A fecundity to mortality ratio, population size variability and the chance for a mammal species to be listed on the red list.
How is a species' propensity to vary in size over time related to its chances to be listed on the Red List (Red Book), that is to face the risk of extinction? Here I suggest that the linkage between the range of population fluctuations and chance of listing may be established on the basis of the ratio of species' annual fecundity to annual mortality of adults, B/M. For 23 mammalian species inhabiting the vast tracts of Western Siberia, the range of population fluctuations is found to be equal or at least proportional to B/M. Further, this ratio is estimated for a larger set of 90 mammalian species from the territory and coastal waters of the former Soviet Union, of which 25 species are listed in the Red Book of the USSR. The distribution of the Red Book species over the gradient of B/M is clearly non-uniform: most of them have low B/M, which leads to a negative relationship between chance of listing and B/M. The positive relation between population size variability and B/M and the negative relation between chance of listing and B/M suggest the resulting negative relation between chance of listing and population size variability. Both the positive and the negative relations of, respectively, population size variability and chance of listing on B/M are logically justified since B/M is a measure of the population growth rate: it is the total lifetime offspring and an upper estimate of the growth rate per generation time. Fast-growing, more resilient species tend to be more resistant to extinction and hence to have low chance of listing, but simultaneously are able to fluctuate widely. Thus, so long as population growth rate affects both chance of listing and population size variability, high variability implies low chance of listing.
Polishchuk
Leonard V
LV
Department of General Ecology, Biological Faculty, M. V. Lomonosov Moscow State University, 119899 Moscow, Vorobjovy Gory, Russia. LV@Polishchuk.msk.ru
D000818:Animals; D003247:Conservation of Natural Resources; D005298:Fertility; D008322:Mammals; D008954:Models, Biological; D009026:Mortality; D011156:Population Density; D011158:Population Growth; D011159:Population Surveillance; D012800:Siberia; D014586:USSR