Gecele Matos Paggi

Cross‐species transfer of nuclear microsatellite markers: potential and limitations

Molecular ecologists increasingly require ‘universal’ genetic markers that can easily be transferred between species. The distribution of cross‐species transferability of nuclear microsatellite loci is highly uneven across taxa, being greater in animals and highly variable in flowering plants. The potential for successful cross‐species transfer appears highest in species with long generation times, mixed or outcrossing breeding systems, and where genome size in the target species is small compared to the source. We discuss the implications of these findings and close with an outlook on potential alternative sources of cross‐species transferable markers.

Fertility of Vriesea gigantea Gaud. (Bromeliaceae) in southern Brazil

Plant fertility is a central subject of many questions in plant evolutionary and conservation biology. Pollen availability, abiotic resources, and flowering pattern can limit fruit and seed production. Open pollination and pollen supplementation studies are used to estimate any pollen limitation in natural populations. To study the impact of these factors on the reproductive success of Vriesea gigantea, an epiphytic bromeliad in the Atlantic Rainforest in Brazil, its fertility in four natural populations in Itapuã State Park was assessed by considering plant and inflorescence size, flower production, fruit and seed set, flower and fruit set pattern, and seed viability and germination rate. Supplemental pollination in adult plants was used to determine whether fruit production in V. gigantea is limited by reception of pollen. The results showed that V. gigantea has a high production of flowers, fruits, and seeds. Seeds are highly viable in all populations, presenting an average germination rate of 94% (SE ± 3.5). Plants of V. gigantea from Itapuã State Park are highly fertile. The high proportion of fruit and seed set after manual hand pollination indicates that the species is self-compatible. Pollination treatments showed evidence of pollinator limitation in the Itapuã State Park population.

Genetic structure and phenotypic variation in wild populations of the medicinal tetraploid species Bromelia antiacantha (Bromeliaceae)

UNLABELLED PREMISE OF THE STUDY The patterns of genetic structure in plant populations are mainly related to the species life history and breeding system, and knowledge of these patterns is necessary for the management, use, and conservation of biological diversity. Polyploidy is considered an important mode of evolution in plants, but few studies have evaluated genetic structure of polyploid populations. We studied the patterns of genetic structure and morphological variation of Bromelia antiacantha (Bromeliaceae) populations, a polyploid terrestrial species. • METHODS Microsatellite markers and morphological analyses were used to explore patterns of genetic and morphological diversity in wild populations of B. antiacantha. • KEY RESULTS The results of our simple-sequence repeat analyses supported that B. antiacantha is a polyploid species. The inbreeding coefficients were high and significant in all populations (F(IS) = 0.431), indicating homozygote excess. Bromelia antiacantha showed high levels of genetic differentiation among populations (F(ST) = 0.224) and therefore was highly structured. High morphological variation was observed in fruit phenotypic traits in the populations studied. • CONCLUSIONS The levels of genetic diversity and the pattern of the populations structure may be related to the low recruitment of seeds, clonal reproduction, and the populations colonization history. The genetic and morphological variability displayed in this study are important issues in planning the conservation and exploitation of this resource in a sustainable way.

Mating system variation and assortative mating of sympatric bromeliads (Pitcairnia spp.) endemic to neotropical inselbergs

PREMISE OF THE STUDY The mating system is an important component of the complex set of reproductive isolation barriers causing plant speciation. However, empirical evidence showing that the mating system may promote reproductive isolation in co-occurring species is limited. The mechanisms by which the mating system can act as a reproductive isolation barrier are also largely unknown. METHODS Here we studied progeny arrays genotyped with microsatellites and patterns of stigma-anther separation (herkogamy) to understand the role of mating system shifts in promoting reproductive isolation between two hybridizing taxa with porous genomes, Pitcairnia albiflos and P. staminea (Bromeliaceae). KEY RESULTS In P. staminea, we detected increased selfing and reduced herkogamy in one sympatric relative to two allopatric populations, consistent with mating system shifts in sympatry acting to maintain the species integrity of P. staminea when in contact with P. albiflos. CONCLUSIONS Mating system variation is a result of several factors acting simultaneously in these populations. We report mating system shifts as one possible reproductive barrier between these species, acting in addition to numerous other prezygotic (i.e., flower phenology and pollination syndromes) and postzygotic barriers (Bateson-Dobzhansky-Muller genetic incompatibilities).

Microsatellites in the endangered species Dyckia distachya (Bromeliaceae) and cross-amplification in other bromeliads.

Microsatellite markers were isolated in Dyckia distachya, an endangered bromeliad from southern Brazil, which will be useful to assess the population genetic structure and reproductive success in introduced and natural populations of this species. Twenty microsatellite loci were developed from an enriched genomic library, and nine of these were amplified. The loci were characterized in 43 individuals from introduced and wild D. distachya populations. All nine loci were polymorphic, with four to ten alleles per locus. In an introduced population the observed and expected heterozygosities ranged from 0.136–0.667 and 0.543–0.877, respectively, while in a wild population it ranged from 0.000 to 0.895 and from 0.050 to 0.811, respectively. The development of these microsatellite markers will contribute to investigations of the reproductive potential and viability of introduced populations of D. distachya as well as the single known wild population. Cross-amplification in other Bromeliaceae species was successful, with high rates in four loci, demonstrating the applicability of these microsatellite markers in other taxa.