Answer:
spirit of cooperation ended abruptly in 1960, when the Soviets shot down an American U-2 spy plane over their territory"-755
Explanation:
President Dwight D. Eisenhower (1890-1969) was the 34th president of the United States of America between 1953 to 1961. He worked well with the Soviet leader Nikita Khrushchev to thaw the cold war at the end of 1950s. In May 1960, their cooperation ended prematurely when diplomatic crises erupted because the Union of Soviet Socialist Republics (USSR) were said to have gunned down an American U-2 spy plane in Soviet air space.
President Eisenhower was compelled to admit to the soviets that the central intelligence unit of his country has been sending out spy missions for several years in the USSR.
1. Answer;
They evolved separately as they moved north and became two separate species.
Explanation;
The greenish warblers weren't geographically isolated, but they migrated around the Tibetan Plateau, evolving separately until they were no longer able to interbreed when both species (East and West) contacted in Siberia.
Greenish warblers were thought to have evolved from a single ancestral population that gradually diverged into two new species as it expanded northwards around the Tibetan plateau.
2. Answer;
- Their plumage patterns.
- Genetics and history
Explanation;
West Siberian greenish warblers (P. t. viridanus) and east Siberian greenish warblers (P. t. plumbeitarsus) differ subtly in their plumage patterns, most notably in their wing bars, which are used in communication. While viridanus has a single wing bar, plumbeitarsus has two. Around the southern side of the ring, plumage patterns change gradually.
Additionally, the two northern forms viridanus and plumbeitarsus are highly distinct genetically, but there is a gradient in genetic characteristics through the southern ring of populations. The greenish warblers were once confined to the southern portion of their range and then expanded northward along two pathways, evolving differences as they moved north. When the two expanding fronts met in central Siberia, they were different enough that they do not interbreed.
The 15th Amendment to the Constitution granted African American men the right to vote by declaring that the "right of citizens of the United States to vote shall not be denied or abridged by the United States or by any state on account of race, color, or previous condition of servitude." Although ratified on February 3, 1870, the promise of the 15th Amendment would not be fully realized for almost a century. Through the use of poll taxes, literacy tests and other means, Southern states were able to effectively disenfranchise African Americans. It would take the passage of the Voting Rights Act of 1965 before the majority of African Americans in the South were registered to vote.
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It was a United States foreign policy document. It stated that if European nations tried to colonize land or interfere with states in north or South America it would be seen as acts of aggression which then required us intervention
