Local adaptation of seed and seedling traits along a natural aridity gradient may both predict and constrain adaptive responses to climate change

Herbivory and water availability interact to shape the adaptive landscape in the perennial forb, Boechera stricta

Abiotic and biotic factors interact to influence phenotypic evolution; however, identifying the causal agents of selection that drive the evolution and expression of traits remains challenging. In a field common garden, we manipulated water availability and herbivore abundance across 3 years, and evaluated clinal variation in functional traits and phenology, phenotypic plasticity, local adaptation, and selection using diverse accessions of the perennial forb, Boechera stricta. Consistent with expectations, drought stress exacerbated damage from herbivores. We found significant plasticity and genetic clines in foliar and phenological traits. Water availability and herbivory interacted to exert selection, even on traits like flowering duration, which showed no clinal variation. Furthermore, the direction of selection on specific leaf area in response to water availability mirrored the genetic cline and plasticity, suggesting that variation in water levels across the landscape influences the evolution of this trait. Finally, both herbivory and water availability likely contribute to local adaptation. This work emphasizes the additive and synergistic roles of abiotic and biotic factors in shaping phenotypic variation across environmental gradients.

The geographic scale of population-level variation in growth and nodulation differs for two species of prairie clover

PREMISE

Prairies are among the most threatened biomes due to changing patterns of climate and land use, yet information on genetic variation in key species that would inform conservation is often limited. We assessed evidence for the geographic scale of population-level variation in growth of two species of prairie clover and of their symbiotic associations with nitrogen-fixing bacteria.

METHODS

Seed representing two species, Dalea candida and D. purpurea, from the same five source populations were planted into an experimental site in Minnesota. We assessed variation within and among source populations in plant growth and in numbers of nodules and evaluated the relationship of growth and nodulation levels.

RESULTS

Plant growth varied among source populations, with greater differences among populations of D. purpurea than of D. candida. We did not detect a relationship between plant growth and distance of source populations from the experimental site. Populations of both species were equally likely to develop nodules at the experimental site, but the numbers of nodules were lowest for the most distantly sourced populations. Plant growth was positively correlated with the number of nodules, and this relationship varied considerably within and among populations.

CONCLUSIONS

Environmental heterogeneity at local and regional scales maintains substantial levels of genetic variation in plant populations within remnant prairie preserves. Further, association with rhizobia at a restoration site can improve growth of widely sourced plant populations. The in situ maintenance of plant genetic variation and species diversity provides resources for conservation and maintenance of prairie biomes.

Seed quality as a proxy of climate-ready orphan legumes: the need for a multidisciplinary and multi-actor vision

In developing countries, orphan legumes stand at the forefront in the struggle against climate change. Their high nutrient value is crucial in malnutrition and chronic diseases prevention. However, as the 'orphan' definition suggests, their seed systems are still underestimated and seed production is scanty. Seed priming is an effective, sustainable strategy to boost seed quality in orphan legumes for which up-to-date guidelines are required to guarantee reliable and reproducible results. How far are we along this path? What do we expect from seed priming? This brings to other relevant questions. What is the socio-economic relevance of orphan legumes in the Mediterranean Basin? How to potentiate a broader cultivation in specific regions? The case study of the BENEFIT-Med (Boosting technologies of orphan legumes towards resilient farming systems) project, developed by multidisciplinary research networks, envisions a roadmap for producing new knowledge and innovative technologies to improve seed productivity through priming, with the long-term objective of promoting sustainability and food security for/in the climate-sensitive regions. This review highlights the existing drawbacks that must be overcome before orphan legumes could reach the state of 'climate-ready crops'. Only by the integration of knowledge in seed biology, technology and agronomy, the barrier existing between research bench and local agricultural fields may be overcome, generating high-impact technical innovations for orphan legumes. We intend to provide a powerful message to encourage future research in line with the United Nations Agenda 2030 for Sustainable Development.

Resurrected seeds from herbarium specimens reveal rapid evolution of drought resistance in a selfing annual

PREMISE

Increased aridity and drought associated with climate change are exerting unprecedented selection pressures on plant populations. Whether populations can rapidly adapt, and which life history traits might confer increased fitness under drought, remain outstanding questions.

METHODS

We utilized a resurrection ecology approach, leveraging dormant seeds from herbarium collections to assess whether populations of Plantago patagonica from the semi-arid Colorado Plateau have rapidly evolved in response to approximately ten years of intense drought in the region. We quantified multiple traits associated with drought escape and drought resistance and assessed the survival of ancestors and descendants under simulated drought.

RESULTS

Descendant populations displayed a significant shift in resource allocation, in which they invested less in reproductive tissues and relatively more in both above- and below-ground vegetative tissues. Plants with greater leaf biomass survived longer under terminal drought; moreover, even after accounting for the effect of increased leaf biomass, descendant seedlings survived drought longer than their ancestors.

CONCLUSIONS

Our results document rapid adaptive evolution in response to climate change in a selfing annual and suggest that shifts in tissue allocation strategies may underlie adaptive responses to drought in arid or semi-arid environments. This work also illustrates a novel approach, documenting that under specific circumstances, seeds from herbarium specimens may provide an untapped source of dormant propagules for future resurrection experiments.