This study explores the use of the hierarchical ensemble filter to determine the localized influence of observations in the Weather Research and Forecasting ensemble square root filtering(WRF-EnSRF)assimilation system...This study explores the use of the hierarchical ensemble filter to determine the localized influence of observations in the Weather Research and Forecasting ensemble square root filtering(WRF-EnSRF)assimilation system.With error correlations between observations and background field state variables considered,the adaptive localization approach is applied to conduct a series of ideal storm-scale data assimilation experiments using simulated Doppler radar data.Comparisons between adaptive and empirical localization methods are made,and the feasibility of adaptive localization for storm-scale ensemble Kalman filter assimilation is demonstrated.Unlike empirical localization,which relies on prior knowledge of distance between observations and background field,the hierarchical ensemble filter provides continuously updating localization influence weights adaptively.The adaptive scheme improves assimilation quality during rapid storm development and enhances assimilation of reflectivity observations.The characteristics of both the observation type and the storm development stage should be considered when identifying the most appropriate localization method.Ultimately,combining empirical and adaptive methods can optimize assimilation quality.展开更多
Underwater images are inherently degraded by color distortion,contrast reduction,and uneven brightness,primarily due to light absorption and scattering in water.To mitigate these challenges,a novel enhancement approac...Underwater images are inherently degraded by color distortion,contrast reduction,and uneven brightness,primarily due to light absorption and scattering in water.To mitigate these challenges,a novel enhancement approach is proposed,integrating Local Adaptive Color Correction(LACC)with contrast enhancement based on adaptive Rayleigh distribution stretching and CLAHE(LACC-RCE).Conventional color correction methods predominantly employ global adjustment strategies,which are often inadequate for handling spatially varying color distortions.In contrast,the proposed LACC method incorporates local color analysis,tone-weighted control,and spatially adaptive adjustments,allowing for region-specific color correction.This approach effectively enhances color fidelity and perceptual naturalness,addressing the limitations of global correction techniques.For contrast enhancement,the proposed method leverages the global mapping characteristics of the Rayleigh distribution to improve overall contrast,while CLAHE is employed to adaptively enhance local regions.A weighted fusion strategy is then applied to synthesize high-quality underwater images.Experimental results indicate that LACC-RCE surpasses conventional methods in color restoration,contrast optimization,and detail preservation,thereby enhancing the visual quality of underwater images.This improvement facilitates more reliable inputs for underwater object detection and recognition tasks.展开更多
In soft sensor field, just-in-time learning(JITL) is an effective approach to model nonlinear and time varying processes. However, most similarity criterions in JITL are computed in the input space only while ignoring...In soft sensor field, just-in-time learning(JITL) is an effective approach to model nonlinear and time varying processes. However, most similarity criterions in JITL are computed in the input space only while ignoring important output information, which may lead to inaccurate construction of relevant sample set. To solve this problem, we propose a novel supervised feature extraction method suitable for the regression problem called supervised local and non-local structure preserving projections(SLNSPP), in which both input and output information can be easily and effectively incorporated through a newly defined similarity index. The SLNSPP can not only retain the virtue of locality preserving projections but also prevent faraway points from nearing after projection,which endues SLNSPP with powerful discriminating ability. Such two good properties of SLNSPP are desirable for JITL as they are expected to enhance the accuracy of similar sample selection. Consequently, we present a SLNSPP-JITL framework for developing adaptive soft sensor, including a sparse learning strategy to limit the scale and update the frequency of database. Finally, two case studies are conducted with benchmark datasets to evaluate the performance of the proposed schemes. The results demonstrate the effectiveness of LNSPP and SLNSPP.展开更多
To overcome the obstacles of poor feature extraction and little prior information on the appearance of infrared dim small targets,we propose a multi-domain attention-guided pyramid network(MAGPNet).Specifically,we des...To overcome the obstacles of poor feature extraction and little prior information on the appearance of infrared dim small targets,we propose a multi-domain attention-guided pyramid network(MAGPNet).Specifically,we design three modules to ensure that salient features of small targets can be acquired and retained in the multi-scale feature maps.To improve the adaptability of the network for targets of different sizes,we design a kernel aggregation attention block with a receptive field attention branch and weight the feature maps under different perceptual fields with attention mechanism.Based on the research on human vision system,we further propose an adaptive local contrast measure module to enhance the local features of infrared small targets.With this parameterized component,we can implement the information aggregation of multi-scale contrast saliency maps.Finally,to fully utilize the information within spatial and channel domains in feature maps of different scales,we propose the mixed spatial-channel attention-guided fusion module to achieve high-quality fusion effects while ensuring that the small target features can be preserved at deep layers.Experiments on public datasets demonstrate that our MAGPNet can achieve a better performance over other state-of-the-art methods in terms of the intersection of union,Precision,Recall,and F-measure.In addition,we conduct detailed ablation studies to verify the effectiveness of each component in our network.展开更多
