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Genetics and Molecular Biology |
2Department of Genetics and Plant Breeding, University of Agricultural Sciences, G.K.V.K., Bangalore 560 065, India 3Department of Crop Physiology, University of Agricultural Sciences, G.K.V.K., Bangalore 560 065, India 4Biology Department, Concordia University, 1455 de Maisonneuve Boulevard, Montreal, Quebec, H3G 1M8 Canada
Dalbergia sissoo, a wind-dispersed tropical tree, exhibits high intrafruit seed abortion. Of the four to five ovules in the flower, generally one and occasionally two or three develop to maturity. It has been proposed that the seed abortion is a consequence of intense sibling competition for maternal resources and that this competition occurs as an inverse function of the genetic relatedness among the developing seeds. Accordingly, developing seeds compete intensely when they are genetically less related but tend to develop together when genetically more related. We tested this hypothesis by comparing the genetic similarity among the pairs of seeds developing within a pod with that among (a) random pairs from the pool of all seeds, (b) random pairs from single-seeded pods, and (c) random pairs from two-seeded pods, using both randomly amplified polymorphic DNA (RAPD) and isozymes in five trees. We found that the pairs of seeds developing within a pod are genetically more similar than any random pairs of seeds in a tree. Thus the formation of two-seeded pods appear to be associated with increased genetic relatedness among the developing seeds. We discuss the results in the context of possible fitness advantages and then discuss the possible mechanisms that promote tolerance among related seeds.
Key Words: Dalbergia sissoo Fabaceae genetic relatedness inclusive fitness kin selection seed abortion sibling rivalry
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R. A. RIBEIRO, A. C. SIMOES RAMOS, J. P. DE LEMOS FILHO, and M. B. LOVATO Genetic Variation in Remnant Populations of Dalbergia nigra (Papilionoideae), an Endangered Tree from the Brazilian Atlantic Forest Ann. Bot., June 1, 2005; 95(7): 1171 - 1177. [Abstract] [Full Text] [PDF] |
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