Interaction between ants and fruits of Guapira opposita (Nyctaginaceae) in a Brazilian sandy plain rainforest: ant effects on seeds and seedlings

Abstract

This study examines the dispersal system of Guapira opposita in a tropical sandy rainforest in southeast Brazil. Guapira trees produce small fruits with a high protein content (28.4%) and low lipid content (0.3%), and the plant is primarily dispersed by birds. Mature fruits of G. opposita can fall spontaneously with the pulp intact, or be dropped by birds with bits of pulp attached. In either case, ground-dwelling ants rapidly remove the fruits to their nest (93% after 12 h). The ponerine ants Odontomachus chelifer and Pachycondyla striata are the main seed vectors among the ants, and together account for 56% (20 of 36) of the ant-fruit interactions recorded on the forest floor. Individual workers of O. chelifer and P. striata transport single fruits to their nests. Bits of pulp are fed to larvae and worker nestmates, and intact seeds are discarded outside the nest. Germination success in Guapira is higher for cleaned seeds (pulp removed) than for seeds coated by pulp. Guapira seedlings and juveniles are more frequent close to Odontomachus nests than at sites without such nests. Soil samples from Odontomachus nests had greater penetrability, and higher concentrations of P, K, and Ca than random soil samples. Field experiments suggest that the association between G. opposita seedlings and O. chelifer nests can potentially render the plant some protection against herbivores. Results indicate that fruit displacement by ponerine ants play an important role in the biology of G. opposita seeds and seedlings in the sandy forest, and illustrate the complex nature of the dispersal ecology of tropical tree species.

Relocation of Croton sonderianus (Euphorbiaceae) seeds by Pheidole fallax Mayr (Formicidae): a case of post-dispersal seed protection by ants?

“…The predator-avoidance hypothesis has already received some support, mostly in temperate forests (Heithaus 1981, Higashi et al 1989 and sclerophyll vegetation (Hughes & Westoby 1990), while our indings represent the irst evidence from the neotropics (but see Passos & Oliveira 2004 for seedling protection by a Neotropical ant species). Furthermore, the classical evidence of predator-avoidance refers to ant-mediated removal of those seeds that eventually drop around parents, which reduces the chance of seeds being detected by predators (Heithaus 1981, Higashi et al 1989, Smith et al 1989, Ohkawara & Higashi 1994, Ohkawara et al 1997, while P. fallax services include not only seed-removal from parental spots, but mainly seed discarding/piling plus nest-mediated protection.…”

Does Atta laevigata (Smith, 1858) act as Solanum lycocarpum seed dispersers?

“…Seeds with this resource are collected and carried to the nests, where they are discarded after the removal of this structure (Passos & Oliveira, 2004). …”

“…Moreover, the dispersion of seeds can provide, for plants species, reduced parasites and predators attack sand intraspecific competition after germination (Janzen, 1970), the colonization of new habitats (Howe & Smallwood, 1982) and the influence on recruitment patterns of plant species in tropical ecosystems (Farji-Brener & Silva, 1996;Böhning-Gaese et al, 1999;Passos & Oliveira, 2002). In this matter, Moutinho et al (2003) and Passos & Oliveira (2004) emphasize the importance of ants to carry the seeds to places known as more favorable for germination, such as their nests.…”

The vascular flora and vegetation of Queimada Grande Island, São Paulo State, southeastern Brazil

“…Based on the information about the collection sites found on herbarium labels, species were assigned to one or more of the following habitat classes: forest interior, forest edges (interfaces between forests and open areas), rock outcrop vegetation, anthropogenic vegetation, and banana plantation. By consulting the literature (Ichaso 1980, Pennington et al 1981, Pennington 1990, Lorenzi 1998, Barroso et al 1999, Bovini et al 2001, Wanderley et al 2001, 2002, 2003, 2009, 2012, Mansano et al 2004, Passos & Oliveira 2004, Reis 2006, Souza & Morim 2008, Ferreira 2009, Gomes-Costa & Alves 2012, Silva-Luz et al 2012, Ferreira & Miotto 2013, Soares Neto et al 2014, specialists, and through examinations of material deposited at the RB Herbarium, the species of angiosperms were classified into four major groups according to the morphological criteria of Pijl (1982): 1) anemochoric, with diaspores adapted to wind dispersal; 2) zoochoric, with diaspores adapted to animal dispersal; 3) hydrochoric, with diaspores adapted to water dispersal; and 4) autochoric, with diaspores displaying no apparent specific adaptation to the above dispersal agents, including barochoric species (gravity dispersal) and those with explosive dispersal. By consulting the same aforementioned sources, we also determined which species are autochthonous to ombrophilous forests and/or pioneer formations (sensu IBGE 2012): beach ridge vegetation (restinga; Lacerda et al 1993) and rock outcrop vegetation (Meirelles et al 1999), of the Atlantic Forest complex in southeastern Brazil, and which species are associated with anthropically disturbed areas (ruderal species; sensu Moro et al 2012).…”

“…The tree species on QGI are mostly zoochoric, producing small fleshy fruits or arilate seeds consumed by the island's avifauna (e.g., Pineschi 1990, Lorenzi 1998, Passos & Oliveira 2004. Due to the absence of frugivorous mammals on QGI (Marques et al 2002), birds are apparently the main local dispersers of those diaspores, and several species are known to feed on the fruits of Guapira opposita, Myrsine guianensis, and Syagrus romanzoffiana, which fructify during long periods of time and represent an important food resource for the local avifauna (Montanhini 2010).…”