Population Dynamics and Conservation Status Assessment of Threatened Wildlife Species in Changing Ecosystems

Abstract

Evaluating the conservation status of threatened wildlife species entails knowledge about the current species and population loss rates and the demographic methods employed to establish the viability of surviving populations. This literature review provides information on the trends in global extinction rates, the occurrence of population-level decline even among those species that have not gone extinct, and the methodologies applied in measuring the viability of populations for the purpose of explaining how population dynamics influence conservation status evaluation within changing ecosystems. Extremely conservative estimations under very cautious assumptions about the background extinction rates indicate that the current extinction rate of vertebrates is far much higher than the pre-human background rates, hence confirming the occurrence of the sixth extinction event. Apart from the extinction data of the species, there is information on defaunation, which is the reduction in population abundance of animals prior to their extinction. Standardized population indicators in thousands of vertebrate population time series demonstrate the ongoing global decline in population abundance among surviving species. On an individual species basis, research done using a meta-analysis of minimum viable population size serves as a measure against which one can compare the demographics of the existing populations. All together, these findings suggest that for proper conservation status assessment, there needs to be incorporation of information on extinction rates, trends in abundance, and population viability measures.