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Tandemly organized rRNA genes are a typical example of a multigene family, where individual members evolve co-ordinately within—but independently between—species due to gene conversion and unequal crossing over. More frequently, in eukaryotic species with an interspecies hybrid origin, expression of unhomogenized rRNA genes from one progenitor is epigenetically silenced because of nucleolus dominance, and distinct rRNA genes may lose functionality and evolve faster. Interestingly, we obtained unusual ribosomal gene sequences from Oryza species that showed great diversity and did not appear in the present rice genomic sequence. The diversity of rDNA sequences indicated that the homogenization in rice is incomplete and explains the introgression of distinct rRNA gene families into ancestral rice genomes before speciation and continent separation. The divergent large subunit (LSU) ribosomal genes are expressed, some of them differentially, depending on the N fertilization of plants. Detection of differential transcripts of the rRNA genes suggested that rRNA gene families are not functionally equivalent. Phylogenetic analysis assigned Oryza species branching order to monocots, and monocot lineages probably have the same ecological origin by molecular clock calculation. Therefore, our results suggested that the geographical distances of continent-separation cause barriers to the gene flow and homogenization among Oryza species which requires further explanation. [ABSTRACT FROM AUTHOR]

Tandemly organized rRNA genes are a typical example of a multigene family, where individual members evolve co-ordinately within—but independently between—species due to gene conversion and unequal crossing over. More frequently, in eukaryotic species with an interspecies hybrid origin, expression of unhomogenized rRNA genes from one progenitor is epigenetically silenced because of nucleolus dominance, and distinct rRNA genes may lose functionality and evolve faster. Interestingly, we obtained unusual ribosomal gene sequences from Oryza species that showed great diversity and did not appear in the present rice genomic sequence. The diversity of rDNA sequences indicated that the homogenization in rice is incomplete and explains the introgression of distinct rRNA gene families into ancestral rice genomes before speciation and continent separation. The divergent large subunit (LSU) ribosomal genes are expressed, some of them differentially, depending on the N fertilization of plants. Detection of differential transcripts of the rRNA genes suggested that rRNA gene families are not functionally equivalent. Phylogenetic analysis assigned Oryza species branching order to monocots, and monocot lineages probably have the same ecological origin by molecular clock calculation. Therefore, our results suggested that the geographical distances of continent-separation cause barriers to the gene flow and homogenization among Oryza species which requires further explanation.

Rapid urbanization development and construction has seriously threatened the connectivity of habitat patches in cities and hindered the construction of ecological networks in highly urbanized areas. Among them, China is affected by early compressed urbanization, and the broken ecological space in cities and towns has attracted the extensive interest of researchers. To avoid the subjective randomness and single analysis of ecological space in urbanization areas, this paper takes the central urban area of Wuhan as the main research area. It comprehensively evaluates the ecological network space by combining the MSPA-MCR model. The main conclusions are as follows: (1) Identifying the ecological landscape types with important ecological significance in the study area: Core (88.29%), Islet (0.25%), Perf (0.63%), Edge (9.74%), Loop (0.22%), and Bridge (0.14%). Through the dPC landscape index, seven important ecological sources south of the middle reaches of the Yangtze River were identified. (2) According to the comprehensive factors of natural and human factors constructed by the MCR model, the minimum cumulative ecological resistance surface was established, with an average value of 2.65, a maximum value of 4.70, and a minimum value of 1.00, showing a trend that the ecological resistance values in the central and eastern parts are lower than those in the western part. (3) According to the standard deviation ellipse, the distribution direction of NE–SW in ecological sources was analyzed. The ecological sources distributed in the north were less, and the spatial distribution was scattered on the whole. The strong global positive correlation and local spatial aggregation characteristics of ecological resistance surface were evaluated according to spatial autocorrelation. Based on the gravity model, the interaction intensity of ecological corridors between source areas was evaluated, and the importance of ecological corridor protection and restoration was quantitatively analyzed. The research results provide scientific and reasonable references and a basis for ecological planning of Wuhan central city.

