Summary
Dalbergia sissoo, a wind-dispersed tropical tree, shows a positively skewed distribution of seeds per pod. This is attributed to the enhanced dispersal advantage of few-seeded pods due to their reduced wing loading (ratio of weight to pod surface area) and low settling velocity. The proximate mechanisms causing the positively skewed distribution were investigated. The distribution could not be attributed to the distribution pattern of ovule number per ovary, pollen grain limitation, lack of ovule fertilization, or post-fertilization elimination of many-seeded pods. Rather, it was caused by the post-fertilization abortion of seeds within a pod 2 weeks after fertilization. This intra-pod seed abortion (IPSA) is due to a dominance hierarchy of fertilized ovules from the distal (near stigma) to the basal end, generated by the temporal differences in fertilization. The dominant developing seeds at the distal end cause the abortion of others through the production and diffusion of an aborting agent. When the dominance hierarchy of the siblings is not intense, pods are formed with more than one seed. We argue that the positively skewed distribution of seeds per pod is not due to maternal regulation but is a result of sibling rivalry. We propose that this sibling rivalry is generated by genetic differences in pollen grain fitness and disucss the results in the context of parent-offspring conflict.
Similar content being viewed by others
References
Augspurger CK (1986) Double and single seeded indehiscent legumes of Platipodium elegans: consequences for wind dispersal and seedling growth and survival. Biotropica 18:45–50
Augspurger CK, Hogan KP (1983) Wind dispersal of fruits with variable seed number in a tropical tree (Lonchocarpus pentaphyllus: Leguminosae). Am J Bot 70:1031–1037
Bawa KS, Buckley DP (1987) Seed: ovule ratios, selective seed abortion and mating systems in Leguminosae. In: Stirton CH, Zarucchi JL (eds) Advances in legume biology. Miss Bot Gard Monogr Syst Bot (in press)
Bawa KS, Webb CJ (1984) Flower, fruit, and seed abortion in tropical forest trees: implications for the evolution of paternal and maternal reproductive patterns. Am J Bot 71:736–751
Casper BB, Wiens D (1981) Fixed rates of random ovule abortion in Cryptantha flava (Boraginaceae) and its possible relation to seed dispersal. Ecology 62:866–869
Green DS (1980) The terminal velocity and dispersal of spinning samaras. Am J Bot 67:1218–1224
Janzen DH (1982) Variation in average seed size and fruit seededness in a fruit crop of the Guanacaste tree (Enterolobium cyclocarpus). Am J Bot 69:1169–1178
Maheshwari P (1950) An introduction to the embryology of angiosperms. McGraw Hill, New York
Mogensen HL (1975) Ovule abortion in Quercus (Fagaceae). Am J Bot 652:160–165
Ridley HN (1930) The dispersal of plants throughout the world. Reeve, Ashford, U.K.
Smith CC, Fretwell SD (1974) The optimal balance between size and number of offspring. Am Nat 108:499–506
Willson MF, Schemske DH (1980) Pollinator limitation, fruit production and floral display in Pawpaw (Asimina triloba). Bull Torrey Bot Club 107:401–408
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Ganeshaiah, K.N., Shaanker, R.U. Seed abortion in wind-dispersed pods of Dalbergia sissoo: maternal regulation or sibling rivalry?. Oecologia 77, 135–139 (1988). https://doi.org/10.1007/BF00380936
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00380936