Abstract
Monoecious figs reward their pollinators—agaonid wasps—by allocating a proportion of the flowers for egg laying, and retain the rest for seed production. It has been suggested that these proportions could be regulated by producing short-styled and long-styled flowers such that pollinator wasps could only use the former as their ovipositor does not reach the ovules of the latter. Thus the wasps can lay eggs only in the short-styled flowers and raise their offspring, and the ovules of uninfested, long-styled flowers can develop into seeds. This implied that figs bear dimorphic female flowers, with a bimodal distribution of style length. However, recent studies have shown that style length is distributed normally, with no evidence of bimodality. Therefore the regulation of allocation of flowers to the wasps does not seem to be through the production of two distinct kinds of female flowers. In this article we suggest that two factors govern the proportion of flowers rewarded to the wasps: (i) passive regulation, which is a consequence of the optimization of wasp ovipositor length, and (ii) active regulation, where figs are selected to enhance the variance of style length. We show that these arguments lead to certain predictions about the optimum ovipositor length, the proportion of the flowers available to the wasps, and the coefficient of variation of style length. We also show that data for 18 fig-wasp associations conform well with these predictions. We finally suggest that the regulatory process outlined here can be extended to evolution of style length in dioecious fig species also.
Similar content being viewed by others
References
Bronstein J. L. 1988 Mutualism, antagonism, and the fig-pollinator interaction.Ecology 69: 1298–1302
Bronstein J. L. 1992 Seed predators as mutualists: ecology and evolution of the fig-pollinator interaction.Insect-Plant Interactions IV: 2–43
Chopra R, N. and Kaur H. 1969 Pollination and fertilization in someFicus species.Beitr. Biol. Pflanz. 45: 441–446
Compton S. G. and Nefdt R. J. C. 1990 The figs and fig-wasps ofFicus burtt-davyii.Mitt. Inst. Allg. Bot. Hamburg 23a: 441–450
Condit I. J. 1947The Fig. Chronica Botanica (Waltham, MA, USA:)
Corner E. J. H. 1985Ficus (Moraceae) and Hymenoptera (Chalcidoidea): figs and pollinators.Biol. J. Linn. Soc. 25: 187–195
Galil J. 1977 Fig biology.Endeavour 1: 52–56
Galil J. and Eisikowitch D. 1968a Flowering cycles and fruit types inFicus sycomorus in Israel.New Phytol. 67: 745–758
Galil J. and Eisikowitch D. 1968b On the pollination ecology ofFicus sycomorus in East Africa.Ecology 49: 259–269
Galil J. and Eisikowitch D. 1968c On the pollination ecology ofFicus religiosa in Israel.Phytomorphology 18: 356–363
Galil J. and Eisikowitch D. 1971 Studies on mutualistic symbiosis between syconia and sycophilous wasps in monoecious figs.New Phytol. 70: 773–787
Galil J. and Eisikowitch D. 1973 Topocentric and ethodynamic pollination. inPollination and dispersal (eds.) N. B. M. Brantjes and H. F. Linskens (Nijmegen: Department of Botany, University of Nijmegen). pp. 85–100
Galil J. and Eisikowitch D. 1974 Further studies on the pollination ecology ofFicus sycomorus. II. Pollen filling and emptying byCeratosolen arabicus Mayr.New Phytol. 73: 551–528
Grandi G. 1920 Studio morfologico e biologico dellaBlastophaga psenes (L.).Ball. Lab. Zool. Partice 14: 63–204
Janzen D. H. 1979a How to be a fig?Annu. Rev. Ecol. Syst. 10: 13–51
Janzen D. H. 1979b How many babies do figs pay for more babies?Biotropica 11: 48–50
Johri B. M. and Konar R. N. 1956 The floral morphology and embryology ofFicus religiosa Linn.Phytomorphology 6: 97–111
Kathuria P. 1995 Reproductive strategies of common figs: Fig-fig-wasp interactions. M.Sc. (Agri.) thesis, University of Agricultural Sciences, Bangalore
Kathuria P., Ganeshaiah K. N., Uma Shaanker R. and Vasudeva R. 1995 Is there dimorphism for style lengths in monoecious figs?Curr. Sci. 68: 1047–1049
Kjellberg F., Anstett M.-C. and Herre E. A. 1994 Yucca sex.Nature 370: 604
Kjellberg F., Michaloud G. and Valdeyron G. 1987 TheFicus-Ficus pollinator mutualism: how can it be evolutionarily stable? inInsects-Plants (eds.) V. Labeyrie, G. Fabres and D. Lachaise (Dordrecht: W. Junk) pp. 335–340
Moore P. D. 1994 The Yucca expediency.Nature 368: 588–589
Murray M G. 1985 Figs (Ficus spp.) and wasps (Chalcidoidea, Agaonidae): hypotheses for an ancient symbiosis.Biol. J. Linn. Soc. 26: 69–81
Nefdt R. J. C. 1989 Interactions between fig wasps and their host figs. M.S. thesis submitted to Rhodes University, South Africa
Newton L. E. and Lomo A. 1979 The pollination ofFicus vogelii in Ghana.Bat. J, Linn. Soc. 78: 21–30
Patel A., Hossaert-McKey M. and McKey D. 1993 Ficus-pollinator research in India: Past, present and future.Curr. Sci. 65: 243–253
Pemberton C. E. 1921 The fig wasp in relation to the development of fertile seeds in the Moreton Bay fig.The Hawaiian Planters’ Record 24: 297–319
Ramirez B. W. 1969 Fig wasps: mechanism of pollen transfer.Science 163: 580–581
Ramirez B. W. 1974 Coevolution ofFicus and Agaonidae.Ann. Miss. Bot. Gard. 61: 770–780
Ramirez B. W. 1978 Evolution of mechanisms to carry pollen in Agaonidae (Hymenoptera, Chalcidoidea).Tijdschr. Entomol. 121: 279–293
Wiebes J. T. 1979 Co-evolution of figs and their insect pollinators.Annu. Rev. Ecol. Syst. 10: 1–12
Wiebes J. T. 1984 Fig wasp-fig co-evolution.Antenna 8: 122–127
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Ganeshaiah, K.N., Kathuria, P., Uma Shaanker, R. et al. Evolution of style-length variability in figs and optimization of ovipositor length in their pollinator wasps: A coevolutionary model. J. Genet. 74, 25–39 (1995). https://doi.org/10.1007/BF02924244
Received:
Revised:
Issue Date:
DOI: https://doi.org/10.1007/BF02924244