Molecular Ecology (2006) 15, 1481–1492 doi: 10.1111/j.1365-294X.2006.02849.x © 2006 Blackwell Publishing Ltd Blackwell Publishing Ltd When log-dwellers meet loggers: impacts of forest fragmentation on two endemic log-dwelling beetles in southeastern Australia C. SCHMUKI,* C. VORBURGER,† D. RUNCIMAN,* S. MACEACHERN *‡ and P. SUNNUCKS *§ *Department of Genetics, La Trobe University, Victoria 3086, Australia, †Institute of Zoology, University of Zürich, 8057 Zürich, Switzerland, ‡Department of Primary Industries, Victoria 3059, Australia, §School of Biological Sciences and Australian Centre for Biodiversity: Analysis, Policy and Management, Monash University, Victoria 3800, Australia Abstract Anthropogenic activities continue to cause massive fragmentation and reduction of forest area worldwide. With fragmentation and reduction of habitat recognized as the greatest threats to biodiversity, the implementation of improved, informed and conservation-based forestry practices is essential, and requires a greater understanding of the responses of dif- ferent organisms to forest fragmentation. While genetic techniques can add invaluable insights to fragmentation studies they have rarely been employed, particularly for multiple species. In the present study, we combined genetic information, obtained from allozyme loci and anonymous single copy nuclear DNA markers, with ecological data to investigate the impacts of forest fragmentation on two log-dwelling beetles with different life histo- ries, in an ‘islands of bush in a sea of pine’ model, at Tumut in New South Wales, Australia. Both the relatively mobile (i.e. has high dispersal ability and /or broad habitat range) Adelium calosomoides and the less mobile Apasis puncticeps showed reduced mobility and gene flow in fragmented compared to continuous forest: there was significantly greater iso- lation by distance and stronger local structure revealed by spatial autocorrelation in frag- mented forest. Analysis of patch and species characteristics revealed that genetic and demographic structure may be influenced by log degradation class for both species, and number of potential dispersal barriers, distance from continuous forest and desiccation intolerance/moisture preference for Ap. puncticeps. Thus the pine plantation matrix poses a barrier or filter for gene flow and mobility in both beetle species. Keywords: Adeliini, allozymes, anonymous nuclear DNA markers, Coleoptera, dispersal, forest fragmentation, gene flow, Lagriinae, mobility, Tenebrionidae Received 7 September 2005; revision accepted 14 November 2005 Introduction Impacts on biodiversity through loss and fragmentation of forest Fragmentation and reduction of habitat are recognized as the greatest threats to biodiversity (WCMC 1992), yet anthro- pogenic practices continue to cause massive fragmentation and reduction of forest area worldwide. At the same time, there is rapidly accumulating evidence that attendant negative impacts undermine the productivity and sustainability of forestry (Norton 1996; Grove 2002a, b). Thus, the implemen- tation of informed, conservation-based forestry practices has the potential to improve both the long-term viability of forestry and retention of biodiversity. Forest fragmentation reduces once-continuous areas of forest into smaller, less-connected and isolated remnants, usually receiving fewer migrants and less gene flow. Impeded movement of individuals and their genes have a range of demographic and genetic impacts (Frankham et al . 2002), including increased genetic differentiation between populations, reduced genetic variation within populations, Correspondence: Christina Schmuki, Fax: 613 9905 5613; E-mail: christina.schmuki@sci.monash.edu.au *Address at which the greatest proportion of the work was completed.