Dioecy, Monoecy, and Their Ecological Correlates in the Littoral Forest of Madagascar

作者：Vary Laura B^*; Gillen Daniel L; Randrianjanahary Miramasonadro; Lowry Porter P II; Sakai Ann K; Weller Stephen G

来源：Biotropica, 2011, 43(5): 582-590.

DOI：10.1111/j.1744-7429.2010.00742.x

• breeding systems
• classification and regression trees (CART)
• fleshy fruits
• multinomial logistic regression
• small flowers
• woody habit

Dioecy is a rare breeding system in flowering plants, but one that has evolved multiple times in different plant lineages. Dioecious species are commonly associated with several ecological traits, including woody habit, fleshy fruit, and small, inconspicuous flowers, although the significance of these correlations has been debated extensively. Monoecy is a breeding system that may lead to the evolution of dioecy, but ecological correlates of monoecious species have rarely been analyzed. We determined the diversity of breeding systems in the littoral forests of Madagascar and used multivariate methods to estimate which ecological traits have the strongest association with dioecy and are the best predictors of breeding systems. The Malagasy littoral forest flora is a well-documented subset of the Malagasy flora, with 13 percent of total species diversity in an area < 1 percent of the island's total. We found high levels of dioecy (18.4%) and monoecy (9.2%), similar to incidences in other tropical floras. Using multinomial logistic regression, dioecy has the strongest association with woody habit and fleshy fruit. Monoecious species have a strong association with small flowers, although this association does not hold at higher taxonomic levels. Using classification and regression tree (CART) methods, the best predictors of dioecy are woody habit and fleshy fruit; monoecy is equally predicted by fleshy and dry fruit. For the Malagasy littoral forest, both methods provide further support for the importance of woody habit and fleshy fruit in the evolution of dioecy.

• 出版日期2011-9