Insights into the evolution and taxonomic meaning of seed fatty acid profiles in Campomanesia (Myrtaceae)

This study explores the composition, taxonomic significance, and evolutionary history of seed fatty acid (FA) profiles in Campomanesia (Myrtaceae), a South American genus comprising approximately 45 species. Seed oils from six Campomanesia species were analyzed using gas chromatography and mass spectrometry. FA-based clustering was then compared with molecular phylogeny derived from nuclear and plastid markers, with Psidium guajava and Feijoa sellowiana included as outgroups. The results revealed a high degree of congruence between FA composition and phylogenetic relationships, as well as species-specific FA profiles that were consistent across individuals from different populations, highlighting their potential as reliable taxonomic markers. While P. guajava and F. sellowiana exhibited high linoleic acid content, Campomanesia species presented more balanced proportions of saturated and monounsaturated FA. Ancestral state reconstructions indicated a consistent evolutionary trend toward reduced proportions of unsaturated FA within Campomanesia. Although correlations with climatic variables such as temperature and precipitation were weak and statistically non-significant, a strong phylogenetic signal was detected. These findings suggest that genetic drift, rather than climate-driven selection, may have played a dominant role in shaping FA profiles, reinforcing their potential utility in taxonomic studies of the genus.