Abstract
Araucaria (Araucaria angustifolia (Bert.) O. Ktze) is a primarily dioecious species threatened with extinction that plays an important social and economic role especially in the southern region of Brazil. The aim of this work is to investigate the diversity and likely determinants of genetic lineages in this species for conservation management. For this, a collection of 30-year-old Araucaria was used. Accessions collected from 12 sites across the species range were analyzed, with ten individuals per site. The SSR genotyping was conducted with 15 loci and the data were analyzed using several complementary approaches. Descriptive statistics among sampling sites were used and diversity was partitioned non-hierarchically to estimate the size and composition of genetic clusters using a Bayesian assignment method. To explore possible biological implications of differences between Niche Models and habitat suitability, a series of statistical procedures were used, and tests were carried out using the software ENM Tools and Maxent. Populations from the southernmost zone showed higher genetic variation and a lower inbreeding coefficient compared to the northernmost zone, which may correlate with their isolation. A positive relation between genetic differentiation and geographic distance was observed. Two genetic groups (southernmost and northernmost zones) were evident. The Niche modelling showed separate ranges for each genetic lineage suggesting that differences in selection pressure may be playing a role in the apparent differentiation and may be adaptive. Finally, an evident correlation was observed between genetic data and habitat suitability. The two distinct groups observed must be considered as independent units for conservation and hybridization in breeding programs.
Highlights
Many forest species from diverse biomes are currently threatened with extinction
The levels of genetic diversity measured as expected heterozygosity is quite similar to values estimated for natural populations
The estimations obtained in this study suggest that the EMBRAPA’s Active Germplasm Collection (AGC) can be considered an important repository of the genetic resources of araucaria from the populations where samples were collected to establish this active germplasm collection
Summary
Many forest species from diverse biomes are currently threatened with extinction. The establishment of criteria for genetic conservation is a difficult task. The use of niche model and population genetic studies are tools currently applied to study the distribution and diversity of natural populations indicating populations for genetic conservation. This article aims to identify araucaria populations groups aiming at genetic conservation of this species. Conservation of genetic diversity is a challenge for strongly fragmented species as result of anthropic activities, since the biological aspects, as diversity, phylogeny and reproductive pattern, among others are still unknown. Brazil is mega-biodiverse detainer, the strong fragmentation of forests, as a consequence of exploitation and change in land use, has been responsible for threats and extinction of thousands of animal and plant species
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