We are studying a pair of different terrestrial flatworms (Phylum Platyhelminthes: Class Terricola) at our main comparative phylogeography study site at
Tallaganda State Forest / National Park, NSW
We have been comparing how genetic patterning of a fast-moving flatworm compares with that of a slower-moving species, with particular emphasis on the contact zones between separate subregions of the forest within our 100 Km transect at Tallaganda & Badja (southern region NSW).
Such comparative phylogeographic studies of organisms of low mobility and/or high habitat specificity remain rare, yet they have the ability to hold detailed palaeoecological signal. We analysed mitochondrial Cytochrome Oxidase I (COI) was analysed in the two species of terrestrial flatworm, and applied suite of advanced phylogenetics approaches and demographic estimation procedures to examine responses to historical processes in a model system (Tallaganda) comprising 5 catchment-based microregions about which palaeoecological assumptions have been made. Both species present DNA sequence-based evidence of recent population growth, yet strong regional localization of groups of related haplotypes to the proposed microbiogeographic regions - indicating the presence of regional refugia. The locale predicted to hold the highest quality refuges from cool, dry conditions (the Eastern Slopes Region), is indicated to have been a long-term refuge in both species, but not the only one: A.
lucasi appears to also show long-term persistance in the northernmost (Harold’s Cross) region. Other areas show evidence of population expansions and greater haplotypic simplicity. Despite these similarities, assuming a standard evolution rate for mtDNA, the two flatworms show very different temporal patterns: deep sequence divergences in A.
lucasi indicate occupation of refuges in the region since the Pliocene / early Pleistocene, which in contrast, COI sequences in C. coerulea coalesce within the Pleistocene, indicating much more recent (re)colonization. While the two species share similar broad patterns of contemporary regional endemism, the longer tenure and greater microendemism of Artioposthia
lucasi suggests much greater ability to persistent in the face of impacts of cool, dry periods.
We are also investigating some of the natural history traits (reproductive output, growth rates, food preferences) of these understudied animals. For example, hatching, growth and feeding of baby flatworms:
