Types and structure of plant communities in the Yellow River Delta were investigated by using detrended canonical correspondence analyses (DCCAs) and a two-way indicator species analysis (TWINSPAN). The distributi...Types and structure of plant communities in the Yellow River Delta were investigated by using detrended canonical correspondence analyses (DCCAs) and a two-way indicator species analysis (TWINSPAN). The distribution pattern and influential factors of the plant communities were also analyzed by testing elevation, slope, soil characteristics, longitude and latitude of 134 vegetation samples collected by representative plot sampling methods. Results showed that all the 134 vegetation samples could be divided into seven vegetation groups, separately dominated by Robinia pseucdoacacia, Imperata cylindrical, Miscanthus saccharifleus, Suaeda salsa, Aeluropus sinensis, Phragmites australis and Tamarix chinensis. The vegetation distribution pattern was mainly related to elevation, ground water depth and soil characteristics such as salinity and soluble potassium. Among the factors affecting distribution pattern of the plant communities, the species matrix explained by non-spatial environmental variation accounts for 45.2% of total variation. Spatial variation and spatial-structured environmental variation explain 11.8%, and 2.2%, respectively. Remained 40.8% of undetermined variation is attributed to biological and stochastic factors.展开更多
[Objective] The aim was to identify the ploidy of sweet clover induced by colchicine. [Method] The sweet clover germinating seeds and colchicine solution were used for materials to research colchicine-induced Melilotu...[Objective] The aim was to identify the ploidy of sweet clover induced by colchicine. [Method] The sweet clover germinating seeds and colchicine solution were used for materials to research colchicine-induced Melilotus. [Result] The results showed that the concentration of 0.2% colchicine solution could induced double sweet clover which showed corresponding features of polyploidy plants as a whole showed great features. [Conclusion] Sweet clover induced by colchicine was polyploidy.展开更多
To provide an insight into the molecular basis of heterosis, differential display of mRNA was used to analyze the difference of gene expression between wheat (Triticum aestivum L.) heterotic hybrid A, nonheterotic hyb...To provide an insight into the molecular basis of heterosis, differential display of mRNA was used to analyze the difference of gene expression between wheat (Triticum aestivum L.) heterotic hybrid A, nonheterotic hybrid B and their parental inbreds in the primary roots. By using 5′ end random primers in combination with three one-base-anchored primers, it was found that 22.5% and 22.9% of 877 total displayed cDNAs were differentially expressed between hybrid A, B and their parents, respectively. Both quantitative and qualitative differences in gene expression between hybrids and their parental inbreds were obvious, indicating that the patterns of gene expression in hybrids alter significantly as compared to their corresponding parents. On the other hand, by using MADS-box gene specific 5′ end primer for DDRT-PCR, we found that nearly all of the displayed cDNA fragments were polymorphic between hybrids and their parents, and major difference occurred in qualitative level, in which hybrid specific-expressed and silenced genes are the major two patterns, suggesting that MADS-box gene may be important for manifestation of differential gene expression and wheat heterosis. In comparison with our previous results by using seedling leaves, it is indicated that differential gene expression between hybrids and parents is dependent on the tissues tested, and more differentially expressed genes were observed in the primary roots than in the seedling leaves. Therefore, it is concluded that the expressions of both randomly displayed cDNAs and transcription factor genes, such as MADS-box, alter significantly between hybrids and their parents, which might be responsible for the observed heterosis.展开更多
Environmental characteristics are often the factors that determine the distribution of species in nature. However, species response vis-A-vis these factors differs. For a better understanding of the phenomenon, we hav...Environmental characteristics are often the factors that determine the distribution of species in nature. However, species response vis-A-vis these factors differs. For a better understanding of the phenomenon, we have conducted this study which consists of following the spatio-temporal evolution of two species of Oribatida (Scheloribates sp. and Galumna sp.). The sites which have been the subject of this study, are situated in different bioclimatic zones presenting a very different climatic, edaphic, nutritional, and