What help ensure the survival of a species?

Genetic variation. The is this variation that is the essence of evolution. Without genetic differences amongst individuals, "survival the the fittest" would not it is in likely. Either all survive, or every perish.

You are watching: Variation occurs when chromosomes are shuffled in _____.

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api/deki/files/18054/517px-Chromosomal_Recombination.svg.png?revision=1&size=bestfit&width=409&height=264" />Figure (PageIndex2):​​​​​ ​​Crossing-over. A maternal strand the DNA is presented in red. A head strand the DNA is shown in blue. Crossing end produces 2 chromosomes that have not previously existed. The procedure of recombination entails the breakage and rejoining that parental chromosomes (M, F). This outcomes in the generation that novel chromosomes (C1, C2) that share DNA from both parents.

During prophase I, chromosomes condense and also become visible inside the nucleus. Together the nuclear envelope starts to break down, homologous chromosomes relocate closer together. The synaptonemal complex, a lattice the proteins between the homologous chromosomes, forms at details locations, dispersing to cover the whole length of the chromosomes. The chop pairing that the homologous chromosomes is dubbed synapsis. In synapsis, the genes on the chromatids of the homologous chromosomes are aligned v each other. The synaptonemal facility also supports the exchange the chromosomal segments between non-sister homologous chromatids in a process called crossing over. The crossover events are the very first source of genetic variation produced by meiosis. A solitary crossover event between homologous non-sister chromatids leads to one exchange the DNA in between chromosomes. Adhering to crossover, the synaptonemal complex breaks down and the cohesin connection in between homologous pairs is also removed. At the finish of prophase I, the pairs are organized together just at the chiasmata; castle are referred to as tetrads because the four sister chromatids of every pair that homologous chromosomes are currently visible.

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non sister chromatids of tetrad exchanged their genetic materialvariation occurs when chromosomes are shuffled in _____.