CONSERVATION managers are not taking scientific evidence into account when drawing up their plans, a survey of projects in the UK and Australia has found. Faced with species or habitats on the brink of extinction, managers are taking emergency action that may leave them as vulnerable as ever in the long term.
The need for a more rigorous approach is highlighted by an analysis of the acclaimed breeding programme that has rescued the Espa帽ola tortoise in the Galapagos Islands. From just 14 individuals, the population has increased to over 800.
鈥淚t is obvious that the Esp帽aola tortoise would be extinct by now [without] this programme,鈥� says Michel Milinkovitch of the Free University of Brussels (ULB) in Belgium, who has studied the revived population. But he concludes that the animals鈥� lack of genetic diversity means they could yet be wiped out.
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By 1965, hunting and habitat destruction had all but killed off the population of 3000 Espa帽ola tortoises. Conservationists transferred the two remaining males and 12 females to the Charles Darwin Research Station on Santa Cruz Island as an emergency measure, and began breeding them. The first animals were reintroduced to the wild in 1975 and the colony now numbers between 800 and 1000.
But from a study of 134 of this population, Milinkovitch found that it has a genetic diversity equivalent to roughly 11 unrelated breeding individuals (Proceedings of the Royal Society B, DOI: 10.1098/rspb.2003.2607). For a healthy population of this size the figure would typically be 300.
The diversity is so low because some of the pioneers contributed far more to the gene pool than others, Milinkovitch found. For instance, one male nicknamed Super Macho, added to the group in 1977 from San Diego zoo, sired nearly 80 of the individuals they sampled. 鈥淗e really skewed the population,鈥� says team member James Gibbs from the State University of New York, Syracuse. Such low diversity means the animals are extremely vulnerable to habitat changes or disease.
In what the team hopes will be a textbook case of scientists and conservation managers working together, they are trying to ensure that other males get more of a look-in. They also want to encourage females who have not produced many young to breed.
But such cooperation is unusual. Most conservation managers regard genetic studies like Milinkovitch鈥檚 as 鈥渙bscure and academic鈥�, Gibbs says. Indeed, the World Conservation Union (IUCN) guidelines on species reintroductions do not mention how to avoid inbreeding or any problems associated with low genetic diversity.
This view is backed up by a study by Andrew Pullin at the University of Birmingham in the UK and colleagues. Pullin鈥檚 team analysed 141 questionnaires filled out by conservationists at seven UK-based organisations, which asked about the scientific input that went into drawing up management plans.
Two-thirds of respondents said they had neither time nor money to look up the scientific literature, and a similar number said they hardly ever consulted anyone else when building their plans. And of 38 management plans, none included an evaluation of the scientific evidence in favour of the actions it proposed. 鈥淚t鈥檚 a global problem,鈥� says Pullin, whose findings will appear in a future issue of Biological Conservation. Research in Australia paints a similar picture, he says.
Gibbs also points out that scientists often make little effort to disseminate or explain their work to conservationists in the field, and rarely ask the questions managers want answered.