PREMISE OF THE STUDY: Understanding the origin of ecosystems and their changes through time is important. Two mutually contrasting types of grasslands existed in the Arctic: dry- and cold-adapted grasslands of the Pleistocene dominated by Poaceae species, and presently dominating graminoid grasslands composed of sedges and rushes. We studied the taxon recruitment of the Arctic fl ora for Carex , the most species-rich and widespread genus of the Arctic. In this study we explore the possible geographical and altitudinal origins of the species, their ecological provenance in terms of soil moisture and light requirements, and salt tolerance. METHODS: We addressed these questions in a phylogenetic context using the latest megaphylogeny of Carex comprising almost all Arctic species and about half of the genus’ total species diversity. Ecological data were extracted from the literature and analyzed for each clade comprising Arctic species. KEY RESULTS: Arctic Carex species were observed in 48 independent lineages. Almost all areas north of the meridional zone of the Northern Hemisphere may have served as sources of Arctic lineages. Source areas are unrelated to the distribution within the Arctic. Arctic species evolved in lowland and high mountain clades; mostly in wet, rarely in dry adapted clades that occur principally in open conditions. Salt tolerant Arctic species occur in fi ve clades. CONCLUSIONS: Many independent lineages of diff erent geographical areas and ecological backgrounds provided species for the northernmost ecosystem; clear main sources were not discernible. Carex shows the whole dynamic of ecosystem assembly from a seemingly simple immigration of preadapted species, evolution in geographical distant areas, to species radiations in the North. [ABSTRACT FROM AUTHOR]

Cows with a long economic use have strong constitution, good health, high milk yield and good reproductive function. However, when changing operating conditions, which are very different from the conditions of origin Schwyz cows, there is a change of adaptive responses. The aim was to establish economic and biological qualities Schwyz breed cows of different ecological origin in conditions of Ukrainian Steppe. Exterior and constitutional features studied in Schwyz of mature purebred cows on 2-3 month of lactation, exploited in the dairy industrial complex of "Ekaterynoslavskiy", near the town of Dnepr. Experimental animals were formed into three groups: in group I were selected cows (n = 17) of Sumy selection, which were controlled; in groups II and III Austrian cows for 15 goals in each groups. To characterize the exterior of cows using a measuring tape and measuring stick were carried out animal measurements, to characterize the constitutional features - calculated the indexes physique. These somatometric data indicate that purebred cows of Schwyz were quite tall, since the height at withers was slightly higher than 140 cm. At the same time, purebred cows of Austrian breeding II and III groups on this indicator almost identical and exceed on 2,51% (P <0,01) of their analogues I group of Sumy selection. For all experimental animals was characterized by a straight of line back, provides almost the same indicators of heights in the back and lower back. In Austrian cows groups II and III height of the back of almost 143 cm, which was close to an indicator of height at the withers. At the same time, Schwyz cows of Sumy selection I (control) group of the height of the back, too, corresponds to the value of height at the withers, and therefore inferior indicator II and III groups by 2,17% (P <0,05). The croup of all Schwyz animals sufficiently wide and long and, above all, the croup are straight. It is not revealed significant differences in the experimental cows in terms of depth and width of the chest, which, on average respectively 74,4-75,9 and 48,9- 49,9 cm. Girth thorax animals of different ecological origin is large enough and is 203,1-200,4 cm. Length of the body of these animals is not significantly different, and is 169-170,8 sm. It is found that the highest width of hip joints in cows of II group and amounts to 55,2 cm, whereas in cows of III group less on 4,55% (P <0,01) and 52,8 cm. The lowest value of the width of the back of the cows I (control) group and an average is 50,9 cm, which is inferior to the II and III groups, respectively, to 8,45 (P <0,001) and 3,73% (P <0,05). It is proved that the index of high limbs of Schwyz cows of different ecological origin is sufficient and in animals of II group was 48,2%, which exceeds the control (I) group of animals 4,15% (P <0,05). The index format of the experimental animal groups II and III are respectively is 117,7 and 118,8%. Thus in control (I) group it is 122%, that exceeds indicators of the animals of groups II and III, respectively, 3,52 and 2,62% (P <0,05). Austrian Schwyz cow II and III group are characterized by almost one indicator of pelvic-thoracic index, which is 90-90, 2% and in cows of the Sumy selection at the level of 92,4%. Thoracic index purebred of Schwyz livestock II group of the Austrian selection is 67, 1%, whereas analogues III group, which were heifers and adapted in the steppe zone of Ukraine in the autumn, this indicator does not exceed 64,4%. Experimental Schwyz breed cows behind compactness are relate more to the dairy type, as this index varies 117,4 - 120,3%. So somatometric indicators of Schwyz livestock of different ecological origin described as a well-consolidated breed with harmonious physique. By indices physique animals have a strong constitution with a good general state of the organism. Further studies will be used to establish communication between the strength constitution of Schwyz cows of different ecological origin and the level of implementation of the productive capacity, as well as the reproductive ability in a large industrial complex in the steppe zone of Ukraine. [ABSTRACT FROM AUTHOR]

