Organisms provide some of the most sensitive indicators of climate change and evolutionary responses are becoming apparent in species with short generation times. Large datasets on genetic polymorphism that can provide an historical benchmark against which to test for recent evolutionary responses are very rare, but an exception is found in the brown-lipped banded snail (Cepaea nemoralis). This species is sensitive to its thermal environment and exhibits several polymorphisms of shell colour and banding pattern affecting shell albedo in the majority of populations within its native range in Europe. We tested for evolutionary changes in shell albedo that might have been driven by the warming of the climate in Europe over the last half century by compiling an historical dataset for 6,515 native populations of C. nemoralis and comparing this with new data on nearly 3,000 populations. The new data were sampled mainly in 2009 through the Evolution MegaLab, a citizen science project that engaged thousands of volunteers in 15 countries throughout Europe in the biggest such exercise ever undertaken. A known geographic cline in the frequency of the colour phenotype with the highest albedo (yellow) was shown to have persisted and a difference in colour frequency between woodland and more open habitats was confirmed, but there was no general increase in the frequency of yellow shells. This may have been because snails adapted to a warming climate through behavioural thermoregulation. By contrast, we detected an unexpected decrease in the frequency of Unbanded shells and an increase in the Mid-banded morph. Neither of these evolutionary changes appears to be a direct response to climate change, indicating that the influence of other selective agents, possibly related to changing predation pressure and habitat change with effects on micro-climate.

Europe has a long history of human pressure on freshwater ecosystems. As pressure continues to grow and new threats emerge, there is an urgent need for conservation of freshwater biodiversity and its ecosystem services. However, whilst some taxonomic groups, mainly vertebrates, have received a disproportionate amount of attention and funds, other groups remain largely off the public and scientific radar. Freshwater mussels (Bivalvia, Unionida) are an alarming example of this conservation bias and here we point out six conceptual areas that need immediate and long‐term attention: knowledge, threats, socioeconomics, conservation, governance and education. The proposed roadmap aims to advance research, policy and education by identifying the most pressing priorities for the short‐ and long‐term conservation of freshwater mussels across Europe.

Cepaea nemoralis shell colour and banding morphs were studied in southeastern Poland, at the eastern edge of its distribution in Europe. Overall, 73% of shells were yellow, 94% were banded and 73% of banded shells were mid-banded. The frequency of yellow shells was significantly higher in open (median 85%) than in shaded habitats (median 60%). Distribution of banding frequencies was consistent with climatic rather than visual selection. Colonies in open habitats were significantly less polymorphic than colonies in shaded habitats, indicating that in more extreme climatic conditions, selection can act against certain genotypes. Analysis of a Wroclaw diagram suggests different possible ways of adaptation to the same habitat type, depending on the initial gene pools. These results conform to a pattern over the whole range, where an increase in the frequency of the yellow phenotype is observed from the north to the south of Europe both within open and shaded habitats, but with significant differences between those habitat types. This can have important consequences for the interpretation of distributional data; results must be considered habitat by habitat.

The present study reports on a natural experiment with twelve replicates in which rapid, predictable and consistent divergence of Cepaea nemoralis pop

Successful rehabilitation programmes of river–floodplain systems require understanding of environmental impacts of restoring hydrological connectivity. The present study is based on a field experiment carried out between 2008 and 2013 in a floodplain of a lowland river in northern Poland, in which two oxbow lakes isolated in the 1920s were reconnected to the main river channel. Water and macroinvertebrate samples were collected three to four times a year from six sites (n = 114). After reconnection, water quality in the oxbow lakes improved and diversity and abundance of macrozoobenthos increased, especially the density of Oligochaeta, Malacostraca, Trichoptera, Bivalvia and Gastropoda, while the density of Diptera decreased. Water flow and physico-chemical variables were the most important factors explaining their variance. A direct inflow of water into the reconnected oxbow lakes occurred only during the first 2 years of the study, followed by silting and overgrowing of the inlet to the upper arm. We propose that creating semi-lotic side channels connected to the river with one arm and only occasionally flushed with fresh river water is one of the most effective restoration strategies. However, at the whole river scale, the maintenance of diversified hydrological connections is the optimal solution.