Historical Environmental Changes Research Articles

Tracing the dynamics of Late Holocene Tropical Peatland: A case study from the Bram Itam Peatland Protection Area, Coastal Sumatra, Indonesia

Tropical peatland ecosystems in Southeast Asia offer essential ecological services but face various threats such as sea level alterations, climate change and human activities. However, our understanding of the origins of peatlands and their dynamics is still limited. Reconstruction of historical vegetation and environmental changes is imperative to comprehend tropical peatlands' origins, evolution and responses to natural factors (e.g., precipitation, sea level) and to human influences (e.g., agriculture). This study employed a multi-proxy palaeoecological analysis, encompassing pollen and spore analysis, macro-charcoal examination, and radiocarbon dating, using a sediment core extracted from the Bram Itam Peatland protection area in Tanjung Jabung Barat, Jambi province. The investigation highlights four distinct palynological periods: from ca. 4750 to 1250 cal yr BP, a dominant mangrove forest thrived in the study area during high sea levels; from 1250 to 450 cal yr BP, as sea levels receded, the mangrove forest was replaced by swampy vegetation, and peatland forests developed under the influence of high precipitation, while agricultural activities with possible rice cultivation were conducted remote from the study area; from 450 cal yr BP to 1950 CE, a mature peatland forest developed. There was no evidence of agricultural practice during this period. After 1950, intensive human activities, including logging, oil palm plantation, and rice cultivation, profoundly impacted the peatland vegetation. The presence of cereal pollen dates back to around 1250 cal yr BP and the introduction of oil palm (Elaeis guineensis) since roughly 1950 CE may indicate potentially enduring changes in agricultural practices of local people in the study area. This study of peatland vegetation dynamics and environmental changes in the Bram Itam peatlands highlights its change from mangrove forest to a matured peatland forest influenced by climate, sea level and human activities.

Shared phylogeographic patterns and environmental responses of co-distributed soybean pests: Insights from comparative phylogeographic studies of Riptortus pedestris and Riptortus linearis in the subtropics of East Asia

Comparative phylogeographic studies of closely related species sharing co-distribution areas can elucidate the role of shared historical factors and environmental changes in shaping their phylogeographic pattern. The bean bugs, Riptortus pedestris and Riptortus linearis, which both inhabit subtropical regions in East Asia, are recognized as highly destructive soybean pests. Many previous studies have investigated the biological characteristics, pheromones, chemicals and control mechanisms of these two pests, but few studies have explored their phylogeographic patterns and underlying factors. In this study, we generated a double-digest restriction site-associated DNA sequencing (ddRAD-seq) dataset to investigate phylogeographic patterns and construct ecological niche models (ENM) for both Riptortus species. Our findings revealed similar niche occupancies and population genetic structures between the two species, with each comprising two phylogeographic lineages (i.e., the mainland China and the Indochina Peninsula clades) that diverged approximately 0.1 and 0.3 million years ago, respectively. This divergence likely resulted from the combined effects of temperatures variation and geographical barriers in the mountainous regions of Southwest China. Further demographic history and ENM analyses suggested that both pests underwent rapid expansion prior to the Last Glacial Maximum (LGM). Furthermore, ENM predicts a northward shift of both pests into new soybean-producing regions due to global warming. Our study indicated that co-distribution soybean pests with overlapping ecological niches and similar life histories in subtropical regions of East Asia exhibit congruent phylogeographic and demographic patterns in response to shared historical biogeographic drivers.

