Pollination biology of <em>Agave horrida</em> (Agavaceae) in the Chichinautzin mountain range, in Central Mexico”

Abstract

Background: the predictability of nectarivorous bats and their greater fecundity efficiency promote specialized pollination systems in columnar cactus in central Mexico. Some authors have suggested the same pollination pattern for Agave genus, and even when recent meta-analysis does not find such pattern, they have suggested this could be due to the lack of descriptive studies of pollination for this genus. Hypothesis: according to the chiropterophily syndrome of its flowers, the most efficient pollinator of Agave horrida will be nectarivorous bats leading to a pollination system with a specialist tendency in this agave species. Methods: we studied the floral biology of A. horrida, its floral offer (density of flowers in a given area), visitor rate, and visitor abundance, and conducted exclusion experiments for diurnal and nocturnal visitors. Results: A. horrida has protandric flowers with chiropterophilous characteristics (larger nectar production at night and nocturnal anther dehiscence and stigma receptivity). Nectarivorous bats were the most frequent flower visitors and the guild that most frequently presented pollen on their bodies. Pollinator exclusion experiments show that both birds and bats can successfully pollinate A. horrida. Nevertheless, the predictability and abundance of the nectarivorous bat Leptonycteris nivalis, along with the greater fruit and seed production than birds, makes it the most efficient pollinator. Conclusions: our results support the hypothesis of a specialized pollination system towards nectarivorous bats in agaves in central Mexico. Keywords: Agave horrida; Leptonycteris nivalis; pollination biology, Chichinautzin mountain range. ResumenAntecedentes: la predictibilidad de murciélagos nectarívoros y su mayor eficiencia en la fecundación de las flores promueven sistemas de polinización especialistas en los cactus columnares del centro de México. Aunque algunos autores han sugerido el mismo patrón en la polinización del género Agave, resultados de meta-análisis recientes no encuentran dicho patrón, sugiriendo que esto se debe a los pocos estudios disponibles sobre polinización de agaves. Hipótesis: de acuerdo al síndrome quiropterófilo de sus flores, el polinizador más eficiente de Agave horrida serían los murciélagos nectarívoros; lo anterior conduciría a un sistema de polinización quiropterófilo en A. horrida. Especies de estudio: Agave horrida y sus visitantes florales. Sitio y años de estudio: Pedregal de la sierra del Chichinautzin, México, en el año 2005. Métodos: estudiamos la biología floral de A. horrida, la tasa de visita y la abundancia de visitantes florales y realizamos experimentos de exclusión de polinizadores. Resultados: A. horrida tiene flores quiropterófilas (producción de néctar, dehiscencia de las anteras y receptividad nocturnas). Los murciélagos nectarívoros son los visitantes florales más abundantes y el gremio que más frecuentemente presenta polen en su cuerpo. Los experimentos de exclusión muestran que aves y murciélagos polinizan a A. horrida. Si...

Historical, temporal, and geographic dynamism of the interaction between Agave and Leptonycteris nectar‐feeding bats

“…When an Agave taxon had a small (nested) distribution within a bat distribution, the geographic correlation value was not significant; however, this is not evidence that the interaction is not happening. Many studies have reported the primary role that nectar‐feeding bats play in the pollination of Agave (Álvarez and González‐Quintero, 1970; Easterla, 1972; Howell, 1979; Howell and Hart, 1980; Howell and Roth, 1981; Arizaga et al, 2000; Molina‐Freaner and Eguiarte, 2003; Scott, 2004; Rocha et al, 2005; Sánchez and Medellin, 2007; Trejo, 2013; Flores‐Torres and Galindo‐Escamilla, 2017). For this reason, we believe that as a product of the strict methodology and considering the cases of disparity in the area sizes, the interaction events may have been underestimated in our study.…”

“…Even when a few Agave spp. are pollinated mainly by daytime visitors (i.e., A. toumeyana, A. parviflora, A. chrysantha, A. marmorata ), such as birds and insects (Schaffer and Schaffer, 1977; Slauson, 2000; Ornelas et al, 2002), several researchers have recorded a close ecological relationship between the genus Agave and Leptonycteris nivalis and L. yerbabuenae (Álvarez and González‐Quintero, 1970; Easterla, 1972; Howell, 1979; Howell and Hart, 1980; Howell and Roth, 1981; Arizaga et al, 2000; Molina‐Freaner and Eguiarte, 2003; Scott, 2004; Rocha et al, 2005; Sánchez and Medellin, 2007; Trejo, 2013; Flores‐Torres and Galindo‐Escamilla, 2017; Flores‐Abreu et al, 2019; Martínez, 2019). While there are several studies that address the Agave –bat interaction, these only analyze some Agave spp.…”