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Andromonoecy and high fruit abortion in Anthonotha noldeae in a West African montane forest
Merodie A. Beavon and Hazel M. Chapman
Plant Systematics and Evolution
Vol. 296, No. 3/4 (October 2011), pp. 217-224
Published by: Springer
Stable URL: http://www.jstor.org/stable/43558243
Page Count: 8
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Anthonotha noldeae (Rossberg) Exell et Hillc. Leguminosae, Caesalpinioideae, an Afromontane forest canopy tree, produces a superabundance of flowers, but few (1.1%) initiate fruits, and even fewer (0.44%) reach maturity and disperse. Fifty-three percent of fruits are predated. A. noldeae is andromonoecious. Over all 20 trees for which we counted floral gender ratios (hermaphrodite vs. staminate flowers), the ratio was 2.1:1. There was significant (F₁₉,₃₇₉ = 8.52; p < 0.001) variation in the proportion of the two flower types produced among individuals. Floral gender ratios did not predict the proportion of mature fruits produced on a tree (r² = 0.066; p = 0.273), or its phenotypic gender (Gi)—which is defined as the contribution of an individual tree to the next generation in terms of female function relative to all other individuals in the population (r² = 0.069; p = 0.262). Gi varied among trees from 0 (functionally male) to 0.8.There was no correlation between tree size and phenotypic gender (r = 0.08; p = 0.74; n = 20). Open flowers initiated significantly more fruits than bagged or caged flowers (p = 0.0073), showing A. noldeae relies on birds to produce fruits. However, 80% of visits to flowers were made by insects, while only 20% of visits were from pollinating sunbirds. While low fruit initiation was the most restrictive reproductive step, low pollination rates combined with insect robbers, fungal attacks and high levels of predation of immature fruits may contribute to the extremely low fruit set in A. noldeae.
Plant Systematics and Evolution © 2011 Springer