Trace element of small lake sediments sensitively recorded environmental changes in the watershed: Implications for mining history and urbanization

Lake sediments serve as a sink for trace elements and provide a record of watershed changes resulting from anthropogenic activities and natural processes. In this study, eight trace elements in the sediments of Lake Aha, an urban lake in Guiyang City, Southwest China, were investigated to reveal the effects of historical coal mining and rapid urbanization in the watershed. Results showed that the median contents of measured trace elements in order of Zn (220.00 mg/kg) > Ni (98.16 mg/kg) > Cr (70.26 mg/kg) > Cu (66.20 mg/kg) > As (58.14 mg/kg) > Co (41.66 mg/kg) > Pb (28.33 mg/kg) > Cd (1.39 mg/kg). Except for Cr and Pb, the median concentrations of Cd, As, Zn, Ni, Co, and Cu were 4.64, 2.33, 2.00, 1.92, 1.81, and 1.09 times higher than regional natural background values respectively. Trace element contents in sediments of the center of the lake were significantly higher than in the rest of the sediment cores, resulting from relatively stable hydrodynamic processes in the region. Vertical variation of trace elements indicated that the fluctuations in the intensity of coal mining activities in the tributaries were effectively tracked by variations of trace element levels in the middle layer sediments of the Youyu River and Baiyan River estuaries. The elevated concentrations of Pb in the surface sediments of the Jinzhong River estuary reflected the rapid urbanization in the basin over the past 20 years. PMF analysis demonstrated that As, Cd, and Pb in sediments were from a mixture of natural and urban activities, and Cu, Zn, Ni, and Co originated from coal mining. This study provides important information for comprehending the anthropogenic activities of small-scale lakes and historical environmental changes.

Herbarium specimens reveal that mycorrhizal type does not mediate declining temperate tree nitrogen status over a century of environmental change.

Rising atmospheric carbon dioxide concentrations (CO2) and atmospheric nitrogen (N) deposition have contrasting effects on ectomycorrhizal (EM) and arbuscular mycorrhizal (AM) symbioses, potentially mediating forest responses to environmental change. In this study, we evaluated the cumulative effects of historical environmental change on N concentrations and δ15N values in AM plants, EM plants, EM fungi, and saprotrophic fungi using herbarium specimens collected in Minnesota, USA from 1871 to 2016. To better understand mycorrhizal mediation of foliar δ15N, we also analyzed a subset of previously published foliar δ15N values from across the United States to parse the effects of N deposition and CO2 rise. Over the last century in Minnesota, N concentrations declined among all groups except saprotrophic fungi. δ15N also declined among all groups of plants and fungi; however, foliar δ15N declined less in EM plants than in AM plants. In the analysis of previously published foliar δ15N values, this slope difference between EM and AM plants was better explained by nitrogen deposition than by CO2 rise. Mycorrhizal type did not explain trajectories of plant N concentrations. Instead, plants and EM fungi exhibited similar declines in N concentrations, consistent with declining forest N status despite moderate levels of N deposition.

Maximizing UAV Coverage in Maritime Wireless Networks: A Multiagent Reinforcement Learning Approach

In the field of ocean data monitoring, collaborative control and path planning of unmanned aerial vehicles (UAVs) are essential for improving data collection efficiency and quality. In this study, we focus on how to utilize multiple UAVs to efficiently cover the target area in ocean data monitoring tasks. First, we propose a multiagent deep reinforcement learning (DRL)-based path-planning method for multiple UAVs to perform efficient coverage tasks in a target area in the field of ocean data monitoring. Additionally, the traditional Multi-Agent Twin Delayed Deep Deterministic policy gradient (MATD3) algorithm only considers the current state of the agents, leading to poor performance in path planning. To address this issue, we introduce an improved MATD3 algorithm with the integration of a stacked long short-term memory (S-LSTM) network to incorporate the historical interaction information and environmental changes among agents. Finally, the experimental results demonstrate that the proposed MATD3-Stacked_LSTM algorithm can effectively improve the efficiency and practicality of UAV path planning by achieving a high coverage rate of the target area and reducing the redundant coverage rate among UAVs compared with two other advanced DRL algorithms.

Geochemical records of human-induced environmental changes in two small remote lakes of Songnen Plain, Northeast China.

