Historical Climate Change Research Articles

SURFACE AREA EVALUATION OF MOSUL DOM LAKE USING SATELLITE IMAGERY TECHNIQUE

Due to water resources such as Tigris and Euphrates rivers, tributaries branches, marshlands and lakes, Iraq is considered, generally in the world and especially in Middle East, as one of the richest countries. These resources are already affected by the consequences of climate change increasingly. One of the most vital projects in Iraq is Mosul Dam (in the northern of Iraq), thus, Mosul Dam lake (MDL), in term of surface area, was observed and studied during the prior 35 years (1984-2019) to detect the effects of historical climate changes on surface area. Satellite data of Landsat has been used in this study based on route 170 and line 35. Best and cloud-free satellite images were downloaded from US Geological Survey. Eventually, ArcGIS technique was used to process and analyze the satellite images. The result displayed that average surface area and parameter of study area was about 242 km2 and 432 km consecutively. Relationship between surface area (A) and parameter (P) of study area has been generated and formulated. Furthermore, the correlation coefficient between surface area and parameter was about 71%. Coefficient of variance (COV) was found also to be about 0.271. Minimum surface area and parameter of study area were recorded in Sep. 2018 of about 171 km2 and 350 km respectively regardless the dates before the operating Mosul Dam, whereas, maximum A and P lake was found to be 337 km2 and 664 km in April,1994 respectively. The analysis showed that the exponential curve representing the best relationship between P and A.

Nuclear phylogeography of the temperate tree species Chiranthodendron pentadactylon (Malvaceae): Quaternary relicts in Mesoamerican cloud forests

BackgroundThe Mexican hand tree or Canac (Chiranthodendron pentadactylon) is a temperate tree species of cloud and pine-oak forests of southern Mexico and Guatemala. Its characteristic hand-shaped flower is used in folk medicine and has constituted the iconic symbol of the Sociedad Botánica de México since 1940. Here, the evolutionary history of this species was estimated through phylogeographic analyses of nuclear DNA sequences obtained through restriction site associated DNA sequencing and ecological niche modeling. Total genomic DNA was extracted from leaf samples obtained from a representative number (5 to 10 per sampling site) of individuals distributed along the species geographic range. In Mexico, population is comprised by spatially isolated individuals which may follow the trends of cloud forest fragmentation. By contrast, in Guatemala Chiranthodendron may constitute a canopy dominant species near the Acatenango volcano. The distributional range of this species encompasses geographic provinces separated by the Isthmus of Tehuantepec.The objectives of the study were to: (i) estimate its genetic structure to define whether the observed range disjunction exerted by the Isthmus of Tehuantepec translates into separate populations, (ii) link population divergence timing and demographic trends to historical climate change, and (iii) test hypotheses related to Pleistocene refugia.ResultsPatterns of genetic diversity indicated high levels of genetic differentiation between populations separated by the Isthmus. The western and eastern population diverged approximately 0.873 Million years ago (Ma). Demographic analyses supported a simultaneous split from an ancestral population and rapid expansion from a small stock approximately 0.2 Ma corresponding to a glacial period. The populations have remained stable since the LIG (130 Kilo years ago (Ka)). Species distribution modelling (SDM) predicted a decrease in potential distribution in the Last Interglacial (LIG) and an increase during the Last Glacial Maximum (LGM) (22 Ka), Mid-Holocene (6 Ka) and present times.ConclusionsDivergence time estimations support the hypothesis that populations represent Quaternary relict elements of a species with broader and northernmost distribution. Pleistocene climatic shifts exerted major influence on the distribution of populations allowing dispersion during episodes of suitable climatic conditions and structuring during the first interglacial with a time period length of 100 Kilo years (Kyr) and the vicariant influence of the Isthmus. Limited demographic expansion and population connectivity during the LGM supports the moist forest hypothesis model.

