title: The taxonomy of multivalent orientation: six modes of alternate or one?
abstract: Unlike adjacent I and II, alternate I and II orientations of interchange and tetrasome quadrivalents can be considered extremes within one particular population of orientations (alternate) and thus lack sufficient distinction to justify a separate taxonomic status. Within the population up to six types may be distinguished, but the biological significance of this distinction is small.
mesh_terms: D000818:Animals; D002503:Centromere / Q000502:physiology; D002869:Chromosome Aberrations; D002875:Chromosomes / Q000502:physiology*; D005828:Genetics, Population; D006579:Heterozygote; D008957:Models, Genetic