altitudinal characteristics. The variability of ecological factors showed that the behavior of two species differs. Indeed, Scheloribates sp. is present in all sites except in Biskra whereas Galumna sp. is present only in sites belonging to humid and sub humid bioclimatic zones. Moreover, Scheloribates sp. appears more tolerant of environmental changes while Galumna sp. is more stringent and its presence is marked only in the sites where ecological conditions are better. Thus, it can be noted that the spatial and temporal distribution of oribatid is not only conditioned solely by environmental factors but also by intrinsic factors specific to each species. The specific behavior of Galumna sp. and the tolerance of Scheloribates sp. are interesting and can be the subject of bioindicator species that can inform us about the changes that effect whether natural or anthropogenic environment.展开更多
This work analyzes the discourse and the practice of the youth from the Catholic Church (CC) in order to present experiences and dialogues present in contemporary Catholicism. The purpose of this paper is to analyze...This work analyzes the discourse and the practice of the youth from the Catholic Church (CC) in order to present experiences and dialogues present in contemporary Catholicism. The purpose of this paper is to analyze how Catholic groups work, in particular groups of Pastoral Youth and Charismatic Renovation prayer groups. As a result, observations are presented from an ethnographic work in groups identified with the spirituality of Liberation Theology and from charismatic ones. Besides, the text shows, from participants' experiences, the differences between both perspectives of religious living and the detachment and lack of dialogue which exists inside Catholicism.展开更多
A comprehensive appraisal is performed on the newly bred of 28 hybrid middle-season rice combinations, with Yangliangyou 6 as a control, a total of 29 combinations, in terms of high and stable yield, adaptability and ...A comprehensive appraisal is performed on the newly bred of 28 hybrid middle-season rice combinations, with Yangliangyou 6 as a control, a total of 29 combinations, in terms of high and stable yield, adaptability and disease resistance. Two-line hybrid combinations have a total of 24, accounting for 82.76% of the exhibition, but there were only 5 three-line hybrid combinations have accounting for 17.24% of the exhibition. There are 13 high-quality two-line cross combinations, representing 54.17% of the two-line hybrid combinations. In the 8 hybrid combinations, whose yield per unit area is more than that of the control, 7 are two-line hybrid combinations, and the last one is the three-line hybrid combination. There are 15 two-line hybrid combinations with whole growth period 10 d shorter than Yangliangyou 6.展开更多
In this paper, the characteristics and yield performance of new variety Xi-angyou196 were introduced, and its high-yielding cuItivation techniques were summa-rized, finally, the corresponding matching cuItivation tech...In this paper, the characteristics and yield performance of new variety Xi-angyou196 were introduced, and its high-yielding cuItivation techniques were summa-rized, finally, the corresponding matching cuItivation techniques through experiment and demonstration were put forward.展开更多
Flatfish or flounder moves one eye to change body proportion into vertebral asymmetry during metamorphosis, during which some become sinistral while others dextral. However, the mechanism behinds the eye-position has ...Flatfish or flounder moves one eye to change body proportion into vertebral asymmetry during metamorphosis, during which some become sinistral while others dextral. However, the mechanism behinds the eye-position has not been well understood. In this research, hybrids between Japanese flounder(♀) and stone flounder (♂) show mixed eye-location in both dextral type and sinistral type, and thus become good samples for studying the eye-migration. mRNAs from pro-metamorphosis sinistral and dextral hybrids larvae were screened with classical differential display RT-PCR (DD-RT-PCR) and representational difference analysis of cDNA (cDNA-RDA); 30 and 47 putative fragments were isolated, respectively. The cDNA fragments of creatine kinase and trypsinogen 2 precursor genes isolated by cDNA-RDA exhibited eye-position expression patterns during metamorphosis. However, none of the fragments was proved to be related to flatfishes’ eye-position specifically. Therefore, further studies and more sensitive gene isolated methods are needed to solve the problems.展开更多