Non-signaling functions of coloration include thermoregulation(thermal melanism hypothesis),protection against ultraviolet radiation(photoprotection hypothesis),and concealment from predators(crypsis hypothesis).We in...Non-signaling functions of coloration include thermoregulation(thermal melanism hypothesis),protection against ultraviolet radiation(photoprotection hypothesis),and concealment from predators(crypsis hypothesis).We investigated whether dorsal coloration in 19 populations of spiny-footed lizards,Acanthodactylus erythrurus,across the Iberian Peninsula varies according to these functions.We captured adult males and females in each population and calculated standardized dorsum brightness estimates from photographs.We also calculated standardized ground luminosity estimates and gathered information on latitude,altitude,mean annual temperature,and mean annual solar radiation for each location.Males showed a higher percentage of black coloration and a more contrasted dorsum than females,suggesting different selection pressures on dorsal coloration in both sexes.Furthermore,males showed a darker dorsum and a higher percentage of black coloration at higher altitudes and when the ground was darker.In contrast,females exhibited a darker dorsum only when the ground was darker and a higher percentage of black coloration only at higher altitudes.We also observed that the variation of dorsum luminosity within males and the variation of dorsum luminosity among females within populations were both positively related to the variation of ground luminosity among different points within locations.Latitude,temperature,and solar radiation were not signifcantly related to dorsal coloration in either sex.Our results support the photoprotection and crypsis hypotheses in males and,to some extent,in females,whereas the thermal melanism hypothesis is weakly supported in both sexes.These fndings suggest that there is local adaptation in the dorsal coloration of the spiny-footed lizard.展开更多
Tetracentron sinense is a‘living fossil’tree in East Asia.Understanding how this‘living fossil’responds to climate change and adapts to local environments is critical for its conservation.Here,we used resequenced ...Tetracentron sinense is a‘living fossil’tree in East Asia.Understanding how this‘living fossil’responds to climate change and adapts to local environments is critical for its conservation.Here,we used resequenced genomes to clarify the evolutionary history and adaptive potential of T.sinense.We identifiedsix divergent lineages in T.sinense:three lineages from southwestern China(Yunnan Province)and three lineages from the central subtropical region of China.Additionally,we detected hybridization events between some adjacent lineages.Demographic analysis revealed that over the past 10,000 years the effective population size(Ne)of three T.sinense lineages(i.e.,NORTH,SWEST,and YNWEST)increased after their last bottleneck and then remained stable,whereas that of the remaining three lineages(i.e.,YSEAST,YC,and EAST)declined steadily.The decline in effective population size in the Yunnan lineages aligned well with the decrease in genome-wide diversity and a significantincrease in the frequency of runs of homozygosity.Deleterious variants and positively selected sites were involved in the evolution of different lineages.Further,genotype–environment association(GEA)analyses indicated adaptation to temperature-and precipitation-related factors.Genomic offset analyses found the most vulnerable populations,while SC and SC-yad were predicted to better handle extreme changes.Our findingsprovide insights into the evolutionary history and conservation of T.sinense and enhance our understanding of the evolution of living fossil species.展开更多
Local adaptation is critical for plant survivals and reproductions in the context of global environmental change.Heterogeneous environments impose various selection pressures that influence the fitness of organisms an...Local adaptation is critical for plant survivals and reproductions in the context of global environmental change.Heterogeneous environments impose various selection pressures that influence the fitness of organisms and leave genomic signatures during the process of adaptation to local environments.However,unveiling the genomic signatures of adaptation still poses a major challenge especially for perennials due to limited genomic resources.Here,we utilized Actinidia eriantha,a Chinese endemic liana,as a model case to detect drivers of local adaptation and adaptive signals through landscape genomics for 311 individuals collected from 25 populations.Our results demonstrated precipitation and solar radiation were two crucial factors influencing the patterns of genetic variations and driving adaptive processes.We further uncovered a set of genes involved in adaptation to heterogeneous environments.Among them,AeERF110 showed high genetic differentiation between populations and was confirmed to be involved in local adaptation via changes in allele frequency along with precipitation(Prec_03)and solar radiation(Srad_03)in native habitats separately,implying that adaptive loci frequently exhibited environmental and geographic signals.In addition,we assessed genetic offsets of populations under four future climate models and revealed that populations from middle and east clusters faced higher risks in adapting to future environments,which should address more attentions.Taken together,our study opens new perspectives for understanding the genetic underpinnings of local adaptation in plants to environmental changes in a more comprehensive fashion and offered the guides on applications in conservation efforts.展开更多
Understanding how environmental adaptation varies among families within a species is critical to adapt forestry activities such as management and breeding to possible future climate change.The present study examined h...Understanding how environmental adaptation varies among families within a species is critical to adapt forestry activities such as management and breeding to possible future climate change.The present study examined home-site advantage and local advantage in growth and basic density of wood in 36 families of Chamaecyparis obtuse(Siebold et Zucc.)Endl.,reciprocally planted at two progeny test sites with differing climatic conditions in Japan.A significant home-site advantage for growth was detected between the lowland and mountainous regions within the Kanto breeding region.In addition,the effects of climate differentials between the selection site of mating parents and the progeny test site on growth and basic density were inves-tigated.As a result,temperature was identified as the most significant climatic factor attributed to local adaptation for growth traits.Elongation and radial growth were adversely influenced when the progeny test site temperature exceeded the provenance temperature by more than 2°C.Therefore,it is crucial to account for temperature differences between the provenance and the planting site to adapt afforestation and forest tree breeding to climate change in the future.展开更多