The abundance and composition of aliphatic hydrocarbon biomarkers were determined in dated sediment cores from Lakes Qijiapao (QJP) and Huoshaoheipao (HSH) in the Songnen Plain, Northeast China, to investigate historical environmental changes in these lakes and identify likely controlling factors. Based on these results, the recent environmental history of the two lakes can be divided into three periods. Before 1950, low Paq values (avg. 0.23 and 0.27, respectively) and middle-chain n-alkane abundances (normalized to total organic carbon, avg. 14.82 and 16.01µgg-1 TOC, respectively) in both lakes suggested low aquatic productivity and the limited input of submerged macrophyte organic matter (OM). However, the significant increase in the abundance of short-chain n-alkanes in Lake HSH (from 8.34 to 16.68µgg-1 TOC) indicated the emergence of early nutrient enrichment in the lake. From 1950 to 2000, marked increase in the abundance of middle-chain n-alkanes (avg. 21.72 and 22.62µgg-1 TOC in Lakes QJP and HSH, respectively) and Paq values indicated that both lakes had undergone eutrophication because of the population explosion and agricultural intensification. From 2000 to 2013, the abundance of short- and middle-chain n-alkanes in Lake QJP markedly exceeded those in Lake HSH and indicated a larger eutrophication in Lake QJP, which could be caused by the development of ecotourism in Lake HSH and the concomitant increase in aquaculture in Lake QJP in recent years. The highest abundance of C30 αβ-hopane (~ 10.24µgg-1 TOC) and the lowest CPIH values in Lake QJP revealed a possible petroleum pollution since 2008. Taken together, lake eutrophication in the Songnen Plain accelerated after 1950 and was influenced primarily by agriculture and aquaculture. This is in contrast to lakes in other regions of China (such as the Yangtze River Basin and Yunnan Province), where urbanization and industrialization have exerted a dominant influence on the lake environment.

Timescale lessons of Durinskia baltica (Kryptoperidiniaceae, Dinophyta) from freshwater through a molecular phylogeny

Background: The evolutionary pattern of dinophytes is complex and requires comprehensive taxonomic studies addressing the species' development and morphology, ecology, evolution, and genetics.
 Questions: How recent was the transition of D. baltica from Mexico to freshwater based on a calibrated phylogeny tree of the Kryptoperidiniaceae?
 Studied species and data description: Durinskia baltica, Kryptoperidiniaceae and the known fossil record of dinotoms (endosymbiont diatom-host dinophytes).
 Study sites and dates: Xochimilco, Mexico City. 2010 to 2019.
 Methods: Phylogenies were constructed with Bayesian inferences and host sequences were calibrated with a relaxed clock method.
 Results: We obtained genetic sequences of the 18S rDNA sector in the host and the rbcL sector in the endosymbiont. The Nitzschia-type endosymbiont is genetically distinct from endosymbionts of other dinotomes with the same diatom type. In contrast, considering the known freshwater species of Durinskia, the genetic relationship between hosts is robust and of recent origin. The antiquity of the Mexican sequence coincides with the geological origin of the Xochimilco basin, suggesting particularities in the evolutionary history of dinotomes linked to the geographic regions they inhabit.
 Conclusions: Our evolutionary scenario with a calibrated phylogeny indicates that the transition of Durinskia baltica to freshwater in the Xochimilco basin is geologically contextualized. The historical environmental change of Lake Xochimilco with respect to salinity corresponds with an initial colonization of D. baltica in a brackish environment and its subsequent adaptation to freshwater.

Succession and environmental response of sediment bacterial communities in the Liao River Estuary at the centenary scale

Microbial community succession in turbulent estuarine environments is key to the understanding of microbial community development in estuaries. Centennial-scale sediment core samples collected from the Liao River Estuary (LRE) channel bar and side beaches were studied for geochemistry and 16S rRNA gene-based bacterial analyses. The results showed that bacterial community composition significantly differed between the sediments of the two sides of the channel bar, with Campilobacterota and Bacteroidota being dominant bacterial phyla in the tributary (T1, T2) and mainstream (MS1, MS2) sediment, respectively. Co-occurrence network of the bacterial community at the genus level showed more centralized and compacted topological features in tributary with weaker hydrodynamic, and the keystone taxas were Halioglobus, Luteolibacter, and Lutibacter in the bacterial community. The bacterial network structure had more edges and larger average degree in LRE sediments from the stage of the year 2016–2009 and the stage before 1939, which was possibly related to hydrodynamic conditions and nutrients. Stochastic processes (dispersal limitation) were the key factors driving bacterial community assembly in the LRE sediments. In addition, total organic carbon (TOC), total sulfur (TS), and grain size were the main deterministic factors affecting the change of bacterial community structure. Relative microbial abundance has the potential to indicate geologically historical environmental changes. This study provided a new perspective to reveal the succession and response of bacterial communities under frequent fluctuation environments.

