Evidence for clonality, breeding system, genetic diversity and genetic structure in large and small populations of Melaleuca deanei (Myrtaceae)

Abstract

Melaleuca deanei F.Muell. is a rare, serotinous shrub with a naturally restricted distribution centred over the sandstone ridges around Sydney. Sexual reproduction and seedling recruitment occur rarely, and plants appear to spread and persist largely by clonal root suckering. A potentially outcrossing breeding system, combined with extensive clonality, place M. deanei at a high risk of reproductive failure. Knowledge of the extent of its clonality and breeding system, and an understanding of the distribution and abundance of genetic diversity within and among its populations, will assist conservation management. The present study reports on the extent of clonality, breeding system, levels of genetic diversity, and population differentiation within small, medium and large populations of M. deanei from the northern and southern distribution regions. Multiple stems were found to comprise single genets up to ~10 m diameter on the ground and molecular evidence points to an outcrossing breeding system. Genetic diversity was positively correlated with population size and significant genetic differentiation was shown between northern and southern regions using clustering analyses. Recommendations for in situ and ex situ conservation management based on these results are provided.