CONNECTION OF THE LEVEL OF DIVERSITY OF M IGER TAXA WITH THE DEGREE OF SPECIALIZATION OF GENERA AND SPECIES - (ILLUSTRATED BY CERTAIN GROUPS OF PALEOZOIC INVERTEBRATES)

The dynamics of diversity, average span of existence (SE), and average index of geographical distribution (IGD) were investigated in six gro ups of Paleozoic marine invertebrates. These were: class Regulares (Ar chaeocyatha), orders Trepostomida and Cystoporida (Bryozoa), Athyridia (Brachiopoda), Nautilida (Cephalopoda), and subclass Rugosa (Coelente rata). Positive correlation has been found between SE and IGD, whereas both were negatively correlated with the number of genera and species per group. It was supposed that SE and IGD reflect the average size o f the adaptive zone of a genus. The observed correlations are in agree ment with the hypothesis of a relatively constant size of adaptive zon es for higher taxa (classes, subclasses, orders). At different time in tervals this zone can be divided either into a small number of large n onspecialized subunits or into many small specialized ones.