Extrafloral nectar fuels ant life in deserts

Interactions mediated by extrafloral nectary (EFN)-bearing plants that reward ants with a sweet liquid secretion are well documented in temperate and tropical habitats. However, their distribution and abundance in deserts are poorly known. In this study, we test the predictions that biotic interactions between EFN plants and ants are abundant and common also in arid communities and that EFNs are only functional when new vegetative and reproductive structures are developing. In a seasonal desert of northwestern Argentina, we surveyed the richness and phenology of EFN plants and their associated ants and examined the patterns in ant–plant interaction networks. We found that 25 ant species and 11 EFN-bearing plant species were linked together through 96 pairs of associations. Plants bearing EFNs were abundant, representing ca. 19 % of the species encountered in transects and 24 % of the plant cover. Most ant species sampled (ca. 77 %) fed on EF nectar. Interactions showed a marked seasonal pattern: EFN secretion was directly related to plant phenology and correlated with the time of highest ant ground activity. Our results reveal that EFN-mediated interactions are ecologically relevant components of deserts, and that EFN-bearing plants are crucial for the survival of desert ant communities.Fil: Aranda Rickert, Adriana Marina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Regional de Investigaciones Cientificas y Transferencia Tecnológica de Anillaco; ArgentinaFil: Diez, Patricia Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Regional de Investigaciones Cientificas y Transferencia Tecnológica de Anillaco; ArgentinaFil: Marazzi, Brigitte. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Nordeste. Instituto de Botánica del Nordeste (i); Argentin

Ant Communities along a Gradient of Plant Succession in Mexican Tropical Coastal Dunes

Most of Mexican coastal dunes from the Gulf of Mexico have been severely disturbed by human activities. In the state of Veracruz, the La Mancha Reserve is a very well preserved coastal community of sand dunes, where plant successional gradients are determined by topography. In this study we assessed species richness, diversity and faunal composition of ant assemblages in four plant physiognomies along a gradient of plant succession: grassland, shrub, deciduous forest and subdeciduous forest. Using standardized and non-standardized sampling methods we found a total of 121 ant species distributed in 41 genera and seven subfamilies. Grassland was the poorest site (21 species) and subdeciduous forest the richest (102 species). Seven species, with records in ≥10% of samples, accounted 40.8% of total species occurrences: Solenopsis molesta (21.6%), S. geminata (19.5%), Azteca velox (14%), Brachymyrmex sp. 1LM (11.7%), Dorymyrmex bicolor (11.2%), Camponotus planatus (11%) and Pheidole susannae (10.7%). Faunal composition between sites was highly different. Nearly 40% of all species were found in a single site. In all sites but grassland we found high abundances of several species typical of disturbed ecosystems, indicating high levels of disturbance. A species similarity analysis clustered forests in one group and grassland and shrub in another, both groups separated by more than 60% of dissimilarity. Similarity of ant assemblages suggests that deciduous and subdeciduous forests represent advanced stages of two different and independent successional paths

Ants Visit Nectaries Of Epidendrum Denticulatum (orchidaceae) In A Brazilian Rainforest: Effects On Herbivory And Pollination.

Epidendrum denticulatum (Orchidaceae) produces nectar on the petioles of buds, flowers, and fruits (extrafloral nectaries) but no nectar is found on its flowers, and it is probably a deceptive species. In the Brazilian Atlantic rainforest, some aspects of both the ecology and behavior of Camponotus sericeiventris (Formicinae) and Ectatomma tuberculatum (Ponerinae), two ant species foraging on E. denticulatum extrafloral nectaries, were investigated. Both experiments, using termites as baits and field observations, suggest that these ant species are able to prevent reproductive organ herbivory, without affecting pollinator behaviour. Since a low fruit set is often cited as a characteristic of the family, especially for deceptive species, ants attracted to orchid inflorescences protect reproductive structures and increase the probability of pollination success. Epidendrum denticulatum flowers were visited and probably pollinated by Heliconius erato (Nymphalidae) and Euphyes leptosema (Hesperiidae).63455155

