snails

Other Appeals

Appeal to support the research of Dr Justin Gerlach, College Lecturer in Biological Sciences

Our Fellows and College Lecturers are doing very interesting work and as a way of supporting their research interests as well as making what they are doing more widely known, we wish actively to support their research where no other funding is available.  This summer the College is offering Petreans the opportunity to contribute to a fund of £5,000 towards Dr Justin Gerlach's research trip to the South Pacific to investigate the current status of the Partula snail in remote mountainous areas of Polynesian islands. This additional funding will enable him to use helicopters to reach areas that would otherwise be inaccessible. All contributors to the fund will receive reports on Justin's progress!  Please contact Ann Munro in the Development Office if this is something you wish to support. Justin writes as follows:

Partula snails

The 104 species Partula tree-snails of the south Pacific islands are one of the most threatened group of animals, with all species at risk of extinction and 67% of the French Polynesian species are already extinct.

These snails have surprisingly significant connections to science and human endeavour. The first species to be described, Partula faba, was collected on Captain Cook’s first expedition to the Pacific in 1768. This was part of first international scientific research project, to map the Transit of Venus. The snail was not collected by Cook himself, but by Joseph Banks’ team who were the first official naturalists on a British vessel.

This shell was brought back to Britain and illustrated by Thomas Martyn in the ‘Universal Conchologist’, a book that set a new standard for biological illustration that was to influence art publishing and scientific reporting throughout the 19th century.

150 years later Partula became the subject of the first field study of genetics. In 1906 Henry Crampton started investigating the inheritance of colour patterns and direction of shell coiling on Tahiti and then the other French Polynesian islands. This work was picked up by Professors Bryan Clarke and Jim Murray in 1962 who transferred it to the laboratory. For the next 20 years Partula were one of the central animals in the development of genetics as a science.

This came to an end in the 1980s due to in introduction of the predatory snail Euglandina rosea. This devastated wild populations throughout the Pacific, resulting in the extinction of 42 species. The laboratory populations then became the basis of a conservation programme, added to with the rescue of the few snails that could still be found in the wild. Partula are now the focus of the longest running invertebrate conservation programme, which has led to many developments in zoo population management, data handling and invertebrate pathology.

The recent decline of the predator now gives an opportunity for reintroduction. Experimental releases took place in 2015 and 2016 with encouraging results. A point of concern is that a new predator has now been found, the flatworm Platydemus manokwari. This is probably responsible for the decline of the predatory Euglandina snails, but their likely impact on Partula is not known.

My research aims to investigate the effects of the flatworm and to survey the French Polynesian islands for surviving Partula populations. A few Partula species were able to coexist with the predators, albeit in extremely low numbers. In addition to this there have been sightings of some individuals at the tops of the islands, where predators are absent (so far). Nothing is known of the status of these species due to the difficulty of reaching these sites. The most intriguing of all is Partula meyeri, discovered in 1995 at the summit of Raiatea island during a brief botanical expedition. As this site can only be reached by helicopter it has not been searched since, and has never been visited by a zoologist.

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