THE EVOLUTION OF LIFE-HISTORY TRAITS IN PARASITIC AND FREE-LIVING PLATYHELMINTHES - A NEW PERSPECTIVE

Parasite life histories have been assumed to be shaped by their partic ular mode of existence. To test this hypothesis. we investigate the re lationships between life history trails of free-living and parasitic p latyhelminthes, Using phylogenetically independent contrasts we examin e patterns of interspecific covariation in adult size, progeny volume, daily fecundity, total reproductive capacity, age at first reproducti on and longevity. The correlations obtained indicate a similar causal chain of life history variations for free-living and parasitic platyhe lminthes. These results suggest that increased longevity favours delay ed reproduction. Furthermore, growth pattern determines adult body siz e and age at maturity. For platyhelminthes, whether free-living or par asitic, the total reproductive capacity is found to be directly determ ined by the size of the worm. Within this group the parasitic way of l ife does not seem to influence the basic patterns of life history evol ution.