Cost-effective restoration for carbon sequestration across Brazil's biomes.

Tropical ecosystems are central to the global focus on halting and reversing habitat destruction as a means of mitigating carbon emissions. Brazil has been highlighted as a vital part of global climate agreements because, whilst ongoing land-use change causes it to be the world's fifth biggest greenhouse gas emitting country, it also has one of the greatest potentials to implement ecosystem restoration. Global carbon markets provide the opportunity of a financially viable way to implement restoration projects at scale. However, except for rainforests, the restoration potential of many major tropical biomes is not widely recognised, with the result that carbon sequestration potential may be squandered. We synthesize data on land availability, land degradation status, restoration costs, area of native vegetation remaining, carbon storage potential and carbon market prices for 5475 municipalities across Brazil's major biomes, including the savannas and tropical dry forests. Using a modelling analysis, we determine how fast restoration could be implemented across these biomes within existing carbon markets. We argue that even with a sole focus on carbon, we must restore other tropical biomes, as well as rainforests, to effectively increase benefits. The inclusion of dry forests and savannas doubles the area which could be restored in a financially viable manner, increasing the potential CO2e sequestered >40 % above that offered by rainforests alone. Importantly, we show that in the short-term avoiding emissions through conservation will be necessary for Brazil to achieve it's 2030 climate goal, because it can sequester 1.5 to 4.3 Pg of CO2e by 2030, relative to 0.127 Pg CO2e from restoration. However, in the longer term, restoration across all biomes in Brazil could draw down between 3.9 and 9.8 Pg of CO2e from the atmosphere by 2050 and 2080.

Tracking of Host Defenses and Phylogeny During the Radiation of Neotropical Inga-Feeding Sawflies (Hymenoptera; Argidae).

Coevolutionary theory has long predicted that the arms race between plants and herbivores is a major driver of host selection and diversification. At a local scale, plant defenses contribute significantly to the structure of herbivore assemblages and the high alpha diversity of plants in tropical rain forests. However, the general importance of plant defenses in host associations and divergence at regional scales remains unclear. Here, we examine the role of plant defensive traits and phylogeny in the evolution of host range and species divergence in leaf-feeding sawflies of the family Argidae associated with Neotropical trees in the genus Inga throughout the Amazon, the Guiana Shield and Panama. Our analyses show that the phylogenies of both the sawfly herbivores and their Inga hosts are congruent, and that sawflies radiated at approximately the same time, or more recently than their Inga hosts. Analyses controlling for phylogenetic effects show that the evolution of host use in the sawflies associated with Inga is better correlated with Inga chemistry than with Inga phylogeny, suggesting a pattern of delayed host tracking closely tied to host chemistry. Finally, phylogenetic analyses show that sister species of Inga-sawflies are dispersed across the Neotropics, suggesting a role for allopatric divergence and vicariance in Inga diversification. These results are consistent with the idea that host defensive traits play a key role not only in structuring the herbivore assemblages at a single site, but also in the processes shaping host association and species divergence at a regional scale.

Recent colonization of the Galápagos by the tree Geoffroea spinosa Jacq. (Leguminosae).

This study puts together genetic data and an approximate bayesian computation (ABC) approach to infer the time at which the tree Geoffroea spinosa colonized the Galápagos Islands. The genetic diversity and differentiation between Peru and Galápagos population samples, estimated using three chloroplast spacers and six microsatellite loci, reveal significant differences between two mainland regions separated by the Andes mountains (Inter Andean vs. Pacific Coast) as well as a significant genetic differentiation of island populations. Microsatellites identify two distinct geographical clusters, the Galápagos and the mainland, and chloroplast markers show a private haplotype in the Galápagos. The nuclear distinctiveness of the Inter Andean populations suggests current restricted pollen flow, but chloroplast points to cross-Andean dispersals via seeds, indicating that the Andes might not be an effective biogeographical barrier. The ABC analyses clearly point to the colonization of the Galápagos within the last 160,000 years and possibly as recently as 4750 years ago (475 generations). Founder events associated with colonization of the two islands where the species occurs are detected, with Española having been colonized after Floreana. We discuss two nonmutually exclusive possibilities for the colonization of the Galápagos, recent natural dispersal vs. human introduction.

