Quantifying the extinction vortex.
We developed a database of 10 wild vertebrate populations whose declines to extinction were monitored over at least 12 years. We quantitatively characterized the final declines of these well-monitored populations and tested key theoretical predictions about the process of extinction, obtaining two primary results. First, we found evidence of logarithmic scaling of time-to-extinction as a function of population size for each of the 10 populations. Second, two lines of evidence suggested that these extinction-bound populations collectively exhibited dynamics akin to those theoretically proposed to occur in extinction vortices. Specifically, retrospective analyses suggested that a population size of n individuals within a decade of extinction was somehow less valuable to persistence than the same population size was earlier. Likewise, both year-to-year rates of decline and year-to-year variability increased as the time-to-extinction decreased. Together, these results provide key empirical insights into extinction dynamics, an important topic that has received extensive theoretical attention.
Fagan
William F
WF
Holmes
E E
EE
D000818:Animals; D005075:Biological Evolution; D003198:Computer Simulation; D016208:Databases, Factual; D008954:Models, Biological; D011157:Population Dynamics; D013997:Time Factors; D014714:Vertebrates / Q000235:genetics / Q000502:physiology*