N+N nominal sentence is an important structure type of nominal sentences in Mandarin Chinese. Attributive-center, combination, apposition and subject-predicate are its main structure types. In main literary genres, ...N+N nominal sentence is an important structure type of nominal sentences in Mandarin Chinese. Attributive-center, combination, apposition and subject-predicate are its main structure types. In main literary genres, the distribution of N+N nominal sentence shows a certain trend of dominant hierarchy: poem﹥drama﹥novel﹥prose. No matter what kind of literary genres, attributive-center structure is the type with maximum quantity, while appositive structure is the type with minimum quantity. Statistical result indicates that most of N+N nominal sentence is nominal and its use is limited by genres. Function of N+N nominal sentence is textual. When it comes to discourse, it can be used as theme, rheme and dual identity of theme and rheme based on the theory of Theme-Rheme (T-R) structure pattern. It does not only construct the information structure to deliver textual information, but also its a vital means of discourse cohesion and coherence.展开更多
[Objective] This study aimed to examine indicative roles of texture representing soil organic carbon presence and variability subsequent to cultivation under cold temperate climates with seasonal freeze-thaw events. [...[Objective] This study aimed to examine indicative roles of texture representing soil organic carbon presence and variability subsequent to cultivation under cold temperate climates with seasonal freeze-thaw events. [Method] Three chronosequences were selected for paired comparisons. Soil samples were collected at six depths with a 10 cm increment. Analysis of variance with general linear model and regression was performed for statistical analysis. [Result] In seasonally frozen soils where fragmentation of macroaggregates was stimulated, soil organic carbon level was positively associated with clay + silt proportion due to a wider textural range, better than sole clay content. Exponential function better fitted the experimental data to present progressively increased effectiveness of clay + silt content in maintaining carbon. Clay content explained 12%-41% and 14%-43% of variation via linear and exponential functions, respectively. Accordingly, clay + silt content explained 47%-65% and 46%-70%. [Conclusion] Texture reflected soil organic carbon occurrence as consequences of reclamation. For seasonally frozen soils with wider textural ranges, it is robust to adapt clay + silt content as dependent variable and exponential function. The generated algorithms provided an available pathway to estimate soil organic carbon losses following cultivation and to evaluate soil fertility.展开更多
The planning Yalong-River water transfer project will transfer 5.65 billion cubic meters water from the Yalong River into the Yellow River per year.The Yalong River will be dramatically impacted hydrologically and eco...The planning Yalong-River water transfer project will transfer 5.65 billion cubic meters water from the Yalong River into the Yellow River per year.The Yalong River will be dramatically impacted hydrologically and ecologically because more than 60% of the runoff will be diverted.An ecohydrological model was used to evaluate the impacts of the project on river corridor and wetland in this study.Schizothorax is a typical plateau river species and was used as the indicator species for assessment of the impact of water transfer project.The model simulated the habitat area of Schizothorax in the reach between the Reba Dam and the Ganzi Hydrology Station on the Yalong River.The Reba Dam,A'an Dam and Renda Dam will be constructed in the Yalong River for enhancing the water level for water diversion into the Yellow River.The velocity,channel width,runoff,and water depth will be reduced due to the water transfer,especially during flood season.The reduction in the velocity,channel width,runoff and water depth will occur mainly in the reach near the three dams and the reduction will be reduced to a minimum level in a distance about 100 km downstream of the dams.The maximum net water loss of Kasha Lake is only 1197200 m3,only 0.3% of runoff flowing into the lake.The project cannot bring adverse effect on the lake.The habitat area of Schizothorax in the Yalong River might be reduced if the water was transferred from the Reba Dam.The habitat area of this species will be reduced more than 40%.展开更多
