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The phylum Echinodermata has been one of the most widely recognized and studied group of invertebrates since ancient times. The phenotype of an individual is the end product of a highly complex set of interactive events between the genotype and environment. It represents not only morphological attributes, but physiological, biochemical, and behavioral ones as well. The genetic composition of ecotypes depends on their phenotypic flexibility which is ultimately determined by the genotype. Interpopulation morphological variation has been studied for a number of regular echinoids. Environmental factors might produce phenocopies of genetically determined plate arrangements by imposing a differential effect on the rates at which rearrangements proceed. Gaining an improved understanding of the factors that influence phenotypic variation among extant echinoderms provides information that is valuable for the interpretation of paleoenvironmental conditions and the phylogenetic status of fossil forms. All species of echinoderms express some degree of phenotypic variability, whether it is related to sex, age, or ecological differences. |
