Characterizing population vulnerability for 758 species

We investigate relationships between life history traits and the character of population dynamics as revealed by time series data. Our classification of time series is according to 'extinction category,' where we identify thr ee classes of populations: (i) weakly varying populations with such high gr owth rates that long-term persistence is likely (unless some extreme catast rophe occurs); (ii) populations with such low growth rates that average pop ulation size must be large to buffer them against extinction in a variable environment; and (iii) highly variable populations that fluctuate so dramat ically that dispersal or some other refuge mechanism is likely to be key to their avoidance of extinction. Using 1941 time series representing 758 spe cies from the Global Population Dynamics Database, we find that, depending on the form of density dependence one assumes, between 46 and 90% of specie s exhibit dynamics that are so variable that even large carrying capacities could not buffer them against extinction on a 100-year time horizon. The f act that such a large proportion of population dynamics are so locally vari able vindicates the growing realization that dispersal, habitat connectedne ss, and large-scale processes are key to local persistence. Furthermore, fo r mammals, simply by knowing body size, age at first reproduction, and aver age number of offspring we could correctly predict extinction categories fo r 83% of species (60 of 72).