Populations that have recently diverged offer a powerful model for studying evolution. Ecological differences are expected to generate divergent selection on multiple traits, including neurobiological ones. Animals mu...Populations that have recently diverged offer a powerful model for studying evolution. Ecological differences are expected to generate divergent selection on multiple traits, including neurobiological ones. Animals must detect, process, and act on information from their surroundings and the form of this information can be highly dependent on the environment. We might expect different environments to generate divergent selection not only on the sensory organs, but also on the brain regions responsible for processing sensory information. Here, we test this hypothesis using recently evolved reproductively isolated species pairs of threespine stickleback fish Gasterosteus aculeatus that have well-described differences in many morphological and behavioral traits corre- lating with ecological differences. We use a state-of-the-art method, magnetic resonance imaging, to get accurate volumetric data for 2 sensory processing regions, the olfactory bulbs and optic tecta. We found a tight correlation between ecology and the size of these brain regions relative to total brain size in 2 lakes with intact species pairs. Limnetic fish, which rely heavily on vision, had relatively larger optic tecta and smaller olfactory bulbs compared with benthic fish, which utilize olfaction to a greater extent. Benthic fish also had larger total brain volumes relative to their body size compared with limnetic fish. These differences were erased in a collapsed species pair in Enos Lake where anthropogenic disturbance has led to intense hybridization. Together these data indicate that evolution of sensory processing regions can occur rapidly and independently.展开更多
Ecological niche modeling has emerged as an useful tool in the investigation of the phylogeographic histories of species or communities in a region. The high biodiversity (oftentimes cryptic), and complex geography ...Ecological niche modeling has emerged as an useful tool in the investigation of the phylogeographic histories of species or communities in a region. The high biodiversity (oftentimes cryptic), and complex geography and geological history of Southeast Asia particularly call for multipronged approaches in phylogeographic investigations. Past studies have focused on taxa that are associated with lowland rainforests, which is the dominant natural vegetation type. Here, we combine published phylogenetic data, ecological niche modeling and paleo-climate models to reveal potential drivers of divergence in two open-forest bird species, the oriental magpie-robin Copsychus saularis and Coppersmith barbet Megalaima haemacephala. In spite of broad overlap in current distributions, there are subtle differences in their climatic niches, which result in different responses to past climatic changes. For C saularis, both Last Glacial Maximum climate models indicated that the entire Sundaland was climati- cally suitable, while phylogenetic analyses found divergent eastern and western Sundaland lineages. We thus postulate that this genetic divergence was a result of past separations of coastal habitats into eastern and western portions due to the emergence of Sunda shelf as sea-level fell. The current separation of morphological subspecies in Borneo is maintained by low climatic suitability (high annual rainfall) in certain regions. The extirpation of M. haemacephala from Borneo and southern Malay Peninsula might have been driven by unsuitable conditions (high temperature seasonality) in central Sundaland and/or the lack of open woodlands. Our study shows that ecological niche modeling adds a powerful dimension to our attempt to understand lineage evolution in space [Current Zoology 61 (5): 922-934, 2015].展开更多
基金Foundation project: This study was financially supported by the Na- tional Natural Science Foundation of China (No. 40771172) and the orientation project of the Chinese Academy of Sciences (No. kzcx2-yw-308)
文摘Types and structure of plant communities in the Yellow River Delta were investigated by using detrended canonical correspondence analyses (DCCAs) and a two-way indicator species analysis (TWINSPAN). The distribution pattern and influential factors of the plant communities were also analyzed by testing elevation, slope, soil characteristics, longitude and latitude of 134 vegetation samples collected by representative plot sampling methods. Results showed that all the 134 vegetation samples could be divided into seven vegetation groups, separately dominated by Robinia pseucdoacacia, Imperata cylindrical, Miscanthus saccharifleus, Suaeda salsa, Aeluropus sinensis, Phragmites australis and Tamarix chinensis. The vegetation distribution pattern was mainly related to elevation, ground water depth and soil characteristics such as salinity and soluble potassium. Among the factors affecting distribution pattern of the plant communities, the species matrix explained by non-spatial environmental variation accounts for 45.2% of total variation. Spatial variation and spatial-structured environmental variation explain 11.8%, and 2.2%, respectively. Remained 40.8% of undetermined variation is attributed to biological and stochastic factors.
