Abstract

Amphipholis squamata is a small ophiuroid considered to be distributed worldwide except in Polar Regions. Numerous colour varieties were reported fur this species, which is also bioluminescent. It is hermaphrodite and brood protecting; both selfing and outcrossing occur. A high genetic variability was observed among adult individuals belonging to very close (Mediterranean) local populations. Three distant populations were investigated in order to characterize morphological, physiological and genetic variability. In the population of Normandy (France), Amphipholis were collected under stones of tide pools; ophiuroids from Sicily (Italy) were collected in a Cymodocea nodosa meadow from a lagoon completely isolated from the sea. since 10 years; individuals from Santa Barbara (USA) were sampled in the aquarium system of the Marine Institute. Four colour varieties are studied throughout the sampled populations and each exhibits its own capability to produce light: (1) a spotted variety is present in the 3 populations and produces light of high intensity; (2) the orange, grey and black varieties are only present in the population of Normandy and produce light of lower intensity. Genetic variations were revealed by RAPDs. Preliminary results indicate that generic structure is homogenous for each colour variety within a population while, as expected, it shows inter-population variations for the same variety. This suggests that polychromatism and bioluminescence might be good indicators of variability of genotypes only at an intra-population level.