Figure 1. A schematic representation of changes in ploidy in Acipenseriformes. M = macro-, m = microchromosomesly more symmetric than karyotypes of other acipen- content data) and l6n-ploid (according to DNA
serids. A schematic course of possible cytogenetic content data) species. The octoploid 240-chromo-
evolution within the Acipenseriformes is presented some sturgeon species seem to have originated in-
in Figure 1. dependently in different regions. The closely relat-
Cytogenetic data are helpful for understanding edA. gueldenstaedtiiandA. persicusmay have a
some relationships within the genus Acipenser, common origin and a common octoploid ancestor.
where polyploidization was one of the main genetic Molecular data point to the close relatedness ofA.
mechanisms of speciation. The diversification of dueldenstaedtiitoA. baerii(see below).
this genuswasaccompanied by an appearance of Acipenser medirostris andA. transmontanus
octoploid (according to the karyotypic and DNA have many similar characteristics in morphology,