis on genetic diversity of Varanus salvator. [Method] 20 random primers were used for PCR amplification of genomic DNA of 36 individuals of V. salvator. [Result] 10 primers could produce highly reproducible RAPD bands. A total of 2 952 DNA fragments were successfully amplified. Each individual got 82 amplified bands on average,47 of which showed polymorphism. The polymorphic locus percent was 57.32%. The genetic distance among 36 individuals ranged from 0.035 9 to 0.335 9 with an average of 0.135 9. The Nei＇s gene diversity index （H） and Shannon＇s information index （I） were 0.181 9 and 0.263 0,respectively,indicating that V. salvator had greater genetic diversity. [Conclusion] The phylogenetic tree was inferred by using UPGMA analysis,it was found that the 36 individuals could be classified as one group,and there was no obvious population differentiation.

Compressive Biomechanics of the Reptilian Intervertebral Joint

This study compared the pre-sacral intervertebral joints of the American alligator(Alligator mississippiensis)with those from specimens of Varanus.These two taxa were chosen because they have similar number of pre-sacral vertebrae and similar body weights;however,Varanus can move bipedally and has diarthrotic intervertebral joints,whereas Alligator has intervertebral discs and cannot move bipedally.This study consisted of three objectives:(1)to document the anatomy of the intervertebral joint,(2)to quantify the compressive biomechanics of the intervertebral joints and explore which features contributed to compression resistance,and(3)to quantify the impact of compression on the intervertebral foramen and spinal nerves in these two taxa.The experimental results revealed that the diarthrotic intervertebral joints of Varanus were significantly(4x)stiffer than the intervertebral disc of Alligator,and that a significant component of this increased stiffness arose from the facet joints.Compressing the intervertebral joints of the two taxa caused a reduction in foraminal area,but the magnitude of this reduction was not significantly different.We hypothesize that the main factor preventing spinal nerve impingement in Varanus during gravitational compression is the relatively small size of the spinal ganglion/nerve relative to the foraminal area.

Eliciting conditioned taste aversion in lizards:Live toxic prey are more effective than scent and taste cues alone

Conditioned taste aversion(CTA)is an adaptive learning mechanism whereby a consumer associates the taste of a certain food with symptoms caused by a toxic substance,and thereafter avoids eating that type of food.Recently,wildlife researchers have employed CTA to discourage native fauna from ingesting toxic cane toads(Rhinella marina),a species that is invading tropical Australia.In this paper,we compare the results of 2 sets of CTA trials on large varanid lizards(“goannas,”Varanus panoptes).One set of trials(described in this paper)exposed recently-captured lizards to sausages made from cane toad flesh,laced with a nausea-inducing chemical(lithium chloride)to reinforce the aversion response.The other trials(in a recently-published paper,reviewed herein)exposed free-ranging lizards to live juvenile cane toads.The effectiveness of the training was judged by how long a lizard survived in the wild before it was killed(fatally poisoned)by a cane toad.Both stimuli elicited rapid aversion to live toads,but the CTA response did not enhance survival rates of the sausage-trained goannas after they were released into the wild.In contrast,the goannas exposed to live juvenile toads exhibited higher long-term survival rates than did untrained conspecifics.Our results suggest that although it is relatively easy to elicit short-term aversion to toad cues in goannas,a biologically realistic stimulus(live toads,encountered by free-ranging predators)is most effective at buffering these reptiles from the impact of invasive toxic prey.