Although H. melpomene and H. cydno occasionally hybridize in nature (less than 0.1%), reproductive isolation is strong, with ecological isolation and colour pattern associated mate choice playing the major role [ 12, 22, 23].
Subgroup A comprised all accessions with red fruits from Akanteng and Kobriso (A1, A2 and A4), while Subgroup B comprised accessions with yellow fruits from Akanteng and Kobriso (A3 and A5), suggesting that the subgrouping was based on fruit colour and not ecological location.
The red colour morph might have ecological advantages such as absorption of solar radiation [ 33] and lower choice selection by parasitoids [ 34].
Some of the cones possess coloured intracellular filters that tune the spectral sensitivity functions of the photoreceptors, enhancing the ability to discriminate between objects on the basis of colour, including those of ecological significance.
We discuss our findings within a phylogenetic and biochemical context, and comment on a possible ecological role for bilirubin as a colour signal to attract animal dispersers and pollinators.
They are also concordant with mate choice, colour pattern, host plant choice, and other ecological parameters known to differ between the species that hybridize [ 62, 63, 87].
On an ecological level, Team Sky's decision to switch their kit colour from black and blue to black and green for the Tour de France, to coincide with their chief sponsor's campaign, is beyond reproach.
Perhaps most notably, a number of studies have linked ecological and sexual divergence among African cichlids to divergence in colour vision genes, the opsins [ 31, 32].
The intense colour of the spent wash effluent leads to crucial ecological issue when released untreated into the environment.
Interest in yellow skin colour might likewise be the result of some anomalous ecological or cultural factor, and it would therefore be instructive to attempt replication of our findings in populations with differing social and ecological backgrounds.