基金Supported by General Project of Education Department in Helongjiang (11531263)Key Project of Science and Technology Bureau, Helongjiang Land Reclamation Bureau (HNKXIV-08-06-09)~~
文摘[Objective] The aim was to identify the ploidy of sweet clover induced by colchicine. [Method] The sweet clover germinating seeds and colchicine solution were used for materials to research colchicine-induced Melilotus. [Result] The results showed that the concentration of 0.2% colchicine solution could induced double sweet clover which showed corresponding features of polyploidy plants as a whole showed great features. [Conclusion] Sweet clover induced by colchicine was polyploidy.
文摘To provide an insight into the molecular basis of heterosis, differential display of mRNA was used to analyze the difference of gene expression between wheat (Triticum aestivum L.) heterotic hybrid A, nonheterotic hybrid B and their parental inbreds in the primary roots. By using 5′ end random primers in combination with three one-base-anchored primers, it was found that 22.5% and 22.9% of 877 total displayed cDNAs were differentially expressed between hybrid A, B and their parents, respectively. Both quantitative and qualitative differences in gene expression between hybrids and their parental inbreds were obvious, indicating that the patterns of gene expression in hybrids alter significantly as compared to their corresponding parents. On the other hand, by using MADS-box gene specific 5′ end primer for DDRT-PCR, we found that nearly all of the displayed cDNA fragments were polymorphic between hybrids and their parents, and major difference occurred in qualitative level, in which hybrid specific-expressed and silenced genes are the major two patterns, suggesting that MADS-box gene may be important for manifestation of differential gene expression and wheat heterosis. In comparison with our previous results by using seedling leaves, it is indicated that differential gene expression between hybrids and parents is dependent on the tissues tested, and more differentially expressed genes were observed in the primary roots than in the seedling leaves. Therefore, it is concluded that the expressions of both randomly displayed cDNAs and transcription factor genes, such as MADS-box, alter significantly between hybrids and their parents, which might be responsible for the observed heterosis.
文摘Environmental characteristics are often the factors that determine the distribution of species in nature. However, species response vis-A-vis these factors differs. For a better understanding of the phenomenon, we have conducted this study which consists of following the spatio-temporal evolution of two species of Oribatida (Scheloribates sp. and Galumna sp.). The sites which have been the subject of this study, are situated in different bioclimatic zones presenting a very different climatic, edaphic, nutritional, and altitudinal characteristics. The variability of ecological factors showed that the behavior of two species differs. Indeed, Scheloribates sp. is present in all sites except in Biskra whereas Galumna sp. is present only in sites belonging to humid and sub humid bioclimatic zones. Moreover, Scheloribates sp. appears more tolerant of environmental changes while Galumna sp. is more stringent and its presence is marked only in the sites where ecological conditions are better. Thus, it can be noted that the spatial and temporal distribution of oribatid is not only conditioned solely by environmental factors but also by intrinsic factors specific to each species. The specific behavior of Galumna sp. and the tolerance of Scheloribates sp. are interesting and can be the subject of bioindicator species that can inform us about the changes that effect whether natural or anthropogenic environment.
文摘This work analyzes the discourse and the practice of the youth from the Catholic Church (CC) in order to present experiences and dialogues present in contemporary Catholicism. The purpose of this paper is to analyze how Catholic groups work, in particular groups of Pastoral Youth and Charismatic Renovation prayer groups. As a result, observations are presented from an ethnographic work in groups identified with the spirituality of Liberation Theology and from charismatic ones. Besides, the text shows, from participants' experiences, the differences between both perspectives of religious living and the detachment and lack of dialogue which exists inside Catholicism.
基金Supported by Wuhan Experimental Station of National Rice Industry Technology System(CARS-01-63)Hubei Key Research and Development Technology Program(2014ABA021)National Agricultural Science Technology Achievement Transformation Fund(2014GB2D100579)~~
文摘A comprehensive appraisal is performed on the newly bred of 28 hybrid middle-season rice combinations, with Yangliangyou 6 as a control, a total of 29 combinations, in terms of high and stable yield, adaptability and disease resistance. Two-line hybrid combinations have a total of 24, accounting for 82.76% of the exhibition, but there were only 5 three-line hybrid combinations have accounting for 17.24% of the exhibition. There are 13 high-quality two-line cross combinations, representing 54.17% of the two-line hybrid combinations. In the 8 hybrid combinations, whose yield per unit area is more than that of the control, 7 are two-line hybrid combinations, and the last one is the three-line hybrid combination. There are 15 two-line hybrid combinations with whole growth period 10 d shorter than Yangliangyou 6.
