A biogeographic and ecological perspective to the evolution of reproductive behaviour in the family Salamandridae.

Amphibians have a complex reproductive behaviour, which shows the highest diversity among tetrapodes. The family Salamandridae, distributed across the entire Holarctic, is one of the most diverse groups of extant salamanders comprising 114 species in 21 genera. The family has a remarkable diversity of courtship modes, amplexus and sperm transfer. It is often hypothesised that this diversity has evolved in adaptation to a specific mating and/or breeding habitat. We test this hypothesis based upon a phylogenetic reconstruction using the complete mitochondrial genome sequences of 45 Salamandridae species, representing all existing genera. We used ancestral character state reconstruction methods and geographic range models and applied relaxed Bayesian molecular clock models to discuss the results in a temporal framework of Salamandridae evolution. Our results show that the family Salamandridae started to diversify in the Late Cretaceous (ca. 87 mya) and is of Western Palearctic origin. Ancestral character state reconstruction predicts that its common ancestor was oviparous, mated on land without amplexus and probably showed a pin wheel spermatophore transfer, which is still found in the Italian endemic Salamandrina terdigidata. Our results suggest that several colonization of continents with subsequent radiations took place, once to the Nearctic and twice into Eastern Asian realms. However, these events were only in one case associated with a change in mating behaviour (dorsal amplexus in Nearctic newts). Around the Cretaceous-Paleogene boundary (K-Pg boundary) several Salamandridae lineages further diverged, again with no obvious changes in mating behaviour. Overall, there is no significant signal for mating character evolution being caused by changes in habitat type, with only a slight tendency that changes in mating habitat might have led to changes in the type of sperm transfer which in turn was associated with changes in the presence or absence of amplexus.

Future of keeping pet reptiles and amphibians: towards integrating animal welfare, human health and environmental sustainability.

The keeping of exotic pets is currently under debate and governments of several countries are increasingly exploring the regulation, or even the banning, of exotic pet keeping. Major concerns are issues of public health and safety, animal welfare and biodiversity conservation. The keeping of reptiles and amphibians in captivity encompasses all the potential issues identified with keeping exotic pets, and many of those relating to traditional domestic pets. Within the context of risks posed by pets in general, the authors argue for the responsible and sustainable keeping of reptile and amphibian pets by private persons, based on scientific evidence and on the authors' own expertise (veterinary medicine, captive husbandry, conservation biology).

A survey for Batrachochytrium dendrobatidis in endangered and highly susceptible Vietnamese salamanders (Tylototriton spp.).

Until now, Asian amphibians appear to have largely escaped declines driven by chytridiomycosis. Vietnamese salamanders that belong to the genus Tylototriton are rare and have a patchy distribution in mountainous areas, falling within the proposed environmental envelope of chytrid infections, surrounded by Batrachochytrium dendrobatidis infected regions. If these salamanders are susceptible to chytridiomycosis, then their populations could be highly vulnerable after the introduction of B. dendrobatidis. Examination for the presence of the chytrid fungus in skin swabs from 19 Tylototriton asperrimus and 104 Tylototriton vietnamensis by using quantitative polymerase chain reaction was performed. Susceptibility of T. asperrimus to experimental infection by using the global panzootic lineage (BdGPL) strain of B. dendrobatidis was examined. The fungus was absent in all samples from all wild salamanders examined. Inoculation with the BdGPL strain resulted in mortality of all five inoculated salamanders within 3 weeks after inoculation with infected animals that manifested severe orthokeratotic hyperkeratosis, epidermal hyperplasia, and spongiosis. Although infection by B. dendrobatidis currently appears absent in Vietnamese Tylototriton populations, the rarity of these animals, their pronounced susceptibility to chytridiomycosis, an apparently suitable environmental context and increasing likelihood of the pathogen being introduced, together suggest the need of urgent measures to avoid future scenarios of extinction as witnessed in Central America and Australia.

The dorsal tail tubercle of Mertensiella caucasica and M. luschani (Amphibia: Salamandridae).

Males of the two species of Mertensiella (M. caucasica and M. luschani) possess a tubercle projecting from the skin of the dorsal tail base, the single morphological character that defines the genus. The dorsal tail tubercle functions during courtship, and its role is similar in both species. The tubercle is inserted into the cloaca of the female during ventral amplexus, shortly before the male deposits a spermatophore. Histological examination, however, revealed that the dorsal tubercles differ structurally between the two species. In M. caucasica, the tubercle consists primarily of elongate mucous glands, with granular glands occurring only at the base. Both mucous and granular glands of the tubercle are larger than those in typical skin. Unlike typical skin, however, mucous glands are larger than granular glands. In M. luschani, mucous glands and granular glands occur throughout the tubercle, and the granular glands are larger than the mucous glands, although both types are larger than those in typical skin. The dorsal tubercles of M. caucasica and M. luschani may not be homologous structures and may have resulted from convergent evolution. J Morphol 232:93-105, 1997. © 1997 Wiley-Liss, Inc.