Evolution of multiple competitors; experimental evolution using a natural protozoan community.

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This study will test a long-standing concept in ecology that if two species utilize very similar resources, either one or both will evolve to use different resources, or one will be driven locally extinct. This concept is foundational to our understanding of how biological communities are organized. Using microbes found in the water-filled leaves of pitcher plants, this project will test this principle and its predictions about how species interactions evolve. A novel experimental approach will be used that compares the evolution of multiple species occurring in communities of increasing species diversity. Much of community ecology assumes that each species has its own ideal ecological role, called the niche, and that evolution can lead species to change their niche to limit resource competition from other species. Darwin's finches provide a good example, where these bird species evolved to be more different when together on islands, as compared to when they were alone. However, predictions about the evolution of the niche become more difficult in complex communities where many species may evolve at the same time. In addition to conducting greenhouse experiments involving pitcher plant microbial communities, the PIs will train undergraduate and graduate students as well as develop educational activities that target Florida science standards. This work will address long-standing hypotheses that competition leads to niche partitioning and character displacement. The evolutionary patterns of protozoa species will be quantified in 1-, 2, and 4-species communities, using pitcher plants grown in the greenhouse. This design can be used to ask if species evolve differently in communities of increasing complexity. The theory of niche partitioning, which is thought to lead to coexistence, will be supported if species co-evolve to have reduced competitive interactions, while niche convergence would be supported if increased competitive interactions evolve in multispecies systems. Specific traits such as cell size and other physical characteristics associated with feeding in the protozoa will also be quantified. Next-generation DNA sequencing will be used to quantifying how the protozoa evolving in different combinations affect the underlying bacterial community.