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Abstract Background Developing a greater understanding of population genetic structure in lowland tropical plant species is highly relevant to our knowledge of increasingly fragmented forests and to the conservation of threatened species. Specific studies are particularly needed for taxa whose population dynamics are further impacted by human harvesting practices. One such case is the fishtail or xaté palm (Chamaedorea ernesti-augusti) of Central America, whose wild-collected leaves are becoming progressively more important to the global ornamental industry. We use microsatellite markers to describe the population genetics of this species in Belize and test the effects of climate change and deforestation on its recent and historical effective population size. Results We found high levels of inbreeding coupled with moderate or high allelic diversity within populations. Overall high gene flow was observed, with a north and south gradient and ongoing differentiation at smaller spatial scales. Immigration rates among populations were more difficult to discern, with minimal evidence for isolation by distance. We infer a tenfold reduction in effective population size ca. 10,000 years ago, but fail to detect changes attributable to Mayan or contemporary deforestation. Conclusion Populations of C. ernesti-augusti are genetically heterogeneous demes at a local spatial scale, but are widely connected at a regional level in Belize. We suggest that the inferred patterns in population genetic structure are the result of the colonization of this species into Belize following expansion of humid forests in combination with demographic and mating patterns. Within populations, we hypothesize that low aggregated population density over large areas, short distance pollen dispersal via thrips, low adult survival, and low fruiting combined with early flowering may contribute towards local inbreeding via genetic drift. Relatively high levels of regional connectivity are likely the result of animal-mediated long-distance seed dispersal. The greatest present threat to the species is the potential onset of inbreeding depression as the result of increased human harvesting activities. Future genetic studies in understory palms should focus on both fine-scale and landscape-level genetic structure.

Cycads are the only early seed plants that have evolved a specialized root to host endophytic bacteria that fix nitrogen. To provide evolutionary and functional insights into this million-year old symbiosis, we investigate endophytic bacterial sub-communities isolated from coralloid roots of species from Dioon (Zamiaceae) sampled from their natural habitats. We employed a sub-community co-culture experimental strategy to reveal both predominant and rare bacteria, which were characterized using phylogenomics and detailed metabolic annotation. Diazotrophic plant endophytes, including Bradyrhizobium, Burkholderia, Mesorhizobium, Rhizobium, and Nostoc species, dominated the epiphyte-free sub-communities. Draft genomes of six cyanobacteria species were obtained after shotgun metagenomics of selected sub-communities. These data were used for whole-genome inferences that suggest two Dioon- specific monophyletic groups, and a level of specialization characteristic of co-evolved symbiotic relationships. Furthermore, the genomes of these cyanobacteria were found to encode unique biosynthetic gene clusters, predicted to direct the synthesis of specialized metabolites, mainly involving peptides. After combining genome mining with detection of pigment emissions using multiphoton excitation fluorescence microscopy, we also show that Caulobacter species co-exist with cyanobacteria, and may interact with them by means of a novel indigoidine-like specialized metabolite. We provide an unprecedented view of the composition of the cycad coralloid root, including phylogenetic and functional patterns mediated by specialized metabolites that may be important for the evolution of ancient symbiotic adaptations. [ABSTRACT FROM AUTHOR]

In the present investigation, the morphological variability of 11 populations of wild piquin chili (Capsicum annuum var. glabriusculum) of the Mountain range Gorda and Semidesert of Queretaro (Municipalities of Arroyo Seco, Jalpan of Serra, Toliman and Cadereyta de Montes) and Guanajuato (Municipality of Xichu). The characterization was carried out under greenhouse conditions at the Technological Institute of Roque (ITR) located in Celaya, Guanajuato, Mexico. The 44 characters were recorded in seedling, plant, flowering, fruit maturity and seed. The principal component analysis (CP) showed that the first three components explained 56.6% of the total morphological variability. The CP1 was explained by the characteristics of weight (0.326), width (0.301) and fruit length (0.271), leaf density (0.277) and seed diameter (0.297). In CP2, the variables that contributed most to the expression of the variation were width (0.329) and leaf pubescence (0.317) and finally, in CP3, the shape of the fruit (0.344) and color of the anthers (- 0.308) were the most important characters. On the other hand, the cluster analysis generated four groups, group I included the G3 (Rosa of Castilla), G2 (Palmitas The Tanque), G1 (The Tanque) populations, all of the Mountain range Gorda in Guanajuato. Group II was made up of population Q7 (The Patol, Querétaro). Group III was formed by population Q5 (Presa Jalpan, Querétaro) and finally, group IV was integrated by six populations, Q4 (San Antonio Tancoyol), Q8 (Higuerillas stream), Q6 (Higuerillas The Shote), Q2 (The Refugio solar-huerta), Q3 (Tancoyol Road to Tancoyol) and Q1 (The Chilar Refuge), all of the State of Querétaro. The morphological diversity found in this species tells us that this native plant should be conserved and that it can be easily integrated into a program of sustainable use of the flora of the region. [ABSTRACT FROM AUTHOR]

Abstract: The Mauritia flexuosa L.f. palm is known as the “tree of life” given its importance as fundamental food and construction resources for humans. The species is broadly distributed in wet habitats of Amazonia and dry habitats of the Amazon and Orinoco river basins and in the Cerrado savanna. We collected 179 individuals from eight different localities throughout these habitats and used microsatellites to characterize their population structure and patterns of gene flow. Overall, we found high genetic variation, except in one savanna locality. Gene flow between populations is largely congruent with river basins and the direction of water flow within and among them, suggesting their importance for seed dispersal. Further, rivers have had a higher frequency of human settlements than forested sites, contributing to population diversity and structure through increased human use and consumption of M. flexuosa along rivers. Gene flow patterns revealed that migrants are sourced primarily from within the same river basin, such as those from Madeira and Tapajós basins. Our work suggests that rivers and their inhabitants are a critical element of the landscape in Amazonia and have impacted the dispersal and subsequent distribution of tropical palm species, as shown by the patterns of genetic variation in M. flexuosa. [ABSTRACT FROM AUTHOR]