ACCORDING to a recent study as reported by AFP, some endangered species may face extinction risk that is upto a hundred times greater than previously thought. By overlooking random differences between individuals in a given population, researchers may have badly underestimated the perils confronting threatened wildlife, the study says. Many larger populations previously considered relatively safe would actually be at risk, says the lead author of the study, Brett Melbourne, a professor at the University of Colorado. There are more than 16,000 species worldwide threatened with extinction, according to the International Conservation Union (IUCN). One in four mammals, one in eight birds and one in three amphibians are on the IUCN’s endangered species ‘Red List’.
The models used draw up such lists typically look only at two risk factors. First, individual death within a small population, such as Indian tigers or rare whales. When a species dwindles beyond a certain point, even the loss of a handful of individuals can have devastating long-term consequences. There are less than 400 specimens of several species of whale, for example, and probably no more than 4,000 tigers roaming in the wild. The second factor is environmental conditions that can influence birth and death rates, such as habitat destruction, or fluctuations in temperature or rainfall, both of which can be linked to climate change. Two other determinants, according to the study, must be taken into account – male-to-female ratios in a species, and a wider definition of randomness in individual births and deaths. These complex variables can determine whether a fragile population can overcome a sudden decline in numbers for habitat loss, or will be wiped out. The new mathematical tool will be most useful to assess the survival prospects of species whose numbers can suddenly fluctuate and for which data is limited.