An experimental study of competitive interference between Anigozanthos manglesii D. Don, A. humilis Lindl. and their F1 Hybrids (Haemodoraceae)

Poor competitive ability has been invoked often to explain the confinement of hybrids to disturbed ecotones at the junction of parental habitats. This hypothesis has not as yet been verified in an experimental study. Two-month-old seedlings of Anigozanthos manglesii, A, humilis and synthesized F1 hybrids were grown singly and in various paired combinations in small pots for 172 days to test for competitive interactions. F1 hybrids and A. manglesii performed comparably in most competition trials, while A. humilis suffered a considerable competitive disadvantage. It is proposed that competitive interactions may play a minor role in confining naturally occurring F1 hybrids to ecotonal areas between habitats preferentially occupied by A. humilis and A. manglesii. Spatial limitations on pollen and seed flow appear to be the major factors controlling hybrid distribution in this case.