School of Agriculture, Food and Ecosystem Sciences - Research Publications

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    Counting the cost of revegetation: is direct seeding cheaper than planting tube-stock?
    Ede, F ; Greet, J ; Dabal, R ; Robertson, D ; Smith, R (University of New England, Armidale, 2018)
    Direct seeding is often assumed to be cheaper than planting tube–stock, but limited data exist to compare the relative costs of the two techniques. At four riparian sites in Victoria, we assessed the number of plants established over time in the months after direct seeding or planting. The costs of surviving plants and of weed management were calculated. Plants were 11 times cheaper when established by seeding ($1.88/plant) than when planted ($21.03/plant). Incorporating weed management costs, direct seeding was 1.3–2.4 times more cost–effective than planting tube–stock, although costs were high for both techniques.
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    Unravelling the Paradox of Loss of Genetic Variation during Invasion: Superclones May Explain the Success of a Clonal Invader
    Caron, V ; Ede, FJ ; Sunnucks, P ; Zhang, Y (PUBLIC LIBRARY SCIENCE, 2014-06-10)
    Clonality is a common characteristic of successful invasive species, but general principles underpinning the success of clonal invaders are not established. A number of mechanisms could contribute to invasion success including clones with broad tolerances and preferences, specialist clones and adaptation in situ. The majority of studies to date have been of plants and some invertebrate parthenogens, particularly aphids, and have not necessarily caught invasion at very early stages. Here we describe the early stages of an invasion by a Northern Hemisphere Hymenopteran model in three different land masses in the Southern Hemisphere. Nematus oligospilus Förster (Hymenoptera: Tenthredinidae), a sawfly feeding on willows (Salix spp.), was recently introduced to the Southern Hemisphere where it has become invasive and is strictly parthenogenetic. In this study, the number of N. oligospilus clones, their distribution in the landscape and on different willow hosts in South Africa, New Zealand and Australia were assessed using 25 microsatellite markers. Evidence is presented for the presence of two very common and widespread multilocus genotypes (MLGs) or 'superclones' dominating in the three countries. Rarer MLGs were closely related to the most widespread superclone; it is plausible that all N. oligospilus individuals were derived from a single clone. A few initial introductions to Australia and New Zealand seemed to have occurred. Our results point towards a separate introduction in Western Australia, potentially from South Africa. Rarer clones that were dominant locally putatively arose in situ, and might be locally favoured, or simply have not yet had time to spread. Data presented represent rare baseline data early in the invasion process for insights into the mechanisms that underlie the success of a global invader, and develop Nematus oligospilus as a valuable model to understand invasion genetics of clonal pests.