Genetic structure among morphotypes of the endangered Brazilian palm Euterpe edulis Mart (Arecaceae)

Abstract

Euterpe edulis (Arecaceae) Mart has high ecological and economic importance providing food resources for more than 58 species of birds and 20 species of mammals, including humans. E. edulis is the second most exploited nontimber product from Brazilian Atlantic Forest. Due to overexploitation and destruction of habitats, E. edulis is threatened by extinction. Euterpe edulis populations have large morphological variations, with individuals having green, red, or yellow leaf sheath. However, no study has related phenotypic distinctions between populations and their levels of genetic structure. Thus, this study aimed to evaluate the diversity and genetic structure of different E. edulis morphotypes. We sampled 250 adult individuals in eight populations with the different morphotypes. Using 14 microsatellite markers, we access genetic diversity through population genetic parameters calculated in the GenAlex program and the diveRsity package in R. We used the Wilcoxon test to verify population bottlenecks and the genetic distance of Nei and Bayesian analysis for genetic clusters. The eight populations showed low allele richness, low observed heterozygosity, and high inbreeding values (f). In addition, six of the eight populations experienced genetic bottlenecks, which would partly explain the low genetic diversity in populations. Cluster analysis identified two clusters (K = 2), with green morphotype genetically distinguishing from yellow and red morphotypes. Thus, we show, for the first time, a strong genetic structure among E. edulis morphotypes even for geographically close populations.

Keywords: ecotypes; genetic bottleneck; palm; population genetics; tropical rainforest.

FIGURE 1

Phenotypic distinction between the (a) green (b) yellow and (c) red morphotypes found in the populations of E. edulis

FIGURE 2

Map of Brazil, highlighting the state of Bahia and the Distrito Federal, indicating the region of the study with the current forest cover. (a) Populations of E. edulis sampled in Bahia and (b) Populations of E. edulis analyzed in Distrito Federal. Populations colors (blue or green) indicate the grouping (ΔK = 2) assigned in the Structure software. Map data: Atlas of the Atlantic Forest remnants of the year 2016 obtained from SOS Mata Atlântica (https://www.sosma.org.br) and State Geoinformation System—SIEG of the state of Goiás (http://www2.sieg.go.gov.br/). AE, Farm Alto da Esperança; BS, Farm Boa Sorte; BN, Brasilia National Park; BR, Una Biological Reserve; EV, Private Reserve of Natural Patrimony Estação Veracel; EU, Ecoparque de Una; RE, Roncador Ecological Reserve; ST, Private Reserve of Natural Patrimony Serra do Teimoso. The population morphotype is indicated by the names yellow, red, or green

FIGURE 3

Heatmap of the eight populations of E. edulis with Euclidean distance and clust average method using the distance of Nei (1978), indicating the two groups established (group 1 blue lines and group 2 with pink lines). AE, Farm Alto da Esperança; BN, Brasilia National Park; BS, Farm Boa Sorte; BR, Una Biological Reserve; EV, Private Reserve of Natural Patrimony Estação Veracel; EU, Ecoparque de Una; RE, Roncador Ecological Reserve; ST, Private Reserve of Natural Patrimony Serra do Teimoso. The population morphotype is indicated by the names yellow, red, and green

FIGURE 4

STRUCTURE bar plots for E. edulis sampled in eight populations. Each sampled individual of E. edulis is represented by a single vertical line with different colors (green and blue) representing assignment probabilities to the two inferred genetic clusters (ΔK = 2). AE, Farm Alto da Esperança; BS, Farm Boa Sorte; BN, Brasilia National Park; BR, Una Biological Reserve; EV, Private Reserve of Natural Patrimony Estação Veracel; EU, Ecoparque de Una; RE, Roncador Ecological Reserve; ST, Private Reserve of Natural Patrimony Serra do Teimoso. The population morphotype is indicated by the names yellow, red, or green