TEMPERATURE AND TROPHIC STRUCTURE ARE DRIVING MICROBIAL PRODUCTIVITY ALONG A BIOGEOGRAPHICAL GRADIENT.
Gray, S.M., Poisot, T., Harvey, E.,Mouquet, N., Miller, T.E. and Gravel, D. (2016).
Ecography, 39,981-989, doi:10.1111/ecog.01748
Key message : We investigated the effects of specific nutrients (carbon, phosphorus, and nitrogen), as well as a top predator (the mosquito Wyeomyia smithii), on the structure of the detritivore community found in the water-filled leaves of the pitcher plant Sarracenia purpurea. The concentrations of three nutrients and the presence of the predators were manipulated in a factorial design, while the response of the remaining community was quantified. Bacterial growth was found to be strongly carbon-limited and somewhat less limited by phosphorus and there was an interaction between the effects of the two nutrients. Neither carbon or phosphorus addition affected protozoan or rotifer abundance, and nitrogen had only a minor effect. The presence of the predator, however, significantly reduced the abundance of the four numerically dominant bacteriovores. There were no interactions between top-down and bottom-up effects; the strong direct reciprocal effects between adjacent trophic levels seem to be greatly attenuated as they are propagated farther up or down the food chain.
Sarracenia purpurea, commonly known as the Purple Pitcher Plant, is a carnivorous perennial native to North America's nutrient-poor, acidic bogs and swamps. Its modified leaves form pitcher-like traps, which use a combination of coloration, scent, and nectar to lure and trap insects. Inside, insects are broken down by the plant's enzymes and symbiotic microorganisms, allowing the plant to extract essential nutrients, particularly nitrogen and phosphorus, from its prey. This unique carnivory method is vital for the plant's survival in nutrient-deprived habitats. Beyond its intriguing feeding habits, S. purpurea supports a microecosystem within its pitchers, including specialized bacteria and invertebrates, and has mutualistic relationships with many species. While not endangered, its habitats face threats from human activities, emphasizing the need for conservation efforts to protect both the plant and the intricate wetland ecosystems it represents. Photo (c) Nicolas Mouquet.
OTHER TOPICS: Aesthetics of Biodiversity, Biodiversity & Ecosystem Functioning, Biogeography, Macroecology & Ecophylogenetics, Experimental Evolution,
Functional Biogeography, Functional Rarity, Metacommunities, Metaecosystems, Reviews and Synthesis, Trophic Biogeography & Metaweb