Final Report Summary - ORIGENE (Understanding the Origin of Species: Ecological Genomics and Transcriptomics on Oceanic Islands)
The project aims at understanding how species originate, especially a highly controversial process called 'sympatric speciation', that is, the evolution of new species without geographic isolation. Our work has focused on two species of the palm genus Howea from Lord Howe Island (LHI), a minute volcanic island in the Tasman Sea. These palms are now regarded as one of the most compelling examples of sympatric speciation, although this view is still hotly disputed by some authors. Population genetic and ecological data are necessary to provide a more coherent and comprehensive understanding of this emerging model system. Using new genetic data, we were able to confirm that gene flow between these palm species appeared to be extremely limited and restricted to early-generation hybrids. We concluded that these palms originated on Lord Howe Island, that is, speciation was indeed sympatric. We then sequenced the entire genome and transcriptomes of these palms and identified the genes involved in the make-up of the species. To evaluate to which extend the Howea palms represent a unique case of speciation, we also surveyed other species of flowering plants endemic to Lord Howe Island, as well as the flora of another oceanic island, Isla de Cocos. Using genetic and evolutionary data, we were able to demonstrate that about 10% of these species represented new cases of sympatric speciation similar to the palm example on LHI. In contyrat, sympatric speciation did not occur on Cocos island, making LHI a truly unique system thus far.