Question

Why can't 2 different species mate to produce an offspring?

Answer 1

Absence of homologous chromosomes.

Explanation:

Production of offspring depends on the pairing of homologous during the meiotic division for the production of gametes. Homologous chromosomes are essential for sexual reproduction and offspring. But in the case of mating of un-related species, the homolodous are absent. So, in case mating of un-related species never produce offsprings.
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