Topological structure of plant-bee networks in four Mexican environments

We analyzed the topological structure (e.g., links per species, connectance, core-periphery analyses, specialization, nestedness, modularity) of plant-bee interactions of four areas in Mexico. We used qualitative data (binary networks). Mexico exhibits a complex geography and community variation that can affect bee networks. Network architecture is variable within large spatial scales, thus our results should vary according to site characteristics (La Mancha and Totula in Veracruz, Carrillo Puerto in Quintana Roo, and the Tehuacan-Cuicatlan valley, in Puebla), type of vegetation, endemism, altitude, size of area sampled. Network topology varied among sites, and the presence of nested or modular patterns was analyzed for robustness to simulated species extinctions. The lowest species richness was recorded for the Quintana Roo site (15 plant, 25 bee species), and the highest for the Tehuacan-Cuicatlan valley site (88 plant, 231 bee species). There was a tendency to have more connected networks when species richness was low and networks with greater species richness had a higher number of interactions. The distribution of interactions differed between environments but not due to network size and all were significantly nested. The robustness to cumulative extinctions showed a different pattern at each site; the most robust network was at Carrillo Puerto, which also was the site with less species. Sites with more endemic species (e.g. Tehuacan) had more specialized interactions, and were more susceptible to extinction

Understanding the Complex Structure of a Plant-Floral Visitor Network from Different Perspectives in Coastal Veracruz, Mexico

Our premise was to understand the basic structure of the flower-flower visitor community at La Mancha in Veracruz, Mexico. We used network analyses to study the structure of this community. In particular, to analyze, (1) if flower color and shape (“as a limited portion of the traditional floral syndromes definition”) were linked to the arrival of certain floral visitors, (2) if visits to flowers were generalist, specific and/or modular; and (3) which plant species, if any, in the core of the network could affect the stability of floral visitors. In order to analyze the organization of the plant-floral visitor community, we prepared network graphics using Pajek, nestedness (as NODF) with Aninhado, and modularity with the SA algorithm. The network obtained was nested suggesting that generalist species (with the most associations) were interacting with specialists (with fewer associations). Furthermore, floral visitors (Hymenoptera, Diptera, Lepidoptera and Trochiilidae) did not exhibit a particular preference for a specific flower color or shape, each pollinator group visited most flowers/colors/shapes considered. The same was similar for all 14 resulting modules. As in other studies, we suggest that pollination leans to generalization rather than to specialization. We suggest that maybe seasonality/food resource could be the factors to analyze as the next step in floral visits which may be the answer to modularity in this seasonal ecosystem

Mammals of Cabo Blanco: History, diversity, and conservation after 45 years of regrowth of a Costa Rican dry forest

Reserva Natural Absoluta Cabo Blanco, a strongly seasonal deciduous forest located at the southernmost tip of northwestern Costa Rica's Nicoya Peninsula, was established in 1963 and is the country's oldest nationally protected reserve. The peninsula has been occupied for millennia and is a heavily impacted landscape, and, unfortunately, its biotic diversity is among the most poorly studied in Central America. As part of multiyear studies of the flora and fauna of the region, we assess the changes in vegetation and the terrestrial mammal community from earlier times to the present day. Through historical records, interviews with long-term residents of the area, and our studies over the past decade, we document changes in forest cover, settlement, and land use, and assess the changes in species diversity and in mammal species’ abundance. We then discuss the ecology of the mammal species on the peninsula, emphasizing the role that humans have played in influencing population levels. After 45 years of protection, the forest structure of the 3100 ha reserve differs markedly from that observed in the early 20th Century and it is quite heterogeneous. Species diversity of both the native vegetation and the mammals is substantial in the regenerating forest. The known mammal fauna included at least 37 species of non-flying mammals and 39 species of bats. Six species (Geoffroy's Spider Monkey, Giant Anteater, White-lipped Peccary, Central American Red Brocket Deer, Baird's Tapir, and Jaguar) have been extirpated from the reserve. Poaching of game species continues and will be difficult to eliminate completely. Nevertheless, with regenerating habitats, coupled with protection of wildlife, reestablishment of the reserve's native species has been dramatic both in terms of species diversity and abundance. The reserve is not in a defaunated condition. Many mammalian frugivores, seed dispersers, and/or seed predators are common and most top mammalian predators are present. We present several testable hypotheses regarding the significance of this mammalian community in the context of other Neotropical forest mammal and plant communities. Rapid expansion of tourism in this region has the potential to affect the reserve adversely. In recent years, the reserve has served as an important site for teaching tropical biology courses. Small reserves, such as Cabo Blanco, even if not connected to larger protected areas through corridors, provide critical habitat for native flora and fauna, a source of genetic stock, and valuable regional teaching and research sites

