Altitudinal variation for stress resistance traits and thermal adaptation in adult Drosophila buzzatii from the New World

Authors

  • J. G. SØRENSEN,

    1. Department of Ecology and Genetics, Institute of Biology, Aarhus Centre for Environmental Stress Research (ACES), University of Aarhus, Ny Munkegade, Aarhus C, Denmark
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  • F. M. NORRY,

    1. Department of Ecology and Genetics, Institute of Biology, Aarhus Centre for Environmental Stress Research (ACES), University of Aarhus, Ny Munkegade, Aarhus C, Denmark
    2. Departamento de Ecología, Genética y Evolución, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
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  • A. C. SCANNAPIECO,

    1. Departamento de Ecología, Genética y Evolución, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
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  • V. LOESCHCKE

    1. Department of Ecology and Genetics, Institute of Biology, Aarhus Centre for Environmental Stress Research (ACES), University of Aarhus, Ny Munkegade, Aarhus C, Denmark
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J. G. Sørensen, Aarhus Centre for Environmental Stress Research (ACES), Department of Ecology and Genetics, Institute of Biology, University of Aarhus, Ny Munkegade, Buildg. 540, DK-8000 Aarhus C, Denmark.
Tel.: ++45 8942 3135; fax: ++45 8612 7191;
e-mail: biojgs@biology.au.dk

Abstract

Multiple stress resistance traits were investigated in the cactophilic fly Drosophila buzzatii. Adults from seven populations derived from North-Western Argentina were compared with respect to traits relevant for thermal stress resistance and for resistance to other forms of environmental stress. The populations were collected along an altitudinal gradient spanning more than 2000 m in height, showing large climatic differences. The results suggest that knock-down resistance to heat stress, desiccation resistance and Hsp70 expression at a relatively severe stressful temperature best reflect thermal adaptation in this species. Furthermore, cold resistance seemed to be of less importance than heat resistance, at least for the adult life stage, in these populations. Clinal variation in thermal resistance traits over short geographical distances suggests relatively strong adaptive differentiation of the populations. This study provides the first evidence for altitudinal differentiation in stress-related traits, and suggests that Hsp70 expression level can be related to altitudinal clines of heat-stress resistance.

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