The classification of the legume family proposed here addresses the long-known non-monophyly of the traditionally recognised subfamily Caesalpinioideae, by recognising six robustly supported monophyletic subfamilies. This new classification uses as its framework the most comprehensive phylogenetic analyses of legumes to date, based on plastid matK gene sequences, and including near-complete sampling of genera (698 of the currently recognised 765 genera) and ca. 20% (3696) of known species. The matK gene region has been the most widely sequenced across the legumes, and in most legume lineages, this gene region is sufficiently variable to yield well-supported clades. This analysis resolves the same major clades as in other phylogenies of whole plastid and nuclear gene sets (with much sparser taxon sampling). Our analysis improves upon previous studies that have used large phylogenies of the Leguminosae for addressing evolutionary questions, because it maximises generic sampling and provides a phylogenetic tree that is based on a fully curated set of sequences that are vouchered and taxonomically validated. The phylogenetic trees obtained and the underlying data are available to browse and download, facilitating subsequent analyses that require evolutionary trees. Here we propose a new community-endorsed classification of the family that reflects the phylogenetic structure that is consistently resolved and recognises six subfamilies in Leguminosae: a recircumscribed Caesalpinioideae DC., Cercidoideae Legume Phylogeny Working Group (stat. nov.), Detarioideae Burmeist., Dialioideae Legume Phylogeny Working Group (stat. nov.), Duparquetioideae Legume Phylogeny Working Group (stat. nov.), and Papilionoideae DC. The traditionally recognised subfamily Mimosoideae is a distinct clade nested within the recircumscribed Caesalpinioideae and is referred to informally as the mimosoid clade pending a forthcoming formal tribal and/or cladebased classification of the new Caesalpinioideae. We provide a key for subfamily identification, descriptions with diagnostic charactertistics for the subfamilies, figures illustrating their floral and fruit diversity, and lists of genera by subfamily. This new classification of Leguminosae represents a consensus view of the international legume systematics community; it invokes both compromise and practicality of use.

A new subfamily classification of the leguminosae based on a taxonomically comprehensive phylogeny

Evolution of secondary metabolites in legumes (Fabaceae)

A revision of the Leguminosae of Madagascar is soon to be completed, covering some 670 species (c. 565 native to Madagascar of which 449 endemic) including 6 new genera and 121 new species. It has provided the basis for a pilot project applying computer mapping (GIS) to the investigation of ecological parameters which determine the extent of species distributions. Vegetation maps, based on these parameters, are being used for planning and managing the conservation of biodiversity in Madagascar.

The Leguminosae of Madagascar

Seed dormancy is expected to provide ecological advantages by adjusting germination to the favorable growth period. However, many species produce nondormant seeds, particularly in wet tropical forests, a biogeographic pattern that is not well accounted for in current models. We hypothesized that the global distribution of dormant seeds derives from their adaptive value in predictably fluctuating (i.e. seasonal) environments. However, the advantage conferred by dormancy might ultimately depend on other seed attributes, particularly size. This general model was tested within a phylogenetically informed framework using a data set comprising > 216 000 world-wide observations of Fabaceae, spanning three orders of magnitude in seed size and including both dormant and nondormant seeds. Our results confirmed our hypothesis: nondormant seeds can only evolve in climates with long growing seasons and/or in lineages that produce larger seeds. Conversely, dormancy should be evolutionarily stable in temperate lineages with small seeds. When the favorable season is fleeting, seed dormancy is the only adaptive strategy. Based on these results, we predict that, within a given lineage, taxa producing larger, nondormant seeds will necessarily predominate in aseasonal environments, while plants bearing small, dormant seeds will be dominant under short growing seasons.

https://nph.onlinelibrary.wiley.com/doi/epdf/10.1111/nph.14498

Global biogeography of seed dormancy is determined by seasonality and seed size: a case study in the legumes.

Secondary tropical forests that are in a state of regeneration following clearing for agriculture are now more abundant than primary forests. Yet, despite their large spatial extent and important role in the global carbon (C) cycle, secondary tropical forests are understudied, which challenges our ability to predict how tropical landscapes will respond to future disturbance and global change. We summarize research advances on alterations to C and nutrient dynamics during reforestation and how these are influenced by ecosystem state factors. During forest succession, aboveground biomass stocks and litter fluxes increase in a predictable way, but patterns in soil C dynamics are highly variable. The heterogeneous response of nutrients to reforestation is influenced by multiple factors, including losses incurred during prior land use and management. In contrast to primary tropical forests, where productivity is often limited by rock-derived nutrients, secondary forest growth may be more limited by nutrients f...

Ecosystem Processes and Biogeochemical Cycles in Secondary Tropical Forest Succession

While many plant species are considered threatened under anthropogenic pressure, it remains uncertain how rapidly we are losing plant species diversity. To fill this gap, we propose a Global Legume Diversity Assessment (GLDA) as the first step of a global plant diversity assessment. Here we describe the concept of GLDA and its feasibility by reviewing relevant approaches and data availability. We conclude that Fabaceae is a good proxy for overall angiosperm diversity in many habitats and that much relevant data for GLDA are available. As indicators of states, we propose comparison of species richness with phylogenetic and functional diversity to obtain an integrated picture of diversity. As indicators of trends, species loss rate and extinction risks should be assessed. Specimen records and plot data provide key resources for assessing legume diversity at a global scale, and distribution modeling based on these records provide key methods for assessing states and trends of legume diversity. GLDA has started in Asia, and we call for a truly global legume diversity assessment by wider geographic collabora- tions among various scientists.

/pdf/global-legume-diversity-assessment-concepts-key-indicators-2j1ve01qrc.pdf

Chen Bin

Papers

Global legume diversity assessment: Concepts, key indicators, and strategies