Genetic diversity, mating system and reproductive phenology of Mimosa scabrella Benth: Implications for seed collection

Abstract

Ecological restoration requires seed sources of native species with sufficient genetic diversity to maintain the evolutionary potential of subsequent populations. Studies elucidating genetic variability, mating system, and reproductive phenology are crucial for designing seed collection strategies. These aspects were evaluated in two populations of Mimosa scabrella (Bom Retiro-BR and Urupema-URU, Santa Catarina) to support such strategies. Genetic variation was analyzed using nine isozyme systems in 50 adult trees per population. The same markers were employed in open pollinated progeny arrays, from both populations, to evaluate the mating system. Phenological observations were conducted for one year in 30 individuals per population. Genetic variation revealed high diversity (HE= 0.190 in BR; 0.245 in URU), but significant fixation indexes (f= 0.237 in BR; 0.156 in URU). The species exhibited a mixed mating system, predominantly outcrossed (tm= 0.852 in BR; 0.801 in URU), with selfing, biparental inbreeding, and correlated matings, resulting in high coancestry and low effective variance size. To retain an effective size of 100 individuals non-inbred and unrelated, it is recommended to collect seeds from at least 37 seed trees in BR and 39 in URU, spaced at distances higher than 50 m. Phenological patterns showed synchronized winter flowering and fruit dehiscence between February and March, delayed in URU by one month, and influenced by climatic variables. These results confirm both populations as valuable seed sources for restoration, with specific recommendations to maximize genetic representativeness and adaptive potential.