Sex-specific plant responses to light intensity and canopy openness: Implications for spatial segregation of the sexes

Kristen E. Groen, Christopher R. Stieha, Philip H. Crowley, David Nicholas McLetchie

Research output: Contribution to journalArticlepeer-review

26 Scopus citations


In seed plants, the proximate causes of spatial segregation of the sexes (SSS) and its association with environmental variation are thought to be linked to sex-specific morphological and physiological variation. To address the general question of linkage among SSS, plant traits and environmental gradients, Marchantia inflexa was used, for which male plants are found under more open tree canopy than females. We hypothesized that males are adapted to higher light intensity and are better able to tolerate water stress than females, as is the case with seed plants. We tested for sex-specific habitat and trait relationships by quantifying plant traits (morphological and physiological) and estimates of the light conditions (percent canopy openness and light intensity) in the field. Using path analysis, we found that edge pore density in both sexes was negatively correlated with canopy openness, while in males, edge pore density had a weak but positive relationship to light intensity. These responses suggest that canopy openness and light intensity have opposing effects on edge pore density in males and that males might be more responsive to water stress than females. Additionally, the greater importance of female support tissue, which functions as storage, in explaining and being explained by other variables in the path analysis, relative to male support tissue, may reflect sex-specific allocation differences related to resources needed for female function.

Original languageEnglish
Pages (from-to)561-570
Number of pages10
Issue number3
StatePublished - Feb 2010

Bibliographical note

Funding Information:
Acknowledgments We thank L. Campbell, L. Reynolds, and M. Yusuf for assistance, R. Hernandez of William Beebe Tropical Research Station (aka Simla) for assistance with the data loggers, H. Truszczynska for statistical guidance, and S. Gleeson, R. McLetchie, D. Miller, L. Stark and anonymous reviewers for comments that improved the manuscript. We thank the Wildlife Section of the Forestry Division of the Republic of Trinidad and Tobago for collection and export permits, and the Water and Sewage Authority for access to the Quare and North Oropuche locations. Funding was provided by a Gertrude Flora Ribble research scholar award and travel assistance from the Biology Department, University of Kentucky (K. E. G.), Fulbright Program 2006-2007, Institute of International Education, U.S. Department of State, and University of Kentucky Graduate School for research support (C. R. S.), and USA National Science Foundation grants DEB 9974086 (D. N. M., PI; P. H. C., co-PI), DEB 0219762 & IOB 0416281 (D. N. M.). The experiments comply with the current laws of Trinidad and Tobago.


  • Light-condition measures
  • Sex-specific responses
  • Sexual dimorphisms
  • Spatial segregation of the sexes

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics


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