At risk of population decline? An ecological and genetic approach to the threatened palm species Butia eriospatha (Arecaceae) of Southern Brazil.

To estimate the risk of population decline for the threatened palm species Butia eriospatha, we investigated the patterns of demography, natural regeneration, herbivory, and the levels of genetic diversity using 9 microsatellite loci from both adults and seedlings sampled from 4 populations in Southern Brazil (n = 330). Our results indicate that cattle grazing in B. eriospatha population areas severely affect their demographic structure. Three B. eriospatha populations showed a bimodal age structure made up of adult plants and seedlings and high rates (>77%) of livestock herbivory. For 1 population, we describe and quantify for the first time the occurrence of 6 ontogenetic stages for this threatened palm species. Populations of B. eriospatha showed high levels of genetic differentiation (F ST adult plants = 0.287, F ST seedlings = 0.175). The amount of observed heterozygosity differed significantly between small (H O = 0.329) and large populations (H O = 0.461), indicating that small populations can be more susceptible to genetic drift. With no recruitment and a mortality rate of 2.0%, we show that the populations investigated in this study would be at an extremely high risk of local extinction, with a greater than 50% reduction in the effective population size, in the next 40 years. Although this study highlights the importance of analyzing both population ecology parameters and genetic data to better understand the level of risk facing threatened species, we emphasize that policy actions are urgently needed for effective conservation of this vulnerable biological resource.

The same but different: monomorphic microsatellite markers as a new tool for genetic analysis.

PREMISE OF THE STUDY: The nucleotide variation at a microsatellite locus lacking length polymorphisms among its alleles was assessed to generate an informative tool for genetic analysis. METHODS AND RESULTS: From a set of microsatellite markers, a monomorphic microsatellite locus developed for the palm species Butia eriospatha was used to elucidate whether there are polymorphic sites in its flanking regions. DNA sequences ≈133 bp long were obtained. Aligned sequences show variation at 17 polymorphic sites with both insertions and nucleotide substitutions. Fourteen distinct sequences (alleles) among 22 individuals were identified. The percent sequence difference varied from 0.0 to 5%, indicating that there is significant variation among sequences. CONCLUSIONS: Due to significant levels of information and sequence diversity on a simple sequence repeat (SSR) locus of identical size, our study highlights that this molecular marker class can be a useful tool for population genetics and evolutionary studies for many plant species.

Microsatellite markers for Butia eriospatha (Arecaceae), a vulnerable palm species from the Atlantic Rainforest of Brazil.

PREMISE OF THE STUDY: Microsatellite markers were developed for the vulnerable palm species Butia eriospatha (Mart. ex Drude) Becc. to investigate genetic diversity, spatial genetic structure, mating system, and population dynamics. METHODS AND RESULTS: From a genomic library enriched for GA/CA repeats, 14 sets of primers were isolated and characterized for 50 B. eriospatha samples from two populations. The number of alleles per locus ranged from 2 to 6 (with amplified dinucleotide repeat-based primers); the observed and expected heterozygosities ranged from 0.000 to 1.000 and from 0.120 to 0.690, respectively. At least 86% of primers were also amplified for Butia catarinensis Noblick & Lorenzi, another threatened palm species from the Atlantic Rainforest in Brazil. CONCLUSIONS: The new marker set described here will be useful for studies of population genetics of B. eriospatha, and they have been shown to be applicable for other species from the Butia genus.

Internal genetic structure and outcrossing rate in a natural population of Araucaria angustifolia (Bert.) O. Kuntze.

The internal genetic structure and outcrossing rate of a population of Araucaria angustifolia (Bert.) O. Kuntze were investigated using 16 allozyme loci. Estimates of the mean number of alleles per loci (1.6), percentage of polymorphic loci (43.8%), and expected genetic diversity (0.170) were similar to those obtained for other gymnosperms. The analysis of spatial autocorrelation demonstrated the presence of internal structure in the first distance classes (up to 70 m), suggesting the presence of family structure. The outcrossing rate was high (0.956), as expected for a dioecious species. However, it was different from unity, indicating outcrossings between related individuals and corroborating the presence of internal genetic structure. The results of this study have implications for the methodologies used in conservation collections and for the use or analysis of this forest species.