When incompletely isolated taxa coexist in a patchy environment （e.g. mosaic hybrid zones, host-race complexes）, patterns of variation may differ between selected traits/genes and neutral markers. While the genetic ...When incompletely isolated taxa coexist in a patchy environment （e.g. mosaic hybrid zones, host-race complexes）, patterns of variation may differ between selected traits/genes and neutral markers. While the genetic structure of selected traits/loci tends to coincide with habitat variables （producing Genetic-Environment Association or GEA）, genetic differentiation at neutral loci unlinked to any selected locus rather depends on geographic connectivity at a large scale （e.g. Isolation- By-Distance or IBD）, although these loci often display GEA at a small scale. This discrepancy has been repeatedly taken as evi- dence for parallel primary divergence driven by local adaptation. We argue that this interpretation needs to be addressed more thoroughly by considering the alternative hypothesis that speciation was initiated in allopatry and secondary introgression has subsequently erased the signal of past differentiation at neutral loci. We present a model of neutral introgression after secondary contact in a mosaic hybrid zone, which describes how GEAs dissipate with time and how neutral variation self-organizes accord- ing to the environmental and geographic structures. We show that although neutral loci can be affected by environmental selection they are often more affected by history and connectivity： the neutral structure retains the initial geographic separation more than it correlates with the environment during the colonization and introgression phases, and then converges to a migration-drift balance, the most frequent outcome of which is GEA at a local scale but IBD at a large scale. This is the exact pattern usually attributed to parallel ecological speciation. Introgression is heterogeneous in space and depends on the landscape structure （e.g. it is faster in small patches, which are more impacted by immigration）. Furthermore, there is no directionality in the association and it is possi- ble to observe reversed GEAs between distant regions. We argue that the history of differentiation should ideally be reconstructed with selected loci or neutral loci linked to them, not neutral ones, and review some case studies for which the hypothesis of a long co-existence of co-adapted genetic backgrounds might have been refuted too hastily [Current Zoology 59 （1）： 72-86, 2013].展开更多
Increased productivity in sorghum has been achieved in the developed world using hybrids.Despite their yield advantage,introduced hybrids have not been adopted in Ethiopia due to the lack of adaptive traits,their shor...Increased productivity in sorghum has been achieved in the developed world using hybrids.Despite their yield advantage,introduced hybrids have not been adopted in Ethiopia due to the lack of adaptive traits,their short plant stature and small grain size.This study was conducted to investigate hybrid performance and the magnitude of heterosis of locally adapted genotypes in addition to introduced hybrids in three contrasting environments in Ethiopia.In total,139 hybrids,derived from introduced seed parents crossed with locally adapted genotypes and introduced R lines,were evaluated.Overall,the hybrids matured earlier than the adapted parents,but had higher grain yield,plant height,grain number and grain weight in all environments.The lowland adapted hybrids displayed a mean better parent heterosis(BPH) of19%,equating to 1160 kg ha-1and a 29% mean increase in grain yield,in addition to increased plant height and grain weight,in comparison to the hybrids derived from the introduced R lines.The mean BPH for grain yield for the highland adapted hybrids was 16% in the highland and 52%in the intermediate environment equating to 698 kg ha-1and 2031 kg ha-1,respectively,in addition to increased grain weight.The magnitude of heterosis observed for each hybrid group was related to the genetic distance between the parental lines.The majority of hybrids also showed superiority over the standard check varieties.In general,hybrids from locally adapted genotypes were superior in grain yield,plant height and grain weight compared to the high parents and introduced hybrids indicating the potential for hybrids to increase productivity while addressing farmers' required traits.展开更多
Highly fecund marine species with dispersive life-history stages often display large population sizes and wide geographic distribution ranges. Consequently, they are expected to experience reduced genetic drift, effic...Highly fecund marine species with dispersive life-history stages often display large population sizes and wide geographic distribution ranges. Consequently, they are expected to experience reduced genetic drift, efficient selection fueled by frequent adaptive mutations, and high migration loads. This has important consequences for understanding how local adaptation proceeds in the sea. A key issue in this regard, relates to the genetic architecture underlying fitness traits. Theory predicts that adaptation may involve many genes but with a high variance in effect size. Therefore, the effect of selection on allele frequencies may be substantial for the largest effect size loci, but insignificant for small effect genes. In such a context, the performance of population genomic methods to unravel the genetic basis of adaptation depends on the fraction of adaptive genetic variance explained by the cumulative effect of outlier loci. Here, we address some methodological challenges associated with the detection of local adaptation using molecular approaches. We provide an overview of genome scan methods to detect selection, including those assuming complex demographic models that better describe spatial population structure. We then focus on quantitative genetics approaches that search for genotype-phenotype associations at different genomic scales, including genome-wide methods evaluating the cumulative effect of variants. We argue that the limited power of single locus tests can be alleviated by the use of polygenic scores to estimate the joint contribution of candidate variants to phenotypic variation.展开更多
The genetic adaptations of various organisms to heterogeneous environments in the northwestern Pacific remain poorly understood.Heterogeneous genomic divergence among populations may reflect environmentalselection.Adv...The genetic adaptations of various organisms to heterogeneous environments in the northwestern Pacific remain poorly understood.Heterogeneous genomic divergence among populations may reflect environmentalselection.Advancingour understanding of the mechanisms by which organisms adapt to different temperatures in response to climate change and predicting the adaptive potential and ecological consequences of anthropogenic global warming are critical.We sequenced the whole genomes of Japanese whiting(Sillago japonica)specimens collected from different latitudinal locations along the coastal waters of China and Japan to detect possible thermal adaptations.Using population genomics,a total of 5.48 million single nucleotide polymorphisms(SNPs)from five populations revealed a complete genetic break between the Chinese and Japanese groups,which was attributed to both geographic distance and local adaptation.The shared natural selection genes between two isolated populations(i.e.,Zhoushan and Ise Bay/Tokyo Bay)indicated possible parallel evolution at the genetic level induced by temperature.These genes also indicated that the process of temperature selection on isolated populations is repeatable.Moreover,we observed natural candidate genes related to membrane fluidity,possibly underlying adaptation to cold environmental stress.These findings advance our understanding of the genetic mechanisms underlying the rapid adaptations of fish species.Species distribution projection models suggested that the Chinese and Japanese groups may have different responses to future climate change,with the former expanding and the latter contracting.The findings of this study enhance our understanding of genetic differentiation and adaptation to changing environments.展开更多