Temporal Variation In The Abundance And Richness Of Foliage-dwelling Ants Mediated By Extrafloral Nectar

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Plants bearing extrafloral nectaries (EFNs) are common in the Brazilian cerrado savanna, where climatic conditions having marked seasonality influence arboreal ant fauna organization. These ant-plant interactions have rarely been studied at community level. Here, we tested whether: 1) EFN-bearing plants are more visited by ants than EFN-lacking plants; 2) ant visitation is higher in the rainy season than in dry season; 3) plants producing young leaves are more visited than those lacking young leaves in the rainy season; 4) during the dry season, plants with old leaves and flowers are more visited than plants with young leaves and bare of leaves or flowers; 5) the composition of visiting ant fauna differs between plants with and without EFNs. Field work was done in a cerrado reserve near Uberlandia, MG State, Brazil, along ten transects (total area 3,000 m(2)), in the rainy (October-January) and dry seasons (April-July) of 2010-2011. Plants (72 species; 762 individuals) were checked three times per season for ant presence. Results showed that 21 species (29%) and 266 individuals (35%) possessed EFNs. These plants attracted 38 ant species (36 in rainy, 26 in dry season). In the rainy season, plants with EFNs had higher ant abundance/richness than plants without EFNs, but in the dry season, EFN presence did not influence ant visitation. Plant phenology affected ant richness and abundance in different ways: plants with young leaves possessed higher ant richness in the rainy season, but in the dry season ant abundance was higher on plants possessing old leaves or flowers. The species composition of plant-associated ant communities, however, did not differ between plants with and without EFNs in either season. These findings suggest that the effect of EFN presence on a community of plant-visiting ants is context dependent, being conditioned to seasonal variation.117Conselho Nacional de Desenvolvimento Cientifico e TecnologicoFundacao de Amparo a Pesquisa do Estado de Sao PauloConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Flower-mediated plant-butterfly interactions in an heterogeneous tropical coastal ecosystem