基金Supported by Major Scientific and Technological Project of Jiangxi Province(20114ABF03106)Achievements Transformation and Extension in Nanchang City(2013HZLL1005)the Great Transfer and Transformation Program of S&T Achievements in Jiangxi Province(20141BBI90001)~~
文摘In this paper, the characteristics and yield performance of new variety Xi-angyou196 were introduced, and its high-yielding cuItivation techniques were summa-rized, finally, the corresponding matching cuItivation techniques through experiment and demonstration were put forward.
基金Supported by National Natural Science Foundation of China (No. 30600455)the National Basic Research Program of China (973 Program, No.2004CB117402)
文摘Flatfish or flounder moves one eye to change body proportion into vertebral asymmetry during metamorphosis, during which some become sinistral while others dextral. However, the mechanism behinds the eye-position has not been well understood. In this research, hybrids between Japanese flounder(♀) and stone flounder (♂) show mixed eye-location in both dextral type and sinistral type, and thus become good samples for studying the eye-migration. mRNAs from pro-metamorphosis sinistral and dextral hybrids larvae were screened with classical differential display RT-PCR (DD-RT-PCR) and representational difference analysis of cDNA (cDNA-RDA); 30 and 47 putative fragments were isolated, respectively. The cDNA fragments of creatine kinase and trypsinogen 2 precursor genes isolated by cDNA-RDA exhibited eye-position expression patterns during metamorphosis. However, none of the fragments was proved to be related to flatfishes’ eye-position specifically. Therefore, further studies and more sensitive gene isolated methods are needed to solve the problems.
文摘N+N nominal sentence is an important structure type of nominal sentences in Mandarin Chinese. Attributive-center, combination, apposition and subject-predicate are its main structure types. In main literary genres, the distribution of N+N nominal sentence shows a certain trend of dominant hierarchy: poem﹥drama﹥novel﹥prose. No matter what kind of literary genres, attributive-center structure is the type with maximum quantity, while appositive structure is the type with minimum quantity. Statistical result indicates that most of N+N nominal sentence is nominal and its use is limited by genres. Function of N+N nominal sentence is textual. When it comes to discourse, it can be used as theme, rheme and dual identity of theme and rheme based on the theory of Theme-Rheme (T-R) structure pattern. It does not only construct the information structure to deliver textual information, but also its a vital means of discourse cohesion and coherence.
基金Supported by the National Natural Science Foundation of China(41171384,41271414and 41301529)
文摘[Objective] This study aimed to examine indicative roles of texture representing soil organic carbon presence and variability subsequent to cultivation under cold temperate climates with seasonal freeze-thaw events. [Method] Three chronosequences were selected for paired comparisons. Soil samples were collected at six depths with a 10 cm increment. Analysis of variance with general linear model and regression was performed for statistical analysis. [Result] In seasonally frozen soils where fragmentation of macroaggregates was stimulated, soil organic carbon level was positively associated with clay + silt proportion due to a wider textural range, better than sole clay content. Exponential function better fitted the experimental data to present progressively increased effectiveness of clay + silt content in maintaining carbon. Clay content explained 12%-41% and 14%-43% of variation via linear and exponential functions, respectively. Accordingly, clay + silt content explained 47%-65% and 46%-70%. [Conclusion] Texture reflected soil organic carbon occurrence as consequences of reclamation. For seasonally frozen soils with wider textural ranges, it is robust to adapt clay + silt content as dependent variable and exponential function. The generated algorithms provided an available pathway to estimate soil organic carbon losses following cultivation and to evaluate soil fertility.
