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Dejean, A., Grangier, J., Leroy, C., Orivel, J., & Gilbernau, M. (2008). Nest site selection and induced response in a dominant arboreal ant species. Naturwissenschaften, 95(9), 885–889.
Abstract: It is well known that arboreal ants, both territorially dominant species and plant ants (e.g., species associated with myrmecophytes or plants housing them in hollow structures), protect their host trees from defoliators. Nevertheless, the presence of an induced defense, suggested by the fact that the workers discovering a leaf wound recruit nestmates, is only known for plant ants. Based on the results from a field study, we show here (1) that colonies of Azteca chartifex, a territorially dominant, neotropical arboreal ant species, mostly selected Goupia glabra (Goupiaceae) trees in which to build their principal carton nests and (2) that plant signals induced workers to recruit nestmates, which patrol the leaves, likely providing the plant with a biotic defense. Furthermore, the number of recruited workers was clearly higher on G. glabra, their most frequently selected host tree species, than on other tree species. These results show that contrary to what was previously believed, induced responses are also found in territorially dominant arboreal ants and so are not limited to the specific associations between myrmecophytes and plant ants.
Keywords: ant-plant relationships; biotic defense; induced responses; predation
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Turcotte, M. M., Thomsen, C. J. M., Broadhead, G. T., Fine, P. V. A., Godfrey, R. M., Lamarre, G. P. A., et al. (2014). Percentage leaf herbivory across vascular plant species. Ecology, 95(3), 788.
Abstract: Herbivory is viewed as a major driver of plant evolution and the most important energy pathway from plants to higher trophic levels. Therefore, understanding patterns of herbivory on plants remains a key focus in evolution and ecology. The evolutionary impacts of leaf herbivory include altering plant fitness, local adaptation, the evolution of defenses, and the diversification of plants as well as natural enemies. Leaf herbivory also impacts ecological processes such as plant productivity, community composition, and ecosystem nutrient cycling. Understanding the impact of herbivory on these ecological and evolutionary processes requires species-specific, as opposed to community-level, measures of herbivory. In addition, species-specific data enables the use of modern comparative methods to account for phylogenetic non-independence. Although hundreds of studies have measured natural rates of leaf consumption, we are unaware of any accessible compilation of these data. We created such a data set to provide the raw data needed to test general hypotheses relating to plant?herbivore interactions and to test the influence of biotic and abiotic factors on herbivory rates across large spatial scales. A large repository will make this endeavor more efficient and robust. In total, we compiled 2641 population-level measures for either annual or daily rates of leaf herbivory across 1145 species of vascular plants collected from 189 studies. All damage measures represent natural occurrences of herbivory that span numerous angiosperm, gymnosperm, and fern species. To enable researchers to explore the causes of variation in herbivory and how these might interact, we added information about the study sites including: geolocation, climate classification, habitat descriptions (e.g., seashore, grassland, forest, agricultural fields), and plant trait information concerning growth form and duration (e.g., annual vs. perennial). We also included extensive details of the methodology used to measure leaf damage, including seasons and months of sampling, age of leaves, and the method used to estimate percentage area missing. We anticipate that these data will make it possible to test important hypotheses in the plant?herbivore literature, including the plant apparency hypothesis, the latitudinal-herbivory defense hypothesis, the resource availability hypothesis, and the macroevolutionary escalation of defense hypothesis.
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Jaouen, G., Almeras, T., Coutand, C., & Fournier, M. (2007). How to determine sapling buckling risk with only a few measurements. Am. J. Bot., 94(10), 1583–1593.
