XVI International Botanical Congess

Cuticular hydrocarbons are thought to provide an important barrier to permeability across the cuticular membrane. Hydrocarbon profiles may be under selection for longer mean chain lengths in plants growing under conditions of greater aridity. Hydrocarbon composition of two members of the mediterranean live oak complex (Quercus ilex and Q. rotundifolia) was compared in half sib progeny. Substitution of shorter chain alkanes C25 and C27 by C29 and C31 in Q. rotundifolia was heritable, providing evidence for genetic differentiation of these two taxa. The longer mean hydrocarbon chain lengths in cuticular waxes of Q.rotundifolia is consistent with genetic adaptation to reduced cuticular permeability in these populations from the more arid conditions of the Iberian peninsula.