Allopolyploid Speciation Accompanied by Gene Flow in a Tree Fern

Hybridization in plants may result in hybrid speciation or introgression and, thus, is now widely understood to be an important mechanism of species diversity on an evolutionary timescale. Hybridization is particularly common in ferns, as is polyploidy, which often results from hybrid crosses. Nevertheless, hybrid speciation as an evolutionary process in fern lineages remains poorly understood. Here, we employ flow cytometry, phylogeny, genomewide single nucleotide polymorphism data sets, and admixture and coalescent modeling to show that the scaly tree fern, Gymnosphaera metteniana is a naturally occurring allotetraploid species derived from hybridization between the diploids, G.denticulata and G.gigantea. Moreover, we detected ongoing gene flow between the hybrid species and its progenitors, and we found that G.gigantea and G.metteniana inhabit distinct niches, whereas climatic niches of G.denticulata and G.metteniana largely overlap. Taken together, these results suggest that either some degree of intrinsic genetic isolation between the hybrid species and its parental progenitors or ecological isolation over short distances may be playing an important role in the evolution of reproductive barriers. Historical climate change may have facilitated the origin of G.metteniana, with the timing of hybridization coinciding with a period of intensification of the East Asian monsoon during the Pliocene and Pleistocene periods in southern China. Our study of allotetraploid G.metteniana represents the first genomic-level documentation of hybrid speciation in scaly tree ferns and, thus, provides a new perspective on evolution in the lineage.

Genomic insights into historical population dynamics, local adaptation, and climate change vulnerability of the East Asian Tertiary relict Euptelea (Eupteleaceae).

The warm‐temperate and subtropical climate zones of East Asia are a hotspot of plant species richness and endemism, including a noticeable number of species‐poor Tertiary relict tree genera. However, little is understood about when East Asian Tertiary relict plants diversified, how they responded demographically to past environmental change, and to what extent their current genomic composition (and adaptive capacity) might mitigate the effects of global warming. Here, we obtained genomic (RAD‐SNP) data for 171 samples from two extant species of Euptelea in China (24 E. pleiosperma populations) and Japan (11 E. polyandra populations) to elucidate their divergence and demographic histories, genome‐wide associations with current environmental variables, and genomic vulnerability to future climate change. Our results indicate that Late Miocene changes in climate and/or sea level promoted species divergence, whereas Late Pliocene uplifting in southwest China likely fostered lineage divergence within E. pleiosperma. Its subsequent range expansion into central/east (CE) China bears genomic signatures of climate‐driven selection, yet extant CE populations are predicted to be most vulnerable to future climate change. For E. polyandra, geography was the only significant predictor of genomic variation. Our findings indicate a profound impact of Late Neogene geological and climate change on the evolutionary history of Euptelea, with much stronger signals of local adaptation left in China than in Japan. This study deepens our understanding of the complex evolutionary forces that influence the distribution of genetic variation of Tertiary relict trees, and provides insights into their susceptibility to global change and potential for adaptive responses. Our results lay the groundwork for future conservation and restoration programs for Euptelea.

Trends and spatial patterns of 20th century temperature, rainfall and PET in the semi-arid Logone River basin, Sub-Saharan Africa

Sub-Saharan floodplains are sensitive to climatic changes in their upstream drainage basin, a major concern is given the dependency of millions of people for their daily subsistence. Understanding hydroclimatic trends and variability is critical for developing integrated coupled human and natural system models to evaluate future scenarios of vulnerability. Here we describe the historical climatic changes in the Logone River basin using grid-based climatic data during a time of concomitant human hydrological modification of the floodplain. Temporal trends were analysed by comparing two periods i.e. 1901/1921–1961 (pre-1960) and 1961–2013 (post-1960). Trends were analysed spatially based on the basin's two Köppen climatic zones: savanna (Aw) covering the southern upstream areas and semi-arid hot (BSh) covering the northern downstream areas. The results show significant increasing trends in maximum and minimum temperatures and potential evapotranspiration (PET), and non-significant decreasing trends in annual rainfall and number of rainy days, across the study area. These climatic changes on temporal and spatial scales play an important role for the coupled natural and human systems in the Logone floodplain.