Abstract: Tree buckling risk (actual height/critical buckling height) is an important biomechanical trait of plant growth strategies, and one that contributes to species coexistence. To estimate the diversity of this trait among wide samples, a method that minimizes damage to the plants is necessary. On the basis of the rarely used, complete version of Greenhill's model (1881, Proceedings of the Cambridge Philosophical Society 4(2): 65-73), we precisely measured all the necessary parameters on a sample of 236 saplings of 16 species. Then, using sensitivity (variance) analysis, regressions between successive models for risk factors and species ranks and the use of these models on samples of self- and nonself-supporting saplings, we tested different degrees of simplification up to the most simple and widely used formula that assumes that the tree is a cylindrical homogeneous pole. The size factor had the greatest effect on buckling risk, followed by the form factor and the modulus of elasticity of the wood. Therefore, estimates of buckling risk must consider not only the wood properties but especially the form factor. Finally, we proposed a simple but accurate method of assessing tree buckling risk that is applicable to a wide range of samples and that requires mostly nondestructive measurements.
Keywords: biomechanics; critical buckling height; French Guiana; risk factor; sapling; stem form; tropical rain forest; trunk volume
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LaPierre, L., Hespenheide, H., & Dejean, A. (2007). Wasps robbing food from ants: a frequent behavior? Naturwissenschaften, 94(12), 997–1001.
Abstract: Food robbing, or cleptobiosis, has been well documented throughout the animal kingdom. For insects, intrafamilial food robbing is known among ants, but social wasps (Vespidae; Polistinae) taking food from ants has, to the best of our knowledge, never been reported. In this paper, we present two cases involving social wasps robbing food from ants associated with myrmecophytes. (1) Polybioides tabida F. (Ropalidiini) rob pieces of prey from Tetraponera aethiops Smith (Formicidae; Pseudomyrmecinae) specifically associated with Barteria fistulosa Mast. (Passifloraceae). (2) Charterginus spp. (Epiponini) rob food bodies from myrmecophytic Cecropia (Cecropiaceae) exploited by their Azteca mutualists (Formicidae; Dolichoderinae) or by opportunistic ants (that also attack cleptobiotic wasps). We note here that wasps gather food bodies (1) when ants are not yet active; (2) when ants are active, but avoiding any contact with them by flying off when attacked; and (3) through the coordinated efforts of two to five wasps, wherein one of them prevents the ants from leaving their nest, while the other wasps freely gather the food bodies. We suggest that these interactions are more common than previously thought.
Keywords: cleptobiosis; social wasps; charterginus; polybioides; plant-ants
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Baraloto, C., & Forget, P. M. (2007). Seed size, seedling morphology, and response to deep shade and damage in neotropical rain forest trees. Am. J. Bot., 94(6), 901–911.
Abstract: To investigate the existence of coordinated sets of seedling traits adapted to contrasting establishment conditions, we examined evolutionary convergence in seedling traits for 299 French Guianan woody plant species and the stress response in a shadehouse of species representing seed size gradients within five major cotyledon morphology types. The French Guianan woody plant community has larger seeds than other tropical forest communities and the largest proportion of hypogeal cotyledon type (59.2%) reported for tropical forests. Yet the community includes many species with intermediate size seeds that produce seedlings with different cotyledonal morphologies. A split-plot factorial design with two light levels (0.8% and 16.1% PAR) and four damage treatments (control, seed damage, leaf damage, stem damage) was used in the shadehouse experiment. Although larger-seeded species had higher survival and slower growth, these patterns were better explained by cotyledon type than by seed mass. Even larger-seeded species with foliar cotyledons grew faster than species with reserve-type cotyledons, and survival after stem grazing was five times higher in seedlings with hypogeal cotyledons than with epigeal cotyledons. Thus, to predict seedling performance using seed size, seedling morphology must also be considered.
Keywords: cotyledons; French Guiana; functional morphology; herbivory; life history; phylogeny; regeneration strategy; shade tolerance
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Delabie, J. H. C., Groc, S., & Dejean, A. (2011). The tramp ant technomyrmex vitiensis (Hymenoptera: Formicidae: Dolichoderinae) on South America. Fla. Entomol., 94(3), 688–689.
