Range-wide neutral and adaptive genetic structure of an endemic herb from Amazonian Savannas.

Mabel P Ortiz-Vera,Pedro L Viana,Amanda R Silva,Carolina S Carvalho,Rodolfo Jaffé,Luciana C Resende-Moreira,Eder C M Lanes,Mohamed Abdelaziz

doi:10.1093/aobpla/plaa003

Abstract

Conserving genetic diversity in rare and narrowly distributed endemic species is essential to maintain their evolutionary potential and minimize extinction risk under future environmental change. In this study we assess neutral and adaptive genetic structure and genetic diversity in Brasilianthus carajensis (Melastomataceae), an endemic herb from Amazonian Savannas. Using RAD sequencing we identified a total of 9365 SNPs in 150 individuals collected across the species’ entire distribution range. Relying on assumption-free genetic clustering methods and environmental association tests we then compared neutral with adaptive genetic structure. We found three neutral and six adaptive genetic clusters, which could be considered management units (MU) and adaptive units (AU), respectively. Pairwise genetic differentiation (FST) ranged between 0.024 and 0.048, and even though effective population sizes were below 100, no significant inbreeding was found in any inferred cluster. Nearly 10 % of all analysed sequences contained loci associated with temperature and precipitation, from which only 25 sequences contained annotated proteins, with some of them being very relevant for physiological processes in plants. Our findings provide a detailed insight into genetic diversity, neutral and adaptive genetic structure in a rare endemic herb, which can help guide conservation and management actions to avoid the loss of unique genetic variation.

Highlights

The assessment of population genetic structure has frequently been employed to delineate conservation units (Moritz 1994; Frankham et al 2017; Coates et al 2018)
Our findings provide a detailed insight into genetic diversity, neutral and adaptive genetic structure in a rare endemic herb, which can help guide conservation and management actions to avoid the loss of unique genetic variation
Genetic variation that is exposed to natural selection can exhibit different spatial patterns than those shown by neutral genetic variation (Van Wyngaarden et al 2017; Barbosa et al 2018), and provides valuable insights on how likely individuals are to survive under certain environmental conditions and the strength of local adaptations across real landscapes (Moritz 1999; McKay et al 2005; Edmands 2007; Frankham et al 2017)

Summary

Introduction

The assessment of population genetic structure has frequently been employed to delineate conservation units (Moritz 1994; Frankham et al 2017; Coates et al 2018). Received: 2 August 2019; Editorial decision: 21 January 2020; Accepted: 28 January 2020 2 | AoB PLANTS, 2020, Vol 12, No 1 discussed types of conservation units (Frankham et al 2017; Coates et al 2018) These are delimited based on neutral genetic variation (which is not subject to natural selection), and mainly reflect the interplay between gene flow and genetic drift (Holderegger et al 2006; Funk et al 2012). While a few studies have assessed both neutral and adaptive genetic differentiation in economically important species (Moore et al 2014; Candy et al 2015; Batista et al 2016; Van Wyngaarden et al 2017; Gugger et al 2018; Jaffé et al 2019), less have done so in species of conservation concern (Rodríguez-Quilón et al 2016; Barbosa et al 2018; Martins et al 2018; Borrell et al 2019; Li et al 2019)

Methods

Results

Conclusion