Reproductive biology of Pachira aquatica Aubl. (Malvaceae: Bombacoideae): a tropical tree pollinated by bats, sphingid moths and honey bees JESÚS R. HERNÁNDEZ-MONTERO and VINICIO J. SOSA Red de Ecología Funcional, Instituto de Ecología A.C., Apdo. Postal 63, CP 91000, Xalapa, Veracruz, Mexico Abstract We investigated the reproductive biology, including the floral biology, pollination biology, breeding system and reproductive success, of Pachira aquatica, a native and dominant tropical tree of fresh water wetlands, throughout the coastal plain of the Gulf of Mexico. The flowers present nocturnal anthesis, copious nectar production and sugar concentration (range 18–23%) suitable for nocturnal visitors such as bats and sphingid moths. The main nocturnal visitors were bats and sphingid moths while bees were the main diurnal visitors. There were no differences in legitimate visitation rates among bats, moths and honey bees. Bats and honey bees fed mainly on pollen while moths fed on nectar, suggesting resource partitioning. Eight species of bats carried pollen but Leptonycteris yerbabuenae is probably the most effective pollinator due to its higher pollen loads. The sphingid moths Manduca rustica, Cocytius duponchel and Eumorpha satellitia were recorded visiting flowers. Hand pollination experiments indicated a pre- dominant outcrossing breeding system. Open pollination experiments resulted in a null fruit set, indicating pollen limitation; however, mean reproductive success, according to a seasonal census, was 17 ± 3%; these contrasting results could be explained by the seasonal availability of pollinators. We conclude that P. aquatica is an outcrossing species with a pollination system originally specialized for bats and sphingid moths, which could be driven to a multimodal pollination system due to the introduction of honey bees to tropical America. Keywords: bees, breeding system, chiropterophily, floral biology, Malvaceae, sphingophily. Received 13 June 2014; revision received 3 May 2015; accepted 13 May 2015 Introduction Trees of the Bombacoideae subfamily, such as Ceiba pentandra, C. aesculifolia, C. grandiflora, Pachira quinata and Pseudobombax ellipticum, are predominantly self- incompatible and thus depend on pollinators to reproduce sexually (Fuchs et al. 2003; Quesada et al. 2004; Aguilar et al. 2006; Lobo et al. 2013). Bombacoideae trees are mainly pollinated by bats but can have alternative pollina- tors (Baum 1995; Fleming et al. 2009). Although a flower species may have multiple visitors, not all of these are effective pollinators nor do they contribute equally to reproduction because of differences in visitor foraging behavior and compatibility between the floral features and the visitor morphology (Eguiarte et al. 1987; Baum 1995; Hernández-Conrique et al. 2007). Breeding and pol- lination systems both determine the reproductive success of plants; these two factors are key to understanding the effects that landscape fragmentation may have on the reproductive success of natural populations (Kearns et al. 1998). Pachira aquatica Aubl. (Malvaceae: Bombacoideae) is a native, dominant tropical tree of tropical freshwater for- ested wetlands on the coastal plain of the Gulf of Mexico (Infante Mata et al. 2011). It has been proposed as a species with potential for use in wetland restoration because of its high germination capacity (Infante Mata & Moreno Casasola 2005). Due to the morphological char- acteristics of its flowers, it can be catalogued as a chiropterophylic species; however, it also presents char- acteristics (i.e. fragrant odor and long tubular corolla) that fit a sphingophylic syndrome (Quiroz et al. 1986; Correspondence: Jesús R. Hernández-Montero Email: jesus.hdezmontero@gmail.com Plant Species Biology (2015) ••, ••–•• doi: 10.1111/1442-1984.12096 © 2015 The Society for the Study of Species Biology Plant Species Biology (2016) 31, 125–134 doi: 10.1111/1442-1984.12096 © 2015 The Society for the Study of Species Biology