Dynamic changes in the population structure ofEscherichia coliin the Yeongsan River basin of South Korea

AbstractMore than 70% of South Korea has mountainous terrain, which leads to significant spatiotemporal variability of rainfall. The country is exposed to the risk of flash floods owing to orographic rainfall. Rainfall observations are important in mountainous regions because flood control measures depend strongly on rainfall data. In particular, radar rainfall data are useful in these regions because of the limitations of rain gauges. However, radar rainfall data include errors despite the development of improved estimation techniques for their calculation. Further, the radar does not provide accurate data during heavy rainfall in mountainous areas. This study presents a radar rainfall adjustment method that considers the elevation in mountainous regions. Gauge rainfall and radar rainfall field data are modified by using standardized ordinary cokriging considering the elevation, and the conditional merging technique is used for combining the two types of data. For evaluating the proposed technique, the Han River basin was selected; a high correlation between rainfall and elevation can be seen in this basin. Further, the proposed technique was compared with the mean field bias and original conditional merging techniques. Comparison with kriged rainfall showed that the proposed method has a lesser tendency to oversmooth the rainfall distribution when compared with the other methods, and the optimal mean areal rainfall is very similar to the value obtained using gauges. It reveals that the proposed method can be applied to an area with significantly varying elevation, such as the Han River basin, to obtain radar rainfall data of high accuracy.

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Population structure, growth and reproduction of Tropidophoxinellus alburnoides (STEINDACHNER 1866) in an intermittent stream of the Guadalquivir River basin (southern Spain)

Archiv für Hydrobiologie ◽

10.1127/archiv-hydrobiol/130/1994/359 ◽

1994 ◽

Vol 130 (3) ◽

pp. 359-369

Author(s):

Carlos Fernández-Delgado ◽

Mercedes Herrera

Keyword(s):

Population Structure ◽

River Basin ◽

Southern Spain ◽

Intermittent Stream ◽

Guadalquivir River ◽

Growth And Reproduction

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Genetic diversity and population structure of black cottonwood (Populus deltoides) revealed using simple sequence repeat markers

BMC Genetics ◽

10.1186/s12863-019-0805-1 ◽

2020 ◽

Vol 21 (1) ◽

Author(s):

Cun Chen ◽

Yanguang Chu ◽

Changjun Ding ◽

Xiaohua Su ◽

Qinjun Huang

Keyword(s):

Genetic Diversity ◽

Population Structure ◽

Genetic Differentiation ◽

River Basin ◽

Simple Sequence Repeat ◽

Populus Deltoides ◽

Sequence Repeat ◽

Black Cottonwood ◽

High Genetic Diversity ◽

Simple Sequence

Abstract Background Black cottonwood (Populus deltoides) is one of the keystone forest tree species, and has become the main breeding parents in poplar hybrid breeding. However, the genetic diversity and population structure of the introduced resources are not fully understood. Results In the present study, five loci containing null alleles were excluded and 15 pairs of SSR (simple sequence repeat) primers were used to analyze the genetic diversity and population structure of 384 individuals from six provenances (Missouri, Iowa, Washington, Louisiana, and Tennessee (USA), and Quebec in Canada) of P. deltoides. Ultimately, 108 alleles (Na) were detected; the expected heterozygosity (He) per locus ranged from 0.070 to 0.905, and the average polymorphic information content (PIC) was 0.535. The provenance ‘Was’ had a relatively low genetic diversity, while ‘Que’, ‘Lou’, and ‘Ten’ provenances had high genetic diversity, with Shannon’s information index (I) above 1.0. The mean coefficient of genetic differentiation (Fst) and gene flow (Nm) were 0.129 and 1.931, respectively. Analysis of molecular variance (AMOVA) showed that 84.88% of the genetic variation originated from individuals. Based on principal coordinate analysis (PCoA) and STRUCTURE cluster analysis, individuals distributed in the Mississippi River Basin were roughly classified as one group, while those distributed in the St. Lawrence River Basin and Columbia River Basin were classified as another group. The cluster analysis based on the population level showed that provenance ‘Iow’ had a small gene flow and high degree of genetic differentiation compared with the other provenances, and was classified into one group. There was a significant relationship between genetic distance and geographical distance. Conclusions P. deltoides resources have high genetic diversity and there is a moderate level of genetic differentiation among provenances. Geographical isolation and natural conditions may be the main factors causing genetic differences among individuals. Individuals reflecting population genetic information can be selected to build a core germplasm bank. Meanwhile, the results could provide theoretical support for the scientific management and efficient utilization of P. deltoides genetic resources, and promote the development of molecular marker-assisted breeding of poplar.

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