Sistemática molecular: comparación entre diferentes métodos y sus aplicaciones

The use of molec ular techniques to solve sys tema tic problems has become very popular in recent years. One technique used in botany is DNA/DNA hybridization , in which single strands of DNA from closely related genera or species are reassociated , but requires that differences in sequences between taxa are lower than 20%. Iso and allozyme electrophoresis is another technique which has the advantage of a wider range of applications, such as the divergence of infraespecific taxa, species delimitation , phylogenetic reconstruction , hybrid speciation, and detection of polyploidy. Restriction enzymes are used to cut ribosomal DNA to detect differences at the species level, for species complexes and among genera. These enzymes are also used to cut chloroplast DNA to determine the ancestry of cultivated plants, as well as, to de limit subgeneric, tribal, subfamilial, order, subclass or class classifications. Nucleotide sequences have been used in nuclear or chloroplast genes utilizing slow evolving genes for separation at the family or subfamily levels and fast evolving genes for delimiting genera, subgenera or sections.