Genetic recombination.
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   Recombinant phenotypes can be explained by crossing over of homologous
   chromosomes
<P>
   In  the female, crossing over can occur between b and vg in Meiosis I,
   which then segregate in Meiosis II and yield recombinant gametes.
<P>
   In the male, crossing over yields no new allele combinations.
<P>
   continue