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Seed size-mediated dormancy thresholds: A case for the selective pressure of fire on physically dormant species

Journal Article


Abstract


  • In physically dormant species, fire-generated heat breaks seed dormancy, with dormancy-breaking temperature thresholds varying among species. Fire-related heating decreases with depth, due to the insulating effects of soil. Concurrently, smaller-seeded species are restricted to germinating near the surface because of limited reserves within such seeds. We hypothesized that dormancy-breaking temperature thresholds of physically dormant species would be higher in smaller-seeded species, to ensure emergence is restricted to shallower soil depths, and that seed survivorship would follow the same pattern. This was tested experimentally for 14 species from south-eastern Australia, and by using a larger data set of species compiled from the literature to assess if any patterns hold across a broader group. Seed size was negatively related to dormancy-breaking temperature thresholds. Mortality at 100 °C showed a positive relationship with seed size. Our findings suggest that small-seeded species are subject to firerelated selection pressure that results in higher dormancy-breaking temperature thresholds and resistant to hotter temperatures, which may act as a depth detection mechanism. By using a broader range of species, we highlight that this relationship is strong and representative of species across a number of phylogenetic groups.

UOW Authors


  •   Borala Liyanage, Ganesha (external author)
  •   Ooi, Mark

Publication Date


  • 2018

Citation


  • Liyanage, G. S. & Ooi, M. K. J. (2018). Seed size-mediated dormancy thresholds: A case for the selective pressure of fire on physically dormant species. Biological Journal of the Linnean Society, 123 (1), 135-143.

Scopus Eid


  • 2-s2.0-85040602500

Ro Metadata Url


  • http://ro.uow.edu.au/smhpapers/5304

Number Of Pages


  • 8

Start Page


  • 135

End Page


  • 143

Volume


  • 123

Issue


  • 1

Place Of Publication


  • United Kingdom

Abstract


  • In physically dormant species, fire-generated heat breaks seed dormancy, with dormancy-breaking temperature thresholds varying among species. Fire-related heating decreases with depth, due to the insulating effects of soil. Concurrently, smaller-seeded species are restricted to germinating near the surface because of limited reserves within such seeds. We hypothesized that dormancy-breaking temperature thresholds of physically dormant species would be higher in smaller-seeded species, to ensure emergence is restricted to shallower soil depths, and that seed survivorship would follow the same pattern. This was tested experimentally for 14 species from south-eastern Australia, and by using a larger data set of species compiled from the literature to assess if any patterns hold across a broader group. Seed size was negatively related to dormancy-breaking temperature thresholds. Mortality at 100 °C showed a positive relationship with seed size. Our findings suggest that small-seeded species are subject to firerelated selection pressure that results in higher dormancy-breaking temperature thresholds and resistant to hotter temperatures, which may act as a depth detection mechanism. By using a broader range of species, we highlight that this relationship is strong and representative of species across a number of phylogenetic groups.

UOW Authors


  •   Borala Liyanage, Ganesha (external author)
  •   Ooi, Mark

Publication Date


  • 2018

Citation


  • Liyanage, G. S. & Ooi, M. K. J. (2018). Seed size-mediated dormancy thresholds: A case for the selective pressure of fire on physically dormant species. Biological Journal of the Linnean Society, 123 (1), 135-143.

Scopus Eid


  • 2-s2.0-85040602500

Ro Metadata Url


  • http://ro.uow.edu.au/smhpapers/5304

Number Of Pages


  • 8

Start Page


  • 135

End Page


  • 143

Volume


  • 123

Issue


  • 1

Place Of Publication


  • United Kingdom