scholarly journals Trends in streamflow and precipitation for selected sites in the Elkhorn River Basin and in streamflow in the Salt Creek and Platte River Basins, Nebraska, 1961–2011

2020 ◽  
Author(s):  
Benjamin J. Dietsch ◽  
Kellan R. Strauch
Keyword(s):  
River Basin ◽  
River Basins ◽  
Platte River ◽  
Salt Creek

Identification of sibling species in the genus Eucyclops from water-bodies of Ukraine and Russia using crossbreeding studies

2014 ◽  
Vol 25 (1-2) ◽  
pp. 61-68 ◽  
Author(s):  
V. I. Monchenko ◽  
L. P. Gaponova ◽  
V. R. Alekseev
Keyword(s):  
Cryptic Species ◽  
River Basin ◽  
Black Sea ◽  
Species Complex ◽  
River Basins ◽  
Water Bodies ◽  
Similar Species ◽  
Basin Water ◽  
Different Populations ◽  
Baltic Sea Basin

Crossbreeding experiments were used to estimate cryptic species in water bodies of Ukraine and Russia because the most useful criterion in species independence is reproductive isolation. The problem of cryptic species in the genus Eucyclops was examined using interpopulation crosses of populations collected from Baltic Sea basin (pond of Strelka river basin) and Black Sea basin (water-reservoires of Dnieper, Dniester and Danube rivers basins). The results of reciprocal crosses in Eucyclops serrulatus-group are shown that E. serrulatus from different populations but from water bodies belonging to the same river basin crossed each others successfully. The interpopulation crosses of E. serrulatus populations collected from different river basins (Dnipro, Danube and Dniester river basins) were sterile. In this group of experiments we assigned evidence of sterility to four categories: 1) incomplete copulation or absence of copulation; 2) nonviable eggs; 3) absence of egg membranes or egg sacs 4) empty egg membranes. These crossbreeding studies suggest the presence of cryptic species in the E. serrulatus inhabiting ecologically different populations in many parts of its range. The same crossbreeding experiments were carries out between Eucyclops serrulatus and morphological similar species – Eucyclops macruroides from Baltic and Black Sea basins. The reciprocal crossings between these two species were sterile. Thus taxonomic heterogeneity among species of genus Eucyclops lower in E. macruroides than in E. serrulatus. The interpopulation crosses of E. macruroides populations collected from distant part of range were fertile. These crossbreeding studies suggest that E. macruroides species complex was evaluated as more stable than E. serrulatus species complex.

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