Effects of crossovers (blue lines) and gene conversion (green lines) in Y(W) palindromes (a) and tandem arrays (b). No effect of a crossover is observed if it occurs within the same gene between sister chromatids (a1 and b2). Gene conversion (nonreciprocal transfer of information) is observed if it occurs between different genes within the same palindrome or between tandem duplicates (a2 and b2). Acentric and dicentric chromosomes are produced from a crossover between different genes in palindromes located in sister chromatids (a3). Acentric chromosomes will not segregate properly, and dicentric chromosomes will likely break and lose information when they are pulled to opposite cell poles . Gene gains and losses are produced from a crossover between different duplicates within array located in sister chromatids (b3).