ABSTRACT
Hybridisation is defi ned as the interbreeding of individuals from two distinct populations (sensu stricto species), which are distinguishable on the basis of one or more heritable characters, following Harrison (1993). Hybrids have been recognised, based on intergrading of characteristic features from parent species, since at least the 1700’s and have been documented among plants, corals, gastropods, crustaceans, insects, amphibians, reptiles, birds, mammals and fi sh (Barton and Hewitt, 1985; Schwenk, 1993; Bierne et al., 2003; van Oppen and Gates, 2006). At least 10% of animals and 25% of plant species are known to hybridise, although the true proportion is probably higher because hybridisation often goes unnoticed (Mallet, 2005, 2007). The fact that hybridisation is not a rare phenomenon but occurs in a considerable
1The Oceans Institute and School of Plant Biology, The University of Western Australia, Crawley 6009, Australia. E-mail: jean-paul.hobbs@uwa.edu.au 2School of Marine and Tropical Biology, James Cook University, Townsville QLD 4811, Australia. E-mail: lynne.vanherwerden@jcu.edu.au 3ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville QLD 4811, Australia. E-mail: morgan.pratchett@jcu.edu.au 4Western Australian Museum Locked Bag 49, Welshpool DC, Perth, Western Australia 6986, Australia. E-mail: gerald.allen@wa.gov.au *Corresponding author
proportion of species, presents a signifi cant challenge to the fundamental biological defi nition of a species (Barton and Hewitt, 1985; Mallet, 2005).
