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Comparative and phylogenetic perspectives of the cleavage process in tailed amphibians

Published online by Cambridge University Press:  02 September 2014

Alexey G. Desnitskiy  and
Spartak N. Litvinchuk
Alexey G. Desnitskiy*
Affiliation:
Department of Embryology, St. Petersburg State University, Universitetskaya nab. 7/9, 199034, St. Petersburg, Russia.
Spartak N. Litvinchuk
Affiliation:
Institute of Cytology, Russian Academy of Sciences, Tikhoretsky pr. 4, 194064, St. Petersburg, Russia.
*
All correspondence to: Alexey G. Desnitskiy. Department of Embryology, St. Petersburg State University, Universitetskaya nab. 7/9, 199034, St. Petersburg, Russia. Tel: +7812 3289453. e-mail: [email protected]
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Summary

The order Caudata includes about 660 species and displays a variety of important developmental traits such as cleavage pattern and egg size. However, the cleavage process of tailed amphibians has never been analyzed within a phylogenetic framework. We use published data on the embryos of 36 species concerning the character of the third cleavage furrow (latitudinal, longitudinal or variable) and the magnitude of synchronous cleavage period (up to 3–4 synchronous cell divisions in the animal hemisphere or a considerably longer series of synchronous divisions followed by midblastula transition). Several species from basal caudate families Cryptobranchidae (Andrias davidianus and Cryptobranchus alleganiensis) and Hynobiidae (Onychodactylus japonicus) as well as several representatives from derived families Plethodontidae (Desmognathus fuscus and Ensatina eschscholtzii) and Proteidae (Necturus maculosus) are characterized by longitudinal furrows of the third cleavage and the loss of synchrony as early as the 8-cell stage. By contrast, many representatives of derived families Ambystomatidae and Salamandridae have latitudinal furrows of the third cleavage and extensive period of synchronous divisions. Our analysis of these ontogenetic characters mapped onto a phylogenetic tree shows that the cleavage pattern of large, yolky eggs with short series of synchronous divisions is an ancestral trait for the tailed amphibians, while the data on the orientation of third cleavage furrows seem to be ambiguous with respect to phylogeny. Nevertheless, the midblastula transition, which is characteristic of the model species Ambystoma mexicanum (Caudata) and Xenopus laevis (Anura), might have evolved convergently in these two amphibian orders.

Keywords

CaudataCleavageEgg sizeMidblastula transitionOntogenetic diversity
Type
Research Article
Information
Zygote , Volume 23 , Issue 5 , October 2015 , pp. 722 - 731
Copyright
Copyright © Cambridge University Press 2014 

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