Study on Holly Leaved Banksia Genetics (Paperback)

Holly leaved banksia (Banksia ilicifolia R. Br.),although widespread through South West Western Australia, has a naturally fragmented distribution, with generally small populations restricted to swales and wetland fringes with depth to groundwater less than 10 m. As such, it provides an excellent model to better understand the ecological genetic consequences of local endemism, population size and natural population fragmentation. My study indicated that although B. ilicifolia showed self-compatibility, it is preferentially outcrossing, with strong inbreeding depression at the early stages of growth. Consequently, the breeding system of B. ilicifolia promotes genetic variation and a high genetic load, but habitat fragmentation may impact on the long-term viability of small, isolated populations exposed to elevated inbreeding. The magnitude of inbreeding depression was related to population size and expressed under stressful conditions. Products of wide outcrossing (over 30 km) showed a heterosis effect over local outcrossing, indicating increased ecological amplitude of offspring following interpopulation mating.