Pollination ecology of Agave macroacantha (Agavaceae) in a Mexican tropical desert. I. Floral biology and pollination mechanisms

Abstract

In a study of sexual reproduction in long-lived semelparous plants, we observed Agave macroacantha in the tropical desert of Tehuacán-Cuicatlán, Mexico, describing duration of flowering, flower phenology, and nectar production patterns. We also performed two manipulative experiments evaluating (a) the seed production efficiency of different crossing systems (selfing, cross-pollination, apomixis, and control), and (b) the effect of different pollinators (diurnal exposure to pollinators, nocturnal exposure, exclusion, and control) on the seeds produced. Flowering occurred from early May to late July and had a mean duration of 29 days in the individual rosettes. The flowers were protandrous; anthesis occurred in the afternoon of the third day after floral opening, and the pistils matured in the afternoon of the fifth day. The stigmas remained receptive from dusk to the following morning. Pollination was mostly allogamous. Nectar was produced principally during the night, from the first stages of floral aperture until the stigmas wilted and flowering ceased. The flowers were visited during the day by hymenoptera, butterflies, and hummingbirds and during the night by bats and moths. Only the nocturnal visitors, however, were successful pollinators. Agave macroacantha is extremely dependent on nocturnal pollinators for its reproductive success.

Day–night fluctuations in floral scent and their effects on reproductive success in Lilium auratum

“…Then, to which type of reproductive success do olfactory cues contribute? Several studies have examined the relative contribution of diurnal and nocturnal pollinators to female reproductive success (Cruden 1973;Haber and Frankie 1982;Jennersten 1988;Guitian et al 1993;Fleming and Holland 1998;Groman and Pellmyr 1999;Arizaga et al 2000;Slauson 2000) and to male and female reproductive successes (Bertin and Willson 1980;Morse and Fritz 1983;Jennersten and Morse 1991;Young 2002). In the latter studies, two patterns have been reported, in addition to the above-stated pattern reported by : diurnal pollinators contribute more to both male and female reproductive successes in Asclepias species (Bertin and Willson 1980;Morse and Fritz 1983;Jennersten and Morse 1991), whereas nocturnal pollinators contribute more to both successes in Silene alba (Young 2002).…”

“…While some plants flower only during a part of the day and rely on either diurnal or nocturnal pollinators, others are visited by both diurnal and nocturnal pollinators (Cruden 1973;Bertin and Willson 1980;Haber and Frankie 1982;Morse and Fritz 1983;Jennersten 1988;Guitian et al 1993;Groman and Pellmyr 1999;Arizaga et al 2000;Slauson 2000;Young 2002;Jürgens et al 2003). For example, Yahara (1998, 1999) showed that both diurnal and nocturnal pollinators are important for reproductive success in Lonicera japonica, which opens at dusk and withers 2 days from anthesis.…”

Pollination ecology of Isoglossa woodii, a long‐lived, synchronously monocarpic herb from coastal forests in South Africa

“…Animal pollination can be quite effective among plants occurring at low density (Borges et al 2003;Byrne et al 2007), potentially eliminating the selective advantage of masting. Nevertheless, animal pollination is a feature of some masting plants (Pías & Guitián 2006), of a number of long-lived monocarps (Aker 1982;Young 1982;Arizaga et al 2000;Price et al 2008) and of at least one long-lived synchronous monocarp (Sharma et al 2008).…”

Ecosystem services across borders: a framework for transboundary conservation policy

“…In the late 1980s, and again in 1996-1997, the genetically homogeneous crops were devastated by pathogens, resulting in substantial economic losses (Valenzuela-Zapata and Nabhan 2003). Higher genetic diversity is related to disease resistance; if bats were allowed to pollinate agave naturally, cross-pollination between different plants would lead to higher genetic diversity and increased pathogen resistance (Arizaga et al 2002). Unless measures are taken to increase the genetic diversity of agave crops, they will continue to be devastated by pathogens (Valenzuela-Zapata and Nabhan 2003).…”