Biochemical genetic markers to identify hybrids between Aloe arborescens and A. ferox (Aloaceae)

Two populations of Aloe arborescens, six A. ferox populations, and a population of natural hybrids between A. arborescens and A. ferox were examined by horizontal starch gel-electrophoresis to assess levels of genetic variation and differentiation at 23 enzyme coding loci. Gene products revealed polymorphism in all of the populations studied, except for the four western populations of A. ferox. This indicates that the latter are founder populations from few parents, displaying only the dominant alleles, and with a possible migration route from east to west (as was also found for other plant taxa in South Africa). Biochemical genetic markers to identify A. arborescens x A. ferox hybrids were found at the DDH-2 and MNR-2 enzyme coding loci. Unique alleles were found in pure A. arborescens and A. ferox populations at these loci, which is an important result because it was not always possible to identify individuals correctly from their morphological characters. Genetic distance (Nei 1978) values between conspecific populations ranged from zero, between the western A. ferox populations, to 0.007 (A. arborescens) and to 0.01 (A. ferox, eastern populations), and it averaged 0.174 between the pure species.