A 241-Year Cryptomeria fortune Tree-Ring Chronology in Humid Subtropical China and Its Linkages with the Pacific Decadal Oscillation

Humid subtropical China is an “oasis” relative to other dry subtropics of the world due to the prevailing of the East Asian summer monsoon (EASM). Although many long climate sensitive tree-rings have been published to understand the historical climate change over various regions in China, long tree-ring chronologies in humid subtropical China are rare due to the difficulty to find old growth trees. This study established a tree-ring chronology spanning from 1776 to 2016 from Cryptomeria fortunei Hooibrenk ex Otto et Dietr in Liancheng area of humid subtropical China, which is also currently the longest chronology in Fujian province. Similar to the climate-growth relationships in neighboring regions, our tree-ring chronology is limited by cold temperature in winter and spring and drought in summer. In addition, a drought stress before the growing season also played a role in limiting the growth of our tree rings. Our climate sensitive tree rings showed different correlations with the Pacific Decadal Oscillation (PDO) in different periods, possibly via modulation of the EASM.

Ecological niche modelling and genetic analyses reveal lack of geographic differentiation of Leptolobium dasycarpum (Leguminosae, Papilionoideae) across the Brazilian savannah

Trees from Brazilian savannah (Cerrado), especially species of the family Leguminosae, generally show genetic discontinuity among their populations. This leads to the formation of geographically delimited groups. This study assesses the effects of historical climatic changes during the Quaternary glaciations on the demography, diversification and spatial distribution of Leptolobium dasycarpum, a useful tree species of the Cerrado, using phylogeography and spatial distribution modelling. We sampled freshly collected and herborized individuals throughout L. dasycarpum’s distribution and sequenced two plastid intergenic spacers (133 plants) and the ITS region from the nuclear ribosomal DNA (124 plants). The current study’s framework incorporated statistical phylogeography, coalescent analyses and ecological niche modelling. The species presented significant differentiation among populations, with no geographically differentiated groups along the Cerrado and no signs of recent demographic changes. The species also experienced a moderate reduction of its suitable niche distribution during the Last Glacial Maximum. Moreover, the data suggested that the ancestral distribution area of L. dasycarpum was the central Cerrado and that colonization of adjacent areas occurred only recently. The results suggested that the central region of the Cerrado is the centre of L. dasycarpum lineage diversification and there are no significant barriers to gene flow among populations from the different regions of Cerrado. Historical climate changes did not impact the demographic history of L. dasycarpum probably due to the demographic stability throughout the Quaternary allied to the life history traces of this species.

Has historic climate change affected the spatial distribution of water-limited wheat yield across Western Australia?

Climate change has likely impacted crop yield potential in major rain-fed crop-growing regions. However, the impact on the spatial pattern across regions is unclear. Here, the wheat belt of Western Australia was used as a case study to investigate the effect of historical climate change on the spatial patterns of water-limited crop yield. We used 117 years (1900–2016) of observed daily climate data on ~ 5 km × ~ 5 km grids to map and quantify the spatial-temporal changes in water-limited wheat yield simulated by the APSIM model. The climate data were split into four periods based on distinct changes in rainfall (Period 1, 1900–1934; Period 2, 1935–1974; Period 3, 1975–1999; and Period 4, 2000–2016). The results showed that the observed decreases in rainfall shifted the regional wheat yield potential towards the southwest of the wheat belt by an average of 70 km between the first and last periods. Observed increases in CO2 counteracted this by about half of this movement. Actual wheat yields achieved by farmers have not decreased, thanks to improvements in crop genetics and management, but the simulated decrease in water-limited yields has meant that actual yields in this region are not as high as they might have been. Future climate change is likely to continue to impact on water-limited crop yield and its spatial pattern in Western Australia. Cropping systems will need to continually evolve to cope with a changing climate, and every aspect of agronomy and genetics needs to be considered. Without continuing improvements, there will likely be a decrease in wheat yield across this cropping region.

