Population genetic study of Polylepis pauta and Polylepis serícea in Pichincha using molecular markers SSRs
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Abstract
Polylepis forests are one of the most vulnerable centers of Andean diversity that have been affected by anthropogenic impacts. In Ecuador there are no studies of genetic structure in this genus, which is fundamental information for genetic conservation.
This study analyzed two species with taxonomic uncertainty, P. pauta and P. sericea, in three populations: Yanacocha, Mojanda, and Cayambe-Coca National Park. Each population consisted of three subpopulations with a total of 142 individuals. DNA was extracted using the CTAB method and was amplified with 5 SSR primers designed for this genus. Eighteen alleles were detected between the two species. Analysis for genetic structure detected two groups. The first one contained the Cayambe-Coca and Mojanda populations and Yanacocha was in the second group. The observed heterogeneity (Ho) for the Cayambe-Coca and Mojanda population was 0.576, and 0.299 for the Yanacocha population. In contrast, the expected heterogeneity (He) was 0.605 and 0.524 for the populations in Cayambe-Coca and Mojanda and Yanacocha. The biggest difference between these statistics was in the Yanacocha population. This could be attributable to one allele selection or inbreeding. Through differentiation analysis it was probed that both population established are different p=0.00072 (α=0.05). The largest source of variation corresponds to within populations differences (AMOVA). Clustering analysis detected a significant clustering in a subpopulation from Mojanda (Moj1). This may be due to a hybrid origin (P.pauta x P. incana) of this population. Correlation between genetic and geographic distance was not detected. Through this study it was possible to differentiate both species; therefore, SSRs were powerful markers to detect genetic diversity, differentiation, and population structure in this genus.
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