Minimum viable population

Populations of endangered species often consist of small numbers that may be trapped in the so-called extinction vortex. This means that the combination of inbreeding, demographic stochasticity, and genetic drift leads to feedback loops that make small populations even smaller (Caughley 1994). According to Klok (2000), the minimum viable population size is species specific because the life history of a species can have a large impact on the outcome of the aforementioned stochastic events. Moreover, the MVP size will also depend on the quality of the habitat and, consequently, on the temporal and spatial distribution and availability of pollutants. 

Metapopulation dynamics is a useful tool in evaluating the consequences of stress over both time and space. A metapopulation is a "population of populations" (Levins 1970) connected through immigration and emigration. The general assumptions are that there is a minimum viable population (MVP) size below which patch extinction will occur. The carrying capacity is the... 

Notes In each case the patch was dosed with an LD10o- Distance between patches is two units, mvp = minimum viable population, cc = carrying capacity. If not explicitly mentioned the population in that patch is extinct. 

Nunney, L. and Campbell, K.A., Assessing minimum viable population size demography meets population genetics. Trends Ecol. Evol, 8, 234, 1993. 

Mixed populations of common brewery contaminants, in beer subjected to a range of temperatures of various times, were examined for viability (Fig. 20.22). Typically with temperatures over 50 C (122°F) an increase in temperature of TC (12 6°F) accelerated the rate of cell-kill ten-fold. Thus at 60°C (140°F) the minimum time required for the population to be killed may be 5 6 min, but at 53°C (127 4°F) it would be 56 min and at 67°C (152-6 F) would be 0 56 min. One Pasteurization Unit (PU) has been defined arbitrarily for the beer as the biological destruction obtained by the holding of a beer for one minute at 60°C (140 F). The effect is a product of (/) the lethal rate (djc/d/, where x is the number of viable micro-organisms per wort volume and t is time in min) and (//) the time of application. Thus PU/min = 139 where a is the temperature (in °C) minus 60°C. Pasteurization Units have been shown to be additive in their effects in a complex treatment where temperature... 

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