Population genetic analysis of two Polylepis microphylla (Wedd.) Bitter (Rosaceae) forests in Ecuador

ABSTRACT

Habitat fragmentation is a severe problem that negatively affects forests around the world. This phenomenon has consequences at a genetic level in populations such as genetic diversity and gene flow reduction. As a result, population fitness decreases, and the possibility of extinction increases. Polylepis (Rosaceae) forests are endemic to the Andes and their distribution reflects hundreds of years of human activities. Polylepis microphylla is the most endangered species of the genus in Ecuador and is represented by only two known forests in Chimborazo province, separated from each other by 1,6 km. The present study focused on i) exploring the genetic structure and connectivity, ii) analyzing the genetic diversity patterns in these two forests of P. microphylla. Parameters such as Fixation index, molecular variance (AMOVA) and genetic diversity estimators were calculated from the haplotypic sequences of one chloroplastic DNA region (trnG intron), one nuclear DNA region (ITS), and the concatenation of both. We found that DNA regions used were highly polymorphic with a total of nine, four and thirteen segregation sites, respectively, and nine, six and fifteen haplotypes, respectively. Also, we detected that both forest work as a single population unit due to low fixation index values (Fst = 0,03822, −0,03883 and −0,00469, respectively), which indicate high gene flow between these two forests. In addition, we detected high genetic diversity reflected by haplotype diversity in both forest (hd = 0,54204, 0,63664 and 0,81682, respectively). Likewise, haplotype relationships were visualized in networks, which demonstrated limited spatial structuring between haplotypes, corroborating the low genetic differentiation among these forests. In conclusion, our results suggest there is a single population unit of P. microphylla in Ecuador. Habitat fragmentation does not seem to have negative effects on the genetic diversity of this species. Nevertheless, the species may be vulnerable to rapid environmental fluctuations despite having relatively high genetic diversity. Its long generational time causes increased susceptibility of P. microphylla to environmental changes and may eventually lead to the extinction of the species in Ecuador.

KEYWORDS:

• Andes
• conservation
• haplotypes
• Polylepis microphylla
• population genetic

Acknowledgments

This study would not have been possible without the support of the Pontificia Universidad Católica del Ecuador (PUCE), through the PUCE research project named “Dinámica y análisis poblacional de los bosques de Polylepis en el Ecuador”. Similarly, we extend our thanks to Ministerio de Ambiente y Agua de Ecuador and the project “Caracterización genética y análisis bioinformático de la biodiversidad de los Parques Nacionales Podocarpus, Sangay, Yacuri y Llanganates” for support. Thanks to the research projects “Diversidad de Plantas Vasculares”, 012-2017-IC-FLO-DNB/MA and “Diversidad Genética de la Flora Ecuatoriana”, MAE-DNB-CM-2018-0082 carried out in conjunction with PUCE, it was possible to collect the botanical and leaf tissue samples. Finally, we thank to Dr R. Gradstein and the two reviewers for their valuable comments.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by Pontificia Universidad Católica del Ecuador through the research project: “Dinámica y análisis poblacional de los bosques de Polylepis en el Ecuador” Grant O13106/QINV0103;Pontificia Universidad Católica del Ecuador (EC) [O13106/QINV0103].