CHANGES IN LAND SNAIL BODY SIZE AS A FUNCTION OF ENVIRONMENTAL AND CLIMATIC FACTORS

Body size of land snails can be an indication of environmental and climatic conditions. Changes in water availability, pH, carbonate availability, plant cover, and topography all may lead to differences in shell size. Understanding how these different factors affect shell size can be useful for deducing how snails adapt. This in turn is useful information for understanding land snail responses to environmental and climatic changes. The Canary Islands, Spain, provide a unique opportunity to study these relationships.

This study explores what is driving the difference in land snail shell size between the eastern and western islands by looking at two genera that inhabit all seven of the Canary Islands, Hemicycla and Caracollina. Size variation from island to island will be measured and factors that could contribute to these differences will be analyzed. We hypothesize that the snails’ sizes are driven by moisture availability, so the eastern islands’ communities will generally be smaller than those from the western islands. Soil samples, rainfall rates, the topography , and other environmental attributes of the islands will be examined to see the different effects they have on the size of the snails. X-ray diffraction (XRD) will be used to determine what minerals are in the soil samples, Loss on Ignition (LOI) will be used to look at the weight percentage of carbonate material that is in the soil samples, and pH level of the soil will be analyzed to see the effects on the growth rate of the snail shells.

Understanding how variables such as carbonate content of the soil, moisture availability, and soil pH affect cosmopolitan genera’s shells may provide insight as to how snails adapt to variations in climate. This may have implications for these species’ abilities to deal with future climate change.