The extraction of water bodies is essential for monitoring water resources,ecosystem services and the hydrological cycle,so analyzing water bodies from remote sensing images is necessary.The water index is designed to...The extraction of water bodies is essential for monitoring water resources,ecosystem services and the hydrological cycle,so analyzing water bodies from remote sensing images is necessary.The water index is designed to highlight water bodies in remote sensing images.We employ a new water index and digital image processing technology to extract water bodies automatically and accurately from Landsat 8 OLI images.Firstly,we preprocess Landsat 8 OLI images with radiometric calibration and atmospheric correction.Subsequently,we apply KT transformation,LBV transformation,AWEI nsh,and HIS transformation to the preprocessed image to calculate a new water index.Then,we perform linear feature enhancement and improve the local adaptive threshold segmentation method to extract small water bodies accurately.Meanwhile,we employ morphological enhancement and improve the local adaptive threshold segmentation method to extract large water bodies.Finally,we combine small and large water bodies to get complete water bodies.Compared with other traditional methods,our method has apparent advantages in water extraction,particularly in the extraction of small water bodies.展开更多
During adaptation to different habitat types, both morphological and behavioral traits can undergo divergent selection. Males often fight for status in dominance hierarchies and rank positions predict reproductive suc...During adaptation to different habitat types, both morphological and behavioral traits can undergo divergent selection. Males often fight for status in dominance hierarchies and rank positions predict reproductive success. Ecotypes with reduced fighting abilities should have low reproductive success when migrating into habitats that harbor ecotypes with superior fighting abilities. Livebearing fishes in the Poecilia mexicana-species complex inhabit not only regular freshwater environments, but also independently colonized sulfidic （H2S-containing） habitats in three river drainages. In the current study, we found fighting intensities in staged contests to be considerably lower in some but not all sulfidic surface ecotypes and the sulfidic cave ecotype compared with populations from non-sulfidic surface sites. This is perhaps due to selection imposed by H2S, which hampers oxygen uptake and transport, as well as cellular respiration. Furthermore, migrants from sulfidic habitats may lose fights even if they do not show overall reduced aggressiveness, as phys- iological performance is likely to be challenged in the non-sulfidic environment to which they are not adapted. To test this hypothesis, we simulated migration of H2S-adapted males into H2S-free waters, as well as H2S-adapted cave-dwelling males into sulfidic surface waters. We found that intruders established dominance less often than resident males, independent of whether or not they showed reduced aggressiveness overall. Our study shows that divergent evolution of male aggressive behavior may also contribute to the maintenance of genetic differentiation in this system and we call for more careful evaluation of male fighting abilities in studies on ecological speciation.展开更多
Global temperatures are increasing rapidly affecting species globally.Understanding if and how different species can adapt fast enough to keep up with increasing temperatures is of vital importance.One mechanism that ...Global temperatures are increasing rapidly affecting species globally.Understanding if and how different species can adapt fast enough to keep up with increasing temperatures is of vital importance.One mechanism that can accelerate adaptation and promote evolutionary rescue is sexual selection.Two different mechanisms by which sexual selection can facilitate adaptation are pre-and postcopulatory sexual selection.However,the relative effects of these different forms of sexual selection in promoting adaptation are unknown.Here,we present the results from an experimental study in which we exposed fruit flies Drosophila melanogaster to either no mate choice or 1 of 2 different sexual selection regimes(pre-and postcopulatory sexual selection)for 6 generations,under different thermal regimes.Populations showed evidence of thermal adaptation under preco-pulatory sexual selection,but this effect was not detected in the postcopulatory sexual selection and the no choice mating regime.We further demonstrate that sexual dimorphism decreased when flies evolved under increasing temperatures,consistent with recent theory predicting more sexually concordant selection under environmental stress.Our results suggest an important role for precopulatory sexual selection in promoting thermal adaptation and evolutionary rescue.展开更多
基金Liaoning Meteorological Bureau Scientific Research Program(202103*)Bohai Regional Science and Technology Collaborative Innovation Fund(QYXM201607)。
文摘This study explores the use of the hierarchical ensemble filter to determine the localized influence of observations in the Weather Research and Forecasting ensemble square root filtering(WRF-EnSRF)assimilation system.With error correlations between observations and background field state variables considered,the adaptive localization approach is applied to conduct a series of ideal storm-scale data assimilation experiments using simulated Doppler radar data.Comparisons between adaptive and empirical localization methods are made,and the feasibility of adaptive localization for storm-scale ensemble Kalman filter assimilation is demonstrated.Unlike empirical localization,which relies on prior knowledge of distance between observations and background field,the hierarchical ensemble filter provides continuously updating localization influence weights adaptively.The adaptive scheme improves assimilation quality during rapid storm development and enhances assimilation of reflectivity observations.The characteristics of both the observation type and the storm development stage should be considered when identifying the most appropriate localization method.Ultimately,combining empirical and adaptive methods can optimize assimilation quality.
