Interconnected patterns of biogeography and evolution.
Analysis of the fauna of the carabid beetles of New Guinea reveals both a broad dispersal pattern and a local turnover pattern that together fit into a world-wide pattern of successive dispersals and replacements that run from large to small areas and from more to less favorable climates. This pattern coincides broadly with a world-wide pattern of species numbers. Evolution by group selection, proceeding most rapidly and effectively where species are most numerous, connects the patterns and can supply the force that gives direction to the dispersal pattern. Directional change at any level of complexity involves movement that results in the formation of diverse groups of units (which are themselves groups of smaller units) and differential survival. This process-generalized group selection-has been continuous from chemical evolution on the earth's surface, through the origin of life, and into successive interacting levels of organic evolution. A corollary is that evolution should make situations favorable to itself, by group selection, and has probably done so in (for example) tropical rain forest, where new information about group evolution may be sought.
Museum of Comparative Zoology, Harvard University, Cambridge, Massachusetts 02138.
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Darlington