The Impact of Climate Change on the Value of Growing Maize as a Biofuel


 
 
 
 Abstract:
 Aim: According to COP23, Climate Change threatens the stability of the planet’s ecosystems, with a tipping point believed to be at only +2°C. With the burning of fossil fuels, held responsible for the release of much of the greenhouse gases, a sensible world- wide strategy is to replace fossil fuel energy sources with renewable ones. The renewable resources such as wind, hydro, geothermal, wave and tidal energies are found in particular geographical locations whereas almost every country is potentially able to exploit PV and biomass. This paper examines the role that changing climate could have on the growing and processing of biomass. The primary concern is that future climates could adversely affect the yield of crops, and hence the potential contribution of biomass to the strategy to combat climate change. Maize, a C4 crop, was selected for the study because it can be processed into biogas or other biofuels. Four different Nigerian agricultural zones growing maize were chosen for the study. Long-term weather data was available for the four sites and this permitted the modelling of future climates.
 Design / Research methods: The results of this study come from modelling future climates and applying this to crop models. This unique work, which has integrated climate change and crop modelling to forecast yield and carbon emissions, reveals how maize responds to the predicted increased temperature, change in rainfall, and the variation in weather patterns. In order to fully assess a biomass crop, the full energy cycle and carbon emissions were estimated based on energy and materials inputs involved in farm management: fertilizer application, and tillage type. For maize to support the replacement strategy mentioned above it is essential that the ratio of energy output to energy input exceeds 1, but of course it should be as large as possible.
 Conclusions / findings: Results demonstrate that the influence of climate change is important and in many scenarios, acts to reduce yield, but that the negative effects can be partially mitigated by careful selection of farm management practices. Yield and carbon footprint is particularly sensitive to the application rate of fertilizer across all locations whilst climate change is the causal driver for the increase in net energy and carbon footprint at most locations. Nonetheless, in order to ensure a successful strategic move towards a low carbon future, and sustainable implementation of biofuel policies, this study provides valuable information for the Nigerian government and policy makers on potential AEZs to cultivate maize under climate change. Further research on the carbon footprint of alternative bioenergy feedstock to assess their environmental carbon footprint and net energy is strongly suggested.
 Originality / value of the article: This paper extends the review on the impact of climate change on maize production to include future impacts on net energy use and carbon footprint using a fully integrated assessment framework. Most studies focus only on current farm energy use and historical climate change impact on farm GHG emissions. 
 
 
 
 

ORCHIDEE MICT-LEAK (r5459), a global model for the production, transport, and transformation of dissolved organic carbon from Arctic permafrost regions – Part 2: Model evaluation over the Lena River basin

Abstract. In this second part of a two-part study, we performed a simulation of the carbon and water budget of the Lena catchment with the land surface model ORCHIDEE MICT-LEAK, enabled to simulate dissolved organic carbon (DOC) production in soils and its transport and fate in high-latitude inland waters. The model results are evaluated for their ability to reproduce the fluxes of DOC and carbon dioxide (CO2) along the soil–inland-water continuum and the exchange of CO2 with the atmosphere, including the evasion outgassing of CO2 from inland waters. We present simulation results over the years 1901–2007 and show that the model is able to broadly reproduce observed state variables and their emergent properties across a range of interacting physical and biogeochemical processes. These include (1) net primary production (NPP), respiration and riverine hydrologic amplitude, seasonality, and inter-annual variation; (2) DOC concentrations, bulk annual flow, and their volumetric attribution at the sub-catchment level; (3) high headwater versus downstream CO2 evasion, an emergent phenomenon consistent with observations over a spectrum of high-latitude observational studies. These quantities obey emergent relationships with environmental variables like air temperature and topographic slope that have been described in the literature. This gives us confidence in reporting the following additional findings: of the ∼34 Tg C yr−1 left over as input to soil matter after NPP is diminished by heterotrophic respiration, 7 Tg C yr−1 is leached and transported into the aquatic system. Of this, over half (3.6 Tg C yr−1) is evaded from the inland water surface back into the atmosphere and the remainder (3.4 Tg C yr−1) flushed out into the Arctic Ocean, mirroring empirically derived studies. These riverine DOC exports represent ∼1.5 % of NPP. DOC exported from the floodplains is dominantly sourced from recent more “labile” terrestrial production in contrast to DOC leached from the rest of the watershed with runoff and drainage, which is mostly sourced from recalcitrant soil and litter. All else equal, both historical climate change (a spring–summer warming of 1.8 ∘C over the catchment) and rising atmospheric CO2 (+85.6 ppm) are diagnosed from factorial simulations to contribute similar significant increases in DOC transport via primary production, although this similarity may not hold in the future.

