We know that during the crossing over of meiosis II, some portions of the paternal chromosome recombine with the maternal chromosome along the chiasmata. And the number of chiasmata varies.

My question is this: If the crossing over is responsible for genetic variation, then does the number of chiasmata increase in the same chromosome in the same species for the sake of the species' survival? And if so, what factors contribute towards increasing that number?

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    $\begingroup$ Welcome to SE Biology! A note - selection virtually never occurs at the level of the species - it is almost always occurs at the level of an individual organism (or gene). So your question might be better framed if you ask about how crossing over might affect the fitness of an individual rather than how it might affect 'the survival of the species'. $\endgroup$
    – user438383
    Aug 27, 2020 at 11:33

1 Answer 1


The number of recombination events (chiasmata) varies dramatically from species to species.

It is also unlikely that this number has any universal relationship to selection, though for specific cases it has been shown that selection can change recombination frequency.

For some more information about the processes controlling this in present-day species and the inferred mechanisms driving among-species variation in recombination frequency, you might see this paper.


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