Céleste Jacq, PhD-student at the School of Life and Environmental Sciences, Deakin University, Warrnambool, Australia, will give a talk for all those interested on Thursday 8 November, 13.00-14.00, in Håkonshallen, Animal Science Building, UMB.
Australia has 21 currently recognised species of galaxiid fish (Osteichthyes: Galaxiidae), 18 of which are endemic. The common jollytail, Galaxias maculatus, is a widespread freshwater fish with a distribution spanning Australia, New Zealand, Patagonian South America and several Pacific Islands. Common jollytail are usually diadromous, with larvae spending up to six months at sea before returning to freshwater to mature. However, this marine larval stage is not obligatory, and as a result populations may persist in entirely landlocked environments. Landlocking results in local adaptation and is considered to have had a significant impact upon the evolution of galaxiid fish over a range of timescales.
South-eastern Australia contains several unique saline lake systems, including the largest permanent saline lake in Australia – Lake Corangamite. The Lake Corangamite complex is a relatively young lake system, having formed in the late Pleistocene and is internationally recognised as a lake of important ecological significance under the Ramsar convention. The lake complex also contains populations of landlocked common jollytail which are currently threatened by prolonged drought periods and predation from introduced fish. Populations of landlocked galaxiids from this unique lake system have been studied using allozyme and mitochondrial DNA methods to determine the extent of genetic differentiation between the two life-history forms. Both mitochondrial DNA and allozyme data reveal significant heterogeneity between the two life-history forms. In addition, there is evidence to suggest the two forms are existing in sympatry in several of the lakes, likely the result of anthropogenic translocation from riverine populations. The overall findings are consistent with the hypothesis that the landlocked populations originated from a larger population present in the former Lake Corangamite before its fragmentation.
