Emergent fungal pathogens in herpetofauna are a concern in both wild and captive populations. We diagnosed dermatomycosis by Paranannizziopsis australasiensis in two panther chameleons (Furcifer pardalis) and suspected it in eight others captured from an established free-living nonnative population in Florida, USA. Chameleons developed skin lesions following recent exposure to cold weather conditions while housed in captivity, approximately 10 mo after capture and 12 wk after being placed in outdoor enclosures. Affected animals were treated with oral voriconazole and terbinafine until most cases resolved; however, medications were ultimately discontinued. Paranannizziopsis australasiensis has not previously been described in chameleons, nor in animals originating from a free-ranging population in the USA. Although the source of P. australasiensis infection is uncertain, we discuss several scenarios related to the pet trade and unique situation of chameleon “ranching” present in the USA.
Rattlesnakes use infrared radiation to detect prey animals such as small mammals and lizards. Because ectotherm locomotor performance depends on temperature, rattlesnakes could use prey temperature to evaluate the potential of lizards to evade attacks. Here, we tested whether hunting rattlesnakes use infrared information to (1) detect and (2) evaluate prey before attack. We expected thermal contrast between prey and background to be the best predictor of predatory behaviour under the prey detection hypothesis, and absolute prey temperature under the prey evaluation hypothesis. We presented lizard carcasses of varying temperatures to free-ranging sidewinder rattlesnakes (Crotalus cerastes) and scored behavioural responses as a function of thermal contrast, absolute lizard temperature, and light level. Thermal contrast and light level were the most salient predictors of snake behaviour. Snakes were more likely to respond to lizards and/or respond at greater distances at night and when thermal contrast was high, supporting the known prey detection function of infrared sensing. Absolute lizard temperature was not an important predictor of snake behaviour; thus, we found no evidence for temperature-based prey evaluation. Infrared sensing is still poorly understood in ecologically relevant contexts; future research will test whether rattlesnakes learn to evaluate prey based on temperature with experience.
Native-range thermal constraints may not reflect the geographical distributions of species introduced from native island ranges in part due to rapid physiological adaptation in species introduced to new environments. Correlative ecological niche models may thus underestimate potential invasive distributions of species from islands. The northern curly-tailed lizard (Leiocephalus carinatus) is established in Florida, including populations north of its native range. Competing hypotheses may explain this distribution: Thermal Matching (distribution reflects thermal conditions of the native range), Thermal Potential (species tolerates thermal extremes absent in the native range) and/or Thermal Flexibility (thermal tolerance reflects local thermal extremes). We rejected the Thermal Matching hypothesis by comparing ecological niche models developed from native vs. native plus invasive distributions; L. carinatus exists in areas of low suitability in Florida as predicted by the native-distribution model. We then compared critical thermal limits of L. carinatus from two non-native populations to evaluate the Thermal Potential and Flexibility hypotheses: one matching native range latitudes, and another 160 km north of the native range that experiences more frequent cold weather events. Critical thermal minima in the northern population were lower than in the south, supporting the Thermal Flexibility hypothesis, whereas critical thermal maxima did not differ.
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