PT  - JOURNAL ARTICLE
AU  - Niels A. G. Kerstes
AU  - Thijmen Breeschoten
AU  - Vincent Kalkman
AU  - Menno Schilthuizen
TI  - Snail shell colour evolution in urban heat islands detected via citizen science
AID  - 10.1101/424564
DP  - 2018 Jan 01
TA  - bioRxiv
PG  - 424564
4099  - http://biorxiv.org/content/early/2018/09/23/424564.short
4100  - http://biorxiv.org/content/early/2018/09/23/424564.full
AB  - The extreme environmental conditions that prevail in cities are known to cause selection pressures leading to adaptive changes in wild, city-dwelling, organisms (“urban evolution”). The urban heat island, elevated temperatures in the city centre due to a combination of generation, reflection, and trapping of heat, is one of the best recognised and most widespread urban environmental factors. Here, we used a citizen-science approach to study the effects of urban heat on genetically-determined shell colour in the land snail Cepaea nemoralis in the Netherlands. We used smartphone applications to obtain colour data on almost 8,000 snails throughout the country. Our analysis shows that snails in urban centres are more likely to be yellow than pink, an effect predicted on the basis of thermal selection. Urban yellow snails are also more likely to carry dark bands at the underside of the shell; these bands might affect thermoregulation in yet underexplored ways.