Background Interspecific interactions play an important role in determining species richness and persistence in a given locality. However at some sites, the studies, especially for interaction networks on adult butterflies are scarce. The present study aimed the following objectives: (1) determine butterfly species richness and diversity that visit flowering plants, (2) compare species richness and diversity in butterfly-plant interactions among six different vegetation types and (3) analyze the structure of butterfly-flowering plant interaction networks mediated by flowers. Methods The study was developed in six vegetation types within the natural reserve of La Mancha, located in Veracruz, Mexico. In each vegetation type, we recorded the frequency of flower visits by butterflies monthly in round plots (of radius 5 m) for 12 months. We calculated Shannon diversity for butterfly species and diversity of interactions per vegetation type. We determined the classic Jaccard similarity index among vegetation types and estimated parameters at network and species-level. Results We found 123 species of butterflies belonging to 11 families and 87 genera. The highest number of species belonged to Hesperiidae (46 species), followed by Nymphalidae (28) and Pieridae (14). The highest butterfly diversity and interaction diversity was observed in pioneer dune vegetation (PDV), coastal dune scrub (CDS) and tropical deciduous flooding forest and wetland (TDF-W). The same order of vegetation types was found for interaction diversity. Highest species similarity was found between PDV-CDS and PDV-TDF. The butterfly-plant interaction network showed a nested structure with one module. The species Ascia monuste, Euptoieta hegesia and Leptotes cassius were the most generalist in the network, while Horama oedippus, E. hegesia, and L. cassius were the species with highest dependencies per plant species. Discussion Our study is important because it constitutes a pioneer study of butterfly-plant interactions in this protected area, at least for adult butterflies; it shows the diversity of interactions among flowering plants and butterflies. Our research constitutes the first approach (at a community level) to explore the functional role of pollination services that butterflies provide to plant communities. We highlighted that open areas show a higher diversity and these areas shared a higher number of species that shaded sites. In the interaction networks parameters, our results highlighted the higher dependence of butterflies by the flowers on which they feed than vice versa. In conclusion, the plant species (as a feeding resource) seem to limit the presence of butterfly species. Thus, this protected area is highly relevant for Lepidoptera diversity and the interaction between these insects and flowering plants. We suggest that studying plant and butterfly diversity in tropical habitats will provide insight into their interspecific interactions and community structure

Caracterización morfológica de los nectarios extraflorales en especies vegetales de la Amazonia brasileña

Background and Aims: Extrafloral nectaries (EFNs) are secretory glands of an aqueous solution composed mainly of sugars, amino acids and lipids, frequently used as food resource by ants, which tend to protect their host plants against herbivorous insects. Although the Amazon forest is recognized worldwide for its high plant diversity, few studies have been carried out in the region that characterize the different morphotypes of EFNs. In this context, our main aim was to perform a brief morphological description of EFNs in the Brazilian Amazonian rainforest. Methods: We established a plot of 6250 m2 in ten forest fragments situated in the state of Acre, Brazilian Amazon. In these plots, we performed intensive field surveys to locate EFN-bearing plant species. Subsequently, we used scanning electron microscopy images to morphologically characterize the EFNs. The morphological descriptions included information about the life form of EFN-bearing plant species, morphotypes of EFNs and their location in different plant structures. Key results: We morphologically characterized 67 EFN-bearing plant species, distributed in 28 genera and 19 families. The botanical families with the highest taxonomic representativeness were Fabaceae, Bignoniaceae and Malpighiaceae. Lianas were the life form with the largest number of EFN-bearing plant species, while elevated EFNs were the most frequent morphotype. Conclusions: The high frequency of elevated EFNs evidences the importance of the ant defense system against herbivory in these Brazilian Amazonian forests, since it has been documented in others works that this morphotype secretes a larger nectar volume, which is an advantage in relation to the attraction potential. Finally, our results indicate the existence of a high diversity of EFN-bearing plant species in this region of the Brazilian Amazon, and an important morphological diversity of associated extrafloral nectaries.Antecedentes y Objetivos: Los nectarios extraflorales (NEFs) son glándulas secretoras de una solución acuosa compuesta principalmente de azúcares, aminoácidos y lípidos, frecuentemente utilizada como recurso alimenticio por hormigas, que tienden a proteger sus plantas hospederas contra insectos herbívoros. Aunque la selva amazónica es reconocida mundialmente por su alta diversidad de plantas, pocos estudios se han realizado en la región que caracterizan las diferentes formas de NEFs. En este contexto, nuestro principal objetivo fue realizar una descripción morfológica de los NEFs en una selva amazónica brasileña. Métodos: Establecimos una parcela de 6250 m2 en diez fragmentos de bosque situados en el estado de Acre, Amazonía Brasileña. En estas parcelas, realizamos recorridos de campo intensivos para localizar especies de plantas portadoras de NEFs. Posteriormente, utilizamos imágenes de microscopía electrónica de barrido para caracterizar morfológicamente los NEFs. Las descripciones morfológicas incluyeron información sobre la forma de vida de las especies de plantas portadoras de NEFs, morfotipos de NEFs y su ubicación en las diferentes estructuras de la planta. Resultados clave: Caracterizamos morfológicamente 67 especies de plantas portadoras de NEFs, distribuidas en 28 géneros y 19 familias. Las familias botánicas con mayor representatividad taxonómica fueron Fabaceae, Bignoniaceae y Malpighiaceae. Las lianas fueron la forma de vida que presentó más especies de plantas portadoras de NEFs, mientras que los NEFs de tipo elevado fueron los más frecuentes. Conclusiones: La mayor frecuencia de NEFs de tipo elevado evidencia la importancia del sistema de defensa de hormigas contra la herbivoria en esta selva amazónica brasileña, ya que se ha documentado en otros trabajos que este morfotipo secreta un mayor volumen de néctar, lo que es una ventaja en relación con el potencial de atracción. Finalmente, nuestros hallazgos indican la existencia de una alta diversidad de especies de plantas portadoras de NEFs en esta región de Amazonía Brasileña, y una importante diversidad morfológica de nectarios extraflorales asociados

