Pre-dispersal seed predation reduces the reproductive compensatory advantage of thrum individuals in Erythroxylum havanense (Erythroxylaceae)
- 114 Downloads
Male-sterility mutations in hermaphroditic species represent the first step in the evolution of gender specialization. Male-sterile individuals commonly compensate the loss of the male function by increasing the number or quality of seeds. Because the magnitude of compensation determines the maintenance of females within populations and the evolution of sexual specialization, plant-animal interactions may affect these evolutionary processes if animals are sensitive to such reproductive asymmetries. Here we explore the effect of seed predation on the reproductive compensation of Erythroxylum havanense, a distylous shrub with morph-biased partial male sterility, during two consecutive years. Seed predation reduced the compensatory advantage of thrums in 1987, but not in 1988. Annual differences in the intensity of seed predation seem to be accounted for differences in the onset and synchrony of flowering. Thus, although seed predators may reduce the compensatory advantage of thrums, their impact is modulated by the environmental cues triggering flowering and insect emergence.
KeywordsErythroxylum havanense Heterostyly Pre-dispersal seed predation Reproductive compensatory advantage Tropical dry-forest
The authors thank María del Carmen Vázquez, Germán Ávila-Sakar, Rubén Pérez-Ishiwara and Gustavo Verduzco for their assistance in the field. They also thank Juan Fornoni for its valuable comments to improve previous versions of this manuscript. This research was supported by grants from UNAM and CONACyT, Mexico.
- Bell WJ (1990) Searching behaviour. The behavioural ecology of finding resources. Chapman and Hall, CambridgeGoogle Scholar
- Charlesworth D (1999) Theories of the evolution of dioecy. In: Geber MA, Dawson TE, Delph LF (eds) Gender and sexual dimorphism in flowering plants. Springer Verlag, Berlin, pp 33–60Google Scholar
- Domínguez CA (1990) Consecuencias ecológicas y evolutivas del patrón de floración sincrónico y masivo de Erythroxylum havanense Jacq. (Erythroxylaceae). Dissertation, Universidad Nacional Autónoma de Mexico, MexicoGoogle Scholar
- Garcia-Oliva F, Camou A, Maass JM (2002) El clima de la región central de la costa del pacífico mexicano. In: Nogüera Aldrete AN, Vega-Rivera JH, García Aldrete AN, Quesada-Avendaño M (eds) Historia natural de Chamela. Instituto de Biología, UNAM, Mexico City, pp 3–10Google Scholar
- Geber MA (1999) Theories of the evolution of sexual dimorphism. In: Geber MA, Dawson TE, Delph LF (eds) Gender and sexual dimorphism in flowering plants. Springer, New York, pp 97–122 Google Scholar
- Gouyon PH, Couvet D (1987) A conflict between two sexes, females and hermaphrodites. In: Stearns SC (ed) The evolution of sex and its consequences. Birkhäuser, Basel, pp 245–261Google Scholar
- Gryj EO, Domínguez CA (1996) Fruit removal and postdispersal survivorship in the tropical dry forest shrub Erythroxylum havanense: ecological and evolutionary implications. Oecologia 108:368–374Google Scholar
- Koelewijin HP, Van Damme JMM (1995) Genetics of male sterility in gynodioecious Plantago coronopus I. Cytoplasmic variation. Genetics 139:1749–1758Google Scholar
- SAS Institute (1999) SAS version 8.00. Cary, North Carolina, USAGoogle Scholar
- SAS Institute (2001) JMP. Version 4.0.4. Cary, North Carolina, USAGoogle Scholar
- Stokes ME, Davis CS, Koch GG (2001) Categorical data analysis using the SAS system. SAS Institute, Cary, North Carolina, USAGoogle Scholar