Existence of Multiple Modes of Reproduction in Lantana Camara, An Invasive Shrub

Good fecundity is essential for many invasive species to maintain their invasive potential.  Lantana camara is among the world's top 10 weedy species and a major invasive species in Florida.  Two interesting phenomena have been observed in this species: existence of a series of polyploids and a fair level of female fertility in these polyploids.  To find the cause(s) of the female fertility in L. camara polyploids, we analyzed the ploidy level distribution in the progeny of tetraploids as well as triploids and pentaploids. Fairly high percentages of pentaploids and/or hexaploids have been observed in the progeny of tetraploids.  These higher-than-parent polyploids suggest a common occurrence of unreduced female gametes in L. camara. A range of ploidy levels was present in the open-pollination (OP) progeny of triploids: aneuploids, higher polyploids (4x and 5x), and triploids. A similar distribution was also seen in the OP progeny of one pentaploid. The appearance of triploids in the offspring of triploids and pentaploids in the offspring of pentaploids seems to indicate possible apomixis in L. camara.  To assess this possibility, we analyzed the ploidy level distribution in the progeny of controlled diploid by tetraploid crosses. In addition to triploids and tetraploids, diploids were also present in the progeny of the controlled crosses.  These diploids shared the same SSR marker banding patterns and morphological characters with their maternal parents, thus being apomictic in nature.  In summary, our ploidy level and molecular marker analyses have provided solid evidence for the existence of multiple modes of reproduction in L. camara.  These reproductive characteristics of L. camara need to be carefully considered in developing and implementing strategies to control the invasiveness of the species.