Celebrate Darwin - collect snails
(February 12th 2009) Thousands of media editors are today celebrating Charles Darwins' Birthday with thousands of articles. Of course, Lab Times itself has also looked for an interesting topic to mark Darwin's 200th anniversary. And we've found one: You can observe Evolution on your own doorstep by simply collecting common garden snails, reports Melanie Estrella.
How are variants of the banded snail,
Cepaea nemoralis, distributed throughout Europe? Europeans are being invited to answer this question. The Museum for Natural History in Berlin, the German Society for Nature Conservation (NABU) and the Helmholtz Centre for Environmental Research (UFZ) in Leipzig have initiated a pan-European participatory project, funded by the Volkswagen Foundation.
These snails populate Europe from Norway to Spain and they come in various colours. Their ornamental shells can be yellow, pink, orange, red or brown and can be decoratively lined with up to five black or white bands. Inherited variations in the colour and band number on the snails' mobile home serve as selective responses to predation and climate.
The designs on some shells keep away the song thrush, which prefers feasting on the black-striped
Cepaea nemoralis and the white-hooped
Cepaea hortensis. Furthermore, the colour of the snail's retreat influences its resident's body temperature. In cold climates, such as woodland, snails with dark shell colours predominate because they heat up faster than lighter ones do. On the other hand, fairer shelled snails are more common in Southern Europe and on grassland. Indeed, grassland habitants also use stripiness as camouflage to fool hungry birds.
Thus, alterations in the distribution of differentially coloured and patterned snails reflects the evolutionary progress of these unhasty molluscs. One possible finding from a census of snail shells might be an increase in the proportion of fair-coloured shells since environmental temperatures have been increasing with climate change. Another finding might show a substantial spread of the snails' range because the numbers of predatory thrushes has been decreasing in many places over the last thirty years.
Participation in this assessment of snail evolution is simple: just look out for the slimy animals in your own back-yard, parks or scrubland, and determine the colour and number of bands on the pretty shells, then record your findings and their location at the website
http://www.evolutionmegalab.org/. The data will immediately show-up on an online map. In this way, step-by-step, a Europe-wide map will appear, illustrating the distribution of the snail variants.
To start with, 200 historic locations are depicted on the map. Within the next few weeks, 700 more will be added. By comparing present-day entries with the historical data for the same areas, it should be possible to track the snail's evolutionary development.
A suitable day to start off as a hobby evolutionist is a warm and rainy one - the climate that all snails prefer, regardless of the design on their shell.
