Plant Ecology and Evolution 148 (2): 229–236, 2015 http://dx.doi.org/10.5091/plecevo.2015.983 Theoretical predictions of plant-pollinator interactions in sympatric species of Psychotria (Rubiaceae) in Cerrado of Brazil José N. Mesquita-Neto, Carlos M. Silva-Neto & Edivani V. Franceschinelli * Laboratório de Biologia Reprodutiva de Plantas, Departamento de Botânica, Instituto de Ciências Biológicas, Universidade Federal de Goiás, 74001-970, Goiânia GO, Brazil *Author for correspondence: edivanif@gmail.com INTRODUCTION Pollinators are essential for the reproduction of at least 90% of forest plant species (Bawa 1990). In addition, they are crucial to maintain food chains in natural environments, because they enable the production of fruits and seeds that sustain frugivores (Moreti et al. 2006). Given the evidence for a decline in pollinator numbers, particularly bees, it is es- pecially important to study the relationships between native plant species and their potential pollinators to inform conser- vation and management strategies. In highly seasonal habitats, sympatric species are often constrained to lower simultaneously (Janzen 1967, Reich & Borchert 1984, Rathcke 1988, Ollerton et al. 2003). Un- der these circumstances, plants may become more tolerant of competition by lengthening lower longevity (e.g. Levin 1978, Motten 1986, Rathcke 1988, Ashman & Schoen 1994, Ashman 2000) or through a iner-grained partitioning of pol- linator activity, for example throughout the day (Levin & Anderson 1970, Ollerton & Lack 1992). On the other hand, convergence of loral morphology among plants of different species that lower simultaneously may be a mutually benei- cial strategy to attract pollinators (Bobisud & Neuhaus 1975, Schemske 1981), since the concentration of loral resources increases lower visitation rates (Augspurger 1980, de Jong et al. 1992, Podolsky 1992). Many sympatric species of Psychotria have similar loral traits and lower at the same time of year (Hamilton 1989, Sakai & Wright 2008). Flowers in this genus are small, have a tubular corolla, whitish colouration and are pollinated by bees, moths, butterlies and lies (Almeida & Alves 2000, Coelho & Barbosa 2004). In addition, they have a number of sexual mechanisms in common, including hermaphroditism, All rights reserved. © 2015 Botanic Garden Meise and Royal Botanical Society of Belgium – ISSN 2032-3921 REGULAR PAPER Background and aims – In highly seasonal habitats, sympatric species are often constrained to lower simultaneously. Many sympatric species of Psychotria have similar loral traits, are pollinated by bees, moths, butterlies and lies and lower at the same time of year. This genus provides an opportunity to analyse the relationships between sympatric congeneric plants and pollinators. Interactions between potentially sympatric Psychotria species and their pollinators were surveyed to assess the occurrence of sharing, specialisation, or generalisation of pollinators and plants in the system. Methods – A dataset compiled from studies of pollination biology of this genus was used to investigate aspects of interactions with shared pollinators and lowering overlap. These data were used to draw a bipartite graph and analyse the interaction network and degree of niche overlap. Key results – In total, the dataset included eight species of potentially co-occurring Psychotria species, which interacted with 24 species of pollinators. The most generalised plant in the network was Psychotria trichophoroides. The pollinators with the highest number of links, and therefore the most important for the network, belonged to orders Hymenoptera and Lepidoptera. Pollinators were shared among Psychotria species, thus pollination niches did overlap (θ = 0.20, P random ≥ observed = 0.04), and plants of this genus depended on pollinators that were generalists among them. Conclusion – The peak of overlap in lowering phenology, when all of the species may potentially co- lower, coincided with the Cerrado rainy season. Since all Psychotria species occurred in sympatry, overlapped in lowering phenology, and had asymmetric interactions with loral visitors, it is possible that pollination facilitation is present in this system. Key words – Brazilian savannah, loral phenology, network biology, niche overlap, pollination, sympatry.