Genetic diversity of Vriesea cacuminis (Bromeliaceae): an endangered and endemic Brazilian species

Development of 15 nuclear microsatellite markers in Deuterocohnia (Pitcairnioideae; Bromeliaceae) using 454 pyrosequencing

PREMISE OF THE STUDY

Microsatellite markers were developed in Deuterocohnia longipetala (Bromeliaceae) to investigate species and subspecies boundaries within the genus and the genetic diversity of natural populations.

METHODS AND RESULTS

We used 454 pyrosequencing to isolate 835 microsatellite loci in D. longipetala. Of 64 loci selected for primer design, 15 were polymorphic among 23 individuals of D. longipetala and 76 individuals of the heterologous subspecies D. meziana subsp. meziana and D. meziana subsp. carmineo-viridiflora. Twelve and 13 of these loci were also polymorphic in one population each of D. brevispicata and D. seramisiana, respectively. Numbers of alleles per locus varied from two to 14 in D. longipetala, two to 12 in D. meziana, one to nine in D. brevispicata, and one to 10 in D. seramisiana. STRUCTURE analyses clearly separated the taxa from each other.

CONCLUSIONS

The 15 new microsatellite markers are promising tools for studying population genetics in Deuterocohnia species.

Genetic diversity and population structure of Vriesea reitzii (Bromeliaceae), a species from the Southern Brazilian Highlands

The Southern Brazilian Highlands are composed by a mosaic of Mixed Ombrophilous Forest (MOF) and grassland formations, an interesting landscape for the study of population structure. We analyzed the genetic diversity within and among populations of the MOF-endemic bromeliad Vriesea reitzii by genotyping seven nuclear microsatellite loci in 187 individuals from six populations. We characterized levels of genetic diversity and assessed the genetic structure among populations. Vriesea reitzii populations showed high levels of genetic variation (number of alleles 28 - 43, allelic richness 3.589 - 5.531) and moderate levels of genetic differentiation (F_ST = 0.123, R_ST = 0.096). The high levels of genetic diversity may be explained by species life-history traits, such as habit and mating system. The moderate structure may be a product of the combination of ancient and contemporary gene flow, resulting from the expansion of the forest in the Holocene, and/or due to facilitated dispersal mediated by the MOF’s mosaic landscape. The genetic results indicated no imminent threat to this bromeliad. However, the species is highly associated with the MOF, putting landscape conservation at the center of conservation efforts for the species’ maintenance.

Diversification of Bromelioideae (Bromeliaceae) in the Brazilian Atlantic rainforest: A case study in Aechmea subgenus Ortgiesia

Aechmea subgenus Ortgiesia comprises ca. 20 species distributed in Brazil, Argentina, Paraguay, and Uruguay, with a center of diversity in the Brazilian Atlantic rainforest. We examined interspecific relationships of Ortgiesia based on Amplified Fragment Length Polymorphisms (AFLP). Ninety-six accessions belonging to 14 species of Ortgiesia were sampled, and genotyped with 11 AFLP primer combinations. The neighbor joining (NJ) tree depicted two main genetic groups within Aechmea subgenus Ortgiesia, and four subgroups. The NJ tree showed short internal branches, indicating an overall shallow genetic divergence among Ortgiesia species as expected for the recently radiated subfamily Bromelioideae. Our results suggest that hybridization and/or incomplete lineage sorting may have hampered the reconstruction of interspecific relationships in Aechmea subgenus Ortgiesia. The mapping of petal color (yellow, blue, pink, or white), inflorescence type (simple or compound), and inflorescence shape (ellipsoid, subcylindric, cylindric, or pyramidal) against the NJ tree indicated that these characters are of limited taxonomic use in Aechmea subgenus Ortgiesia due to homoplasy. An analysis of the current distribution of Ortgiesia identified the southern region of the Brazilian Atlantic rainforest, between latitudes of 26° and 27°S, as the center of diversity for the subgenus.