Dr Dennis O'Dowd
General areas of research include (1) the ecology and management of biological invasions, especially by plants and social insects and (2) ecology and evolution of plant-animal interactions, especially mutualism between plants and animals. Possible honours projects for 2007:
1. Test the enemy release hypothesis for invasion success by comparing recruitment of Italian buckthorn (Rhamnus alaternus) in an area of introduction and origin
The enemy release hypothesis explains the success of introduced invaders (and is the basis for classical biological control). It has rarely been tested. This study would examine the role of enemies (predators and herbivores) on critical transition stages in recruitment (predispersal seed through seedling stages) of R. alternatus in Victoria and compare results to those from its area of origin (Spain).
2. Determine if Australian native ants resist invasion by the introduced Argentine ant
Studies examining the success of introduced species usually focus on species characteristics important to their prowess as an invader. However, attributes of the recipient community can be equally significant. Ant experts have frequently stated that alien ant invasion in Australia is likely to be less successful because its diverse and abundant native ant fauna resists invasion. This study would test this idea by determining outcomes of interactions between the introduced Argentine ant and a variety of native ant species from different functional groups.
3. Out with the old and in with the new: studying outcomes of plant-animal interactions in novel ecosystems
Most of our native ecosystems have many new members – invasive alien species. The usual focus of impact studies is to examine how these new species affect the native ones. However, invasive species are sometimes so diverse and abundant that they interact as frequently with each other as with natives, generating complex and unpredictable outcomes. This study would examine direct and indirect effects of one invader, the Argentine ant, to see whether they facilitate or disrupt seed dispersal of native and introduced plant species.
4. On a sugar high: the role of mutualism between introduced ants and honeydew-secreting insects in driving ant invasions (contingent on funding in 2007)
Introduced ant species frequently form mutualisms with honeydew-producing insects, which may be a key factor in their invasive success and impact. This study would determine if honeydew from sap-sucking insects is a key dietary component of the yellow crazy ant (Anoplolepis gracilipes) on Christmas Island, Indian Ocean and examine its role in the numerical dominance of this invasive ant in island rainforest.
5. Forecast the potential distributions of ant invaders in Australia
Alien ants are routinely intercepted at the Australian border and border breaches by these ants are increasingly common. For example, one of the most notorious of invasive ants, the little fire ant (Wasmannia auropunctata), is now established in Cairns adjacent to bushland and another, the yellow crazy ant (Anoplolepis gracilipes), has been detected recently at multiple locations along the tropical and subtropical coast of eastern Australia. This study would use existing programs (GARP, CLIMEX) and data for known distributions in the area of origin of these ants to predict potential distributions in Australia. Results would provide managers and policymakers with spatially explicit information on risk.
