Paedomorphosis and simplification in the nervous system of salamanders.

G. Roth, Kiisa C Nishikawa, C. Naujoks-Manteuffel, A. Schmidt, D. B. Wake

Research output: Contribution to journalArticle

107 Citations (Scopus)

Abstract

Comparative neuroanatomists since Herrick [1914] have been aware of the paradox that the brain of amphibians, especially salamanders, is less complex than one would expect based on their phylogenetic position among the Tetrapoda. Many features of the brain are less differentiated in salamanders than in tetrapod outgroups, including chondrichthyans and bony fishes, and for some brain characters, the salamander brain is even more simple than that of the agnathans. Here, we perform a cladistic analysis on 23 characters of four sensory systems (visual, auditory, lateral line and olfactory) and the brain. Our taxa include myxinoids, lampreys, chondrichthyans, actinopterygians, Latimeria, Neoceratodus and the lepidosirenid lungfishes, amniotes, frogs, caecilians, salamanders and bolitoglossine salamanders. Of the 23 characters we examined, 19 are most parsimoniously interpreted as secondarily simplified in salamanders from a more complex ancestral state, two characters are equally parsimonious under both hypotheses, one character (well developed ipsilateral retinotectal projections) is more complex in bolitoglossine salamanders than in vertebrates generally, and only one character (migration of neurons in the medial pallium) is most parsimoniously interpreted as retention of the plesiomorphically simple condition. Secondary simplification of the salamander brain appears to result from paedomorphosis, or retention of juvenile or embryonic morphology into adulthood. Paedomorphosis is correlated with an increase in genome size, which in turn is positively correlated with cell size, but negatively correlated with cell proliferation and differentiation rates. Available data suggest that, although increasing genome size and paedomorphosis tend to compromise the function of the salamander brain, compensating mechanisms have evolved that may restore or even enhance brain function.

Original languageEnglish (US)
Pages (from-to)137-170
Number of pages34
JournalBrain, Behavior and Evolution
Volume42
Issue number3
StatePublished - 1993
Externally publishedYes

Fingerprint

pedomorphosis
Urodela
nervous system
salamanders and newts
Nervous System
brain
Brain
Genome Size
genome
caecilians
sensory system
Lampreys
salamander
neoteny
Petromyzontiformes
tetrapod
phylogeny
Amphibians
cladistics
adulthood

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Neuroscience(all)

Cite this

Roth, G., Nishikawa, K. C., Naujoks-Manteuffel, C., Schmidt, A., & Wake, D. B. (1993). Paedomorphosis and simplification in the nervous system of salamanders. Brain, Behavior and Evolution, 42(3), 137-170.

Paedomorphosis and simplification in the nervous system of salamanders. / Roth, G.; Nishikawa, Kiisa C; Naujoks-Manteuffel, C.; Schmidt, A.; Wake, D. B.

In: Brain, Behavior and Evolution, Vol. 42, No. 3, 1993, p. 137-170.

Research output: Contribution to journalArticle

Roth, G, Nishikawa, KC, Naujoks-Manteuffel, C, Schmidt, A & Wake, DB 1993, 'Paedomorphosis and simplification in the nervous system of salamanders.', Brain, Behavior and Evolution, vol. 42, no. 3, pp. 137-170.
Roth, G. ; Nishikawa, Kiisa C ; Naujoks-Manteuffel, C. ; Schmidt, A. ; Wake, D. B. / Paedomorphosis and simplification in the nervous system of salamanders. In: Brain, Behavior and Evolution. 1993 ; Vol. 42, No. 3. pp. 137-170.
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