A new study led by Assistant Professor Brett Melbourne of CU-Boulder's ecology and evolutionary biology department concluded that extinction risks for endangered species are likely being underestimated.

Melbourne explained that the error appeared due to a mathematical "misdiagnosis,"

The current mathematical models used to determine extinction threat, or "red-listed" status, of species worldwide overlook random differences between individuals in a given population. Such differences, which include variations in male-to-female sex ratios as well as size or behavioral variations between individuals that can influence their survival rates and reproductive success, have an unexpectedly large effect on extinction risk calculations, according to the study.

"When we apply our new mathematical model to species extinction rates, it shows that things are worse than we thought," said Melbourne. "By accounting for random differences between individuals, extinction rates for endangered species can be orders of magnitude higher than conservation biologists have believed."

The study was published in the July 3 issue of Nature and it was founded by The National Science Foundation.

The current extinction risk models are based on two factors: the number of random events adversely affecting individuals within a population and the impact of external, random events

However, Melbourne said that two other factors should be considered: sex ratio variations and physical variation between individuals within a population.

For the study, the researchers monitored populations of beetles in lab cages and the results were used to test the new mathematical models. "The results showed the old models misdiagnosed the importance of different types of randomness, much like miscalculating the odds in an unfamiliar game of cards because you didn't know the rules," said Melbourne.

Since natural animal populations are more likely to have larger differences in sex ratios and differences between individuals than the controlled beetle experiment by Melbourne and Hastings, "the effect we have uncovered here will be larger in natural populations," wrote the authors in Nature.

Last year the annual survey published by IUCN revealed a sad and alarming truth: Life on Earth is disappearing fast and will continue to do so unless urgent action is taken.

According to The Red List of Threatened Species compiled by the IUCN one in four mammals and one third of all amphibians are in jeopardy and the most alarming aspect is that the conservation measures had made only a limited impact.

IUCN said that the number of species threatened by extinction is up with 88 percent compared to 2006. In other words, this means that from 41,415 species 16,306 will disappear over the next years.