6533b82afe1ef96bd128b5ec

RESEARCH PRODUCT

Environmental and ontogenetic constraints on developmental stability in the spatangoid sea urchin Echinocardium (Echinoidea)

subject

description

Biogeosciences, UMR-CNRS 5561, Universite de Bourgogne, 6 bd Gabriel, 21000 Dijon, FranceReceived 25 June 2004; accepted for publication 25 July 2005Spatangoid irregular sea urchins are detritivorous benthic organisms particularly prone to variations of environ-ment, and their mode of growth and plate morphology make them an appropriate model to assess the effects of envi-ronmental variations. Two populations of Echinocardium flavescens were sampled in two sites of the Norwegiancoast characterized by contrasted environmental conditions. Different morphological descriptors (plate areas, inter-landmarks distances, overall size, and shape of the posterior ambulacra) were used to appraise interindividual vari-ations, and fluctuating asymmetry. The comparisons were carried out using classical fluctuating asymmetry (FA)methods, as well as Procrustean approaches. The population suspected to be less influenced by anthropic activitiesexhibits lower levels of FA for the size parameters (plate surfaces, interlandmarks distances, and centroid size) thanthe population located in a polluted area. Conversely, it shows higher FA values for the shape parameters (land-marks configuration). Interindividual variations appear to be correlated to FA. Variations are orientated accordingto the main growth axis of the ambulacra, and their intensity is stronger in the large posterior plates, which are alsothe youngest. These results are discussed with respect to architectural constraints involved in the sea urchin growth.© 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 88, 165–177.