Population genetics of wolf spiders of fragmented habitat in the wheat belt of New South Wales

Authors

  • D. J. Colgan,

    Corresponding author
    1. Centre for Biodiversity and Conservation Research, The Australian Museum, 6 College Street, Sydney 2010, Australia
      Dr Don Colgan, Evolutionary Biology Unit, The Australian Museum, 6 College Street, Sydney 2010, Australia. Fax: 612 9320 659; E-mail: donc@austmus.gov.au
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  • S. Brown,

    1. Centre for Biodiversity and Conservation Research, The Australian Museum, 6 College Street, Sydney 2010, Australia
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  • R. E. Major,

    1. Centre for Biodiversity and Conservation Research, The Australian Museum, 6 College Street, Sydney 2010, Australia
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  • F. Christie,

    1. Centre for Biodiversity and Conservation Research, The Australian Museum, 6 College Street, Sydney 2010, Australia
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  • M. R. Gray,

    1. Centre for Biodiversity and Conservation Research, The Australian Museum, 6 College Street, Sydney 2010, Australia
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  • G. Cassis

    1. Centre for Biodiversity and Conservation Research, The Australian Museum, 6 College Street, Sydney 2010, Australia
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Dr Don Colgan, Evolutionary Biology Unit, The Australian Museum, 6 College Street, Sydney 2010, Australia. Fax: 612 9320 659; E-mail: donc@austmus.gov.au

Abstract

Possible effects of habitat fragmentation on the population genetics of a species of wolf spider (Lycosidae) from remnant Callitris woodland in the wheat belt of central western New South Wales in Australia are examined. Single-strand conformational analysis of mitochondrial cytochrome oxidase (subunit 1) was used to characterize the haplotypes of 295 spiders in six blocks each of four woodland sites. DNA sequences were collected from 119 of these spiders to confirm haplotype scoring, allow phylogeny estimation and permit calculation of sequence-based statistics. Intra-block tests do not suggest widespread effects of fragmentation. Genetic diversity is high in all blocks, with 25 haplotypes being identified. Nucleotide diversity is relatively low, as all of the haplotypes are closely related. One block had a significantly low value for the Ewens/Watterson test of neutrality and one block's value was nearly significantly high. Two blocks had nearly significant values of the Harpending Raggedness Index testing for recent population bottlenecks. No other intrablock tests approach significance. Interpopulation comparisons show significant nonhomogeneity of haplotype frequencies globally and in all pairwise comparisons. Relationships between woodland blocks based on haplotype frequencies are discordant with geographical proximity. Haplotype distribution patterns suggest that population structuring existed prior to fragmentation. We develop two measures of genetic distinctiveness to identify subpopulations of interest for conserving evolutionary processes in a species’ regional population. One is based on the sum of pairwise FST values and one on the spatial distribution of genetic variation. High values of the measure suggest a subpopulation might have been recently perturbed and low values that it is relatively undisturbed. The two measures identify different blocks as being of particular interest.

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