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Salinity, not genetic incompatibilities, limits the establishment of the invasive hybrid cattail Typha × glauca in coastal wetlands
  • Joanna Freeland,
  • Marcel Dorken,
  • Kathryn Tisshaw
Joanna Freeland
Trent University
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Marcel Dorken
Trent University
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Kathryn Tisshaw
Trent University
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Abstract

Interspecific hybrid frequencies can vary considerably across contact zones of a single pair of progenitor species. The reasons for this are not well understood, but could help explain processes such as species diversification or the range expansion of invasive hybrids. The widespread cattails Typha latifolia and T. angustifolia seldom hybridize in some parts of their range, but in other areas produce the dominant hybrid T. × glauca. We used a combination of field and greenhouse experiments to investigate why T. × glauca has invaded wetlands in the Laurentian Great Lakes region of southern Ontario, Canada, but is much less common in the coastal wetlands of Nova Scotia in eastern Canada. One potentially important environmental difference between these two regions is salinity. We therefore tested three hypotheses: 1) T. latifolia and T. angustifolia in Nova Scotia are genetically incompatible; 2) the germination or growth of T. × glauca is reduced by salinity; and 3) T. latifolia, a main competitor of T. × glauca, is locally adapted to saline conditions in Nova Scotia. Our experiments showed that Nova Scotia T. latifolia and T. angustifolia are genetically compatible, and that saline conditions do not impede growth of hybrid plants. However, we also found that under conditions of high salinity, germination rates of hybrid seeds were substantially lower than those of Nova Scotia T. latifolia. In addition, germination rates of Nova Scotia T. latifolia were higher than those of Ontario T. latifolia, suggesting local adaptation to salinity in coastal wetlands. This study adds to the growing body of literature which identifies the important roles that local habitat and adaptation can play in the distributions and characteristics of hybrid zones.

Peer review status:ACCEPTED

08 Jul 2020Submitted to Ecology and Evolution
09 Jul 2020Submission Checks Completed
09 Jul 2020Assigned to Editor
13 Jul 2020Reviewer(s) Assigned
21 Jul 2020Review(s) Completed, Editorial Evaluation Pending
27 Jul 2020Editorial Decision: Revise Minor
31 Aug 20201st Revision Received
01 Sep 2020Submission Checks Completed
01 Sep 2020Assigned to Editor
01 Sep 2020Review(s) Completed, Editorial Evaluation Pending
03 Sep 2020Editorial Decision: Accept