Invasion of Kalanchoe by clonal spread

Kalanchoe delagoensis , K. daigremontiana and their hybrid (Houghton’s hybrid) are invasive in tropical regions. One outstanding feature of these Madagascan succulent plants is the growth of clonal propagules from the margin of their leaves. Using eight microsatellite loci, we estimated the genetic diversity of introduced populations of these species and their hybrid in Mexico. For K. daigremontiana and Houghton’s hybrid, we registered one multilocus genotype in all populations, which were separated by several hundred km. The same occurred in K. delagoensis populations where only four multilocus genotypes were present (A, B, C and D), although genotype A accounted for 86 % of all screened individuals of that population. The other three genotypes were in low frequencies and did not present new alleles, indicating that they are very likely derived by sexual recombination. However, sexual reproduction seems not to have occurred in the other populations. The presence of just one genotype of the hybrid suggests that hybridization between K. delagoensis and K. daigremontiana is unlikely, but we cannot discard it because of the absence of private alleles. The lack of genotypic diversity suggests that the invasion by these two species and the hybrid occurred from the introduction of one genotype, and have expanded by clonal growth and human mediated dispersal.