LEECHES (OLIGOCHAETA, EUHIRUDINEA), THEIR PHYLOGENY AND THE EVOLUTIONOF LIFE-HISTORY STRATEGIES

Powerful tests of adaptational hypotheses can be made in the context o f well-supported cladograms by investigating the most parsimonious tra nsformation of intrinsic or extrinsic factors to explain their distrib ution across taxa in a cladogram. Such tests are used here to discover patterns of life-history evolution in leeches; in particular in relat ion to exploitation of terrestrial and aquatic habitats, parental care and resource utilization. Moreover, the relationships among leeches, acanthobdellids and branchiobdellids is reaffirmed as is their collect ive placement within the oligochaetes.