Abstract: Technomyrmex vitiensis is a tramp ant that has spread through many parts of the Old World tropics via human commerce. This species has been previously reported only once in the New World, from San Francisco, California. Here, we report the first records of T. vitiensis in South America, from two sites deep in the forest of French Guiana. It is not clear how these ants were transported to such remote sites, 100 km inland. Copyright © 2011 BioOne All rights reserved.
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Fine, P. V. A., Metz, M. R., Lokvam, J., Mesones, I., Zuniga, J. M. A., Lamarre, G. P. A., et al. (2013). Insect herbivores, chemical innovation, and the evolution of habitat specialization in Amazonian trees. Ecology, 94(8), 1764–1775.
Abstract: Herbivores are often implicated in the generation of the extraordinarily diverse tropical flora. One hypothesis linking enemies to plant diversification posits that the evolution of novel defenses allows plants to escape their enemies and expand their ranges. When range expansion involves entering a new habitat type, this could accelerate defense evolution if habitats contain different assemblages of herbivores and/or divergent resource availabilities that affect plant defense allocation. We evaluated this hypothesis by investigating two sister habitat specialist ecotypes of Protium subserratum (Burseraceae), a common Amazonian tree that occurs in white-sand and terra firme forests. We collected insect herbivores feeding on the plants, assessed whether growth differences between habitats were genetically based using a reciprocal transplant experiment, and sampled multiple populations of both lineages for defense chemistry. Protium subserratum plants were attacked mainly by chrysomelid beetles and cicadellid hemipterans. Assemblages of insect herbivores were dissimilar between populations of ecotypes from different habitats, as well as from the same habitat 100 km distant. Populations from terra firme habitats grew significantly faster than white-sand populations; they were taller, produced more leaf area, and had more chlorophyll. White-sand populations expressed more dry mass of secondary compounds and accumulated more flavone glycosides and oxidized terpenes, whereas terra firme populations produced a coumaroylquinic acid that was absent from white-sand populations. We interpret these results as strong evidence that herbivores and resource availability select for divergent types and amounts of defense investment in white-sand and terra firme lineages of Protium subserratum, which may contribute to habitat-mediated speciation in these trees. © 2013 by the Ecological Society of America.
Keywords: Amazonia; Ecological speciation; Ecotypes; Herbivory; Natural enemies; Plant defense; Protium subserratum; Terra firme forests; Tropical rain forests; White-sand forests
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Amusant, N., Nigg, M., Thibaut, B., & Beauchene, J. (2014). Diversity of decay resistance strategies of durable tropical woods species: Bocoa prouacencsis Aublet, Vouacapoua americana Aublet, Inga alba (Sw.) Wild. Int. Biodeterior. Biodegrad., 94, 103–108.
Abstract: The study of decay resistance in wood is of interest for wood end-users but also for the global carbon balance since wood biodegradation is a key driver of forest ecosystem functioning through its impacts on carbon and nutrient cycling. We studied the density and wood extractive contents in order to understand decay resistance against soil microflora after 90 days exposure of sapwood and heartwood from three Neotropical wood species known for their decay resistance: Bocoa prouacensis, Vouacapoua americana, Inga alba. Decay resistance was correlated with density more than wood extractive content. The results highlighted different decay resistance strategies. In B. prouacensis, both sapwood and heartwood were highly resistant due to the high density and high content of antifungal wood extractives. In V. americana heartwood, decay resistance was due to the high synergistic-acting wood extractive content. Conversely, with the least dense wood species I. alba, we found that decay resistance was due to the antifungal wood extractives synthesized early in the sapwood. In conclusion, we showed that the three wood species with the same level of heartwood decay resistance performance had different decay resistance strategies according to the anatomic and defensive wood traits.
Keywords: Decay resistance; Density; Heartwood; Sapwood; Tropical wood; Wood extractive; Decay resistance; Heartwood; Sapwood; Tropical wood; Wood extractives; Density (specific gravity); Andira aubletii; Bocoa; Inga
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Baraloto, C., Forget, P. M., & Goldberg, D. E. (2005). Seed mass, seedling size and neotropical tree seedling establishment. J. Ecol., 93(6), 1156–1166.