基金Graduate Student Innovation Projects of Beijing University of Civil Engineering and Architecture(No.PG2024121)。
文摘Underwater images are inherently degraded by color distortion,contrast reduction,and uneven brightness,primarily due to light absorption and scattering in water.To mitigate these challenges,a novel enhancement approach is proposed,integrating Local Adaptive Color Correction(LACC)with contrast enhancement based on adaptive Rayleigh distribution stretching and CLAHE(LACC-RCE).Conventional color correction methods predominantly employ global adjustment strategies,which are often inadequate for handling spatially varying color distortions.In contrast,the proposed LACC method incorporates local color analysis,tone-weighted control,and spatially adaptive adjustments,allowing for region-specific color correction.This approach effectively enhances color fidelity and perceptual naturalness,addressing the limitations of global correction techniques.For contrast enhancement,the proposed method leverages the global mapping characteristics of the Rayleigh distribution to improve overall contrast,while CLAHE is employed to adaptively enhance local regions.A weighted fusion strategy is then applied to synthesize high-quality underwater images.Experimental results indicate that LACC-RCE surpasses conventional methods in color restoration,contrast optimization,and detail preservation,thereby enhancing the visual quality of underwater images.This improvement facilitates more reliable inputs for underwater object detection and recognition tasks.
基金Supported by the National Natural Science Foundation of China(61273160)the Fundamental Research Funds for the Central Universities(14CX06067A,13CX05021A)
文摘In soft sensor field, just-in-time learning(JITL) is an effective approach to model nonlinear and time varying processes. However, most similarity criterions in JITL are computed in the input space only while ignoring important output information, which may lead to inaccurate construction of relevant sample set. To solve this problem, we propose a novel supervised feature extraction method suitable for the regression problem called supervised local and non-local structure preserving projections(SLNSPP), in which both input and output information can be easily and effectively incorporated through a newly defined similarity index. The SLNSPP can not only retain the virtue of locality preserving projections but also prevent faraway points from nearing after projection,which endues SLNSPP with powerful discriminating ability. Such two good properties of SLNSPP are desirable for JITL as they are expected to enhance the accuracy of similar sample selection. Consequently, we present a SLNSPP-JITL framework for developing adaptive soft sensor, including a sparse learning strategy to limit the scale and update the frequency of database. Finally, two case studies are conducted with benchmark datasets to evaluate the performance of the proposed schemes. The results demonstrate the effectiveness of LNSPP and SLNSPP.
基金the Industry-University-Research Cooperation Fund Project of the Eighth Research Institute of China Aerospace Science and Technology Corporation(No.USCAST2021-5)。
文摘To overcome the obstacles of poor feature extraction and little prior information on the appearance of infrared dim small targets,we propose a multi-domain attention-guided pyramid network(MAGPNet).Specifically,we design three modules to ensure that salient features of small targets can be acquired and retained in the multi-scale feature maps.To improve the adaptability of the network for targets of different sizes,we design a kernel aggregation attention block with a receptive field attention branch and weight the feature maps under different perceptual fields with attention mechanism.Based on the research on human vision system,we further propose an adaptive local contrast measure module to enhance the local features of infrared small targets.With this parameterized component,we can implement the information aggregation of multi-scale contrast saliency maps.Finally,to fully utilize the information within spatial and channel domains in feature maps of different scales,we propose the mixed spatial-channel attention-guided fusion module to achieve high-quality fusion effects while ensuring that the small target features can be preserved at deep layers.Experiments on public datasets demonstrate that our MAGPNet can achieve a better performance over other state-of-the-art methods in terms of the intersection of union,Precision,Recall,and F-measure.In addition,we conduct detailed ablation studies to verify the effectiveness of each component in our network.
