title: Environmental complexity and biodiversity: the multi-layered evolutionary history of a log-dwelling velvet worm in Montane Temperate Australia.
abstract: Phylogeographic studies provide a framework for understanding the importance of intrinsic versus extrinsic factors in shaping patterns of biodiversity through identifying past and present microevolutionary processes that contributed to lineage divergence. Here we investigate population structure and diversity of the Onychophoran (velvet worm) Euperipatoides rowelli in southeastern Australian montane forests that were not subject to Pleistocene glaciations, and thus likely retained more forest cover than systems under glaciation. Over a ~100 km transect of structurally-connected forest, we found marked nuclear and mitochondrial (mt) DNA genetic structuring, with spatially-localised groups. Patterns from mtDNA and nuclear data broadly corresponded with previously defined geographic regions, consistent with repeated isolation in refuges during Pleistocene climatic cycling. Nevertheless, some E. rowelli genetic contact zones were displaced relative to hypothesized influential landscape structures, implying more recent processes overlying impacts of past environmental history. Major impacts at different timescales were seen in the phylogenetic relationships among mtDNA sequences, which matched geographic relationships and nuclear data only at recent timescales, indicating historical gene flow and/or incomplete lineage sorting. Five major E. rowelli phylogeographic groups were identified, showing substantial but incomplete reproductive isolation despite continuous habitat. Regional distinctiveness, in the face of lineages abutting within forest habitat, could indicate pre- and/or postzygotic gene flow limitation. A potentially functional phenotypic character, colour pattern variation, reflected the geographic patterns in the molecular data. Spatial-genetic patterns broadly match those in previously-studied, co-occurring low-mobility organisms, despite a variety of life histories. We suggest that for E. rowelli, the complex topography and history of the region has led to interplay among limited dispersal ability, historical responses to environmental change, local adaptation, and some resistance to free admixture at geographic secondary contact, leading to strong genetic structuring at fine spatial scale.
authors.affiliation: School of Biological Sciences, Monash University, Melbourne, Victoria, Australia.
authors.forename: James K
authors.initials: JK
authors.lastname: Bull
authors.affiliation: Natural Environment Research Council, British Antarctic Survey, Cambridge, United Kingdom.
authors.forename: Chester J
authors.initials: CJ
authors.lastname: Sands
authors.affiliation: Department of Biology, University of Mississippi, Oxford, Mississippi, United States of America.
authors.forename: Ryan C
authors.initials: RC
authors.lastname: Garrick
authors.affiliation: School of Biological Sciences, Flinders University, Adelaide, South Australia, Australia ; Evolutionary Biology Unit, South Australian Museum, Adelaide, South Australia, Australia.
authors.forename: Michael G
authors.initials: MG
authors.lastname: Gardner
authors.affiliation: Department of Biological Sciences, Macquarie University, Sydney, New South Wales, Australia.
authors.forename: Noel N
authors.initials: NN
authors.lastname: Tait
authors.affiliation: Research School of Biology, Australian National University, Canberra, Australian Capital Territory, Australia.
authors.forename: David A
authors.initials: DA
authors.lastname: Briscoe
authors.affiliation: Research School of Biology, Australian National University, Canberra, Australian Capital Territory, Australia.
authors.forename: David M
authors.initials: DM
authors.lastname: Rowell
authors.affiliation: School of Biological Sciences, Monash University, Melbourne, Victoria, Australia.
authors.forename: Paul
authors.initials: P
authors.lastname: Sunnucks
mesh_terms: D000818:Animals; D001315:Australia; D044822:Biodiversity; D005075:Biological Evolution; D004272:DNA, Mitochondrial; D004777:Environment; D056426:Genetic Loci; D014644:Genetic Variation; D005843:Geography; D010641:Phenotype; D010802:Phylogeny
chemical_list: D004272:DNA, Mitochondrial