Ecophysiological response and morphological adjustment of Argania spinosa L. Skeels under contrasting climates: case study of marginal populations

In this paper, we investigated the seasonal physiological performance and morphological adjustment of Argania spinosa growing under contrasting climatic and biogeographic conditions.Two marginal populations were selected in the main distribution area of the species, one at the Northwest and the other one at the South-west. Trees from the North showed a Mediterranean pattern in Photosynthetic performances, exhibiting maximal carbon assimilation during spring and minimum in summer. In contrast, trees from the South showed a different pattern with maximum values recorded in winter and minimum in spring. Photochemical efficiency of PSII results evidenced the absence of damage to PSII in both sites, probably due to an efficient energy dissipation processed by carotenoid pigments. We recorded increased LMA values in the South, which improves drought resistance. Increasing stomatal length and decreasing stomatal density were registered during the drought season in both populations. A. Spinosa is sensitive to changes in the length of drought stress at its Southern limit. The scarcity of rainfall leading to persistent drought has limited the distribution of the species to the banks of dry Wadis and depressions, where it finds some water compensations during summer. In the North, the summer drought severely impacted the species carbon assimilation.

Use and abuse of the planet in non-rich regions: histories of fracking and windmills in a more than human geographical perspective

<abstract> <p>Remote and marginal areas with scarce and vulnerable populations are "comfortable" settings and suitable places for the development of new extractive activities for energy production. Fracking and modern windmills are often controversial activities in marginal areas for native and local populations, with varying political positions from local elites. The new scalar policies associated with the energy project introduce some of the resistance strategies in the form of more than human geographies or hybrid spatial relationships that characterize recent human geography. This paper explores and suggests possible ways of integrating local interests with regional or national policies based on the "health" of marginal populations, marginal rather than human materiality's and marginal more-than-human.</p> </abstract>

On limits of the distribution range of the Crimean rock lizard Darevskia lindholmi (Sauria: Lacertidae)

New data on the boundaries of the distribution range of the Lindholm rock lizard (Darevskia lindholmi), an endemic of the Crimean Peninsula, are presented. This petrophilous lizard inhabit a wide range of biotopes in various landscape levels of the Mountainous Crimea. The upper boundary of D. lindholmi distribution in the southwest of the Main Range of the Crimean Mountains reaches an elevation of 1,520 m a.s.l. (Ai-Petrinskaya Yayla, KemalEgerek Mountain), while on the other high uplands with altitudes above 1.5 km and colder climate (Babugan and Chatyrdag), the species was traced only up to 1,250–1,320 m a.s.l. The northern border of D. lindholmi range in the western part of the Crimean Mountains runs along the Outer Foothill Range (the right bank of the Alma River), while in the eastern part it corresponds the northernmost rocky massifs of the Inner Foothill Range to the north of 45º N latitude. Isolated marginal populations found in the forest-steppe or phrygana-steppe landscapes of the Foothills and arid Southeastern Coast differs significantly in their distance from the main habitat of the species, lizards’ abundance and density. A hypothetical history of the formation of the current range of the Lindholm lizard is discussed.

Evolution of Autonomous Selfing in Marginal Habitats: Spatiotemporal Variation in the Floral Traits of the Distylous Primula wannanensis

Outcrossing plant species are more likely to exhibit autonomous selfing in marginal habitats to ensure reproduction under conditions of limited pollinator and/or mate availability. Distyly is a classical paradigm that promotes outcrossing; however, little is known about the variation in floral traits associated with distylous syndrome in marginal populations. In this study, we compared the variation in floral traits including stigma and anther height, corolla tube length, herkogamy, and corolla diameter between the central and peripheral populations of the distylous Primula wannanensis, and assessed the variation of floral traits at early and late florescence stages for each population. To evaluate the potential consequences of the variation in floral traits on the mating system, we investigated seed set in each population under both open-pollinated and pollinator-excluded conditions. The flower size of both short- and long-styled morphs was significantly reduced in late-opening flowers compared with early opening flowers in both central and peripheral populations. Sex-organ reciprocity was perfect in early opening flowers; however, it was largely weakened in the late-opening flowers of peripheral populations compared with central populations. Of these flowers, disproportionate change in stigma height (elongated in S-morph and shortened in L-morph) was the main cause of reduced herkogamy, and seed set was fairly high under pollinator-excluded condition. Our results provide empirical support for the hypothesis on the evolution of delayed autonomous selfing in marginal populations of distylous species. Unsatisfactory pollinator service is likely to have promoted reproductive assurance of distylous plants with largely reduced herkogamy mimicking “homostyles.”

