Cover image
A male green frog (Rana clamitans) in Southern Ontario clasps a larger female before mating, in a position known as amplexus. See the paper “Independent evolution of the sexes promotes amphibian diversification” by Stephen P. De Lisle and Locke Rowe: http://dx.doi.org/10.1098/rspb.2014.2213. Photographer: Stephen De Lisle.