SPECIES LONGEVITY AS A FUNCTION OF NICHE BREADTH - EVIDENCE FROM FOSSIL CRINOIDS

High-resolution stratigraphic and taxonomic data indicate that species longevities among Paleozoic (Mississippian) crinoids (Echinodermata) were affected by differences in niche breadth. A strong positive relat ionship exists between niche breadth, measured as the number of enviro nments occupied by a species, and stratigraphic range. The robustness of this pattern is verified by a variety of rarefaction and statistica l techniques confirming the long-held supposition that among animals e cological ''generalists'' have greater species longevities than ecolog ical ''specialists.'' The results also support the hypothesis that spe cialist clades have higher species richness.