UNITING 2 GENERAL PATTERNS IN THE DISTRIBUTION OF SPECIES

Two patterns in the distribution of species have become firmly but ind ependently established in ecology: the species-area curve, which descr ibes how rapidly the number of species increases with area, and the po sitive relation between species' geographical distribution and average local abundance. There is no generally agreed explanation of either p attern, but for both the two main hypotheses are essentially the same: divergence of species along the ecological specialist-generalist cont inuum and colonization-extinction dynamics. A model is described that merges the two mechanisms, predicts both patterns, and thereby shows h ow the two general, but formerly disconnected, patterns are interrelat ed.