Genetic diversity of Plathymenia reticulata Benth. in fragments of Atlantic Forest in southeastern Brazil

Abstract

Studies of genetic diversity in natural populations are important for the definition of conservation strategies, especially in populations reduced by processes of fragmentation and continuous forest extraction. Molecular markers stand out as interesting tools for these studies. The objective of this research was to characterize the diversity and genetic structure of Plathymenia reticulata (Fabaceae), occurring in two fragments of the Montana Semideciduous Forest in the southern of Espírito Santo State, Brazil, using inter-simple sequence repeat (ISSR) molecular markers. DNA samples from 149 individuals were analyzed using 10 ISSR primers, generating 156 fragments, of which 101 were polymorphic (64.74%). The individuals sampled were classified into three units: adult trees (A), a mixture of progenies (B), and young regenerating individuals (C). The number of loci used (N = 101) was greater than that established as optimal number (N = 88), indicating precision in analyses. The genetic diversity index of Nei (H' = 0.407) and the Shannon index (I = 0.594) were found to have high genetic diversity. Besides, through the diversity parameters evaluated, it was possible to confirm that in the areas of natural regeneration and progeny mix there is genetic diversity equivalent to that found in adults. The analysis of molecular variance indicated that most of the genetic variation is found within the groups (96.53%). Genetic differentiation among adult trees was low (Φ = 0.03) indicating that high gene flow rates (N = 12.70) are counteracting the effects of genetic drift. The data obtained allowed to evaluate the potential of adult trees as matrices for seed collection and to obtain seedlings with confirmed genetic variability.

EVALUATION OF DIVERSITY AND GENETIC STRUCTURE AS STRATEGIES FOR CONSERVATION OF NATURAL POPULATIONS OF Dalbergia nigra (Vell.) Allemão ex Benth.

“…However, this estimate corresponds to the historical gene flow, referring to the interaction of populations in the past, when the actual adult trees settled (Kageyama et al, 2003). Nevertheless, the N m value found in this study can be considered low when compared to the values described for other tree species, such as 12.70 for Plathymenia reticulata (Souza et al, 2017) and 13.54 for Senefeldera verticillata (Vieira et al, 2018), which may be favoring the moderate genetic differentiation between populations.…”

“…The satisfactory levels found for the genetic diversity of the species indicate that it has managed to keep up with the disturbances generated by its predatory exploitation and the fragmentation of natural populations, having as a positive factor the fact that they are located in CU's, which restrict selective cutting. Studies with vulnerable and threatened species, such as D. nigra, demonstrated that these species can restore their population, if there is genetic diversity, knowledge and, control over the genetic structure in the occurrence areas (Martinelli and Moraes, 2013;Souza et al, 2017;Mangaravite et al, 2019). This is even more relevant because D. nigra is an allogamous species, that is, it preferably performs cross-fertilization benefited by entomophilous pollination, consequently increasing the genetic diversity.…”

Short-term increase in clonal propagules following disturbance in a natural populationof Eremanthus erythropappus

“…The destruction of natural sites in which tree species belong may often produce a disequilibrium in ecological interactions with pollinators (Mendes et al, 2022) and seed dispersers (Giombini et al, 2009). Studies that have addressed the current genetic diversity of allogamous tropical tree species through molecular markers frequently found high or moderate levels of genetic variation in natural populations (Collevatti et al, 2014, Souza et al, 2017, Muniz et al, 2022. But also becoming more common are studies documenting signi cant reduction in genetic diversity and changes in the genetic structure of populations when comparing conserved forests with sites that underwent habitat loss (Muniz et al, 2022) and fragmentation (Vranckx et al, 2012, González et al, 2020.…”