Ecology of two 'Scaptodrosophila' flower breeding species

Abstract

'Scaptodrosophila hibisci' (Cook et al., 1977) and 'S. aclinata' (McEvey and Barker, 2001) are endemic Australian species that breed in the flowers of a number of 'Hibiscus' species belonging to the section 'Furcaria'. 'Scaptodrosophila hibisci' has been bred from the flowers of five species in eastern Australia, and 'S. aclinata' from 11 species in the Northern Territory. For non-'Furcaria Hibiscus' species, 'H. tiliaceus' is common within the distributions of both 'Scaptodrosophila' species, and 'H. panduriformis' is present within the distribution of 'S. aclinata'. In addition, the introduced species 'H. sabdariffa' (also sect. 'Furcaria') is widespread within the distribution of 'S. aclinata'. These three species are often in close proximity to section 'Furcaria' species with 'S. hibisci' or 'S. aclinata' present, but no adult 'Scaptodrosophila' have been seen in hundreds of flowers of each of these species. Thus an apparently strict hostplant association of both 'S. hibisci' and 'S. aclinata' with endemic Australian 'Hibiscus' species of the section 'Furcaria' has evolved. However, as both 'Scaptodrosophila' species use a range of different 'Hibiscus' species (only 'H. meraukensis' common to both), it seems likely that 'Furcaria' specialization pre-dated the speciation of 'S. hibisci' and 'S. aclinata'.