|
[Print-friendly version]
 Matthew Krosch
Faculty of Science, Biological Systems Research
Thesis Title: Phylogeography of the Gondwanan Orthocladiinae (Diptera: Chironomidae)
Research Summary: Gondwanan sister group relationships are thought to exist within the non-biting midge family Chironomidae (Diptera), whereby, based on morphological and ecological similarities to sister taxa across Gondwanan landmasses, several genera are considered to be members of a relict Gondwanan clade. Existing studies have focused predominantly on the chironomid sub-families Podonominae, Aphroteniinae and Diamesinae, while relationships within and among relict Gondwanan genera in the more cosmopolitan sub-family Orthocladiinae remain relatively unexplored.
Within the Orthocladiinae, one genus thought to be part of the relict Gondwanan clade is the genus Echinocladius. This genus occurs extensively in cool, shaded streams along the east coast of Australia. Currently the position of Echinocladius within the molecular phylogeny of the broader Gondwanan Orthocladiinae clade has not been tested. Furthermore, a recent genetic study of the species Echinocladius martini in north-eastern Queensland suggested that populations were fragmented during the late Pleistocene in response to rainforest contractions brought on by the systemic drying of the Australian continent.
The results of this study also cast doubt on current species designations within the genus, indicating the presence of several previously unknown taxa that appear restricted to extant rainforest refugia. The current project, therefore, will focus on one of the taxa identified in this most recent study, to more accurately determine dispersal abilities and habitat preferences. By incorporating molecular data with information regarding altitude, surrounding vegetation type, in-stream substrate and traditional latitude-longitude data, inferences concerning the effect of restrictions to gene flow can be formulated. Patterns in the data will thus inform ideas of habitat preferences which can then permit predictions of the likely consequences of climate change and habitat fragmentation on members of the genus and freshwater invertebrates as a whole.
|
