The study of assembly of ecological communities provides information about where organisms are located, when, and why. This knowledge is critical for understanding maintenance of biodiversity and how the distribution of organisms will respond to environmental change. Most studies of drivers of community assembly of tropical organisms are limited to observation of static assemblages because manipulations are impractical or impossible. Further, community assembly studies are generally undertaken in natural ecosystems despite that agricultural areas cover large fractions of land area. This project takes advantage of an easily manipulated arboreal twig-nesting ant community in a coffee agroecosystem to experimentally explore multiple factors influencing community assembly. The main objectives are to examine twig-nesting ant life history traits (e.g. colony size, reproductive and dispersal capabilities, and competitive ability), responses of ant communities to agricultural disturbance, and impacts of environmental change and competition with other ants on nest colonization and colony survival. The work will be conducted in a coffee farm in southern Mexico and will involve surveys and manipulative studies. Specifically, surveys will take place in a field that recently experienced drastic agricultural disturbance (forest canopy cutting), and in an uncut control field. Two large-scale experiments with nest additions and reciprocal transplants will directly compare the influence of multiple factors on colony recruitment and survival.
Understanding the factors driving community assembly of ants in coffee agroecosystems will contribute to coffee management and educational goals. Coffee agroecosystems are extremely important from conservation and economic standpoints. Shaded coffee farms provide habitat to threatened tropical diversity and coffee crops provide livelihood to millions. Ants are abundant, important predators that influence resources in tropical agroecosystems. Twig-nesting ants are biological control agents of coffee pests, thus elucidating factors contributing to ant assembly will inform farmer management decisions and contribute to sustainable agricultural production. The project will advance education in independent research for undergraduate and graduate students, and will focus on increasing diversity and representation of women ecologists. The ants collected will enhance museum collections, train students in insect taxonomy and identification, and to contribute to field and online guides for the ants of Mexico.
Overview: The study of assembly of ecological communities provides information about where organisms are located, when, and why. This knowledge is critical for understanding maintenance of biodiversity and how the distribution of organisms will respond to environmental change. Most studies of drivers of community assembly of tropical organisms are limited to observation of static assemblages because manipulations are impractical or impossible. Further, community assembly studies are generally undertaken in natural ecosystems despite that agricultural areas cover large fractions of land area. This project took advantage of an easily manipulated arboreal twig-nesting ant community in a coffee agroecosystem to experimentally explore multiple factors influencing community assembly. The main objectives of the project were to examine twig-nesting ant life history traits (e.g. colony size, reproductive and dispersal capabilities, and competitive ability), responses of ant communities to agricultural disturbance (pruning of canopy trees that shade the coffee shrubs), and impacts of environmental change and competition with other ants on nest colonization and colony survival. The work took place in a coffee farm in southern Mexico and involved surveys and manipulative studies. Specifically, surveys took place in a field that continually experienced drastic agricultural disturbance (canopy tree cutting), and in an undisturbed control area. Two large-scale experiments using artificial nests and nest relocation directly compared the influence of multiple factors on colony recruitment and survival. Results and intellectual merit: We found ~40 species of ants that inhabit coffee twigs and artificial nests placed in coffee farms, and that several different factors influence the number of species and the identities of the ant species encountered. We documented that life history characteristics (e.g. reproductive capability, competitive ability) of twig-nesting ant species strongly differ from one another. Based on our dispersal data, it is more likely that twig-nesting ants colonize new nests by expanding current colonies, rather than by a new queen founding a colony after a nuptial flight. We found that nest colonization is influenced by environmental conditions such as the density of the shade canopy over the coffee plants, and the variety of different sizes of twigs available to the ants and that competition from other ant species can deter nest colonization of available twigs by twig-nesting ants. We also documented that management of the canopy trees within coffee farms (e.g. tree cutting and pruning) strongly affect the identities of ant species that are found in a farm. We have learned basic life history information about a community of ants for which little previous knowledge was available, and have documented the general importance of competitive interactions and environmental characteristics for this community. Overall, our results provide new information detailing that both environmental factors and competition from other species limit the colonization of nests, and the survival of colonies. Our results make general contributions to fields of community ecology and entomology. Broader impacts of the research: Coffee agroecosystems are extremely important from conservation and economic standpoints. Shaded coffee farms provide habitat to threatened tropical diversity and coffee production involves the participation of millions of farm families. Ants are abundant, important predators that influence resources in tropical agroecosystems. Twig-nesting ants are biological control agents of coffee pests, thus elucidating factors contributing to ant assembly have strong implications for farmer management decisions and can contribute to sustainable agricultural production. Thus, the project provided an understanding of the factors that govern twig-nesting ant assembly, and also generated knowledge that may inform management decisions regarding pest management. Understanding alternatives to chemical pest control (i.e., biological pest control by ants) may limit the farmers’ necessity for using pesticides harmful to ecological and human health. The research also contributes to our knowledge of how to conserve biological diversity of insects in the tropics. In addition, the project provided research and educational experiences for sixteen students including several minorities, women, and international students. Students were trained in insect collection and identification, preparing specimens for museum insect collections, data analysis, data entry, and interpretation of scientific findings. Students learned about coffee agroecosystems, the drivers of species diversity and communities, and conservation biology. Many students traveled to Mexico as part of the research project and thus interacted with students and research staff from diverse backgrounds. Students thus learned not only about science, but also about multicultural and international research experiences.
