@article{FussmannEllnerHairston2003,
  author    = {Fussmann, Gregor F. and Ellner, Stephen P. and Hairston, Nelson G.},
  title     = {Evolution as a critical component of plankton dynamics},
  year      = {2003},
  abstract  = {Microevolution is typically ignored as a factor directly affecting on-going population dynamics. We show here that density-dependent natural selection has a direct and measurable effect on a planktonic predator-prey interaction. We kept populations of Brachionus calyciflorus, a monogonont rotifer that exhibits cyclical parthenogenesis, in continuous flow-through cultures (chemostats) for > 900 days. Initially, females frequently produced male offspring, especially at high population densities. We observed rapid evolution, however, towards low propensity to reproduce sexually, and by 750 days, reproduction had become entirely asexual. There was strong selection favouring asexual reproduction because, under the turbulent chemostat regime, males were unable to mate with females, produced no offspring, and so had zero fitness. In replicated chemostat experiments we found that this evolutionary process directly influenced the population dynamics. We observed very specific yet reproducible plankton dynamics that are explained well by a mathematical model that explicitly includes evolution. This model accounts for both asexual and sexual reproduction and treats the propensity to reproduce sexually as a quantitative trait under selection. We suggest that a similar amalgam of ecological and evolutionary mechanisms may drive the dynamics of rapidly reproducing organisms in the wild.},
  language  = {en}
}
@article{YoshidaJonesEllneretal.2003,
  author    = {Yoshida, Takehito and Jones, Laura E. and Ellner, Stephen P. and Fussmann, Gregor F. and Hairston, Jr. and Nelson, G.},
  title     = {Rapid evolution drives ecological dynamics in a predator-prey system},
  year      = {2003},
  abstract  = {Ecological and evolutionary dynamics can occur on similar timescales. However, theoretical predictions of how rapid evolution can affect ecological dynamics are inconclusive and often depend on untested model assumptions. Here we report that rapid prey evolution in response to oscillating predator density affects predator-prey (rotifer-algal) cycles in laboratory microcosms. Our experiments tested explicit predictions from a model for our system that allows prey evolution. We verified the predicted existence of an evolutionary tradeoff between algal competitive ability and defence against consumption, and examined its effects on cycle dynamics by manipulating the evolutionary potential of the prey population. Single-clone algal cultures (lacking genetic variability) produced short cycle periods and typical quarter-period phase lags between prey and predator densities, whereas multi-clonal (genetically variable) algal cultures produced long cycles with prey and predator densities nearly out of phase, exactly as predicted. These results confirm that prey evolution can substantially alter predator-prey dynamics, and therefore that attempts to understand population oscillations in nature cannot neglect potential effects from ongoing rapid evolution.},
  language  = {en}
}
@article{EllnerFussmann2003,
  author    = {Ellner, Stephen P. and Fussmann, Gregor F.},
  title     = {Effects of successional dynamics on metapopulation persistence},
  year      = {2003},
  abstract  = {The classical (Levins) metapopulation scenario envisions a species persisting in a network of habitat patches through a balance between frequent local (within-patch) extinctions and recolonizations. Although this is the dominant paradigm for species in fragmented habitats, empirical support is limited and it has been argued that very restrictive conditions on migration rates are required: high enough for recolonization to balance extinctions, but low enough that local populations do not fluctuate in synchrony. Through simulation and analysis of a stochastic spatial model, we argue that the likelihood of persistence via the classical scenario is strongly affected by some basic properties of within- patch successional dynamics whose importance has not been emphasized in metapopulation theory: the distribution of successional stage durations, and whether patches are "refractory" versus immediately available for recolonization after an extinction has occurred. These properties are tied to the biological causes of extinction (e.g., demographic accident versus regular successional changes) and patch recovery (e.g., recolonization by a host species versus regeneration of an exhausted resource base). Our results indicate that metapopulation theory needs to incorporate the patch-dynamics perspective of a landscape in a dynamic mosaic of successional states, with particular attention to links between colonization-extinction processes and local succession.},
  language  = {en}
}