Genetic differentiation among Psittacanthus rhynchanthus (Loranthaceae) populations: novel phylogeographic patterns in the Mesoamerican tropical lowlands

Historical geological events and climatic changes have played important roles in shaping population differentiation and distribution within species. In this study, we analysed the distribution, expansion and colonization patterns, and genetic differentiation among Psittacanthus rhynchanthus populations in Mesoamerica. Specifically, we determine the effects of major historical events and geographic barriers on population divergence using nuclear and chloroplast DNA sequence data and the impact of Pleistocene glacial cycles on the distribution dynamics of P. rhynchanthus using ecological niche modelling (ENM). Our results showed that P. rhynchanthus populations split into two lineages, one distributed on the Yucatan Peninsula and the second along the Pacific and Atlantic slopes and Honduras, approximately 1 million years ago. The two lineages were fragmented at the last interglacial according to ENM predictions and experienced postglacial range expansion during the Last Glacial Maximum. Analysis of climate differentiation and niche models showed that both lineages have different climatic preferences, where the climatic characteristics of the Yucatan populations are not fully represented in the rest of the distribution range of P. rhynchanthus. Additionally, our study suggests that Pleistocene expansion of suitable habitat, environmental segregation (ecological barrier between regions) and, perhaps host shifts, have acted as the isolation mechanisms between the two lineages. Our results provide new insight as to understanding the distribution and phylogeographic patterns and the possible mechanisms underlying intraspecific evolutionary relationships of plants in the Mesoamerican tropical lowlands.

Stability of the permafrost peatlands carbon pool under climate change and wildfires during the last 150 years in the northern Great Khingan Mountains, China

Peatlands store one-third of the total global soil carbon (C.) despite covering only 3–4% of the global land surface. Most peatlands are distributed in mid-high latitude regions and are even in permafrost regions, are sensitive to climate change and are disturbed by wildfire. Although several studies have focused on the impact of historical climate change and regional human activities on the C. accumulation process in these peatlands, the impact of these factors on the stability of the C. pool remains poorly understood. Here, based on the 210Pb age-depth model, we investigated the historical variations of C. stability during the last 150 years for five typical peatlands in the northern Great Khingan Mountains (Northeast China), an area located in a permafrost region that is sensitive to climate change and to wildfires, which have clearly increased due to regional human activities. The results showed that low C. accumulation rates (CARs) and weakly C. stability in studied peatlands before 1900. While, the increasing anthropogenic wildfire frequency and the residual products (e.g. pyrogenic carbon) increased the CARs and C. stability in peatlands from 1900 to 1980. The mean July temperature is the most important climate factor for peatlands C. stability. After 1980, due to the low wildfire frequencies influenced by human policies, increasing temperatures and decreasing precipitation not only increased the CARs but also markedly increased the C. stability of the peatlands C. pool in the northern Great Khingan Mountains, especially after 2000.

Statistical Downscaling of Daily Temperature and Rainfall Data from Global Circulation Models, in Borkena River Catchment, Ethiopia

