Biomass allocation, growth, and photosynthesis of genotypes from native and introduced ranges of the tropical shrub Clidemia hirta

Saara J. DeWalt, Julie S. Denslow, J. L. Hamrick

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83 Scopus citations

Abstract

We tested the hypothesis that the tropical shrub Clidemia hirta appears more shade tolerant and is more abundant in its introduced than native range because of genetic differences in resource acquisition, allocation, and phenotypic plasticity between native and introduced genotypes. We examined growth, biomass allocation, and photosynthetic parameters of C. hirta grown in a greenhouse from seed collected from four populations in part of its native range (Costa Rica) and four populations in part of its introduced range (Hawaiian Islands). Six-month-old seedlings were placed in high (10.3-13.9 mol m-2 day-1) or low (1.4-4.5 mol m-2 day -1) light treatments and grown for an additional 6 months. Our study provided little evidence that Hawaiian genotypes of C. hirta differed genetically from Costa Rican genotypes in ways that would contribute to differences in habitat distribution or abundance. Some of the genetic differences that were apparent, such as greater allocation to stems and leaf area relative to whole plant biomass in Costa Rican genotypes and greater allocation to roots in Hawaiian genotypes, were contrary to predictions that genotypes from the introduced range would allocate more biomass to growth and less to storage than those from the native range. Hawaiian and Costa Rican genotypes displayed no significant differences in relative growth rates, maximal photosynthetic rates, or specific leaf areas in either light treatment. In the high light environment, however, Hawaiian genotypes allocated more biomass to reproductive parts than Costa Rican genotypes. Phenotypic plasticity for only 1 of 12 morphological and photosynthetic variables was greater for Hawaiian than Costa Rican genotypes. We conclude that genetic shifts in resource use, resource allocation, or plasticity do not contribute to differences in habitat distribution and abundance between the native and introduced ranges of C. hirta.

Original languageEnglish (US)
Pages (from-to)521-531
Number of pages11
JournalOecologia
Volume138
Issue number4
DOIs
StatePublished - Mar 2004
Externally publishedYes

Bibliographical note

Funding Information:
Acknowledgements We thank Andy Tull, Melanie Smith, and Mike Boyd for taking excellent care of the plants in the UGA greenhouse. Kalan Ickes, Amy Bouck, and Jeff Lake provided assistance in the greenhouse. We appreciate the loan of the LI-COR 6400 from Stephen Hubbell and leaf area meter from Lisa Donovan. Rebecca Montgomery provided helpful advice for measuring photosynthesis. We thank Stefan Schnitzer, Rebecca Montgomery, Walt Carson, Dan Bunker, Bill Rogers, and two anonymous reviewers for critically reviewing drafts of this paper. This work was financially supported by the USDA Forest Service Institute for Pacific Islands Forestry and an NSF Dissertation Improvement Grant (0073246).

Keywords

  • Common garden
  • Growth rates
  • Invasive species
  • Phenotypic plasticity
  • Shade tolerance

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