Rapid urbanization development and construction has seriously threatened the connectivity of habitat patches in cities and hindered the construction of ecological networks in highly urbanized areas. Among them, China is affected by early compressed urbanization, and the broken ecological space in cities and towns has attracted the extensive interest of researchers. To avoid the subjective randomness and single analysis of ecological space in urbanization areas, this paper takes the central urban area of Wuhan as the main research area. It comprehensively evaluates the ecological network space by combining the MSPA-MCR model. The main conclusions are as follows: (1) Identifying the ecological landscape types with important ecological significance in the study area: Core (88.29%), Islet (0.25%), Perf (0.63%), Edge (9.74%), Loop (0.22%), and Bridge (0.14%). Through the dPC landscape index, seven important ecological sources south of the middle reaches of the Yangtze River were identified. (2) According to the comprehensive factors of natural and human factors constructed by the MCR model, the minimum cumulative ecological resistance surface was established, with an average value of 2.65, a maximum value of 4.70, and a minimum value of 1.00, showing a trend that the ecological resistance values in the central and eastern parts are lower than those in the western part. (3) According to the standard deviation ellipse, the distribution direction of NE–SW in ecological sources was analyzed. The ecological sources distributed in the north were less, and the spatial distribution was scattered on the whole. The strong global positive correlation and local spatial aggregation characteristics of ecological resistance surface were evaluated according to spatial autocorrelation. Based on the gravity model, the interaction intensity of ecological corridors between source areas was evaluated, and the importance of ecological corridor protection and restoration was quantitatively analyzed. The research results provide scientific and reasonable references and a basis for ecological planning of Wuhan central city. [ABSTRACT FROM AUTHOR]

Premise of the Study: Understanding the origin of ecosystems and their changes through time is important. Two mutually contrasting types of grasslands existed in the Arctic: dry- and cold-adapted grasslands of the Pleistocene dominated by Poaceae species, and presently dominating graminoid grasslands composed of sedges and rushes. We studied the taxon recruitment of the Arctic flora for Carex, the most species-rich and widespread genus of the Arctic. In this study we explore the possible geographical and altitudinal origins of the species, their ecological provenance in terms of soil moisture and light requirements, and salt tolerance., Methods: We addressed these questions in a phylogenetic context using the latest megaphylogeny of Carex comprising almost all Arctic species and about half of the genus' total species diversity. Ecological data were extracted from the literature and analyzed for each clade comprising Arctic species., Key Results: Arctic Carex species were observed in 48 independent lineages. Almost all areas north of the meridional zone of the Northern Hemisphere may have served as sources of Arctic lineages. Source areas are unrelated to the distribution within the Arctic. Arctic species evolved in lowland and high mountain clades; mostly in wet, rarely in dry adapted clades that occur principally in open conditions. Salt tolerant Arctic species occur in five clades., Conclusions: Many independent lineages of different geographical areas and ecological backgrounds provided species for the northernmost ecosystem; clear main sources were not discernible. Carex shows the whole dynamic of ecosystem assembly from a seemingly simple immigration of preadapted species, evolution in geographical distant areas, to species radiations in the North., (© 2017 Botanical Society of America.)