GEOGRAPHICAL PATTERNS FOR RELICT AND YOUNG SPECIES OF BIRDS IN AFRICAAND SOUTH-AMERICA AND IMPLICATIONS FOR CONSERVATION PRIORITIES

By comparing geographical patterns of old and new species with histori cal and ecological processes, interpretations can be made about time p atterns of diversification. Such interpretations can form a basis for developing rationales for ranking biodiversity conservation priorities . The results of the comprehensive study of avian DNA were used to com pare geographical distributions in Africa and South America of species of strong Plio-Pleistocene radiations and species representing older monophyletic branches. Striking patterns, some of them overlooked so f ar, were found. Most old species are widespread across a physiognomic and climatic domain, such as lowland rainforests, and therefore, are n ot specific conservation targets. In contrast, new species have evolve d in well defined places with a special local environment, in particul ar in ecologically equable places inside geologically complex ecotonal regions. High species richness and taxonomic diversity, where maintai ned over wide areas by steady habitat alteration through patch dynamic s, may be easiest to protect by general reforms that integrate regiona l development and protection of ecosystem services, rather than by str ictly site-oriented projects. Areas of active speciation, although sma ll, may have important regulatory functions and a critical role for ma intaining 'evolutionary fronts'. The Tropical Andes Region includes a dozen such places. There is a congruence between the occurrence of old species which have relictual distributions and aggregates of limited- range component species of recent vicariance patterns, indicating that vicariance events take place mainly by isolation in extremely ecologi cally stable areas. Although these places do not necessarily have the highest taxic diversity, they should be top priorities for rapid and c oncentrated conservation action.