Are hybrid species more fit than ancestral parent species in the current hybrid species habitats?

Authors

  • L. A. DONOVAN,

    1. Department of Plant Biology, University of Georgia, Athens, Georgia, USA
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  • D. R. ROSENTHAL,

    1. Department of Plant Biology, University of Georgia, Athens, Georgia, USA
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    • 1

      Present address: USDA/ARS – UIUC Institute for Genomic Biology, Urbana, IL 61801, USA.

  • M. SANCHEZ-VELENOSI,

    1. Department of Plant Biology, University of Georgia, Athens, Georgia, USA
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      Present address: Canadian Institute for Health Information, 4110 Yonge Street, Suite 300, Toronto, ON M2P 2B7, Canada.

  • L. H. RIESEBERG,

    1. Department of Botany, University of British Columbia, Vancouver, BC, Canada
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  • F. LUDWIG

    1. Department of Plant Biology, University of Georgia, Athens, Georgia, USA
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      Present address: Earth System Science and Climate Change group, Wageningen University and Research Centre, 6700 AA Wageningen, the Netherlands.


L. A. Donovan, Department of Plant Biology, 2502 Plant Sciences Building, University of Georgia, Athens 30602, Georgia, USA.
Tel.: +1 706 542 2969; fax: +1 706 542 1805; e-mail: donovan@plantbio.uga.edu

Abstract

Hybrid speciation is thought to be facilitated by escape of early generation hybrids into new habitats, subsequent environmental selection and adaptation. Here, we ask whether two homoploid hybrid plant species (Helianthus anomalus, H. deserticola) diverged sufficiently from their ancestral parent species (H. annuus, H. petiolaris) during hybrid speciation so that they are more fit than the parent species in hybrid species habitats. Hybrid and parental species were reciprocally transplanted into hybrid and parental habitats. Helianthus anomalus was more fit than parental species in the H. anomalus actively moving desert dune habitat. The abilities to tolerate burial and excavation and to obtain nutrients appear to be important for success in the H. anomalus habitat. In contrast, H. deserticola failed to outperform the parental species in the H. deserticola stabilized desert dune habitat, and several possible explanations are discussed. The home site advantage of H. anomalus is consistent with environmental selection having been a mechanism for adaptive divergence and hybrid speciation and supports the use of H. anomalus as a valuable system for further assessment of environmental selection and adaptive traits.

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