Low population genetic structure is consistent with high habitat connectivity in a commercially important fish species (Lutjanus jocu)

The level of habitat availability influences genetic divergence among populations and the genetic diversity within populations. In the marine environment, near-shore species are among the most sensitive to habitat changes. Knowledge of how historical environmental change affected habitat availability and genetic variation can be applied to the development of proactive management strategies of exploited species. Here, we modeled the contemporary and historical distribution of Lutjanus jocu in Brazil. We describe patterns of genomic diversity to better understand how climatic cycles might correlate with the species demographic history and current genetic structure. We show that during the Last Glacial Maximum, there were ecological barriers that are absent today, possibly dividing the range of the species into three geographically separated areas of suitable habitat. Consistent with a historical reduction in habitat area, our analysis of demographic changes shows that L. jocu experienced a severe bottleneck followed by a population size expansion. We also found an absence of genetic structure and similar levels of genetic diversity throughout the sampled range of the species. Collectively, our results suggest that habitat availability changes have not obviously influenced contemporary levels of genetic divergence between populations. However, our demographic analyses suggest that the high sensitivity of this species to environmental change should be taken into consideration for management strategies. Furthermore, the general low levels of genetic structure and inference of high gene flow suggest that L. jocu likely constitutes a single stock in Brazilian waters and, therefore, requires coordinated legislation and management across its distribution.

Anthropogenic-driven chronological increase of sediment organic carbon burial in a river-lake system

Total organic carbon (TOC) in lake sediments from upstream catchments is deposited and buried in substrate, recording historical environmental changes. However, the linkage among natural variability, anthropogenic activity, and TOC burial for has not yet been clarified. This study examined the lake sediments of five 200-cm-deep dated depositional cores in west Dongting lake, China to quantify the magnitude, allocation, and amplitude of TOC burial. 44.47–59.36% of TOC burial flux was buried at 100–200 cm, suggesting lake sediments at deep layers stored considerable carbon. TOC burial rate (BRTOC) decreased along the lake entrance to its body, which was explained by the geochemical differences. Since 1900, BRTOC presented an increasing with a 4–7 times uptrend, showing three sedimentary stages with the increased human disturbance, such as deforestation, hydroelectric facilities. Moreover, the coefficient of variation of BRTOC in the third stage was lower than that in the second stage for the implementation of watershed reforestation and reservoir construction. Our findings stressed that natural variations of lake sedimentation background induced the change of TOC burial among the depositional sites, and enhanced that anthropogenic perturbation drove its chronological increases. This research unveiled the linkage between TOC burial, natural variability, and human disturbance from the perspective of burial evolutions in a lacustrine sedimentary environment.

Ensemble methods based on characterization of dynamism for dynamic multi-objective optimization

Dynamic multi-objective optimization problems involve multiple conflicting and time-dependent objectives that change continuously depending on the environment. Therefore, effectively tracking the movement of the Pareto-optimal front and the Pareto-optimal set (PS) using a single strategy is difficult. In this study, we propose an ensemble method called EMCD, which is based on the characterization of dynamism. EMCD selects different strategies to generate new populations depending on the characteristics of environmental changes. In our proposed algorithm, historical information is used to locate new populations when the current and historical environmental changes are similar. Otherwise, EMCD establishes whether the PS has changed. If the PS changes, individuals from the population of the new environment are generated by using a set of knee points based on the two previous consecutive populations. If not, new populations are generated by using the perturbation-based approach. In addition, we use an adaptive diversity introduction strategy to ensure the solvability of our proposed algorithm in dynamic environments. To verify the effectiveness of EMCD, we compare its performance to that of three state-of-the-art algorithms on fourteen benchmark problems. The experimental results show that EMCD outperforms the comparison algorithms on most of the benchmark problems.

