One of the key sticking points that non-believers like to bring up when criticizing Fortean Zoology is that of “Breeding Population” This is the number of animals which can interbreed freely. It also would, by definition, allow evolutionary change. In other words, this is the number of males and females of a species that is sufficient to reproduce at a rate that would keep the species from extinction.
Within the calculation of Breeding Population is something called Minimum viable population (MVP). This is the lowest number of the population of a species that can survive in the wild. In biology, ecology, and conservation biology, MVP is the smallest possible size at which a biological population can exist without facing extinction from natural disasters or demographic, environmental, or genetic order or plan. This is usually estimated as the population necessary to ensure between 90 and 95 percent probability of survival between 100 to 1,000 years.
A variety of assumptions are required for future forecasting and this causes some debate on the accuracy of any MVP estimate. Proponents of using this number believe that absolute accuracy is not necessary, but rather a tool for approximating for the sake of conservation. In the case of Cryptozoology, an approximation would necessarily be questionable given that such species have yet to even be proven to exist in small numbers.
This Population uncertainty comes from four sources; Demographic stochasticity, Environmental stochasticity, Natural catastrophes, and Genetic stochasticity. Demographic stochasticity is the variability in population growth rates that comes from random differences among individuals (of a breeding species) within a season. This variability will occur even if all individuals have the same expected ability to survive and reproduce and the rate doesn’t change from one generation to the next. It is generally important only in populations that are already fairly small. Certainly in the case of most cryptids, the population will be small. In Crypto terms, Demographic Stochasticity would be the variation of the numbers of offspring in a lake monster, for instance, from year to year, and the morbidity rate of the same period There really is no way that this number can be accurately calculated for any population given that the number of offspring, while usually within a certain range, is not constant. In larger populations, this variability would not be as important.
Environmental Stochasticity is the unpredictable fluctuation in environmental conditions. When we say that a winter was “unusually warm” or “there is a lot less rain this year” we are highlighting a normally occurring environmental fluctuation. Environment also includes the physical, chemical and biological conditions, such as temperature, food availability and the presence of predators. Generally, this fluctuation is used to represent a longer term than just a few years. In the form of an evolutionary time scale, environmental stochasticity affects the overall life history of a species. Environments do change, so these predictions can be unpredictable. Additionally, major environmental changes can occur over long periods of time within the evolutionary age and would affect any predicted “final outcome” of the estimate. For Cryptozoology, this would be a real factor for water “monsters” especially. The creation and changes in the lakes, rivers and even oceans would be difficult to predict.
Along those same lines, natural disasters can factor into the uncertainty of population models. Ice ages, meteor strikes, earthquakes and tsunamis, and volcanic eruptions would certainly affect biological populations. Even small disasters, tornadoes for instance, can potentially wipe out enough of a population to bring it below the MVP. While in modern times, there is a better model for predicting such disasters, it is by no means certain.
Another problem in calculating MVP for small populations is Genetic Stochasticity. Genetic stochasticity refers to changes in the genetic composition of a population unrelated to things like selection, inbreeding, or migration. In small populations, or those with communal inbreeding, this reduced amount of diversity in genetic materials retained within populations would increase the chance that recessive genes become the norm. With disease often tied so closely to genetics, this lack of diversity could be catastrophic. The loss of diversity would limit a species’ ability to adapt to future environmental changes or even reduce the capacity to reproduce at all.
Applying all this relative uncertainty to the populations of cryptids can be problematic at best. What would the MVP of a lake monster be? Without knowing the biological makeup of such creatures, there is no way to tell the genetics or the evolution. We don’t know what they eat, so environment can only partially be supposed. Without knowing the breeding cycles—or even the breeding methods-of such creatures, these shaky estimates become shakier still.
Arm yourself with this knowledge the next time a skeptic decides to come at you with a value for how many of a species are needed to sustain them. They couldn’t possibly know. Until even one is documented, such suppositions are completely baseless.