Genetic differentiation among natural populations of the rare corsican endemic Brassica insularis Moris: Implications for conservation guidelines

Brassica insularis Moris is an endemic Mediterranean member of the Brassica oleracea group which occurs only in Corsica, Sardinia and North Africa. In Corsica, this species is restricted to nine cliff areas. The threat represented by human action, overgrazing and competition fi om garrigue vegetation justifies the need for conservation management. In order to develop a rational conservation programme for this species, a study of genetic variation using allozyme techniques has been undertaken. Population size was found to have no effect on genetic variation. A marked differentiation among populations was however observed, which is consistent with strong genetic drift within populations linked to reduced gene flow among populations. Such differentiation emphasizes the need for conservation of several of these populations. The initial management strategy should involve habitat conservation although off-site techniques would also be a useful complement.