Genetic and morphological diversity and evidence of hybridization in the “sempre-vivas” (Comanthera, Eriocaulaceae) endemic to the Chapada Diamantina, Bahia, Brazil

Abstract

Comanthera species are frequently collected for marketing their scapes and flower heads, and are popularly known as “sempre-vivas” (everlasting flowers), for making various handicrafts. Many of them are endemic to small areas of “campo rupestre” (rocky fields) of the Espinhaço Range, eastern Brazil, which contribute to the increase in their risk of extinction. Comanthera curralensis, C. hatschbachii, C. harleyi and C. borbae are a taxonomically difficult species complex, which eventually occur in sympatry in the northern range of the Chapada Diamantina in the Bahia State, Brazil. We used genetic and morphological data from 13 natural populations of this species complex to assist in taxon delimitation and to investigate the genetic diversity and morphological structuring of populations and species. Both genetic and morphological variability are low, however there is high genetic differentiation between populations. These results and field observations lend support to the re-establishment of C. hatschbachii, previously regarded as synonym of C. curralensis. There is evidence of hybridization/introgression in two populations, both with C. curralensis as one of the parent species: in Morro do Chapéu with C. hatschbachii, and in Umburanas with the recently described C. borbae. The population of C. borbae displayed a high degree of genetic differentiation and has morphological and vegetative characters that support its distinction as an independent lineage. Our work emphasizes the importance of the Morro do Chapéu and Umburanas-Delfino regions for the maintenance of evolutionary processes in Comanthera.