Ultramafic vegetation and soils in the circumboreal region of the Northern Hemisphere

The Evolutionary Genomics of Serpentine Adaptation

Serpentine barrens are among the most challenging settings for plant life. Representing a perfect storm of hazards, serpentines consist of broadly skewed elemental profiles, including abundant toxic metals and low nutrient contents on drought-prone, patchily distributed substrates. Accordingly, plants that can tolerate the challenges of serpentine have fascinated biologists for decades, yielding important insights into adaptation to novel ecologies through physiological change. Here we highlight recent progress from studies which demonstrate the power of serpentine as a model for the genomics of adaptation. Given the moderate - but still tractable - complexity presented by the mix of hazards on serpentine, these venues are well-suited for the experimental inquiry of adaptation both in natural and manipulated conditions. Moreover, the island-like distribution of serpentines across landscapes provides abundant natural replicates, offering power to evolutionary genomic inference. Exciting recent insights into the genomic basis of serpentine adaptation point to a partly shared basis that involves sampling from common allele pools available from retained ancestral polymorphism or via gene flow. However, a lack of integrated studies deconstructing complex adaptations and linking candidate alleles with fitness consequences leaves room for much deeper exploration. Thus, we still seek the crucial direct link between the phenotypic effect of candidate alleles and their measured adaptive value - a prize that is exceedingly rare to achieve in any study of adaptation. We expect that closing this gap is not far off using the promising model systems described here.

Toxic metal(loid)s contamination and potential human health risk assessment in the vicinity of century-old copper smelter, Karabash, Russia

Active smelters release high concentration of multiple toxic metal(loid)s into the environment, degrading the soil cover and posing high risks to human health. The present study investigates Cu along with other metal(loids) such as As, Cd, Hg, Co, Mn, Pb and Zn in the soil collected from the vicinity of Cu smelter, Karabash, Russia, and potential health risks to local children and adults were assessed. The average concentrations of Cu, Zn, Pb, As, Cd, and Hg in the exposed soil were 2698, 1050, 702, 392, 9 and 2 mg kg^-1, respectively, which was significantly (p < 0.05) much higher than reference soil: Cu(107), As(18), Cd(0.3), Hg(0.2), Pb(54) and Zn(125) mg kg^-1. The enrichment factor (EF) for Cu, Hg, Pb and Zn showed significant enrichment, whereas very high enrichment was recorded for As (20.0) and Cd (27.6) suggesting the soil was severely affected by smelting activities. The pollution load index was tenfold higher than the acceptable level of one, whereas potential ecological risk factor showed very high potential risks of Cd and Hg, along with a considerable ecological risk of As and Cu. Very high ecological risk index of 1810 indicates severe degradation of environmental ecosystem. The results of EF, Pearson correlation and principle component analysis were complementary and suggest the anthropogenic source of contamination for Cu, As, Pb, Hg and Cd. The present result suggests As > Pb > Cu in the exposed soil were the major contributors for the health risks and account for 81%, 12% and 5%, and 77%, 12% and 8% of hazard quotient for children and adults, respectively. Noticeably, the health risks to local children dwelling in the vicinity of Cu smelter were 12 and 20 times higher than to adult and the acceptable level of one, respectively. Therefore, in order to reduce the health risk due to metal(loid)s, mitigation measures are needed to remediate the pollution of the exposed soil.

Climate Change and Edaphic Specialists: Irresistible Force Meets Immovable Object?

Species exposed to anthropogenic climate change can acclimate, adapt, move, or be extirpated. It is often assumed that movement will be the dominant response, with populations tracking their climate envelopes in space, but the numerous species restricted to specialized substrates cannot easily move. In warmer regions of the world, such edaphic specialists appear to have accumulated in situ over millions of years, persisting despite climate change by local movements, plastic responses, and genetic adaptation. However, past climates were usually cooler than today and rates of warming slower, while edaphic islands are now exposed to multiple additional threats, including mining. Modeling studies that ignore edaphic constraints on climate change responses may therefore give misleading results for a significant proportion of all taxa.

The Effects of Edaphic and Climatic Factors on Secondary Lichen Chemistry: A Case Study Using Saxicolous Lichens

Diversity of secondary lichen metabolites and their relationship to substrate and environmental parameters were studied in saxicolous lichens in the Middle and South Urals of Russia. Atranorin, usnic acid, gyrophoric acid, zeorin, norstictic acid, antraquinones and stictic acid were found in 73, 42, 41, 37, 36, 35 and 32 species, respectively, of 543 taxa collected. One hundred and ninety six species (i.e., 36% of total species documented) contained no secondary metabolites. Spectra of secondary metabolites of crustose lichens varied on different rock types, while in fruticose and foliose groups only those species without lichen acids were dependent on the substrate type. In Canonical Correspondence Analysis, secondary lichen metabolites were subdivided into groups depending on the concentration of Ca and metals in the substrate. Gyrophoric, lobaric, psoromic, rhizocarpic and stictic acids were common in crustose lichens in metal-poor habitats; species with antraquinones and lichens without any secondary metabolites were most abundant on limestone (alkalic and metal-poor), while other common lichen metabolites had no to minimal dependence on the chemistry of the substrate. The two additional abiotic factors affecting the composition of secondary metabolites were the maximum temperature of the warmest month and elevation. Our results suggest a range of possible relationships exist among lichen acids, rocks and climatic parameters. Furthermore, the same metabolite may affect both accumulation of metals and stress tolerance under unfavorable conditions.