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Research Project: Innovative Strategies and Methods for Improving the Management, Availability, and Utility of Plant Genetic Resource Collections

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Title: Genetic diversity and biogeographic determinants of population structure in Araucaria angustifolia (Bert.) O. Ktze.

item Reeves, Patrick
item Reilley, Ann
item MARCOS STEPHENON, VALDIR - Universidade Federal Do Rio Grande Do Norte
item Richards, Christopher

Submitted to: Conservation Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/19/2019
Publication Date: 2/6/2020
Citation: Aparecida De Sousa, V., Reeves, P.A., Reilley, A.A., Virginia De Aguiar, A., Marcos Stephenon, V., Richards, C.M. 2020. Genetic diversity and biogeographic determinants of population structure in Araucaria angustifolia (Bert.) O. Ktze. Conservation Genetics. 21:217-229.

Interpretive Summary: Araucaria angustifolia (Parana pine) is an iconic southern conifer with both social and economic importance in Brazil. This study focused on the broad geographic and environmental correlations with genetic diversity in this species with the aim of developing a better understanding of the genetic lineages that are currently used for conservation and restoration. The results indicated a significant structure in genetic and environmental data suggesting a biogeographic explanation for the observed structure that involved species range expansion and contraction during cycles of glacial expansion. The data present some useful approaches for combining environmental and genetic data and will improve the way ex situ collections of the species are managed in the future.

Technical Abstract: Araucaria angustifolia is a primarily dioecious species threatened with extinction that plays an important social and economic role especially in the south 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 Paraná pine was used. Accessions collected from 12 sites across the species range were analyzed, with 10 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 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 Modeling showed a geographic line separating both groups, which significantly suggests probably different selection pressures in the distinct ranges, thus leading to the potential for adaptive differentiation. 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.