Collective memory of environmental change and connectedness with nature: Survey evidence from Aotearoa New Zealand

The field of memory studies has, in recent years, experienced a ‘nonhuman turn’ that extends the analytical focus beyond anthropocentric functions of collective remembering. However, while this growing literature has considerably enhanced our understanding of how memories of environmental change may promote a stronger sense of connectedness with nature, the different arguments – developed mainly through critical readings of cultural texts – have yet to be investigated empirically. By means of an original survey of 1,100+ adults in Aotearoa New Zealand, the paper here provides a first step towards addressing the empirical gap in the ‘nonhuman turn’ literature. Two main findings emerge from this analysis. First, knowing about historical environmental change and overestimating the extent of environmental change make it more likely that individuals see themselves as part of nature. Second, the survey demonstrates that the relationship between memories of environmental change and closeness to nature interacts with wider political conflicts over how to remember the colonial past. In particular, the question of who to blame for historical environmental change shapes the effect of ecological memories in different ways, depending on whether respondents identify as European New Zealanders or Indigenous Māori.

The response of tropical cyclone intensity to changes in environmental temperature

Abstract. Theory indicates that tropical cyclone (TC) intensity should respond to environmental temperature changes near the surface and in the TC outflow layer. While the sensitivity of TC intensity to sea surface temperature is well understood, less is known about the role of upper-level stratification. In this paper, we combine historical data analysis and idealised modelling to explore the extent to which historical low-level warming and upper-level stratification can explain observed trends in the TC intensity distribution. Observations and modelling agree that historical global environmental temperature changes coincide with higher lifetime maximum intensities. Observations suggest the response depends on the TC intensity itself. Hurricane-strength storms have intensified at twice the rate of weaker storms per unit surface and upper-tropospheric warming, and we find faster warming of low-level temperatures in hurricane environments than the tropical mean. Idealised simulations respond in the expected sense to various imposed changes in the near-surface temperature and upper-level stratification representing present-day and end-of-century thermal profiles and agree with TCs operating as heat engines. Removing upper-tropospheric warming or stratospheric cooling from end-of-century experiments results in much smaller changes in potential intensity or realised intensity than between present day and the end of the century. A larger proportional change in thermodynamic disequilibrium compared to thermodynamic efficiency in our simulations suggests that disequilibrium, not efficiency, is responsible for much of the intensity increase from present day to the end of the century. The limited change in efficiency is attributable to nearly constant outflow temperature in the simulated TCs among the experiments. Observed sensitivities are generally larger than modelled sensitivities, suggesting that observed TC intensity change responds to a combination of the temperature change and other environmental factors.

Rapid genetic divergence and mitonuclear discordance in the Taliang knobby newt ( Liangshantriton taliangensis, Salamandridae, Caudata) and their driving forces.

The Hengduan Mountains Region (HMR) is the largest “evolutionary frontier” of the northern temperate zone, and the origin and maintenance of species in this area is a research hotspot. Exploring species-specific responses to historical and contemporary environmental changes will improve our understanding of the role of this region in maintaining biodiversity. In this study, mitochondrial and microsatellite diversities were used to assess the contributions of paleogeological events, Pleistocene climatic oscillations, and contemporary landscape characteristics to the rapid intraspecific diversification of Liangshantriton taliangensis, a vulnerable amphibian species endemic to several sky-island mountains in the southeastern HMR. Divergence date estimations suggested that the East Asian monsoon, local uplifting events (Xigeda Formation strata), and Early-Middle Pleistocene transition (EMPT) promoted rapid divergence of L. taliangensis during the Pleistocene, yielding eight mitochondrial lineages and six nuclear genetic lineages. Moreover, population genetic structures were mainly fixed through isolation by resistance. Multiple in situ refugia were identified by ecological niche models and high genetic diversity, which played crucial roles in the persistence and divergence of L. taliangensis during glacial-interglacial cycles. Dramatic climatic fluctuations further promoted recurrent isolation and admixing of populations in scattered glacial refugia. The apparent mitonuclear discordance was likely the result of introgression by secondary contact and/or female-biased dispersal. Postglacial expansion generated two major secondary contact zones (Ganluo (GL) and Chuhongjue (CHJ)). Identification of conservation management units and dispersal corridors offers important recommendations for the conservation of this species.

