Publications by authors named "Amy T Sullivan"
Darwinian selection should preclude cooperation from evolving; yet cooperation is widespread among organisms. We show how kin selection and reciprocal altruism can promote cooperation in diverse 2×2 matrix games (prisoner's dilemma, snowdrift, and hawk-dove). We visualize kin selection as non-random interactions with like-strategies interacting more than by chance.
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- Vertebrate herbivores, including voles, tend to feed on plants that have already been clipped by other animals, indicating a preference for previously grazed plants.
- Voles preferred to clip the stems of two tallgrass prairie species, Desmanthus illinoensis and Echinacea purpurea, that had been previously clipped, except for E. purpurea late in the season when its seeds were ripe.
- Repeated clipping of D. illinoensis resulted in significant reductions in growth and seed production, effects that persisted into the next season, while E. purpurea's seed output was reduced but recovered the following year, highlighting how voles can influence grassland ecosystem dynamics.
The timing of herbivory can be an important factor in the strength and direction of plant response to herbivore damage. To determine the effect of vole herbivory timing within a growing season on tallgrass prairie forbs, we used individual plant enclosures to limit vole access to three species, Desmanthus illinoensis, Echinacea purpurea, and Heliopsis helianthoides, in an experimental restoration in northern Illinois, USA. As part of a long-term experiment, we implemented five vole access treatments in 2003: (1) vole access for the entire growing season, (2) early-season access, (3) mid-season access, (4) late-season access, and (5) no vole access.
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