Abstract: 1 We examined among- and within-species effects of seed mass for seedling establishment from seed to 5 years of age in a field experiment at Paracou, French Guiana. 2 Six seeds of each of eight species were weighed and planted into each of 120 plots (1 m(2)) throughout closed-canopy forest along 12 100-m transects in 1998. 3 We described the microhabitat of each planting site using principal components derived from measurements of light availability, soil moisture, carbon and nitrogen content, and soil phosphorus availability. Although both survival and relative growth rate (RGR) increased with increasing light availability, no other microhabitat variable significantly affected seedling performance. Nor did the magnitude of microhabitat effects on survival or RGR differ among species. 4 Larger-seeded species were more likely to survive from germination to 1 year as well as from 1 to 5 years of age. RGR for seedling height during the first year post-germination was not related to seed mass, but smaller-seeded species did grow slightly faster thereafter. Path analyses revealed that correlations between seed mass and performance were explained in part because larger seeds produced larger initial seedlings, which tended to survive better but grow more slowly. 5 We also analysed within-species effects of seed mass for the larger-seeded Eperua grandiflora and Vouacapoua americana (both Caesalpiniaceae). Larger seeds produced larger seedlings in both species, but larger seeds survived better only for Eperua. Larger seedlings grew more slowly in both species, but did not offset the early (Eperua) and later (Vouacapoua) positive direct effects of seed mass on RGR that may represent contrasting strategies for reserve deployment. 6 Our results demonstrate that seed size influences performance within and among species in part because of indirect effects of initial seedling size. However, we suggest that traits tightly correlated with seed mass at the species level, such as specific leaf area, leaf longevity and photosynthetic capacity, may also contribute to interspecific performance differences.
Keywords: French Guiana; life-history trade-offs; microhabitat; path analysis; regeneration strategy; relative growth rate; seedling survival; shade tolerance
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Dejean, A., Djieto-Lordon, C., & Orivel, J. (2008). The plant ant Tetraponera aethiops (Pseudomyrmecinae) protects its host myrmecophyte Barteria fistulosa (Passifloraceae) through aggressiveness and predation. Biol. J. Linnean Soc., 93(1), 63–69.
Abstract: Plant ants generally provide their host myrmecophytes (i.e. plants that shelter a limited number of ant species in hollow structures) protection from defoliating insects, but the exact nature of this protection is poorly known. It was with this in mind that we studied the association between Tetraponera aethiops F. Smith (Pseudomyrmecinae) and its specific host myrmecophyte Barteria fistulosa Mast. (Passifloraceae). Workers bore entrances into the horizontal hollow branches (domatia) of their host B. fistulosa, near the base of the petiole of the alternate horizontal leaves. They then ambush intruders from the domatia, close to these entrances. After perceiving the vibrations caused when an insect lands on a leaf, they rush to it and sting and generally spreadeagle the insect (only small caterpillars are mastered by single workers). Among the insects likely to defoliate B. fistulosa, adult leaf beetles and large katydids were taken as prey and cut up; single workers then retrieved some pieces, whereas other workers imbibed the prey's haemolymph. Other insects known to defoliate this plant, if unable to escape, were killed and discarded. Small Acrea zetes L. caterpillars were stung and then discarded by single workers; whereas locusts of different sizes were mastered by groups of workers that stung and spreadeagled them before discarding them (although a part of their haemolymph was imbibed). More workers were involved and more time was necessary to master insects taken as prey than those attacked and discarded. Consequently, the protection T. aethiops workers provide to their host B. fistulosa from defoliating insects results from predation, but more often from a type of aggressiveness wherein insects are killed and then discarded. (c) 2008 The Linnean Society of London.
Keywords: ants; plant protection; territorial aggressiveness
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