Leaf traits and intraspecific niche models support two main botanical varieties of Hancornia speciosa Gomes (Apocynaceae)

Abstract

Hancornia speciosa Gomes (mangabeira or mangaba tree) is a Brazilian plant genetic resource with food, pharmacological, and rubber production potential. However, uncertainty remains regarding the number of botanical varieties within the species. This study aimed to validate how many and which infrataxa can be recognized based on morphological and morphometric leaf traits, environmental suitability areas, and ecological niche overlap. Leaves of H. speciosa var. cuyabensis, H. speciosa var. gardneri, H. speciosa var. pubescens, and H. speciosa var. speciosa were obtained from the Mangabeira Germplasm Collection of the Federal University of Goiás (Goiânia, Goiás, Brazil). Ecological Niche Modeling was performed using compiled occurrence records for each botanical variety extracted from scientific publications and bioclimatic variables provided by WorldClim. We found a clear differentiation of H. speciosa var. speciosa in terms of leaf size and shape. Additionally, patterns observed in ecological niche models, Schoener’s D metric, and the similarity tests emphasize the ecological distinction of this botanical variety. In the future, approaches based on high-throughput sequencing and genome-scale analysis may help detect genomic signatures of local adaptation and provide a better understanding of the evolutionary mechanisms within the species. Based on our findings, we propose the existence of at least two main groups in H. speciosa: one consisting exclusively of H. speciosa var. speciosa, and another comprising H. speciosa var. cuyabensis, H. speciosa var. gardneri, and H. speciosa var. pubescens. Expanding our understanding of this infraspecific classification is essential for guiding conservation strategies, breeding programs, and the sustainable use of mangabeira.