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We investigated the potential evolutionary mechanisms associated with maintenance of reproductive species barriers between V. simplex and V. scalaris through morphological and genetic data. Nuclear genomic admixture suggests hybridization in sympatric populations, although interspecific gene flow is low among species in all sympatric zones (N < 0.5). Thus, morphological and genetic divergence (10.99%) between species can be maintained despite ongoing natural hybridization. Cross-evaluation of our genetic and morphological data suggests that species integrity is maintained by the simultaneous action of multiple barriers, such as divergent reproductive systems among species and differences in floral traits.

a b s t r a c tTen polymorphic microsatellite loci were isolated and characterized for Vriesea simplex epiphytic and endemic species from the Brazilian Atlantic Rainforest. The number of alleles per locus ranged from 2 to 16. The observed and expected heterozygosity ranged from 0.000 to 0.414 and 0.068 to 0.795, respectively. All loci departed significantly from HardyeWeinberg equilibrium. Linkage disequilibrium was not detected in any pair of loci. Transferability of 10 loci was positive across ten other Bromeliaceae species. The loci will be used for studying population genetic structure, mating system variation, and the origin and maintenance of reproductive barriers to gene exchange among sympatric Vriesea species.

Morphological variations of individuals and populations of plants have hampered taxonomists from understanding whether such variations are intra- or interspecific. In this research, we study Cryptanthus burle-marxii and C. zonatus, the morphological variations of which overlap, making it difficult to identify them. Both taxa are restricted to the north of the Brazilian Atlantic Forest and are included in the C. zonatus species complex. We applied different methods such as morphological comparison, population genetics using ten nuclear microsatellite markers and ecological niche modelling to study population genetic structure and species delimitation of this species complex. Our analysis revealed that the two genetic clusters were formed possibly because of the presence of a historical geographical barrier in a region called ‘depressão do Abiaí’. The two genetic clusters were concordant with the northern and southern distribution of the complex but incongruent with a morphological variation or current taxonomic delimitation. Thus, we synonymize C. burle-marxii with C. zonatus and re-evaluate its conservation status as endangered.

Thirty-eight nuclear microsatellite loci originally developed for Aechmea caudata Lindm., Orthophytum ophiuroides Louzada & Wand., Pitcairnia albiflos Herb., Vriesea gigantea (Gaud.) and V. simplex (Vell.) Beer were tested in Cryptanthus burle-marxii Leme and C. zonatus (Vis.) Vis. Of the 38 loci tested, 13 were polymorphic. Ten polymorphic microsatellite loci were selected to be amplified and genotyped in one population each of C. burle-marxii and C. zonatus. The observed and expected heterozygosity per locus in the C. burle-marxii population ranged from 0.050 to 0.850 and 0.050 to 0.770, respectively. In C. zonatus, the observed and expected heterozygosity per locus ranged from 0.167 to 0.846 and 0.290 to 0.692, respectively. The O. ophiuroides locus Op52 for the C. zonatus population and P. albiflos locus PaC05 for the two species showed significant departure from HWE. These ten polymorphic loci tested will be used to assess the genetic diversity and structure of the two species of Cryptanthus.