Cryptic Population Dynamics: Rapid Evolution Masks Trophic Interactions
Figure 1
Experimentally Observed Cycles of Algae (Green) and Rotifer (Red) Populations in a Chemostat System
(A) The entire initial algal population was descended from a single algal cell drawn from our stock cultures, and the predator was introduced quickly to limit algal population growth and reduce the opportunity for advantageous genotypes to arise by mutation.
(B) An experiment in which the initial algal population was drawn from multiple sources and genetically variable.
With prey genetic variation eliminated or greatly reduced (A), the system exhibited classical predator-prey cycles with increases in prey abundance followed by increases in predator abundance after a quarter-period lag. When the prey population is genetically heterogeneous and evolving (B), the cycles are longer and the oscillations in predator and prey abundance are almost exactly out of phase. The data are replotted from [42,57].