Reference : On the identification of paedomorphic and overwintering larval newts based on cloacal...
Scientific journals : Article
Life sciences : Zoology
On the identification of paedomorphic and overwintering larval newts based on cloacal shape: review and guidelines
Denoël, Mathieu mailto [Université de Liège > Département de Biologie, Ecologie et Evolution > Biologie du comportement - Ethologie et psychologie animale >]
Current Zoology
Oxford University Press
Yes (verified by ORBi)
United Kingdom
[en] Paedomorphosis ; Giant larvae ; overwintering larvae ; branchiate juveniles ; adulthood ; maturity ; identification ; sex determination ; secondary sexual trait ; cloaca ; newts ; Ichthyosaura alpestris ; Lissotriton helveticus ; Lac de la Cabane ; Larzac ; criterium ; identification ; adult
[en] Paedomorphosis is an alternative process to metamorphosis in which adults retain larval traits at the adult stage. It is frequent in newts and salamanders, where larvae reach sexual maturity without losing their gills. However, in some populations, larvae overwinter in water, while remaining immature. These alternative ontogenetic processes are of particular interest in various research fields, but have different causes and consequences, as only paedomorphosis allows metamorphosis to be bypassed before maturity. It is thus relevant to efficiently identify paedomorphs versus overwintering larvae. In this context, the aim of this paper was threefold: firstly, to perform a meta-analysis of the identification procedures carried out in the literature; secondly, to determine the effectiveness of body size to make inferences about adulthood by surveying natural newt populations of Lissotriton helveticus and Ichthyosaura alpestris, and thirdly, to propose easy guidelines for an accurate distinction between large larvae and paedomorphs based on an external sexual trait, which is essential for reproduction — the cloaca. More than half of the studies in the literature do not mention the diagnostic criteria used for determining adulthood. The criteria mentioned were the presence of mature gonads (10%), eggs laid (4%), courtship behaviour (10%), and external morphological sexual traits (39%) including the cloaca (24%). Body-size thresholds should not be used as a proxy for paedomorphosis, because overwintering larvae can reach a larger size than paedomorphs within the same populations. In contrast, diagnosis based on cloacal external morphology is recommended, as it can be processed by the rapid visual assessment of all caught specimens, thus providing straightforward data at the individual level for both sexes.
Freshwater and OCeanic science Unit of reSearch - FOCUS ; Applied and Fundamental FISH Research Center - AFFISH-RC
F.R.S.-FNRS - Fonds de la Recherche Scientifique ; Fonds Spéciauds de la Recherche (FSR) - University of Liège
Researchers ; Professionals ; Students ; General public
© The Author (2016). Published by Oxford University Press.

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