Statistical downscaling models for temperature and precipitation in Borkena River Catchment, have been developed and applied to calculate the changes in historic, current and future climate changes. Projected changes in precipitation and temperature were analyzed using the outputs from GCMs and stations data (1976-2005) which were collected from 4 observed meteorological stations (predictand) and downscaling using SDSM version 4.2.9a. The study investigated how these changes in temperature and precipitation might translate into changes in livelihoods of people and other biophysical components using impact assessments. The objective of this paper was to evaluate the statistical downscaling methods in estimating monthly average rainfall and temperature, in line with this it was also conducted to project the future climate situation of Borkena River catchment (Ethiopia). Accordingly, the results revealed that both temperatures (maximum and minimum) showed an increasing trend. The result of future temperature from SDSM for RCP4.5 and RCP8.5 show increased rate on annual basis except 202s for RCP4.5. The maximum increasing value will occur for RCP8.5 in the 2020s and 2080s with a value of 1.85°C and 2.82°C for minimum and maximum temperature respectively. Downscaled precipitation results of future time interval of this study indicated decreased precipitation value for both RCP4.5 and RCP8.5 on annual basis. This, may increase water availability stresses in the study area. Therefore, this facilitate the decision makers to incorporate climate change scenarios for devising sustainable strategies, including: water harvesting technologies, supplementary irrigation, using improved seeds, which can tolerate moisture stresses, afforestation and reforestation programs, and soil and water conservation techniques. Moreover, crop diversifications, agricultural extension services access, related strategies, and measures are highly recommended for climate change resiliencies.

The Canadian Earth System Model version 5 (CanESM5.0.3)

Abstract. The Canadian Earth System Model version 5 (CanESM5) is a global model developed to simulate historical climate change and variability, to make centennial-scale projections of future climate, and to produce initialized seasonal and decadal predictions. This paper describes the model components and their coupling, as well as various aspects of model development, including tuning, optimization, and a reproducibility strategy. We also document the stability of the model using a long control simulation, quantify the model's ability to reproduce large-scale features of the historical climate, and evaluate the response of the model to external forcing. CanESM5 is comprised of three-dimensional atmosphere (T63 spectral resolution equivalent roughly to 2.8∘) and ocean (nominally 1∘) general circulation models, a sea-ice model, a land surface scheme, and explicit land and ocean carbon cycle models. The model features relatively coarse resolution and high throughput, which facilitates the production of large ensembles. CanESM5 has a notably higher equilibrium climate sensitivity (5.6 K) than its predecessor, CanESM2 (3.7 K), which we briefly discuss, along with simulated changes over the historical period. CanESM5 simulations contribute to the Coupled Model Intercomparison Project phase 6 (CMIP6) and will be employed for climate science and service applications in Canada.

‘Endangered living fossils’ (ELFs): Long-term survivors through periods of dramatic climate change

Geography and climate have been the main drivers of evolution in recent geological epochs. While new lineages of species have been formed in the last millions of years (speciation) and others have vanished as a result of historical climate changes (extinction), some ancient lineages appear to have persisted to the present day without net diversification. In this paper, evolution of ancient lineages is addressed by combining phylogenetic and conservation approaches to test the concept of ‘endangered living fossil’ (ELF). Using endangered, monospecific genera as starting point, we propose three criteria to identify ELFs (in order): (1) scarcity and narrow distribution of populations, i.e. the species (and thus the genus) is categorised as either ‘endangered’ or ‘critically endangered’ using IUCN criteria; (2) evolutionary distinctiveness, i.e. phylogenetic singularity of a single-species lineage as a result of a null net diversification rate; (iii) ancient divergence, i.e. split from the closest extant relatives predating the dramatic climate changes of particular geological epochs (specifically changes since the Miocene-Pliocene boundary). The vascular flora of the Iberian Peninsula offers a suitable study system to reliably test the ELF concept. Indeed, time-calibrated phylogenies revealed that five of the six critically endangered, monospecific genera endemic to the Iberian Peninsula are ELFs. These five genera appear to have diverged from their closest relatives in the Oligocene (Gyrocaryum), Miocene (Avellara, Castrilanthemum, Gadoria) and around the Miocene-Pliocene boundary (Naufraga). This result entails long-term survival (with no net diversification) through at least three dramatic climate changes: the Messinian Salinity Crisis (late Miocene), the establishment of the mediterranean climate (Pliocene), and the glacial-interglacial cycles (Pleistocene). Using results from the literature, we found examples of ELFs for the mediterranean floras of California (Dodecahema), Chile (Avellanita, Gomortega, Legrandia) and other Mediterranean areas of Europe (Petagnaea, Phitosia). ELFs are unique and threatened lineages representing an exceptional evolutionary heritage, and therefore they should be prioritised in biodiversity research and conservation programs.