基金funded by the European Regional Development Fund(ERDF A way of making Europe)and the Spanish Ministry of Education and Science(grant CGL2008-00137/BOS).
文摘Non-signaling functions of coloration include thermoregulation(thermal melanism hypothesis),protection against ultraviolet radiation(photoprotection hypothesis),and concealment from predators(crypsis hypothesis).We investigated whether dorsal coloration in 19 populations of spiny-footed lizards,Acanthodactylus erythrurus,across the Iberian Peninsula varies according to these functions.We captured adult males and females in each population and calculated standardized dorsum brightness estimates from photographs.We also calculated standardized ground luminosity estimates and gathered information on latitude,altitude,mean annual temperature,and mean annual solar radiation for each location.Males showed a higher percentage of black coloration and a more contrasted dorsum than females,suggesting different selection pressures on dorsal coloration in both sexes.Furthermore,males showed a darker dorsum and a higher percentage of black coloration at higher altitudes and when the ground was darker.In contrast,females exhibited a darker dorsum only when the ground was darker and a higher percentage of black coloration only at higher altitudes.We also observed that the variation of dorsum luminosity within males and the variation of dorsum luminosity among females within populations were both positively related to the variation of ground luminosity among different points within locations.Latitude,temperature,and solar radiation were not signifcantly related to dorsal coloration in either sex.Our results support the photoprotection and crypsis hypotheses in males and,to some extent,in females,whereas the thermal melanism hypothesis is weakly supported in both sexes.These fndings suggest that there is local adaptation in the dorsal coloration of the spiny-footed lizard.
基金supported by the National Natural Science Foundation of China(no.32570426)the Key Basic Research Program of Yunnan Province,China(202101BC070003)+1 种基金the Fundamental Research Funds for the Central Universities(QNTD202502)the STI 2030—Major Program(2022ZD0401605-2).
文摘Tetracentron sinense is a‘living fossil’tree in East Asia.Understanding how this‘living fossil’responds to climate change and adapts to local environments is critical for its conservation.Here,we used resequenced genomes to clarify the evolutionary history and adaptive potential of T.sinense.We identifiedsix divergent lineages in T.sinense:three lineages from southwestern China(Yunnan Province)and three lineages from the central subtropical region of China.Additionally,we detected hybridization events between some adjacent lineages.Demographic analysis revealed that over the past 10,000 years the effective population size(Ne)of three T.sinense lineages(i.e.,NORTH,SWEST,and YNWEST)increased after their last bottleneck and then remained stable,whereas that of the remaining three lineages(i.e.,YSEAST,YC,and EAST)declined steadily.The decline in effective population size in the Yunnan lineages aligned well with the decrease in genome-wide diversity and a significantincrease in the frequency of runs of homozygosity.Deleterious variants and positively selected sites were involved in the evolution of different lineages.Further,genotype–environment association(GEA)analyses indicated adaptation to temperature-and precipitation-related factors.Genomic offset analyses found the most vulnerable populations,while SC and SC-yad were predicted to better handle extreme changes.Our findingsprovide insights into the evolutionary history and conservation of T.sinense and enhance our understanding of the evolution of living fossil species.
基金funded by the National Natural Science Foundation of China(grants number 32070377 and 31770374)Science Fund for Creative Research Groups of the Natural Science Foundation of Hubei Province(2024AFA035).
文摘Local adaptation is critical for plant survivals and reproductions in the context of global environmental change.Heterogeneous environments impose various selection pressures that influence the fitness of organisms and leave genomic signatures during the process of adaptation to local environments.However,unveiling the genomic signatures of adaptation still poses a major challenge especially for perennials due to limited genomic resources.Here,we utilized Actinidia eriantha,a Chinese endemic liana,as a model case to detect drivers of local adaptation and adaptive signals through landscape genomics for 311 individuals collected from 25 populations.Our results demonstrated precipitation and solar radiation were two crucial factors influencing the patterns of genetic variations and driving adaptive processes.We further uncovered a set of genes involved in adaptation to heterogeneous environments.Among them,AeERF110 showed high genetic differentiation between populations and was confirmed to be involved in local adaptation via changes in allele frequency along with precipitation(Prec_03)and solar radiation(Srad_03)in native habitats separately,implying that adaptive loci frequently exhibited environmental and geographic signals.In addition,we assessed genetic offsets of populations under four future climate models and revealed that populations from middle and east clusters faced higher risks in adapting to future environments,which should address more attentions.Taken together,our study opens new perspectives for understanding the genetic underpinnings of local adaptation in plants to environmental changes in a more comprehensive fashion and offered the guides on applications in conservation efforts.
文摘Understanding how environmental adaptation varies among families within a species is critical to adapt forestry activities such as management and breeding to possible future climate change.The present study examined home-site advantage and local advantage in growth and basic density of wood in 36 families of Chamaecyparis obtuse(Siebold et Zucc.)Endl.,reciprocally planted at two progeny test sites with differing climatic conditions in Japan.A significant home-site advantage for growth was detected between the lowland and mountainous regions within the Kanto breeding region.In addition,the effects of climate differentials between the selection site of mating parents and the progeny test site on growth and basic density were inves-tigated.As a result,temperature was identified as the most significant climatic factor attributed to local adaptation for growth traits.Elongation and radial growth were adversely influenced when the progeny test site temperature exceeded the provenance temperature by more than 2°C.Therefore,it is crucial to account for temperature differences between the provenance and the planting site to adapt afforestation and forest tree breeding to climate change in the future.
