Incidence of Extrafloral Nectaries and Their Relationship with Growth and Survival of Lowland Tropical Rain Forest Trees

Abstract

Mutualistic relationships between organisms have long captivated biologists, and extrafloral nectaries, or nectar-producing glands, found on many plants are a good example. The nectar produced from these glands provides food for ants, which may defend the plant from potential herbivores in turn. However, relatively little is known about their impact on the long-term growth and survival of plants that produce them. To better understand the ecological significance of extrafloral nectaries, we examined their incidence on lowland tropical rain forest trees in Yasun ı National Park in Amazonian Ecuador, and collated data from two other tropical lowland forest sites (Barro Colorado Island, Panam a and Pasoh Forest Reserve, Malaysia). At Yasun ı, extrafloral nectaries were found on 137 of 1123 species censused (12.2%), widely distributed among different angiosperm families. This rate of incidence is high but consistent with other tropical locations. Furthermore, this study adds 18 new genera and two new families (Urticaceae and Caricaceae) to the list of taxa exhibiting extrafloral nectaries. Using demographic data from long-term forest dynamics plots at each site, we compared the growth and mortality rates of species with extrafloral nectaries to those without. After controlling for phylogeny, no general relationship between extrafloral nectary presence and demographic rates could be detected, suggesting little demographic signal from any community-wide ecological effects.Abstract in Spanish is available with online material.

The Influence of Tree Diversity on Natural Enemies—a Review of the “Enemies” Hypothesis in Forests

“…Thus, the presence of extrafloral nectary trees may increase ant density, with plants benefiting through reduced damage and increased reproduction [59]. While trees with extrafloral nectaries do not generally grow faster or have higher survival than trees without [110], extrafloral nectar can facilitate top-down control on co-occurring trees lacking this defense trait [111], which may facilitate community-level tree growth [112]. Nectar is generally an important food supplement for nonant predators and parasitoids [113,114], making it likely that the presence of extrafloral nectar trees interferes with "enemies" hypothesis effects.…”

Dear neighbor: Trees with extrafloral nectaries facilitate defense and growth of adjacent undefended trees

“…EFN plants usually engage in food‐for‐protection mutualisms with ants and other predatory arthropods, exchanging nectar for protection against herbivores and pathogens (Bentley, 1977; Heil, 2015). EFN‐bearing plants usually benefit from reduced damage and higher reproduction (Trager et al, 2010) but do not generally grow faster or have higher survival than plants without EFN (Muehleisen et al, 2016).…”

Nutrient transfer supports a beneficial relationship between the canopy ant,Azteca trigona, and its host tree

“…extrafloral nectaries, large dbh). Species hosting extrafloral nectaries were classified in accordance with the database provided by Muehleisen (2013).…”