Even population differentiation for maternal and biparental gene markers in Eugenia uniflora, a widely distributed species from the Brazilian coastal Atlantic rain forest

Abstract

Brazilian cherry (Eugenia uniflora L.) occurs in the Brazilian Atlantic Coastal Tropical Forest from the north‐eastern state of Ceara, to the southernmost state of Rio Grande do Sul. E. uniflora plays an important role in the maintenance of ‘Restinga’ ecosystems, at the interface between forest and strand vegetation. Here, we characterize the genetic diversity, its allocation within and between populations and the possible components of nuclear and cytoplasmic gene flow that determine the spatial distribution of the genetic variability. Five E. uniflora populations encompassing distinct biogeographical components were sampled: populations at extremes of latitudinal distribution, at an oceanic island and close to the major urban centre of Rio de Janeiro. AFLP markers showed that genetic variance among studied populations was moderate (Fst = 0.211) with 78.9% of variability residing within populations. The estimated seed and pollen components of gene flow among populations were approximately equal, with a ratio between 1.003 and 0.713 in function of the cpDNA marker used. The five populations present a considerable genetic structure, as assigned by both nuclear and chloroplastic DNA markers. Our data suggest the existence of different glacial refugia and a limited pollen and seed gene flow, mainly between the southern and the other regions enclosed in the Atlantic rain forest. Therefore, any strategy of conservation and management has to assure the preservation of several populations along the Atlantic coast, to maintain the majority of the intra specific level of diversity.

Myrciaria dubia, an Amazonian fruit: population structure and its implications for germplasm conservation and genetic improvement

“…In accordance with our results, using expressed sequence tag simple sequence repeat markers, Rojas et al (2011) also found high levels of within population variation (80.3%) in Myrciaria dubia preserved at the Active Germplasm Bank in Manaus. Similar results were also reported based on microsatellite markers in other Myrtaceae species such as Melaleuca alternifolia with 93% and Eugenia uniflora with 78.9% (Rossetto et al, 1999;Salgueiro et al, 2004). According to Hamrick (1983), the distribution of genetic variation is not random within populations; instead, it is determined by the reproductive system, the geographical distribution, and the effective population size.…”

Effects of fragmentation on density and population genetics of a threatened tree species in a biodiversity hotspot

“…We expected this pattern because fragmentation has been recent relative to the generation time of these trees, and gene flow appears to be relatively high (N m = 5.23). Similar results of moderate differentiation have been found in other fragmented young Atlantic forest tree species (Seoane et al 2000, Auler et al 2002, Salgueiro et al 2004, Silva et al 2008). …”

“…Also, the relatively high gene flow (N m = 6.58) of the adults represents pre-fragmentation gene flow (Bossart & Prowell 1998). Indeed, outcrossing species generally demonstrate high levels of genetic variation within populations and lower genetic differentiation among populations (Loveless & Hamrick 1984), and similar results have been found in other fragmented Atlantic forest tree species (Seoane et al 2000, Auler et al 2002, Salgueiro et al 2004, Silva et al 2008.…”

Plant morpho-physiological variation under distinct environmental extremes in restinga vegetation

“…For the restinga plants studied in regard to morpho-physiological variations, we are not aware of the phenotypic integration of the various traits examined and therefore we know neither the spectrum of reaction norms (i.e., the set of phenotypes that can be produced by a given genotype exposed to distinct environmental conditions) that confer adaptation to these plants nor the genetic variation that promotes such responses. Genetic studies of restinga plants at the population or individual level are still in their infancy (e.g., Salgueiro et al 2004;Martins et al 2007) and shall be necessary to understand the role of genotypic variation vs. phenotypic plasticity in the process of adaptation from a rainforest habitat at their origin to open, coastal, oligotrophic conditions of the restinga (see also Pertoldi et al 2007).…”