文摘When incompletely isolated taxa coexist in a patchy environment （e.g. mosaic hybrid zones, host-race complexes）, patterns of variation may differ between selected traits/genes and neutral markers. While the genetic structure of selected traits/loci tends to coincide with habitat variables （producing Genetic-Environment Association or GEA）, genetic differentiation at neutral loci unlinked to any selected locus rather depends on geographic connectivity at a large scale （e.g. Isolation- By-Distance or IBD）, although these loci often display GEA at a small scale. This discrepancy has been repeatedly taken as evi- dence for parallel primary divergence driven by local adaptation. We argue that this interpretation needs to be addressed more thoroughly by considering the alternative hypothesis that speciation was initiated in allopatry and secondary introgression has subsequently erased the signal of past differentiation at neutral loci. We present a model of neutral introgression after secondary contact in a mosaic hybrid zone, which describes how GEAs dissipate with time and how neutral variation self-organizes accord- ing to the environmental and geographic structures. We show that although neutral loci can be affected by environmental selection they are often more affected by history and connectivity： the neutral structure retains the initial geographic separation more than it correlates with the environment during the colonization and introgression phases, and then converges to a migration-drift balance, the most frequent outcome of which is GEA at a local scale but IBD at a large scale. This is the exact pattern usually attributed to parallel ecological speciation. Introgression is heterogeneous in space and depends on the landscape structure （e.g. it is faster in small patches, which are more impacted by immigration）. Furthermore, there is no directionality in the association and it is possi- ble to observe reversed GEAs between distant regions. We argue that the history of differentiation should ideally be reconstructed with selected loci or neutral loci linked to them, not neutral ones, and review some case studies for which the hypothesis of a long co-existence of co-adapted genetic backgrounds might have been refuted too hastily [Current Zoology 59 （1）： 72-86, 2013].
基金AusAID (Australian Agency for International Development) for a scholarship supporting TTM,Queensland Alliance for Agriculture and Food Innovation (QAAFI)the Ethiopian Institute of Agricultural Research (EIAR) for financially supporting the research activities
文摘Increased productivity in sorghum has been achieved in the developed world using hybrids.Despite their yield advantage,introduced hybrids have not been adopted in Ethiopia due to the lack of adaptive traits,their short plant stature and small grain size.This study was conducted to investigate hybrid performance and the magnitude of heterosis of locally adapted genotypes in addition to introduced hybrids in three contrasting environments in Ethiopia.In total,139 hybrids,derived from introduced seed parents crossed with locally adapted genotypes and introduced R lines,were evaluated.Overall,the hybrids matured earlier than the adapted parents,but had higher grain yield,plant height,grain number and grain weight in all environments.The lowland adapted hybrids displayed a mean better parent heterosis(BPH) of19%,equating to 1160 kg ha-1and a 29% mean increase in grain yield,in addition to increased plant height and grain weight,in comparison to the hybrids derived from the introduced R lines.The mean BPH for grain yield for the highland adapted hybrids was 16% in the highland and 52%in the intermediate environment equating to 698 kg ha-1and 2031 kg ha-1,respectively,in addition to increased grain weight.The magnitude of heterosis observed for each hybrid group was related to the genetic distance between the parental lines.The majority of hybrids also showed superiority over the standard check varieties.In general,hybrids from locally adapted genotypes were superior in grain yield,plant height and grain weight compared to the high parents and introduced hybrids indicating the potential for hybrids to increase productivity while addressing farmers' required traits.
文摘Highly fecund marine species with dispersive life-history stages often display large population sizes and wide geographic distribution ranges. Consequently, they are expected to experience reduced genetic drift, efficient selection fueled by frequent adaptive mutations, and high migration loads. This has important consequences for understanding how local adaptation proceeds in the sea. A key issue in this regard, relates to the genetic architecture underlying fitness traits. Theory predicts that adaptation may involve many genes but with a high variance in effect size. Therefore, the effect of selection on allele frequencies may be substantial for the largest effect size loci, but insignificant for small effect genes. In such a context, the performance of population genomic methods to unravel the genetic basis of adaptation depends on the fraction of adaptive genetic variance explained by the cumulative effect of outlier loci. Here, we address some methodological challenges associated with the detection of local adaptation using molecular approaches. We provide an overview of genome scan methods to detect selection, including those assuming complex demographic models that better describe spatial population structure. We then focus on quantitative genetics approaches that search for genotype-phenotype associations at different genomic scales, including genome-wide methods evaluating the cumulative effect of variants. We argue that the limited power of single locus tests can be alleviated by the use of polygenic scores to estimate the joint contribution of candidate variants to phenotypic variation.