Historical environmental changes in the Poyang Lake basin (Yangtze River, China) and impacts on agricultural activities

Climate change and human activities have been an important part of studies regarding historical environmental changes in China over the past 2000 years. In this study, we focused on environmental changes, that is, natural disasters and human activities, in the Poyang Lake Basin over the past 2000 years, to analyze interactions between land use cover changes and human activities from the perspective of regional sustainable development. We collected historical records of climate and hydrology, floods and droughts, and rivers and lakes in the Poyang Lake area, and established time sequences for the floods and droughts, lake water level and lake area, amount of farming land, and population, in order to discuss interactions between changes in the environment and the climate, with emphasis on the impacts of extreme events on lake and river basin environment changes. The following results were obtained. First, climate changes in historical periods had wide-ranging and far-reaching impacts on agricultural production, especially disasters caused by climate change. Among the changes in the Poyang Lake basin environment, including river network systems, lake water levels, etc., changes in lake water volume are direct evidence of climate change, adaptation to climate change, and obvious phased characteristics. Second, in the process of changes to the lake and river network in the Poyang Lake Basin, social and economic development is accompanied by evolution of the lake. Increases and decreases in population, the scale of agricultural production, and lake environment changes have direct and significant interactions. Third, the Poyang Lake basin’s environmental changes during the historical period are mainly reflected in the pressure feedback mode of “population–agriculture” in the lake environment.

Mountain biogeography coming full circle: a new '3D' floristic approach provides units for reconstructing evolutionary trajectories.

This article is a Commentary on Li et al. (2021), 232: 1424–1435.

Oxygen Isotope Compositions of Cellulose in Earlywood of Larix cajanderi Determined by Water Source Rather Than Leaf Water Enrichment in a Permafrost Ecosystem, Eastern Siberia

AbstractThe oxygen isotopic composition of tree‐ring cellulose (δ18Ocell) has been widely used to reconstruct historical environmental changes; however, the control factors on δ18Ocell have not been fully constrained—especially in high latitudes. To evaluate the influence of metabolic processes and related environmental factors on δ18Ocell, we analyzed the δ18O values of soil water (1998–2015), stem water (1997–2016), leaf water (3 days in each 2014 and 2015), and tree‐ring cellulose (1981–2016), on a dominant larch species (Larix cajanderi) in an eastern Siberian boreal forest. We determined that the δ18O variability of water sources is dependent on the precipitation, and the 18O enrichment in leaf water is determined by relative humidity. These findings suggest that both water source uptake and leaf water enrichment processes can affect the δ18O values of oxygen‐containing compounds in larch trees in the study site. However, the δ18Ocell (one of the end oxygen‐containing products) was found dependent on water sources on which was related to the amount of summer rainfall in the previous year. This finding significantly differs from that of studies in other areas, which infer the positive correlation between δ18Ocell and leaf water enrichment rather than precipitation or water sources. These differences are predominantly due to the specific conditions of high‐latitude areas, such as the large seasonal δ18O difference in precipitation, the existence of permafrost, and the low growth rate. Our findings contribute toward the development of tree‐ring paleoclimate reconstructions—especially in eastern Siberia.

