Phylogeographic analysis of North American populations of the parasitic herbaceous plant Monotropa hypopitys L. reveals a complex history of range expansion from multiple late glacial refugia

Aim We carried out a phylogeographic study across the range of the herbaceous plant species Monotropa hypopitys L. in North America to determine whether its current disjunct distribution is due to recolonization from separate eastern and western refugia after the Last Glacial Maximum (LGM). Location North America: Pacific Northwest and north‐eastern USA/south‐eastern Canada. Methods Palaeodistribution modelling was carried out to determine suitable climatic regions for M. hypopitys at the LGM. We analysed between 155 and 176 individuals from 39 locations spanning the species’ entire range in North America. Sequence data were obtained for the chloroplast rps2 gene (n = 168) and for the nuclear ITS region (n = 158). Individuals were also genotyped for eight microsatellite loci (n = 176). Interpolation of diversity values was used to visualize the range‐wide distribution of genetic diversity for each of the three marker classes. Minimum spanning networks were constructed showing the relationships between the rps2 and ITS haplotypes, and the geographical distributions of these haplotypes were plotted. The numbers of genetic clusters based on the microsatellite data were estimated using Bayesian clustering approaches. Results The palaeodistribution modelling indicated suitable climate envelopes for M. hypopitys at the LGM in both the Pacific Northwest and south‐eastern USA. High levels of genetic diversity and endemic haplotypes were found in Oregon, the Alexander Archipelago, Wisconsin, and in the south‐eastern part of the species’ distribution range. Main conclusions Our results suggest a complex recolonization history for M. hypopitys in North America, involving persistence in separate eastern and western refugia. A generally high degree of congruence between the different marker classes analysed indicated the presence of multiple refugia, with at least two refugia in each area. In the west, putative refugia were identified in Oregon and the Alexander Archipelago, whereas eastern refugia may have been located in the southern part of the species’ current distribution, as well as in the ‘Driftless Area’. These findings are in contrast to a previous study on the related species Orthilia secunda, which has a similar disjunct distribution to M. hypopitys, but which appears to have recolonized solely from western refugia.     

峨眉山世界遗产地植物多样性全球突出普遍价值及保护

该研究在申遗文本和大量文献资料的基础上,以峨眉山世界遗产地原生植物及植被群落为研究对象,从物种多样性、物种组成、植物区系、植被类型及垂直分布格局等方面,分析论证了峨眉山世界遗产地植物多样性的全球突出普遍价值,并简要概述了当前峨眉山世界遗产地植物受威胁状况以及在保护与发展中出现的问题。结果表明:(1)峨眉山世界遗产地目前拥有高等植物242科3 200种以上,特有植物、孑遗植物种类丰富。(2)与中国其他湿润性亚热带山地森林垂直带谱相比,峨眉山亚热带森林植被类型完整,常绿阔叶林东部类型在山地垂直带谱中占据显著地位,海拔上限最高,跨度最大,具有典型的亚热带常绿阔叶林东部亚区森林群落特点。(3)植物区系复杂,既有热带、亚热带和温带植物区系成份,又有中国—日本与中国—喜马拉雅植物区系分布。(4)受人为活动(旅游发展、基础设施建设等)和自然扰动(气候变暖、地质灾害等)影响,峨眉山世界遗产地植物多样性下降明显,珍稀濒危植物受威胁程度增加,典型群落面积退化,稳定性降低。建议在划定珍稀植物保护区,对植物栖息地进行专门保护的基础上,开展植物多样性、环境因子、人为活动动态监测,预见性地保护其突出普遍价值,实现世界遗产地的可持续发展。     

Prokaryotes in the WAIS Divide ice core reflect source and transport changes between Last Glacial Maximum and the early Holocene

We present the first long‐term, highly resolved prokaryotic cell concentration record obtained from a polar ice core. This record, obtained from the West Antarctic Ice Sheet (WAIS) Divide (WD) ice core, spanned from the Last Glacial Maximum (LGM) to the early Holocene (EH) and showed distinct fluctuations in prokaryotic cell concentration coincident with major climatic states. The time series also revealed a ~1,500‐year periodicity with greater amplitude during the Last Deglaciation (LDG). Higher prokaryotic cell concentration and lower variability occurred during the LGM and EH than during the LDG. A sevenfold decrease in prokaryotic cell concentration coincided with the LGM/LDG transition and the global 19 ka meltwater pulse. Statistical models revealed significant relationships between the prokaryotic cell record and tracers of both marine (sea‐salt sodium [ssNa]) and burning emissions (black carbon [BC]). Collectively, these models, together with visual observations and methanosulfidic acid (MSA) measurements, indicated that the temporal variability in concentration of airborne prokaryotic cells reflected changes in marine/sea‐ice regional environments of the WAIS. Our data revealed that variations in source and transport were the most likely processes producing the significant temporal variations in WD prokaryotic cell concentrations. This record provided strong evidence that airborne prokaryotic cell deposition differed during the LGM, LDG, and EH, and that these changes in cell densities could be explained by different environmental conditions during each of these climatic periods. Our observations provide the first ice‐core time series evidence for a prokaryotic response to long‐term climatic and environmental processes.     

