What most directly causes variation in the offspring of sexually reproducing organisms?

Answer 1

Sexual reproduction allows some of the genetic material from the father and mother to mix producing offsprings that are not identical but resemble the parents in certain charateristics. This combination of genetic material from the father and mother results in the variation of offsprings.

Answer 2

Aside from mutation the sexually reproducing variation is due to independent orientation of chromosomes in meiosis ( two ways the sister chromatids can line up in their tetrads ), crossing over ( non-sister chromatids exchanging sections of genetic material ) and random fertilization in which male and female gametes randomly come together to form zygotes.

Answer 3

There are many reasons. First of all, each parent has two sets of alleles for every gene they have. In the parent, generally, only the dominant gene persists. But when their gametes (sperm/egg) are formed during meiosis only one allele goes to each gamete. So, a gene that was recessive in the father might manifest in the child if the mother also contributes the same recessive gene or a gene that is more recessive than the one the father contributes. Furthermore, during meiosis, alleles line up in there respective chromatids and "crossing over" occurs. Crossing over is basically the trading of alleles from one chromatid to an adjacent chromatid and results in a chromosome that is unique from that of the parent making the contribution. Furthermore, mutations in the gametes can cause additional variation. Inconsistencies with meiosis such as non-disjunction (a case where each gamete does not receive equal genetic material) can result in problems such as Down syndrome or the much less dramatic Turner syndrome, etc.

Answer 4

Human recombination is a significant source of genetic variation.

Answer 5

recombination of alleles

Answer 6

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