For r between 1 and 2, N exhibits damped oscillations. For r greater than 2, N increases in amplitude until a stable limit cycle is established or the population fluctuates chaotically. Time Delay in Continuous Time Models Time delays can cause oscillations in populations. For example, the young may not be able to reproduce immediately, so a delay occurs with respect to birth versus production of offspring. The delay can lead to oscillations in populations and is a density-dependent factor.
Lipid storage allows Daphnia to get through periods of low food availability.
This did not occur for Bosmina , which cannot store significant lipids and cannot withstand periods of lowered food availability. Nicholson studied blowfly larvae and adults to determine what would happen when time delays were experimentally removed. The time delay was caused by a delay in the response of fecundity and mortality to the density of adults in the laboratory. The adults laid fewer eggs, and most of these survived, eliminating the time delay and the oscillations.