The costs and benefits of dispersal in small populations

Dispersal has three major effects on adaptation. First, the gene flow mixes alleles adapted to different environments, potentially hindering (swamping) adaptation. Second, it inflates genetic variance: this aids adaptation to spatially (and temporally) varying environments but if selection is hard, it lowers the mean fitness of the population. Third, neighbourhood size, which determines how weak genetic drift is, increases with dispersal -- when genetic drift is strong, increase of neighbourhood size with dispersal aids adaptation. In this note I focus on the role of dispersal in environments which change smoothly across space, and when local populations are quite small such that genetic drift has a significant effect. Using individual-based simulations, I show that in small populations, even leptokurtic dispersal benefits adaptation, by reducing the power of genetic drift. This has implications for management of small marginal populations: increased gene flow appears beneficial as long as adaptations involves a quantitative, rather than a discrete, trait. However, heavily leptokurtic dispersal will swamp continuous adaptation along steep environmental gradients so that only patches of locally adapted subpopulations remain.

Managing Uncertainty in Scots Pine Range-Wide Adaptation Under Climate Change

Forests provide important ecosystem services and renewable materials. Yet, under a future climate, optimal conditions will likely shift outside the current range for some tree species. This will challenge the persistence of populations to rely on inherent plasticity and genetic diversity to acclimate or adapt to future uncertain conditions. An opportunity to study such processes is offered by Scots pine (Pinus sylvestris L.), a forest tree with a large distribution range including populations locally adapted to a wide variety of environments, which hinders a range-wide assessment of the species to climate change. Here we evaluate tree height growth uncertainty of Scots pine marginal populations in Spain and the Nordic countries linked to their genetic adaptation promoted by different climatic drivers. Our aims are to: (i) review the main climatic drivers of Scots pine adaptation across its range; (ii) undertake provenance-based modeling and prediction of tree height under current and future climate scenarios including four representative concentration pathways (RCPs) and five general circulation models (GCMs) at two extremes of its climatic niche; (iii) estimate uncertainty in population tree height linked to the main drivers of local adaptation that may change among RCPs and GCMs in the Nordic countries and Spain. Our models revealed that tree height adaptation is mostly driven by drought in Spain and by photoperiod in the Nordic countries, whereas the literature review also highlighted temperature as a climatic driver for the Nordic region. Model predictions for the Nordic countries showed an overall increase in tree height but with high uncertainty in magnitude depending on the RCPs and GCMs whereas predictions for Spain showed tree height to be maintained in the north and reduced in the south, but with similar magnitudes among RCPs and GCMs. Both models predicted tree height outside the data range used to develop the models (extrapolation). Predictions using higher emission RCPs resulted in larger extrapolated areas, constituting a further source of uncertainty. An expanded network of Scots pine field trials throughout Europe, facilitated by data collection and international research collaboration, would limit the need for uncertain predictions based on extrapolation.

Landscape and climatic features drive genetic differentiation processes in a South American coastal plant

Background Historical and ecological processes shape patterns of genetic diversity in plant species. Colonization to new environments and geographical landscape features determine, amongst other factors, genetic diversity within- and differentiation between-populations. We analyse the genetic diversity and population structure of Calibrachoa heterophylla to infer the influence of abiotic landscape features on the level of gene flow in this coastal species of the South Atlantic Coastal Plain. Results The C. heterophylla populations located on early-deposited coastal plain regions show higher genetic diversity than those closer to the sea. The genetic differentiation follows a pattern of isolation-by-distance. Landscape features, such as water bodies and wind corridors, and geographical distances equally explain the observed genetic differentiation, whereas the precipitation seasonality exhibits a strong signal for isolation-by-environment in marginal populations. The estimated levels of gene flow suggest that marginal populations had restricted immigration rates enhancing differentiation. Conclusions Topographical features related to coastal plain deposition history influence population differentiation in C. heterophylla. Gene flow is mainly restricted to nearby populations and facilitated by wind fields, albeit without any apparent influence of large water bodies. Furthermore, differential rainfall regimes in marginal populations seem to promote genetic differentiation.

