There are over 500 species of endemic Jamaican terrestrial mollusks. Many Jamaican species have small range sizes, which indicates that active dispersal may be important for their distribution. Traits such as vagility, natal dispersal, breeding dispersal and homing ability that contribute to active dispersal may show correlations with range size, and those traits mapped onto molecular phylogenies may show correlations with lineage diversification rates. Snail instantaneous crawling speed and distance crawled per active period will be used to quantify vagility, with longer scale tracking to assess homing ability and modes of dispersal. The study families, Annulariidae (operculate) and Pleurodontidae (pulmonate), both have molecular phylogenies, and high endemicity and diversity in Jamaica. In September 2019, pilot studies were conducted to test methods for marking and recapturing snails data and for using videography to collecting instantaneous crawling speed. A follow-up study was done in January 2020.
Results/Conclusions
A total of 98 snails were marked, and 24 were recaptured in September 2019. A chi-square test found that annulariids were more likely to be recaptured than pleurodontids in September 2019, with annulariids showing homing ability, generally being recaptured within a meter of where they were released. In January 2020, previously marked snails from September 2019 were found; an additional 38 snails were marked and 33 were recaptured – recaptured snails include 14 individuals marked in September 2019. A chi-square test was performed again (not including those marked in September) but there was no significant difference in likelihood of which kind of snail was likely to be recaptured. Pleurodontids not recaptured in September were recaptured in January which suggests the preliminary result was an artifact of initial handling, and that they likely also have homing ability. Initial results from September 2019 and January 2020 show that different species were active at different times; measurement of crawling speed must be completed on what a snail considers to be a natural surface; and mating and feeding behaviors were interspersed with crawling, making it harder to isolate the latter. These pilot studies and the results will inform future field work.