Phylogeography of Excoecaria acerifolia (Euphorbiaceae) suggests combined effects of historical drainage reorganization events and climatic changes on riparian plants in the Sino–Himalayan region

AbstractIt has been hypothesized that geological and climatic changes in the Sino–Himalayan region played a significant role in evolutionary history. In this study, we tested this hypothesis by investigating the phylogeography of Excoecaria acerifolia (Euphorbiaceae), a riparian plant species that is widely distributed in the hot/warm-dry river valleys of the Sino–Himalayan region. Spatial analysis of molecular variance, a median-joining network and a Bayesian phylogenetic tree based on plastid DNA, all suggested three major lineages corresponding to the Jialing-Min-Dadu (JMD lineage), Jinsha-Yalong-Salween (JY lineage) and Yarlung Tsangpo-Mekong-Red-Nanpan (YMRN lineage) drainage basins. This was also generally supported by the results based on nuclear DNA. The divergence times of these three major lineages based on both datasets fell in the early Pleistocene, coinciding with the period of drainage reorganization events in the Sino–Himalayan region. The diversification times in the lineages were, however, dated back to the mid Pleistocene, corresponding to the Naynayxungla glaciation (0.72–0.50 Mya) and the penultimate glaciation (0.30–0.13 Mya), which were the most and second most severe glaciations in this region, respectively. Furthermore, mismatch analyses, neutrality test and ecological niche modelling suggest long-term demographic stability of the JY and JMD populations, with expansion only in the YMRN populations during the period(s) from the late penultimate glaciation (138.12 Kya) to the Last Interglacial (95.79 Kya), probably because of less extensive glaciations since the late Pleistocene and the gradually warming interglacial stage. Our study provides one of the few pieces of evidence indicating that combined historical drainage reorganization and climatic change since the Pleistocene might also have acted as important factors in the evolutionary history of riparian plants in the region.

Diversity and evolution of New Caledonian endemic Taophila subgenus Lapita (Coleoptera: Chrysomelidae: Eumolpinae)

AbstractNew Caledonia is an important biodiversity hotspot, where numerous plant and animal groups show high levels of species diversity and endemicity, while facing multiple threats to their habitats. Leaf beetles in the subfamily Eumolpinae illustrate this pattern, with species estimates higher than the number of described taxa and distribution ranges that are often consistent with microendemicity. In this study, we increase the knowledge of this group by focusing on the Taophila subgenus Lapita, known from three species but here expanded to eleven with eight new species: T. atlantis sp. nov., T. hermes sp. nov., T. kronos sp. nov., T. oceanica sp. nov., T. olympica sp. nov., T. ouranos sp. nov., T. riberai sp. nov., and T. tridentata sp. nov. Additionally, we infer the evolutionary history of the group using mtDNA markers (COI and rrnS). This phylogeny and the species distribution help hypothesize a model of evolution for this lineage in the context of historical climatic and geological changes of New Caledonia.

Complex responses of phototrophic communities to climate warming during the Holocene of northeastern Ontario, Canada

Historical changes in Holocene climate in northeastern Ontario were quantified using analyses of sedimentary pollen, diatoms, and pigments in a small boreal lake. Modern analog reconstructions of average temperature from Holocene pollen assemblages of Charland Lake showed temperature was ~2°C warmer than present conditions ~7800–4500 cal. yr BP, a time period consistent with the Holocene thermal maximum (HTM). Pollen data suggest a two-phase HTM: warm and dry conditions based on the presence of primarily Pinus spp., followed by warm and wet conditions based on increases in cedar. Overall, algal production was low during the HTM, as reflected by low concentrations of pigments and diatoms. In the late HTM, increases in cedar pollen and planktonic diatoms suggest sustained increases in water levels for the remainder of the Holocene. During the Post-HTM Period (~4500–2000 cal. yr BP), a period that was warmer than today but cooler than the HTM, overall pigment production was significantly higher than all other periods. However, changes in diatom species composition suggest this period was not uniform, with variation occurring between diatoms indicative of higher and lower nutrient levels. The last ~2000 cal. yr BP was less productive than the Post-HTM Period but more productive than the HTM with higher production from diatoms and cyanobacteria. This study suggests that the relationship between climate and lake water production can be quite complex, and that changes in temperature, precipitation, light, lake levels, and mixing patterns are among factors that are related to changes in subfossil phototroph assemblages.

