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Lessons from evolution: developmental plasticity in vertebrates with complex life cycles

Published online by Cambridge University Press:  02 June 2010

R. J. Denver  and
J. Middlemis-Maher
R. J. Denver*
Affiliation:
Department of Molecular, Cellular and Developmental Biology, The University of Michigan, Ann Arbor, MI, USA Department of Ecology and Evolutionary Biology, The University of Michigan, Ann Arbor, MI, USA
J. Middlemis-Maher
Affiliation:
Department of Ecology and Evolutionary Biology, The University of Michigan, Ann Arbor, MI, USA
*
*Address for correspondence: Dr R. J. Denver, PhD, Department of Molecular, Cellular and Developmental Biology, 3065C Kraus Natural Science Building, The University of Michigan, Ann Arbor, MI 48109-1048, USA. (Email rdenver@umich.edu)
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Abstract

Developmental plasticity is the property of a given genotype to produce different phenotypes in response to the environmental conditions experienced during development. Chordates have two basic modes of development, direct and indirect. Direct development (mode of humans) was derived evolutionarily from indirect development (mode of many amphibians), the major difference being the presence of a larval stage with indirect development; larvae undergo metamorphosis to the juvenile adult. In amphibians, environmental conditions experienced during the larval stage can lead to extreme plasticity in behaviour, morphology and the timing of metamorphosis and can cause variation in adult phenotypic expression (carry-over effects, or developmental programming). Hormones of the neuroendocrine stress axis play pivotal roles in mediating environmental effects on animal development. Stress hormones, produced in response to a deteriorating larval habitat, accelerate amphibian metamorphosis; in mammals, stress hormones hasten the onset of parturition and play an important role in pre-term birth caused by intra-uterine stress. While stress hormones can promote survival in a deteriorating larval or intra-uterine habitat, costs may be incurred, such as reduced growth and size at metamorphosis or birth. Furthermore, exposure to elevated stress hormones during the tadpole or foetal stage can cause permanent neurological changes, leading to altered physiology and behaviour later in life. The actions of stress hormones in animal development are evolutionarily conserved, and therefore amphibians can serve as important model organisms for research on the mechanisms of developmental plasticity.

Keywords

Amphibiancorticosteroidsdevelopmental plasticitymetamorphosisthyroid hormone
Type
Reviews
Information
Journal of Developmental Origins of Health and Disease , Volume 1 , Issue 5 , October 2010 , pp. 282 - 291
Copyright
Copyright © Cambridge University Press and the International Society for Developmental Origins of Health and Disease 2010

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