Morph switching in a dimorphic population of <Emphasis Type="Italic">Triturus alpestris</Emphasis> (Amphibia,Caudata) |
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Authors: | Mathieu Denoël Jean-Paul Lena Pierre Joly |
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Institution: | (1) Laboratory of Fish and Amphibian Ethology, Behavioural Biology Unit, Department of Environmental Sciences, University of Liege, Quai Van Beneden 22, 4020 Liege, Belgium;(2) Ecology of Fluvial Hydrosystems, Claude-Bernard Lyon1 University, 69622 Villeurbanne, France |
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Abstract: | The usual life cycle of Alpine newts comprises an aquatic larval stage and a terrestrial juvenile and adult stage. However,
some populations differ from this pattern in exhibiting facultative paedomorphosis where some individuals reach sexual maturity
while retaining larval traits such as gills and gill slits. While paedomorphic newts can, in some circumstances, initiate
metamorphosis, once a newt has commenced metamorphosis, the state is irreversible. Because the frequency of this switching
from one morph to the other has never been quantified in the wild, we attempted to estimate switching rate and survival by
carrying out a 3-year monitoring survey of a population inhabiting an alpine lake. While morph switching did occur in this
population, it involved a relatively low proportion of the paedomorphs (approx. 12%), suggesting that metamorphosis is not
favoured in the study population. The hypothesis of paedomorphic advantage was not supported since neither survival nor body
condition differed between morphs. The ontogenetic pathway of wild Alpine newts is thus characterised by two forks in the
developmental pathway. The first occurs during the larval stage (metamorphosis vs. paedomorphosis), and the second occurs
in paedomorphic adults (switching for metamorphosis vs. continuation of the paedomorphic lifestyle). Such a two-level decision
process may allow individuals to cope with environmental uncertainty. |
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Keywords: | Body condition Facultative paedomorphosis Growth rate Metamorphosis Survival Triturus alpestris |
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