The delayed and geographically heterogeneous diversification of flowering plant families
The Early Cretaceous (145–100 million years ago (Ma)) witnessed the rise of flowering plants (angiosperms), which ultimately lead to profound changes in terrestrial plant communities. However, palaeobotanical evidence shows that the transition to widespread angiosperm-dominated biomes was delayed until the Palaeocene (66–56 Ma). Important aspects of the timing and geographical setting of angiosperm diversification during this period, and the groups involved, remain uncertain. Ramírez-Barahona et al. address these aspects by constructing and dating a new and complete family-level phylogeny, which they integrate with 16 million geographic occurrence records for angiosperms on a global scale. We show substantial time lags (mean, 37–56 Myr) between the origin of families (stem age) and the diversification leading to extant species (crown ages) across the entire angiosperm tree of life. In turn, their results show that families with the shortest lags are overrepresented in temperate and arid biomes compared with tropical biomes.
Nature Ecology & Evolution
LeafMachine: Using machine learning to automate leaf trait extraction from digitized herbarium specimens
Weaver and colleagues trained LeafMachine on 2685 randomly sampled specimens from 138 herbaria and evaluated its performance on specimens spanning 20 diverse families and varying widely in resolution, quality, and layout. LeafMachine successfully extracted at least one leaf measurement from 82.0% and 60.8% of high‐ and low‐resolution images, respectively. Of the unmeasured specimens, only 0.9% and 2.1% of high‐ and low‐resolution images, respectively, were visually judged to have measurable leaves.
Applications in Plant Sciences
Strategies and support for Black, Indigenous, and people of colour in ecology and evolutionary biology
We know that it can be tough to be a person of colour working in ecology and evolution. Here is what has worked for us.
Nature Ecology & Evolution
Massive haplotypes underlie ecotypic differentiation in sunflowers
Species often include multiple ecotypes that are adapted to different environments. However, it is unclear how ecotypes arise and how their distinctive combinations of adaptive alleles are maintained despite hybridization with non-adapted populations. Here, by resequencing 1,506 wild sunflowers from 3 species (Helianthus annuus, Helianthus petiolaris and Helianthus argophyllus), Todesco and colleagues identify 37 large (1–100 Mbp in size), non-recombining haplotype blocks that are associated with numerous ecologically relevant traits, as well as soil and climate characteristics.
Plant secondary metabolites as defenses, regulators, and primary metabolites: the blurred functional trichotomy
Recent work unveils the limits of our current functional classification system for plant metabolites. Viewing secondary metabolites as integrated components of metabolic networks that are dynamically shaped by environmental selection pressures and transcend multiple trophic levels can improve our understanding of plant metabolism and plant–environment interactions.
The global abundance of tree palms
Muscarella et al. assembled a pantropical dataset of 2,548 forest plots (covering 1,191 ha) and quantified tree palm (i.e., ≥10 cm diameter at breast height) abundance relative to co‐occurring non‐palm trees. They compared the relative abundance of tree palms across biogeographical realms and tested for associations with palaeoclimate stability, current climate, edaphic conditions and metrics of forest structure.
Global Ecology and Biogeography
RefPlantNLR: a comprehensive collection of experimentally validated plant NLRs
Kourelis and Kamoun describe a comprehensive reference dataset of experimentally validated plant NLR immune receptors. RefPlantNLR consists of 415 NLRs from 31 genera belonging to 11 orders of flowering plants. They used RefPlantNLR to determine the canonical features of functionally validated plant NLRs. This reference dataset should prove useful for benchmarking NLR annotation tools, guiding comparative analyses of NLRs across the wide spectrum of plant diversity and identifying under-studied taxa.
Cytoskeletal organization in isolated plant cells under geometry control
The cytoskeleton, a network of polymers including microtubules and actin, supports many functions in cells. In plants, the cytoskeleton orientation is an important parameter dictating the direction of cell growth. While light, hormonal, or mechanical signals can affect the cytoskeleton organization, the role of cell geometry remains to be clarified. With a microwell-based approach, Durand-Smet et al. confined plant cells lacking walls in different geometries and found that the cytoskeletons align with the long axis in cells in rectangular wells. Basic geometrical rules of the microtubules are computationally modeled in three dimensions and reveal the role of severing proteins in the shape response, which was observed experimentally. These findings demonstrate how cell geometry feeds back on cytoskeletal organization in plant cells.
Good things take time – diversity effects on tree growth shift from negative to positive during stand development in boreal forests
Jucker et al. explore whether diversity effects on tree growth change predictably during stand development in Finland’s boreal forests. Using tree ring records from mature forests, they tested whether diameter growth trajectories of dominant tree species growing in mixture differed from those in monoculture. They then compared these results with data from the world’s longest running tree diversity experiment, where the same combinations of species sampled in mature forests were planted in 1999.
Journal of Ecology
The fungal collaboration gradient dominates the root economics space in plants
Plant economics run on carbon and nutrients instead of money. Leaf strategies aboveground span an economic spectrum from “live fast and die young” to “slow and steady,” but the economy defined by root strategies belowground remains unclear. Bergmann et al. take a holistic view of the belowground economy and show that root-mycorrhizal collaboration can short circuit a one-dimensional economic spectrum, providing an entire space of economic possibilities.