RESEARCH PAPER Apomixis does not affect visitation to flowers of Melastomataceae, but pollen sterility does F. R. Maia, I. G. Varassin & R. Goldenberg Departamento de Bot^ anica, Setor de Ci^ encias Biol  ogicas, Universidade Federal do Paran a, Curitiba, Paran a, Brazil Keywords Breeding systems; buzz-pollination; pollen viability; pollination. Correspondence F. R. da Maia, Departamento de Bot^ anica, Setor de Ci^ encias Biol  ogicas, Universidade Federal do Paran a, Caixa Postal 19031, 81.531-980 Curitiba, Paran a, Brazil. E-mail: fabiano.botanica@gmail.com Editor N. Vereecken Received: 6 November 2014; Accepted: 1 July 2015 doi:10.1111/plb.12364 ABSTRACT Apomixis is an asexual seed reproduction mechanism thorough which embryos are originated from material tissues inside the ovules, without precedent fertilisation. It allows plants to colonise new habitats, even in places where flower visitors are scarce or where plants are isolate. Apomixis seems to be related to pollen sterility and, in species with flowers that offer pollen as a reward for pollinators, the amount or qual- ity of the pollen offered by these species may influence the amount of the visits and specific composition of the visitors. In order to test this hypothesis, we studied breed- ing systems of 16 species of Melastomataceae and their flower visitors, evaluating composition and abundance of the visits to apomictic and sexual species. Apomictic plants with no viable pollen or with pollen with low viability did not receive visits from pollinators, and consequently probably produce strictly apomictic fruits. On the other hand, apomictic and sexual plants with high pollen viability do receive visits; in this case, apomictic plants may produce fruits and seeds through both sexual and apomictic methods. The species composition of insects visiting Melastomataceae with high pollen viability was similar, regardless of whether the plants were apomictic or not. It seems that pollen viability levels are important to determine visits to the flow- ers irrespective of breeding system. INTRODUCTION Apomixis is an asexual seed reproduction mechanism through which embryos are originated from material tissues inside the ovules, without precedent fertilisation (Hanna 1995; Jefferson & Bicknell 1995; Koltunow et al. 1995; Savidan 2000). Due to lar- ger plasticity associated with polyploid lineages, apomixis allows plant species to colonise new habitats and promote geographic range expansions (H€ orandl & Paun 2007; Santos et al. 2012; Hojsgaard et al. 2014). Apomixis may also lead to reproductive assurance (Holsinger 2000) in places where flower visitors are scarce or where plants are isolated, with no other conspecific individuals to provide pollen exchange (Baker 1967; Jefferson & Bicknell 1995; H€ orandl et al. 2008; Santos et al. 2012). Apomixis seems to be prevalent in some larger families, suggesting a positive role in diversification (Hojsgaard et al. 2014). Melastomataceae is a large, mostly tropical family with both apomictic and sexual species (Renner 1989; Goldenberg & Shepherd 1998; Santos et al. 2012). Apomixis is frequent in the family (Goldenberg & Shepherd 1998; Santos et al. 2012) and is generally associated with polyploidy and hybridisation (Men- des-Rodrigues & Oliveira 2012; Caetano et al. 2013a,b), which in turn are related to different levels of low pollen viability or even complete pollen sterility (Mogie 1992; Richards 1997; Goldenberg & Shepherd 1998; Goldenberg & Varassin 2001). On the other hand, sexual species have high pollen viability (Goldenberg & Shepherd 1998; Goldenberg & Varassin 2001; Hoffmann & Varassin 2011). The latter are mostly dependent on pollinators, which in Melastomataceae are usually bees that are specialised pollen gatherers from flowers with poricidal anthers, performing so-called ‘buzz-pollination’ (Renner 1989). Nevertheless, Melastomateceae species can also be polli- nated by other animals, like flies, wasps or even vertebrates, usually in nectar-producing species (Varassin et al. 2008) and large-pored anthers that release pollen more easily, even to unspecialised visitors (Kribel & Zumbado 2014). One event that has been constantly and informally observed in Melastomataceae is that flowers of the apomictic species are rarely visited, and sometimes have no visitors at all (Renner 1989; Goldenberg & Shepherd 1998; Fendrich T. G. unpub- lished data). Sexual species, however, seem to be intensively visited (Santos et al. 2010; Couto-Pereira et al. 2011; Franco et al. 2011; Brito & Sazima 2012; Fendrich T. G. unpublished data). Although it seems obvious that apomictic species that do not depend on pollinators to set fruits and seeds may be consequently less visited by them, there are species from other angiosperm families in which apomixis seems to be facultative, resulting in mixed breeding systems (Asker & Jerling 1992; Koltunow 1993; Richards 1997; Bicknell & Koltunow 2004; Good-Avila et al. 2008). Moreover, other angiosperm families also have pseudogamic species, i.e. apomictic plants that depend on pollination events to produce seeds, because of endosperm formation (Koltunow 1993; Richards 1997; Sam- paio et al. 2013). From the visitor’s standpoint, one can assume that there is a relationship between apomixis, high proportion of sterile pollen and scarce visits to the flowers, considering that pollen is the reward explored by the visitors. It would be expected that flowers with a low amount of reward should attract no visitors, and visits would be consequently scarce. Therefore, it is expected that flower visitation may vary depending on the breeding system in Melastomataceae species. Plant Biology © 2015 German Botanical Society and The Royal Botanical Society of the Netherlands 1 Plant Biology ISSN 1435-8603