|Past Graduate Students||Andrew Binderup (MS), Troy Simon (PhD)|
|PI||David Reznick (UC Riverside)|
|Co-PIs||Joseph Travis (FL State), Cathy Pringle (UGA), Douglas Fraser (Sienna College), Regis Ferriere (U. of Arizona)|
|Senior Personnel||Michael Kinnison (U. of Maine), Alex Flecker (Cornell), Cameron Ghalambor (Colorado State), Jim Gilliam (NC State), Andrew Hendrey (McGill U.), Paul Bentzen (Dalhousee), Steve Thomas (U. Nebraska), Don deAngelis (USGS)|
|Post-Doctoral Students||Mike Marshall|
|The Guppy Project website|
From Genes to Ecosystems: How Do Ecological and Evolutionary Processes Interact in Nature?
Ecological-evolutionary dynamics was the theme of this large collaborative project, funded by NSF’s Frontiers in Integrative Biology (FIBR) Program from 2007-2013. While ecological processes are known to drive adaptive evolution, the feedback from adaptive evolution to ecological processes has been explored only in theory and simple model systems. These explorations suggest a potentially profound importance for the feedback from evolution to ecological processes. The importance of adaptive dynamics in natural systems remains to be elucidated; doing so requires a target organism that can display significant evolution in a manageable time interval and with measurable ecological consequences. This project evaluated reciprocal feedbacks between evolution and ecosystem processes in both natural streams and artificial stream mesocosms, using a focal species, the guppy (Poecilia reticulata). Our lab was part of the ecosystem team which assessed whether different phenotypes of guppies had differential effects on stream ecosystems properties and processes.We transplanted guppies from sites where they co-occurred with a diversity of predators to streams from which they had been previously excluded by waterfalls. These streams contained a single predator, Anablepsoides hartii, and guppy introductions were designed to evaluate the ecological and co-evolutionary interactions that result. Anablepsoides preys on guppies, but guppies also prey on Anablepsoides. Both organisms feed on benthic macroinvertebrates and algae, so there are multiple interspecific interactions to observe. Our experimental setting benefited from barrier waterfalls that limited upstream dispersal of guppies, but do not exclude Anablepsoides, thus providing a built-in control. We also manipulated light environments in a subset of experimental sites in order to alter basal resources and assess how ecological context influences evolutionary trajectories.Specific goals of the overall project were to do the following:
- Evaluate population dynamics, changes in demography, resource utilization, and evolution, both by mean phenotype and genetic lineage, of the introduced guppies
- Characterize Anablepsoides response to guppy introduction
- Quantify impacts of guppies and Anablepsoides on lower trophic levels
- Determine changes in availability and demand for potentially limiting nutrients
- Manipulate primary productivity to evaluate effects of ecosystem context on life history evolution
- Use our results to further develop eco-evolutionary theory
Research in focal streams was complemented by experiments conducted in existing artificial stream mesocosms that were designed to identify underlying interactions and to examine cause and effect relationships implied by the field introduction experiments. Comparative studies across a wide variety of streams and fish communities were used to refine experimental results.
Methods included the use of the following:
- Molecular genetic markers and mark-recapture to assess individual reproductive success and demographic variables
- Mark-recapture methodologies to characterize population biology of guppies and Anablepsoides
- Naturally-occurring isotopes to assess patterns of resource utilization
- Electric exclosures to assess effects of fish on lower trophic levels
- Ecological stoichiometry to examine nutrient imbalance in trophic interactions
- Isotope tracer experiments to quantify nitrogen flux through ecosystem compartments.