STAGES OF EVOLUTIONARY DEVELOPMENT IN TREPOSTOMID PERLWORTS

An attempt is undertaken to conduct complex exploration of quantitative and qualitative characteristics of trepostomid evolution. It is based on employing new technics of systemic statistical analysis of macroevolutionary processes. Under investigation is dynamics of number of genera, absolute and specific rates of their extinction and appearance, geographic distribution index, and average duration of existence of the genera. Several macroevolutionary trends of general significance manifest themselves in the study case: selective extinction of specialized taxa; gradual increase of proportion of eurybiont genera in the total taxic diversity of the order; regular change of phases of phylogenetic development in the suborders (extensive divergence - fluorishing accompanied by intensive divergence - decline - relic phase); increasing of influence of external conditions on evolution of the order by its development. Independent evolutionary developments of suborders Amplexoporina and Halloporina is shown, and their systemic nature is supposed. Some evidences of mutual influence of evolutionary processes in different Paleozoic perlwort orders are revealed. Some most specific characteristics of trepostomid diversity dynamics are supposed to be explained by their steadiness to effect of variable environment.