‘Sympatric speciation on islands’
Ecological speciation requires divergent selection, reproductive isolation, and a genetic mechanism to link the two. We examined the role of gene expression and coding sequence evolution in this process using two species of Howea palms that have diverged sympatrically on Lord Howe Island, Australia. These palms are associated with distinct soil types and have displaced flowering times, representing an ideal candidate for ecological speciation. We found that differentially expressed loci as well as those with divergent coding sequences between Howea species were associated with known ecological and phenotypic differences, including response to salinity, drought, pH and flowering time. We further validate the scenario of ecological speciation using long-term field experiments and examine islands of divergence across the palms' genomes.