Genetic diversity within a declining natural population of Ferocactus histrix (DC) Lindsay

Abstract

Ferocactus histrix is a barrel cactus that is widespread in Mexico. A population located inLlanos de Ojuelos, a semiarid zone representative of many disturbed regions in northcentral Mexico, was studied. Over a period of 10 years (1997 to 2007), the average number of individuals decreased from 21.95 to 3.53 plants per 300 m 2 . A change in population size structure was also registered over this period of time. In 2008, a plot selected on the basis of plant abundance was established within the population and a genetic analysis was conducted with ISTR and ISSR markers. This analysis revealed low levels of genetic diversity (expected heterozygosity (HE) = 0.073, Shannon index (I) = 0.113 and HE = 0.178, I = 0.271, respectively) compared with those of most studied cacti species. The genetic diversity between the different life stages was also evaluated, and a gradual decrease in levels of genetic variation was observed from adults to juveniles and seedlings ( HE = 0.130, I = 0.192 to HE = 0.103, I = 0.157). These differences, however, were not significant. Loci fixation and a decrease in the frequency of rare alleles were observed in seedling and juvenile classes. The decline in genetic variation may be associated with recent bottlenecks experienced by the population of F. histrix. If the sizes of local populations of F. histrix continue to decrease, genetic variation will be gradually lost, and the risk of extinction will increase.

SELEÇÃO DE PRIMERS INTER SIMPLE SEQUENCE REPEAT EM Melocactus conoideus Buin. & Bred. (Cactaceae), ESPÉCIE ENDÊMICA DO SUDOESTE DA BAHIA, BRASIL

“…Os primers ISSR têm sido aplicados em diferentes espécies de Cactaceae a fim de desvendar questões diversas a exemplo de estudos de variabilidade genética (CASTRO-FELIZ et al, 2014;GANOPOULOS, 2015), análises filogenéticas (REALINI et al, 2015) e identificação de variação somaclonal em raízes cultivadas in vitro (TORRES-SILVA et al, 2018). A maior parte destes trabalhos visa contribuir com informações que permitam auxiliar no manejo das espécies para sua conservação.…”

Traditional management of Cactaceae: Cereus jamacaru DC as the native cactus most managed by rural communities in areas of Caatinga in Brazil

“…Thus, although the planting contributes to a higher density, it does not ensure a high genetic diversity (Santos et al 2008). However, it is still positive since it avoids the loss of variability due to population decline, such as in the case of Ferocactus histrix (DC) Lindsay, a barrel cactus diffused in Mexico, which is losing its genetic variability due to the high decline in the number of individuals and is at a high risk of extinction (Castro-Felix et al 2014).…”

“…Based on plant management in the Mesoamerica, investigations have been evidenced the potential of transformation of human activities on both the landscape and the phenotypic and genetic variation and structure of the species (Barbosa et al 2017, Casas et al 2007, Castro-Felix et al 2014, Rodríguez-Arévalo et al 2006, Ruán-Tejeda et al 2014, and these changes may occur gradually based on the different management regimes used, which may be unconscious and with low intensity, or conscious, systematic and highly intense (Abbo et al 2014, Heiser 1988). The intentional choice of a particular species or phenotype of interest and its protection, promotion, and tolerance are known practices that can cause changes in composition and dynamics of populations and communities and, eventually morphological, physiological, and genetic differentiation with respect to the original populations and communities of the organisms subjected to management .…”

Seleção de primers polimórficos para estudo de diversidade genética em cactáceas

“…Esses estudos, auxiliam o acesso as informações em relação à base genética das espécies, ajudando para um melhor entendimento do status da variabilidade génetica. Trabalhos realizados com espécies de cactaceas permitiram agrupar os genótipos, facilitando análises de uma dada característica pelas semelhanças ou diferenças entre os indivíduos, bem como para a sua seleção e utilização, permitindo um melhor manejo das espécies (Castro-Félix et al 2014, Realini et al 2015, Silva et al 2018a, Vieira et al 2019.…”