The world of ecology and evolutionary biology is about to benefit from high-throughput DNA sequencing. A joint project between the Zoological Society of San Diego and Amersham Pharmacia Biotech (AP Biotech) is set to sequence DNA from every family of mammals.

The two organizations say the result will be the world's most comprehensive database of mammalian mitochondrial DNA. They hope the database will become a major tool for research on the evolution and conservation of mammalian biodiversity. It should also be useful to researchers working on the genetic bases of species' behaviour, biology and evolution.

The collaborators say they will publish regular progress reports, and that the results of the sequencing will be made public “quickly”.

Over the past 25 years, the society — which runs San Diego Zoo — has maintained a collection of cell lines known as the Frozen Zoo. This means that it already has DNA samples from over 100 of the 150 or so mammalian families.

The task of preparing the samples for sequencing is in the hands of AP Biotech company Molecular Dynamics, based in Sunnyvale, California. Robert Feldman, the production, sequencing and collaborations manager, says that his company is keen to develop the experience of broad exposure to a wide and diverse set of DNA sequencing projects. He declined to comment on the cost of the scheme.

Mitochondria are the structures in a cell responsible for most of its respiration and energy production. They are popular with researchers interested in evolution at the molecular level, because they have a single, small (around 16,500 base pairs) chromosome which is passed down from mother to offspring. This makes them easier to analyse than full genomes.

Mitochondrial DNA contains a number of genes that evolve at different rates. This means mitochondria can be used for evolutionary analyses over different time scales.

Oliver Ryder is an adjunct professor of biology at the Center for Reproduction of Endangered Species at the Zoological Society of San Diego, a collaborator on the project and a leading figure in conservation genetics. He says that variation in mitochondrial DNA — even at the family level — will be useful for interpreting the results of conservation genetics studies, and for analysing evolutionary differences between species.

“There are many examples where mitochondrial DNA has provided profound insights into this area of whether populations [of animals] are the same or significantly diverged,” he says. For example, variation in parts of the mitochondrial DNA of cheetahs and gorillas has helped researchers understand the evolutionary diversity of regional populations and subspecies.

“Differences between families will help us understand the difference between genera and species. A lot of work is done on the tips of the evolutionary tree in the absence of the trunk and the limbs,” he adds.

Ryder suggests that the database may also bring a deeper understanding of how mitochondria evolve. At a broader level, the database will offer a “scaffold of data” for interpreting mitochondrial DNA diversity.

Ryder and colleagues recently argued in favour of starting DNA banks to store the world's genomic biodiversity. They believe that collections started now would be useful in the future for reasons we cannot anticipate (see Science 288, 275–277; 2000). He points to the new project's use of the society's Frozen Zoo, as an example of this.

Ryder thinks the database is timely, “given the capacity in genomic sciences and the opportunity in taking the focus away from medical and therapeutic uses for a single species — humans”. Feldman agrees: “This project takes the genetics of endangered species into the genomic era. That for me is very exciting,” he says.