First description of genetic diversity for the genus Metagonimus using the complete cox1 gene sequence

The complete cox1 gene sequence was analysed for Metagonimus suifunensis from eight localities in the Russian southern Far East, and the level of variability was compared with that of Clonorchis sinensis from the same territory of Russia. These species belong to the superfamily Opisthorchioidea, have a similar distribution in the Russian southern Far East and share second intermediate and definitive hosts, but are distinguished by their first intermediate hosts belonging to different orders of caenogastropods. The data obtained showed that the nucleotide sequence variability of the M. suifunensis cox1 gene was significantly lower. This fact is considered in connection with a recent bottleneck passage for the M. suifunensis population, in contrast to C. sinensis, which could be due to the features of the Metagonimus life cycle under seasonal freezing temperatures, as well as historical geological and climatic changes in the Russian Far East. These factors could influence the microevolutionary processes and lead to a decrease in the level of variability in the M. suifunensis population. Based on the combination of genetic data and historical geo-processes in the region, the probable route of M. suifunensis expansion from the northern part of its current area in the Amur River basin to the southern territories of the Russian Far East is justified.

How accurately can the climate sensitivity to hbox {CO}_{2} be estimated from historical climate change?

The equilibrium climate sensitivity (ECS, in K) to hbox {CO}_{2} doubling is a large source of uncertainty in projections of future anthropogenic climate change. Estimates of ECS made from non-equilibrium states or in response to radiative forcings other than hbox {2}times hbox {CO}_{2} are called “effective climate sensitivity” (EffCS, in K). Taking a “perfect-model” approach, using coupled atmosphere–ocean general circulation model (AOGCM) experiments, we evaluate the accuracy with which hbox {CO}_{2} EffCS can be estimated from climate change in the “historical” period (since about 1860). We find that (1) for statistical reasons, unforced variability makes the estimate of historical EffCS both uncertain and biased; it is overestimated by about 10% if the energy balance is applied to the entire historical period, 20% for 30-year periods, and larger factors for interannual variability, (2) systematic uncertainty in historical radiative forcing translates into an uncertainty of {pm },30, {rm to} ,45% (standard deviation) in historical EffCS, (3) the response to the changing relative importance of the forcing agents, principally hbox {CO}_{2} and volcanic aerosol, causes historical EffCS to vary over multidecadal timescales by a factor of two. In recent decades it reached its maximum in the AOGCM historical experiment (similar to the multimodel-mean hbox {CO}_{2} EffCS of 3.6 K from idealised experiments), but its minimum in the real world (1.6 K for an observational estimate for 1985–2011, similar to the multimodel-mean value for volcanic forcing). The real-world variations mean that historical EffCS underestimates hbox {CO}_{2} EffCS by 30% when considering the entire historical period. The difference for recent decades implies that either unforced variability or the response to volcanic forcing causes a much stronger regional pattern of sea surface temperature change in the real world than in AOGCMs. We speculate that this could be explained by a deficiency in simulated coupled atmosphere–ocean feedbacks which reinforce the pattern (resembling the Interdecadal Pacific Oscillation in some respects) that causes the low EffCS. We conclude that energy-balance estimates of hbox {CO}_{2} EffCS are most accurate from periods unaffected by volcanic forcing. Atmosphere GCMs provided with observed sea surface temperature for the 1920s to the 1950s, which was such a period, give a range of about 2.0–4.5 K, agreeing with idealised hbox {CO}_{2} AOGCM experiments; the consistency is a reason for confidence in this range as an estimate of hbox {CO}_{2} EffCS. Unless another explosive volcanic eruption occurs, the first 30 years of the present century may give a more accurate energy-balance historical estimate of this quantity.