Flowering and fruiting phenologies affect plant success and integrate selective pressures from both abiotic and biotic factors (van Schaik et al. 1993). Gentry (1974) ascribed one of the mechanisms for maintenance of high species diversity in tropical plant communities to variations in flowering phenology. Variability in phenological patterns decreases the effects of competition among sympatric plants (Borchert 1983, Newstrom et al. 1994). Webber and Gottsberger (1999) demonstrated phenology displacement in six species within the same genus in Amazonia; this phenology displacement allowed for a better partitioning of pollinators. Wright and Calderon (1995), however, showed that the flowering times were similar among sympatric congeners in Panama.
The phenological displacement hypothesis was tested on the Brazilian sympatric pipers. The few studies about the piper phenology that were previously carried out in Central and South America (Opler et al. 1980, Fleming 1985, Marquis 1988, Marinho-Filho 1991, Wright 1991) found that pipers flower mainly in the dry season. The phenology of each Brazilian Piper species was studied at the population level, on five randomly chosen adult individuals, between January and December 1995. The phenophases were defined as follows:
1) Inflorescence formation: individuals showing inflorescences with flower buds
2) Flowering: individuals showing inflorescences with anthesed flowers
3) Fruiting: individuals showing infructescences
Flowering strategies at the specific level were defined (modified from Morellato 1991, Newstrom et al. 1994) as follows:
1) Continual: at least one individual of a given species incessantly flowers for the entire year (admitting only one single interval of 2 months without flowers in anthesis)
2) Episodic: individuals flower in several intervals of the year, each one separated by months without flowers
3) Seasonal: individuals flower once a year, for at least 4 months.
Continual flowering occurred in P aduncum, P. amalago, P. gaudichaudianum, P. glabratum, and P. macedoi, which presented flowers throughout the year. Episodic flowering was found in P. arboreum and P. crassinervium, which flower simultaneously. Seasonal flowering was observed in P. mikanianum, P. mollicomum, P. regnelli, P. martiana, and P propinqua, which flower at the end of the dry season (Fig. 3.2(A)).
Pipers found in different habitats differed in their phenological patterns. Piper species from the semideciduous forest presented a seasonal pattern, whereas those indifferent to habitat had a continual flowering pattern. Among the pipers with continual flowering, P amalago, P. glabratum, and P. macedoi are insect pollinated; P. gaudichaudianum is wind pollinated; and P. aduncum is both wind and insect pollinated. The episodic P. arboreum is
Piper aduncum A
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