Partula population models
Partula tree snails and the Euglandina threat
Partula snails Partula conservation Euglandina

Partula population models

Justin Gerlach

When I first became involved in Partula conservation in the early 1990s my main interest was in the impacts of the predatory snail Euglandina. At that time I developed a basic population model for partulid snails and Euglandina. This gave a reasonable representation of the pattern of extinction that had been observed in Polynesia. I subsequently realised that the model contained a number of errors.The model contained a number of errors and was based on completely the wrong approach. I am currently revising the population model and have developed a new version, that is simpler and more realistic. A refinement of this is that it allows modeling of the spread of Euglandina across each island. Testing this on Moorea gives a very accurate representation of what we know happened on that island. It also predicts that small populations of one species would survive in some parts of Moorea, even with the presence of the predators. These predicted areas precisely match where Partula taeniata survives today. I am currently constructing the model for Tahiti, which is a much larger challenge due to the size and complexity of the island.

Future extensions will include modeling the effects of climate change.

Although the model works reasonably well at present it does need improvement and for this additional data are needed on Euglandina and, especially, the little known predatory flatworms. I am planning field work to fill in these gaps.

Other interests in Partula:

  • Snailing round the South Seas: a popular science book based around the Partula story
  • Partula - icons of evolution: a monograph on the evolution and diversity of the Partulidae
  • Compiled by Justin Gerlach: contact

    Hosted by Island Biodiversity