Genomics of ecological adaptation in cactophilic XXXX .

@entity1068 @entity219 @entity12570 @entity238
Cactophilic @entity238 species provide a valuable model to study gene-environment interactions and ecological adaptation. @entity238 buzzatii and @entity12570 are two cactophilic species that belong to the repleta group, but have very different geographical distributions and primary host plants. To investigate the genomic basis of ecological adaptation, we sequenced the genome and developmental transcriptome of D. buzzatii and compared its gene content with that of @entity12570 and two other noncactophilic @entity238 species in the same subgenus. The newly sequenced D. buzzatii genome (161.5 Mb) comprises 826 scaffolds (>3 kb) and contains 13,657 annotated protein-coding genes. Using RNA sequencing data of five life-stages we found expression of 15,026 genes, 80% protein-coding genes, and 20% noncoding RNA genes. In total, we detected 1,294 genes putatively under positive selection. Interestingly, among genes under positive selection in the @entity12570 lineage, there is an excess of genes involved in metabolism of heterocyclic compounds that are abundant in Stenocereus cacti and toxic to nonresident @entity238 species. We found 117 orphan genes in the shared D. buzzatii- @entity12570 lineage. In addition, gene duplication analysis identified lineage-specific expanded families with functional annotations associated with proteolysis, @entity219 ion binding, chitin binding, sensory perception, @entity1068 tolerance, immunity, physiology, and reproduction. In summary, we identified genetic signatures of adaptation in the shared D. buzzatii- @entity12570 lineage, and in the two separate D. buzzatii and @entity12570 lineages. Many of the novel lineage-specific genomic features are promising candidates for explaining the adaptation of these species to their distinct ecological niches.
