Critically endangered species given boost by new study
Ruth Hendry
Earth Times
There is no 'magic number' for
saving endangered species, a
new study has found. The
research, published in the
journal Trends in Ecology and
Evolution, offers hope for
species with critically low
populations. These species,
such as the Siberian tiger and
mountain gorilla, were thought
by some scientists to be 'too rare
to save'. Some of the world's
most endangered species exist
in populations far smaller than
previous studies had argued were necessary for survival. A UK-US research team
carried out a review of studies that used Minimum Viable Population (MVP) numbers.
MVP is the estimated minimum size of a population that will give the species a 99 per
cent chance of avoiding extinction over the next 40 generations. If the species'
population size is below the MVP, it can effectively condemn a species to extinction.
Due to limited money and resources, MVP is often used to decide whether or not to
focus conservation efforts on a particular species. After analysing the previous studies,
the UK-US team dismissed the use of a universal MVP in conservation policies. The
authors maintain that there is no 'magic number' for saving endangered species.
Population size required to ensure survival of a species varies greatly, depending on the
specific circumstances in which the population is found. Some species may survive and go on to thrive - with very few individuals. However, some species may need to
have many individuals to thrive. Dr Curt Flather, a research ecologist, makes the point
that ''the extinction of the passenger pigeon, which numbered 3 to 5 billion individuals in
North America during the 1800s, is a reminder that population size is no guarantee
against extinction''. Therefore, conservationists should not give up on a species if its
population is below the MVP figure. More importantly, conservationists should
concentrate on the specific threats each population faces. Without tackling the cause of
a species' decline, no population size will be safe from extinction.