The history of Seasonally Dry Tropical Forests in eastern South America: inferences from the genetic structure of the tree Astronium urundeuva (Anacardiaceae).

Today, the Seasonally Dry Tropical Forests (SDTF) of eastern South America occur as large, well-defined nuclei (e.g. Caatinga in the northeast) and as smaller enclaves within other vegetations (e.g. Cerrado and Chaco). In order to infer the way the present SDTF distribution was attained, the genetic structure of Astronium urundeuva, a tree confined to SDTF, was assessed using two chloroplast spacers and nine microsatellite loci. Five haplotypes were identified, whose distribution was spatially structured. The distribution of the two most common and divergent haplotypes suggested former vicariance and progressive divergence due to isolation. More recent range expansions of these two lineages subsequently occurred, leading to a secondary contact at the southern limit of the Caatinga SDTF nucleus. The multilocus-Bayesian approach using microsatellites consistently identified three groups of populations (Northeast, Central and Southwest). Isolation by distance was found in Northeast and Southwest groups whereas admixture was detected in the Central group, located at the transition between Caatinga and Cerrado domains. All together, the results support the existence of range expansions and secondary contact in the Central group. This study provides arguments that favour the existence of a previously more continuous formation of SDTF in eastern South America.

Do farmers reduce genetic diversity when they domesticate tropical trees? A case study from Amazonia.

Agroforestry ecosystems may be an important resource for conservation and sustainable use of tropical trees, but little is known of the genetic diversity they contain. Inga edulis, a widespread indigenous fruit tree in South America, is used as a model to assess the maintenance of genetic diversity in five planted vs. five natural stands in the Peruvian Amazon. Analysis of five SSR (simple sequence repeat) loci indicated lower allelic variation in planted stands [mean corrected allelic richness 31.3 (planted) and 39.3 (natural), P = 0.009]. Concerns regarding genetic erosion in planted Amazonian tree stands appear valid, although allelic variation on-farm is still relatively high.

Rapid diversification of a species-rich genus of neotropical rain forest trees.

Species richness in the tropics has been attributed to the gradual accumulation of species over a long geological period in stable equatorial climates or, conversely, to speciation in response to late Tertiary geological events and unstable Pleistocene climates. DNA sequence data are consistent with recent diversification in Inga, a species-rich neotropical tree genus. We estimate that speciation was concentrated in the past 10 million years, with many species arising as recently as 2 million years ago. This coincides with the more recent major uplifts of the Andes, the bridging of the Isthmus of Panama, and Quaternary glacial cycles. Inga may be representative of other species-rich neotropical genera with rapid growth and reproduction, which contribute substantially to species numbers in the world's most diverse flora.

The dalbergioid legumes (Fabaceae): delimitation of a pantropical monophyletic clade.

A monophyletic pantropical group of papilionoid legumes, here referred to as the "dalbergioid" legumes, is circumscribed to include all genera previously referred to the tribes Aeschynomeneae and Adesmieae, the subtribe Bryinae of the Desmodieae, and tribe Dalbergieae except Andira, Hymenolobium, Vatairea, and Vataireopsis. This previously undetected group was discovered with phylogenetic analysis of DNA sequences from the chloroplast trnK (including matK) and trnL introns, and the nuclear ribosomal 5.8S and flanking internal transcribed spacers 1 and 2. All dalbergioids belong to one of three well-supported subclades, the Adesmia, Dalbergia, and Pterocarpus clades. The dalbergioid clade and its three main subclades are cryptic in the sense that they are genetically distinct but poorly, if at all, distinguished by nonmolecular data. Traditionally important taxonomic characters, such as arborescent habit, free stamens, and lomented pods, do not provide support for the major clades identified by the molecular analysis. Short shoots, glandular-based trichomes, bilabiate calyces, and aeschynomenoid root nodules, in contrast, are better indicators of relationship at this hierarchical level. The discovery of the dalbergioid clade prompted a re-analysis of root nodule structure and the subsequent finding that the aeschynomenoid root nodule is synapomorphic for the dalbergioids.