Hidden diversity in forest soils: Characterization and comparison of terrestrial flatworm’s communities in two national parks in Spain

Terrestrial flatworms (Platyhelminthes, Tricladida, and Geoplanidae) belong to what is known as cryptic soil fauna of humid forests and are animals not easily found or captured in traps. Nonetheless, they have been demonstrated to be good indicators of the conservation status of their habitat as well as a good model to reconstruct the recent and old events affecting biodiversity. This is mainly due to their delicate constitution, their dependence on the integrity of their habitat, and their very low dispersal capacity. At present, little is known about their communities, except for some studies performed in Brazil. In this work, we analyze for the first time in Europe terrestrial flatworm communities. We have selected two protected areas belonging to the Red Española de Parques Nacionales. Our aims include performing a first study of the species richness and community structure for European terrestrial planarian species at regional and local scale. We evaluate the effect of type of forests in the community composition and flatworms’ abundance, but also have into account the phylogenetic framework (never considered in previous studies) analyzed based on molecular data. We find differences in the species composition among parks, with an astonishingly high diversity of endemic species in the Parque Nacional de Picos de Europa and an extremely low diversity of species in the Parque Nacional de Ordesa y Monte Perdido. These divergent patterns cannot be attributed to differences in physical variables, and in addition, the analyses of their phylogenetic relationships and, for a few species, their genetic structure, point to a more probable historical explanation.     

Why are many anthropogenic agroecosystems particularly species-rich?

Species-rich meadow and pasture habitats are recognised by the European Union Habitats Directive as targets for biodiversity conservation. High species richness is hypothesised to be associated with diversity in plant functional traits and life-history strategies, which are potentially restricted in situations of extremely high and low biomass production. However, variability in functional traits has yet to be investigated across a broad biomass range in nature. We measured variability in a range of functional traits and Grime's competitor, stress-tolerator, ruderal (CSR) strategies for species comprising lowland meadows, subalpine pastures, abandoned grassland and field margins at sites in northern Italy, alongside peak above-ground biomass. The factor most highly and positively correlated with species richness was strategy richness (the number of CSR strategies; Pearson's r = 0.864, P < 0.0001, n = 39), followed by variance in traits involved in leaf resource economics and the timing of flowering. Species richness, trait variance and strategy richness were greatest at intermediate biomass. Thus whilst extremes of biomass production were associated with relatively few taxa exhibiting similar trait values and specialised strategies, greater species richness was apparent in meadows and pastures in which species exhibited divergence in resource economics trait values, reproductive timing and strategy richness.     

Natural underlying mtDNA heteroplasmy as a potential source of intra‐person hiPSC variability

Functional variability among human clones of induced pluripotent stem cells (hiPSCs) remains a limitation in assembling high‐quality biorepositories. Beyond inter‐person variability, the root cause of intra‐person variability remains unknown. Mitochondria guide the required transition from oxidative to glycolytic metabolism in nuclear reprogramming. Moreover, mitochondria have their own genome (mitochondrial DNA [mtDNA]). Herein, we performed mtDNA next‐generation sequencing (NGS) on 84 hiPSC clones derived from a cohort of 19 individuals, including mitochondrial and non‐mitochondrial patients. The analysis of mtDNA variants showed that low levels of potentially pathogenic mutations in the original fibroblasts are revealed through nuclear reprogramming, generating mutant hiPSCs with a detrimental effect in their differentiated progeny. Specifically, hiPSC‐derived cardiomyocytes with expanded mtDNA mutations non‐related with any described human disease, showed impaired mitochondrial respiration, being a potential cause of intra‐person hiPSC variability. We propose mtDNA NGS as a new selection criterion to ensure hiPSC quality for drug discovery and regenerative medicine.     

Simulated effects of low atmospheric CO2 on structure and composition of North American vegetation at the Last Glacial Maximum

1. Physiological experiments have indicated that the lower CO₂ levels of the last glaciation (200 μmol mol^?1) probably reduced plant water-use efficiency (WUE) and that they combined with increased aridity and colder temperatures to alter vegetation structure and composition at the Last Glacial Maximum (LGM). 2. The effects of low CO₂ on vegetation structure were investigated using BIOME3 simulations of leaf area index (LAI), and a two-by-two factorial experimental design (modern/LGM CO₂, modern/LGM climate).3. Using BIOME3, and a combination of lowered CO₂ and simulated LGM climate (from the NCAR-CCM1 model), results in the introduction of additional xeric vegetation types between open woodland and closed-canopy forest along a latitudinal gradient in eastern North America.4. The simulated LAI of LGM vegetation was 25–60% lower in many regions of central and eastern United States relative to modern climate, indicating that glacial vegetation was much more open than today.5. Comparison of factorial simulations show that low atmospheric CO₂ has the potential to alter vegetation structure (LAI) to a greater extent than LGM climate.6. If the magnitude of LAI reductions simulated for glacial North America were global, then low atmospheric CO₂ may have promoted atmospheric warming and increased aridity, through alteration of rates of water and heat exchange with the atmosphere.