The richness and seasonal variation of ant‐plant interactions were compared in four habitats in México: lowland tropical dry forest (La Mancha, Veracruz), coastal sand dune matorral (San Benito, Yucatán), semiarid highland vegetation (Zapotitlán, Puebla), and lower montane humid forest (Xalapa, Veracruz). The effects of temperature and precipitation on the seasonal distribution of the number of ant‐plant interactions differed among habitats. The general linear models fitted to the ant‐plant interaction curves explained 78.8 percent of the variation for La Mancha, 80.1 percent for Zapotitlán, 18 percent for San Benito, and 29.5 percent for Xalapa. Even though rainfall is low in Zapotitlán and San Benito, minimum temperature was the most important factor accounting for the seasonal distribution and low number of interactions. At La Mancha, with milder minimum temperatures and higher water availability, temperature alone did not account for the seasonal distribution and number of interactions, whereas the effect of the precipitation × temperature interaction was highly significant. Xalapa exhibits the lowest temperatures and the highest precipitation, but the role of these factors was only marginal. We suggest that the vegetation at Xalapa, a mixture of tropical and temperate floristic elements, constrains ant‐plant interactions due to a limited presence of nectaries. Also, ants are less abundant in cool and relatively aseasonal habitats. The other habitats have tropical floristic elements that are abundant and frequently have nectar‐producing structures. We report considerable variation among habitats in the number and seasonal distribution of ant‐plant interactions, and suggest that it is due to the effect of variation in environmental parameters, the richness of plants with nectaries in the vegetation, and habitat heterogeneity.

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The results emphasize the strong relationship between floral longevity and pollination in orchids, as well as the influence of reproductive costs on the former.

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Folivory may indirectly impact plant reproduction through changes in sexual expression (i.e., number or proportion of male and female flowers produced), which influence plant-pollinator interactions via changes in pollinator preference or efficiency. This study is an experimental evaluation of the effect that defoliation has on sex expression in the monoecious shrub Cnidoscolus aconitifolius, how such effect varies across sites, as well as how such changes indirectly affect pollinator visitation rates. The present study used three populations of C. aconitifolius, each one located in a different site in Yucatán (México): pasture, deciduous forest and subdeciduous medium height forest and three levels of defoliation: 50 percent, 100 percent, and a control (no damage). Results showed that defoliation reduced significantly the total number of male flowers produced in two of the sites. Defoliation did not impact female flower production or the proportion of female flowers produced. Finally, floral visit rates were not affected by defoliation via changes in sexual expression and neither by site or by the interaction site  defoliation. Findings showed that defoliation had an effect on sex expression in C. aconitifolius, although apparently this change did not affect the plant-pollinator interactions.Abstract in Spanish is available at http://www.blackwell-synery.com/loi/btp.