The Pink pigeon: can genetic rescue save it from extinction?

by Camilla Ryan, NHM and Earlham Institute, University of East Anglia

Camilla is a PhD student studying “Genome wide analysis of drift and selection of drift and selection using historic and contemporary samples of the endangered Mauritius pink pigeon”.  Professor Ian Barnes from the Museum’s Earth Science department is a co-supervisor for her work.

Many people have never heard of the pink pigeon but almost everyone has heard of the Dodo – one of the most famous animals to have ever gone extinct.

Yet there are many similarities between the two birds; they are even related (by evolutionary standards). Both the pink pigeon and the Dodo come from the Island of Mauritius, both are species of pigeon and both have been severely impacted by the arrival of humans on Mauritius. There is one critical difference between the two: while the Dodo is extinct the pink pigeon is not … yet!

The pink pigeon declined to approximately 16 individuals in the 1970’s, due to loss of habitat, introduced predators and introduced pathogens. Thanks to the efforts of Gerald Durrell, Carl Jones, the Durrell Wildlife Trust and the Mauritian Wildlife Foundation (MWF) they currently number about 400 individuals but retain their endangered species status. This is hardly surprising because over 60% of fledglings die due to an invasive pathogen called Trichomonas gallinae. Predators such as cats, monkeys, rats and mongoose raid nests and some studies have shown that over 90% of the eggs produced by pink pigeons are infertile because of the impacts of inbreeding depression (the negative result of breeding closely-related individuals).

Pink pigeon survival

The MWF, with volunteers and researchers led by Professor Carl Jones, continues to work incredibly hard to manage and conserve this bird.They control predators, monitor disease, provide the birds with supplementary feed and it is thanks to their hard work that the pink pigeon survives. While there is little more that we, as researchers, can do about the lack of habitat or presence of predators, perhaps we can help tackle the pink pigeons’ susceptibility to disease and their low fertility using an approach known as genetic rescue. This is a process by which new gene variants are added to a population either naturally or through reintroductions and translocations by conservation management authorities.

This is where museums like the Natural History Museum can help with current conservation problems. Extracting DNA from museum skins provides us with baseline data that allow us to see what a pink pigeons’ genome (its genetic make-up) looked like before the population crashed to 16 individuals. By comparing this older material with current pink pigeon genetic data, we can look at what genetic diversity the pink pigeons may be missing and see if those missing genes could help them adapt to any of their current problems – such as disease.

skings

We then hope, in collaboration with zoos such as the Durrell Wildlife Trust, to be able to look for genetic diversity within the captive population and create a breeding programme that ultimately aims to increase both the overall genetic diversity and the number of disease resistant individuals within the wild population. So far we have sequenced eight historic genomes from the Natural History Museum at Tring, the  Cambridge University Museum of Zoology (all dating from within the 1800s), and other museums such as World Museum Liverpool, National Museum of Ireland, and the Muséum national d’Histoire naturelle in Paris.

DNA sequencing & endangered species

This project is quite literally where the old (samples) meet the new (technology). Although conservation has been known to use innovative technological solutions (for example, using the google glass to help with rhino conservation) this accounts for only a small percentage of projects within the field. Due to poor funding, many cutting-edge techniques that could make a large contribution to the field of conservation are often just out of reach of the scientists who need them.

This is where the genome sequencing company Pacific Biosciences comes in. They offer the chance to use the most up-to-date sequencing technology for free – the catch? Your project must be one of five selected from over 200 by a scientific committee and then compete again for the publics’ vote against the other projects. We need your help, or more specifically, your vote.

Final hurdle – your vote counts!

The pink pigeon project has made it to this final hurdle, although the competition is open to anyone working on any plant or animal, ours is the only one which involves an endangered species, as well as the only team – Earlham Institute and NHM – from the UK to get through.

squab

Pink pigeon young are known as squabs. Endearingly ugly, this squab will have to battle the threat of disease, predators and poor genetic diversity to have a hope of reaching sexual maturity at 6 months old. Photo courtesy of Durrell Wildlife Trust

If we won, the pink pigeon would be the first endangered bird to get its transcriptome (which tells you what genes are being used, what they do and where they can be found in the genome) sequenced using PacBio’s latest methodology, Iso-Seq. This will significantly advance our project, bringing us a step closer to developing a framework that demonstrates how genetics can be implemented alongside more traditional conservation methods to save endangered species like the pink pigeon. Importantly this same framework could then be applied to help save any endangered species, be it the New Zealand Kakapo or the Amur Leopard.

More information can be found on our Facebook page @savethepinkpigeon and, for those who are interested, click here for a short video that will explain more about the project. Please vote at bit.ly/seqthepigeon and help to save the endangered pink pigeon #seqthepigeon.