Palynological evidence from a sub-alpine marsh of enhanced Little Ice Age snowpack in the Marrakech High Atlas, North Africa

The grazing lands of the High Atlas are vulnerable to climate change and the decline of traditional management practices. However, prior to the mid-20th century, there is little information to examine historical environmental change and resilience to past climate variability. Here, we present a new pollen, non-pollen palynomorph (NPP) and microcharcoal record from a sub-alpine marsh (pozzine) at Oukaïmeden, located in the Marrakech High Atlas, Morocco. The record reveals a history of grazing impacts with diverse non-arboreal pollen assemblages dominant throughout the record as well as recurrent shifts between wetter and drier conditions. A large suite of radiocarbon dates (n = 22) constrains the deposit to the last ~ 1,000 years although multiple reversed ages preclude development of a robust age-depth model for all intervals. Between relatively dry conditions during the Medieval period and in the 20th century, intervening wet conditions are observed, which we interpret as a locally enhanced snowpack during the Little Ice Age. Hydrological fluctuations evidenced by wetland pollen and NPPs are possibly associated with centennial-scale precipitation variability evidenced in regional speleothem records. The pollen record reveals an herbaceous grassland flora resilient against climatic fluctuations through the last millennium, possibly supported by sustainable collective management practices (agdal), with grazing indicators suggesting a flourishing pastoral economy. However, during the 20th century, floristic changes and increases in charcoal accumulation point to a decline in management practices, diversification of land-use (including afforestation) and intensification of human activity.

Inferring historical survivals of climate relicts: the effects of climate changes, geography, and population-specific factors on herbaceous hydrangeas.

Climate relicts hold considerable importance because they have resulted from numerous historical changes. However, there are major interspecific variations among the ways by which they survived climate changes. Therefore, investigating the factors and timing that affected population demographics can expand our understanding of how climate relicts responded to historical environmental changes. Here, we examined herbaceous hydrangeas of genus Deinanthe in East Asia, which show limited distributions and a remarkable disjunction between Japan and central China. Chloroplast genome and restriction site-associated DNA sequencing revealed that speciation event occurred in the late Miocene (ca. 7-9 Mya) in response to global climate change. Two lineages apparently remained not branched until the middle Quaternary, and afterwards started to diverge to regional population groups. The narrow endemic species in central China showed lower genetic diversity (He = 0.082), as its population size rapidly decreased during the Holocene due to isolation in montane refugia. Insular populations in the three Japanese islands (He = 0.137-0.160) showed a genetic structure that was inconsistent with sea barriers, indicating that it was shaped in the glacial period when its range retreated to coastal refugia on the exposed sea floor. Demographic modelling by stairway-plot analysis reconstructed variable responses of Japanese populations: some experienced glacial bottlenecks in refugial isolation, while post-glacial range expansion seemingly exerted founder effects on other populations. Overall, this study demonstrated the involvement of not just one, but multiple factors, such as the interplay between climate changes, geography, and other population-specific factors, that determine the demographics of climate relicts.

First genetic record and the phylogenetic relationship of Osteochilus spilurus (Cyprinidae: Labeoninae ) originating from Bangka and Belitung Islands, Indonesia

Abstract. Kurniawan A, Hariati AM, Kurniawan A, Wiadnya DGR. 2021. First genetic record and the phylogenetic relationship of Osteochilus spilurus (Cyprinidae: Labeoninae) originating from Bangka and Belitung Islands, Indonesia. Biodiversitas 22: 794-802. Osteochilus spilurus is a freshwater fish from Southeast Asia. Species identification for this fish in Indonesia is still solely limited to morphological characteristics. Therefore it is highly important to validate using short DNA sequences that have been proven to be fast, effective, and accurate. Fish specimens were collected from Lenggang river in Belitung island, and Lebak river in Bangka island, Indonesia. Mitochondrial cytochrome b gene (cyt b, 408 bp) was amplified and sequenced. We collected fish specimens from Lenggang River in Belitung Island and Lebak River in Bangka Island, Indonesia. The results suggested that individuals from both islands are clustered together with a strong bootstrap value (100%) in a monophyletic clade. The specimens deposited at NCBI as the first Indonesian genetic records. They have a sister lineage to individuals from Sabah, Malaysia, although supported by a low bootstrap value. While geographical connection during the Pleistocene period allowed wide distribution of the species, differences in the evolutionary processes of historical biogeography and environmental changes are the predicted cause of the low genetic similarity. These findings can be used as a sequence reference and basic information for conservation of this species.