A chromosomal crossover is a reciprocal exchange of segments between nonsister chromatids of homologous chromosomes during meiosis. It can change the haplotypes inherited at selected genetic loci; whether it does so depends on the transmitted chromatid and interval.
A meiotic crossover from an alternative pathway that is substantially less subject to interference.
Crossover interference means that an exchange affects the occurrence of other nearby chromosomal crossovers. The Haldane mapping function assumes this dependence is absent. See Meiosis.