EFECTO DE UNA FUENTE DE ALIMENTO EXPERIMENTAL SOBRE UNA ASOCIACIÓN HORMIGA-HEMIPTERO

In order to assess if ants attracted to honeydew-producing Hemiptera switched food sources when offered an additional, considerably rich and abundant food source, we studied the interaction between the plant Solanum lycocarpum (Solanaceae), an efn-lacking shrub, the predominantly diurnal ant Camponotus crassus (Hymenoptera: Formicidae), and two species of membracids (Enchenopa spp.; Homoptera: Membracidae). The study was done during September of 1999 at the Reserva Ecológica of IBGE (ca. 35 km S of Brasilia-DF, Brasil). The results show that ants were attracted both to the experimental food source and to the membracids. Moreover, the mean number of ants visiting the experimental nectary was significantly higher than those visiting the membracids. However, the membracids were never left unattended, which suggests that ants, even though presented with an abundant and rich food source, do not abandon other sources. The latter can be explained due to an increment in the honeydew production rate by the membracids, thus the attention levels of ants does not vary Another possibility is the fidelity of worker ants to a food source and its location. To show that ants switch food sources based on quality and/or quantity, and not merely based of their presence and/or absence, requires future research, both for plants with and without extrafloral nectaries.Estudiamos la asociación entre el arbusto sin nectarios extraflorales (NEF) Solanum lycocarpum (Solanaceae), la hormiga Camponotus crassus (Hymenoptera: Formicidae) y dos especies de membrácidos (Enchenopa spp., Hemiptera: Membracidae) productores de ambrosía, para determinar si las hormigas abandonarían a los membrácidos al ofrecerles experimentalmente una fuente de alimento considerablemente rica y abundante. El estudio se realizó en septiembre de 1999 en la Reserva Ecológica del Instituto Brasileiro de Geografía y Estadística (IBGE) (ca. 35 km al sur de Brasilia-DF, Brasil). Los resultados muestran que las hormigas fueron atraídas tanto al nectario experimental como a los membrácidos. Más aún, el número promedio de hormigas visitando a los nectarios experimentales fue significativamente mayor que el de las que visitaron a los membrácidos. Sin embargo, los membrácidos nunca fueron abandonados, lo que sugiere que las hormigas, a pesar de explotar una fuente abundante de alimento, no abandonan otras fuentes. Lo anterior puede explicarse por un incremento en la tasa de producción de ambrosía por los membrácidos, por lo que los niveles de atención de las hormigas hacia ellos no varía aún en la presencia de una fuente alternativa de alimento. Otra posibilidad puede ser la lealtad de las obreras por un recurso y su ubicación; algunos individuos retornan siempre a un sitio con una fuente de alimento. El poder demostrar que las hormigas cambian de recurso alimenticio basadas en cantidad y/o calidad, y no solamente basadas en la presencia o ausencia de los mismos, requiere de investigaciones futuras, tanto para plantas con como sin NEF