New adaptive peaks for crops – an example from improvement of drought-resilience of sorghum in Ethiopia

As the center of diversity for sorghum [Sorghum bicolor (L.) Moench], elite cultivars selected in Ethiopia are of central importance to sub-Saharan food security. Despite being presumably well adapted to their center of diversity, elite Ethiopian sorghums nonetheless experience constraints to productivity, for example associated with shifting rainfall patterns associated with climate change. A sorghum backcross nested association mapping (BC-NAM) population developed by crossing thirteen diverse lines pre-identified to have various drought resilience mechanisms, with an Ethiopian elite cultivar, Teshale, was tested under three rain-fed environments in Ethiopia. 27, 15, and 15 QTLs with predominantly small additive effects were identified for days to flowering, days to maturity, and plant height, respectively. Many associations detected in this study corresponded closely to known or candidate genes or previously mapped QTLs, supporting their validity. Field tests show drought resilience to be improved by incorporation of adaptations from the diverse donor lines. The expectation that genotypes such as Teshale from near the center of diversity tend to have a history of strong balancing selection, with novel variations more likely to persist in small marginal populations, was strongly supported in that for these three traits, nearly equal numbers of alleles from the donor lines conferred increases and decreases in phenotype relative to the Teshale allele. Such rich variation provides a foundation for selection to traverse a 'valley' of reduced yield and arrive at a new 'adaptive peak', exemplifying the nature of efforts that may be necessary to adapt many crops to new climate extremes.

Millets as Nutre Cereals

Among the growing population (136.64 crs as per2019) many people experience scarcity of food and all. In the 2020 Global Hunger Index, India ranks 94th out of the 107 countries with sufficient data to calculate 2020 GHI scores. With a score of 27.2, India has a level of hunger that is serious (www.un.org/). The United Nations (UN) Food and Agriculture Organization (FAO) predicts that the on-going COVID-19 pandemic will increase this number as developing countries are double-hit by disease and hunger (www.fao.org/2019-ncov/q-and-a/) Disruptions in global supply chains, economic consequences (i.e., loss of jobs and incomes), the ban on the export of agricultural commodities, and price increases are the major reasons for this crisis. Although much attention is being given to the development of vaccines, therapeutic molecules, and preventive measures to combat COVID-19, the invisible threat to the lives and livelihoods of marginal populations through hunger and malnutrition remains largely unaddressed. The focus of the 2019 Global hunger index on ‘The Challenge of Hunger and Climate Change’ underlines the impacts of changing climates on agriculture that include crop failures owing to problems such as seasonal fluctuations, increased insect and pest attacks, and broad-spectrum infection by potential pathogens (www.globalhungerindex.org/).Supplying food grains is an immediate measure to aid the affected population, whereas devising long-term plans to prevent such challenges is the need of the hour. That said, the possibility of a second and third wave of COVID-19 in the near future should not be ignored. In such a case, the UN World Food Programme predicts (UN-WFP; https://insight.wfp.org/) that death due to lack of food would outnumber deaths caused by disease infection. The importance of crop diversity and of mainstreaming underutilized crops that could serve as functional foods has been pointed out before; however, identifying the best candidates of underutilized crops and deploying crop improvement strategies to release better varieties is still in a nascent stage. Mayes et al. Other plant species, including tubers, legumes, and leafy vegetables, also fall within the criteria of underutilized species; however, emphasis is given to small millets because they are capable of reducing the overdependence on major cereals. Three major cereals, namely rice, wheat, and maize, cater for up to 60% of the global food requirements, and this is one of the plausible causes of food and nutritional inadequacies in the hunger hotspots where these crops are largely imported for consumption. Millets, although cultivated marginally in those regions, have the potential to address these inadequacies if their area of cultivation is increased and crop improvement strategies are devised and deployed.

Spatial Genetic Structure of Prunus mongolica in Arid Northwestern China Based on RAD Sequencing Data

The extensive range of sand deserts, gravel deserts, and recent human activities have shaped habitat fragmentation of relict and endangered plants in arid northwestern China. Prunus mongolica is a relict and endangered shrub that is mainly distributed in the study area. In the present study, population genomics was integrated with a species distribution model (SDM) to investigate the spatial genetic diversity and structure of P. mongolica populations in response to habitat fragmentation and create a proposal for the conservation of this endangered species. The results showed that the northern marginal populations were the first isolated from other populations. The SDM suggested that these marginal populations had low levels of habitat suitability during the glacial period. They could not obtain migration corridors, and thus possessed low levels of gene flow connection with other populations. Additionally, several populations underwent secondarily geographical isolation from other central populations, which preserved particular genetic lineages. Genetic diversity was higher in southern populations than in northern ones. It was concluded that long-term geographical isolation after historical habitat fragmentation promoted the divergence of marginal populations and refugial populations along mountains from other populations. The southern populations could have persisted in their distribution ranges and harbored higher levels of genetic diversity than the northern populations, whose distribution ranges fluctuated in response to paleoclimatic changes. We propose that the marginal populations of P. mongolica should be well considered in conservation management.