Temporal morph frequency changes in sand‐dune populations of C epaea nemoralis ( L .)

Changes in morph frequency over time in sand‐dune populations of C epaea nemoralis in the B ritish I sles have been examined using the E volution M egalab database. Frequencies in colonies on a sand dune at B errow, S omerset were estimated in 2008–9. This extends a survey started in 1926 by A. E. B oycott and C . D iver and continued in the mid‐20th C entury by B. C. C larke and J. J. M urray. An increase in the frequency of the mid‐banded morph, noted in earlier work, has continued. The apparent decrease in brown was not confirmed but the yellow frequency has increased. At a range of dunes in the B ritish I sles, comparisons between data from the mid‐20th C entury and the early 21st C entury indicate an increase in yellow and mid‐banded morphs and a decrease in banding and brown morphs. These results differ from the overall trends derived from E urope‐wide comparison of early data with E volution M egalab data, in which banded and mid‐banded increased in frequency, whereas there was no overall change in yellow. The general pattern of regional variation has been retained, although there is also high heterogeneity between samples, suggesting that a variety of factors are involved in explaining the changes. The mean shifts in frequency are consistent with climatic change over the period. Dunes are probably the most likely habitat in which to detect such a change. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society , 2012, 108 , 315–322.