Disentangling the Environmental Factors That Shape Genetic and Phenotypic Leaf Trait Variation in the Tree Qualea grandiflora Across the Brazilian Savanna

Renata Santiago De Oliveira Buzatti,Thais Ribeiro Pfeilsticker,Maria Bernadete Lovato,Renan Pedra De Souza,André Carneiro Muniz,José Pires Lemos-Filho,Vincenzo A Ellis

doi:10.3389/fpls.2019.01580

Renata Santiago De Oliveira Buzatti, Thais Ribeiro Pfeilsticker + Show 5 more

Open Access

https://doi.org/10.3389/fpls.2019.01580

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Abstract

Identifying the environmental factors that shape intraspecific genetic and phenotypic diversity of species can provide insights into the processes that generate and maintain divergence in highly diverse biomes such as the savannas of the Neotropics. Here, we sampled Qualea grandiflora, the most widely distributed tree species in the Cerrado, a large Neotropical savanna. We analyzed genetic variation with microsatellite markers in 23 populations (418 individuals) and phenotypic variation of 10 metamer traits (internode, petiole and corresponding leaf lamina) in 36 populations (744 individuals). To evaluate the role of geography, soil, climate, and wind speed in shaping the divergence of genetic and phenotypic traits among populations, we used Generalized Dissimilarity Modelling. We also used multiple regressions to further investigate the contributions of those environmental factors on leaf trait diversity. We found high genetic diversity, which was geographically structured. Geographic distance was the main factor shaping genetic divergence in Qualea grandiflora, reflecting isolation by distance. Genetic structure was more related to past climatic changes than to the current climate. We also found high metamer trait variation, which seemed largely influenced by precipitation, soil bulk density and wind speed during the period of metamer development. The high degree of metamer trait variation seems to be due to both, phenotypic plasticity and local adaptation to different environmental conditions, and may explain the success of the species in occupying all the Cerrado biome.

Highlights

Understanding the role of environmental factors in shaping genetic and phenotypic intraspecific diversity can provide important insights into the processes that are responsible for the generation and maintenance of biological diversity (Ribeiro et al, 2016b; Ji et al, 2017; Oliveira et al, 2018; Souza et al, 2018)
Qualea grandiflora is a widespread tree in the Cerrado and occurs exclusively in this biome, leading it to be considered a marker of Brazilian savanna species
The genetic diversity was heterogeneous over the populations, with the mean number of alleles per locus (NA) varying from 6.3 to 10.9, allelic richness (AR) varying from 5.1 to 7.7, observed heterozygosity (HO) and expected heterozygosity (HE) ranging from 0.42 to 0.77 and 0.69 to 0.85, respectively (Table 1)

Summary

Introduction

Understanding the role of environmental factors in shaping genetic and phenotypic intraspecific diversity can provide important insights into the processes that are responsible for the generation and maintenance of biological diversity (Ribeiro et al, 2016b; Ji et al, 2017; Oliveira et al, 2018; Souza et al, 2018). In response to environmental factors such as climate and soil, populations can develop local adaptation, a process that results in changes in the genetic composition of populations over multiple generations (Lajoie and Vellend, 2018). Local adaptation can lead to a phenomenon known as isolation by environment – IBE, the association between genetic divergence among populations and environmental differentiation, independent of geographic distance (Sexton et al, 2013; Wang and Bradburd, 2014). Lower investment in leaf blade per total mass of metamer and lower specific petiole length have been found to be associated with more arid climate in Cerrado tree species (Ribeiro et al, 2016b; Souza et al, 2018)

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