基金supported by the National Natural Science Foundation of China (Grant Nos. 51027006,51109224)the National Key Basic Research Program of China ("973" Program) (Grant No. 2010CB951102)the National Key Project of Scientific and Technical Supporting Program (Grant No. 2006BAB04A08)
文摘The planning Yalong-River water transfer project will transfer 5.65 billion cubic meters water from the Yalong River into the Yellow River per year.The Yalong River will be dramatically impacted hydrologically and ecologically because more than 60% of the runoff will be diverted.An ecohydrological model was used to evaluate the impacts of the project on river corridor and wetland in this study.Schizothorax is a typical plateau river species and was used as the indicator species for assessment of the impact of water transfer project.The model simulated the habitat area of Schizothorax in the reach between the Reba Dam and the Ganzi Hydrology Station on the Yalong River.The Reba Dam,A'an Dam and Renda Dam will be constructed in the Yalong River for enhancing the water level for water diversion into the Yellow River.The velocity,channel width,runoff,and water depth will be reduced due to the water transfer,especially during flood season.The reduction in the velocity,channel width,runoff and water depth will occur mainly in the reach near the three dams and the reduction will be reduced to a minimum level in a distance about 100 km downstream of the dams.The maximum net water loss of Kasha Lake is only 1197200 m3,only 0.3% of runoff flowing into the lake.The project cannot bring adverse effect on the lake.The habitat area of Schizothorax in the Yalong River might be reduced if the water was transferred from the Reba Dam.The habitat area of this species will be reduced more than 40%.
文摘Populations that have recently diverged offer a powerful model for studying evolution. Ecological differences are expected to generate divergent selection on multiple traits, including neurobiological ones. Animals must detect, process, and act on information from their surroundings and the form of this information can be highly dependent on the environment. We might expect different environments to generate divergent selection not only on the sensory organs, but also on the brain regions responsible for processing sensory information. Here, we test this hypothesis using recently evolved reproductively isolated species pairs of threespine stickleback fish Gasterosteus aculeatus that have well-described differences in many morphological and behavioral traits corre- lating with ecological differences. We use a state-of-the-art method, magnetic resonance imaging, to get accurate volumetric data for 2 sensory processing regions, the olfactory bulbs and optic tecta. We found a tight correlation between ecology and the size of these brain regions relative to total brain size in 2 lakes with intact species pairs. Limnetic fish, which rely heavily on vision, had relatively larger optic tecta and smaller olfactory bulbs compared with benthic fish, which utilize olfaction to a greater extent. Benthic fish also had larger total brain volumes relative to their body size compared with limnetic fish. These differences were erased in a collapsed species pair in Enos Lake where anthropogenic disturbance has led to intense hybridization. Together these data indicate that evolution of sensory processing regions can occur rapidly and independently.
文摘Ecological niche modeling has emerged as an useful tool in the investigation of the phylogeographic histories of species or communities in a region. The high biodiversity (oftentimes cryptic), and complex geography and geological history of Southeast Asia particularly call for multipronged approaches in phylogeographic investigations. Past studies have focused on taxa that are associated with lowland rainforests, which is the dominant natural vegetation type. Here, we combine published phylogenetic data, ecological niche modeling and paleo-climate models to reveal potential drivers of divergence in two open-forest bird species, the oriental magpie-robin Copsychus saularis and Coppersmith barbet Megalaima haemacephala. In spite of broad overlap in current distributions, there are subtle differences in their climatic niches, which result in different responses to past climatic changes. For C saularis, both Last Glacial Maximum climate models indicated that the entire Sundaland was climati- cally suitable, while phylogenetic analyses found divergent eastern and western Sundaland lineages. We thus postulate that this genetic divergence was a result of past separations of coastal habitats into eastern and western portions due to the emergence of Sunda shelf as sea-level fell. The current separation of morphological subspecies in Borneo is maintained by low climatic suitability (high annual rainfall) in certain regions. The extirpation of M. haemacephala from Borneo and southern Malay Peninsula might have been driven by unsuitable conditions (high temperature seasonality) in central Sundaland and/or the lack of open woodlands. Our study shows that ecological niche modeling adds a powerful dimension to our attempt to understand lineage evolution in space [Current Zoology 61 (5): 922-934, 2015].