title: Landscape genetics informs mesohabitat preference and conservation priorities for a surrogate indicator species in a highly fragmented river system.
abstract: Poor dispersal species represent conservative benchmarks for biodiversity management because they provide insights into ecological processes influenced by habitat fragmentation that are less evident in more dispersive organisms. Here we used the poorly dispersive and threatened river blackfish (Gadopsis marmoratus) as a surrogate indicator system for assessing the effects of fragmentation in highly modified river basins and for prioritizing basin-wide management strategies. We combined individual, population and landscape-based approaches to analyze genetic variation in samples spanning the distribution of the species in Australia's Murray-Darling Basin, one of the world's most degraded freshwater systems. Our results indicate that G. marmoratus displays the hallmark of severe habitat fragmentation with notably scattered, small and demographically isolated populations with very low genetic diversity-a pattern found not only between regions and catchments but also between streams within catchments. By using hierarchically nested population sampling and assessing relationships between genetic uniqueness and genetic diversity across populations, we developed a spatial management framework that includes the selection of populations in need of genetic rescue. Landscape genetics provided an environmental criterion to identify associations between landscape features and ecological processes. Our results further our understanding of the impact that habitat quality and quantity has on habitat specialists with similarly low dispersal. They should also have practical applications for prioritizing both large- and small-scale conservation management actions for organisms inhabiting highly fragmented ecosystems.
authors.affiliation: Molecular Ecology Laboratory, School of Biological Sciences, Flinders University, Adelaide, South Australia, Australia.
authors.forename: J
authors.initials: J
authors.lastname: Lean
authors.affiliation: Evolutionary Biology Unit, South Australian Museum, North Terrace, Adelaide, South Australia, Australia.|Curator of Fishes, Museum and Art Gallery of the Northern Territory, Darwin, Northern Territory, Australia.
authors.forename: M P
authors.initials: MP
authors.lastname: Hammer
authors.affiliation: Institute for Applied Ecology and Collaborative Research Network for Murray-Darling Basin Futures, University of Canberra, Canberra, Australian Capital Territory, Australia.
authors.forename: P J
authors.initials: PJ
authors.lastname: Unmack
authors.affiliation: Evolutionary Biology Unit, South Australian Museum, North Terrace, Adelaide, South Australia, Australia.|School of Biological Sciences, University of Adelaide, Adelaide, South Australia, Australia.
authors.forename: M
authors.initials: M
authors.lastname: Adams
authors.affiliation: Molecular Ecology Laboratory, School of Biological Sciences, Flinders University, Adelaide, South Australia, Australia.
authors.forename: L B
authors.initials: LB
authors.lastname: Beheregaray
mesh_terms: D000818:Animals; D001315:Australia; D003247:Conservation of Natural Resources; D017753:Ecosystem; D005399:Fishes / Q000235:genetics*; D014644:Genetic Variation; D005828:Genetics, Population; D018895:Microsatellite Repeats; D011157:Population Dynamics; D045483:Rivers