Traditional management and genetic diversity of Cereus jamacaru DC. subsp. jamacaru (Cactaceae) in the semi-arid region of Brazil

Abstract

Background: Cereus jamacaru subsp. jamacaru is a columnar cactus with high utilization potential. It is used as of animal feed in the semi-arid region of northeastern Brazil. This study aimed to characterize the knowledge, use, and management of this species in a rural community in the semi-arid region of Brazil.

Methods: Semi-structured interviews were conducted with 35 family heads (n = 104) of the village of Santa Rita. Genetic analyses were carried out to evaluate the structure and genetic diversity of populations exposed to different types of management. A total of 90 individuals, 30 in each stand (wild, managed and cultivated) were selected and georeferenced.

Results:  Interviews revealed that fodder was the most important use category. Both in situ (gathering and tolerance) and ex situ (planting and transplanting) management were recorded. There was no significant difference in genetic diversity between the wild, cultivated, and managed stand. The analysis of molecular variance showed that most of the variation occurs within the populations (99.76%). Based on the Nei´s genetic distance matrix, it was possible to verify in the dendogram that the cultivated population is more distinct than the wild and managed ones.

Conclusions: The different types of use and management practiced demonstrate the high cultural and economic value of the mandacaru. In situ management, involves human selection in favor of individuals more robust and more and larger fruits. This selection is not detected by the genetic analysis performed, although it is possible to infer that gene flow among populations is high thus counteracting effects of selection.

Keywords: Mandacaru; Caatinga; Ethnobotany; traditional population; Columnar cacti.