School of BioSciences - Research Publications

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Author: Hoffmann, Ary × Author: Weeks, Andrew × End date: 2012 × Type: Journal Article ×

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    From parasite to mutualist:: Rapid evolution of Wolbachia in natural populations of Drosophila
    Weeks, AR ; Turelli, M ; Harcombe, WR ; Reynolds, KT ; Hoffmann, AA ; Keller, L (PUBLIC LIBRARY SCIENCE, 2007-05)
    Wolbachia are maternally inherited bacteria that commonly spread through host populations by causing cytoplasmic incompatibility, often expressed as reduced egg hatch when uninfected females mate with infected males. Infected females are frequently less fecund as a consequence of Wolbachia infection. However, theory predicts that because of maternal transmission, these "parasites" will tend to evolve towards a more mutualistic association with their hosts. Drosophila simulans in California provided the classic case of a Wolbachia infection spreading in nature. Cytoplasmic incompatibility allowed the infection to spread through individual populations within a few years and from southern to northern California (more than 700 km) within a decade, despite reducing the fecundity of infected females by 15%-20% under laboratory conditions. Here we show that the Wolbachia in California D. simulans have changed over the last 20 y so that infected females now exhibit an average 10% fecundity advantage over uninfected females in the laboratory. Our data suggest smaller but qualitatively similar changes in relative fecundity in nature and demonstrate that fecundity-increasing Wolbachia variants are currently polymorphic in natural populations.
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    Assessing the benefits and risks of translocations in changing environments: a genetic perspective
    Weeks, AR ; Sgro, CM ; Young, AG ; Frankham, R ; Mitchell, NJ ; Miller, KA ; Byrne, M ; Coates, DJ ; Eldridge, MDB ; Sunnucks, P ; Breed, MF ; James, EA ; Hoffmann, AA (WILEY, 2011-11)
    Translocations are being increasingly proposed as a way of conserving biodiversity, particularly in the management of threatened and keystone species, with the aims of maintaining biodiversity and ecosystem function under the combined pressures of habitat fragmentation and climate change. Evolutionary genetic considerations should be an important part of translocation strategies, but there is often confusion about concepts and goals. Here, we provide a classification of translocations based on specific genetic goals for both threatened species and ecological restoration, separating targets based on 'genetic rescue' of current population fitness from those focused on maintaining adaptive potential. We then provide a framework for assessing the genetic benefits and risks associated with translocations and provide guidelines for managers focused on conserving biodiversity and evolutionary processes. Case studies are developed to illustrate the framework.