基金supported by the National Natural Science Foundation of China(41976083,41776171 and 32072980)。
文摘The genetic adaptations of various organisms to heterogeneous environments in the northwestern Pacific remain poorly understood.Heterogeneous genomic divergence among populations may reflect environmentalselection.Advancingour understanding of the mechanisms by which organisms adapt to different temperatures in response to climate change and predicting the adaptive potential and ecological consequences of anthropogenic global warming are critical.We sequenced the whole genomes of Japanese whiting(Sillago japonica)specimens collected from different latitudinal locations along the coastal waters of China and Japan to detect possible thermal adaptations.Using population genomics,a total of 5.48 million single nucleotide polymorphisms(SNPs)from five populations revealed a complete genetic break between the Chinese and Japanese groups,which was attributed to both geographic distance and local adaptation.The shared natural selection genes between two isolated populations(i.e.,Zhoushan and Ise Bay/Tokyo Bay)indicated possible parallel evolution at the genetic level induced by temperature.These genes also indicated that the process of temperature selection on isolated populations is repeatable.Moreover,we observed natural candidate genes related to membrane fluidity,possibly underlying adaptation to cold environmental stress.These findings advance our understanding of the genetic mechanisms underlying the rapid adaptations of fish species.Species distribution projection models suggested that the Chinese and Japanese groups may have different responses to future climate change,with the former expanding and the latter contracting.The findings of this study enhance our understanding of genetic differentiation and adaptation to changing environments.
基金Auhui Provincial Key Research and Development Project(No.202004a07020050)National Natural Science Foundation of China Youth Program(No.61901006)。
文摘The extraction of water bodies is essential for monitoring water resources,ecosystem services and the hydrological cycle,so analyzing water bodies from remote sensing images is necessary.The water index is designed to highlight water bodies in remote sensing images.We employ a new water index and digital image processing technology to extract water bodies automatically and accurately from Landsat 8 OLI images.Firstly,we preprocess Landsat 8 OLI images with radiometric calibration and atmospheric correction.Subsequently,we apply KT transformation,LBV transformation,AWEI nsh,and HIS transformation to the preprocessed image to calculate a new water index.Then,we perform linear feature enhancement and improve the local adaptive threshold segmentation method to extract small water bodies accurately.Meanwhile,we employ morphological enhancement and improve the local adaptive threshold segmentation method to extract large water bodies.Finally,we combine small and large water bodies to get complete water bodies.Compared with other traditional methods,our method has apparent advantages in water extraction,particularly in the extraction of small water bodies.
文摘During adaptation to different habitat types, both morphological and behavioral traits can undergo divergent selection. Males often fight for status in dominance hierarchies and rank positions predict reproductive success. Ecotypes with reduced fighting abilities should have low reproductive success when migrating into habitats that harbor ecotypes with superior fighting abilities. Livebearing fishes in the Poecilia mexicana-species complex inhabit not only regular freshwater environments, but also independently colonized sulfidic （H2S-containing） habitats in three river drainages. In the current study, we found fighting intensities in staged contests to be considerably lower in some but not all sulfidic surface ecotypes and the sulfidic cave ecotype compared with populations from non-sulfidic surface sites. This is perhaps due to selection imposed by H2S, which hampers oxygen uptake and transport, as well as cellular respiration. Furthermore, migrants from sulfidic habitats may lose fights even if they do not show overall reduced aggressiveness, as phys- iological performance is likely to be challenged in the non-sulfidic environment to which they are not adapted. To test this hypothesis, we simulated migration of H2S-adapted males into H2S-free waters, as well as H2S-adapted cave-dwelling males into sulfidic surface waters. We found that intruders established dominance less often than resident males, independent of whether or not they showed reduced aggressiveness overall. Our study shows that divergent evolution of male aggressive behavior may also contribute to the maintenance of genetic differentiation in this system and we call for more careful evaluation of male fighting abilities in studies on ecological speciation.
基金E.S.was financially supported by the Erasmus ProgrammeE.I.S.was financially supported by research grants from Stina Werners Fond,Gyllenstiernska Krapperupsstiftelsen,Olle Engqvist Byggmastare Foundation and the Swedish Research Council(VR,grant no.2016-03356).
文摘Global temperatures are increasing rapidly affecting species globally.Understanding if and how different species can adapt fast enough to keep up with increasing temperatures is of vital importance.One mechanism that can accelerate adaptation and promote evolutionary rescue is sexual selection.Two different mechanisms by which sexual selection can facilitate adaptation are pre-and postcopulatory sexual selection.However,the relative effects of these different forms of sexual selection in promoting adaptation are unknown.Here,we present the results from an experimental study in which we exposed fruit flies Drosophila melanogaster to either no mate choice or 1 of 2 different sexual selection regimes(pre-and postcopulatory sexual selection)for 6 generations,under different thermal regimes.Populations showed evidence of thermal adaptation under preco-pulatory sexual selection,but this effect was not detected in the postcopulatory sexual selection and the no choice mating regime.We further demonstrate that sexual dimorphism decreased when flies evolved under increasing temperatures,consistent with recent theory predicting more sexually concordant selection under environmental stress.Our results suggest an important role for precopulatory sexual selection in promoting thermal adaptation and evolutionary rescue.
