Chaotic dynamics can select for long-term dormancy

Area of Science:

• Population Ecology
• Evolutionary Biology
• Theoretical Ecology

Background:

• Extended dormancy in populations is typically considered an evolutionary strategy for bet hedging, implying environmental variance.
• Dormancy is usually interpreted as evidence of fluctuating environmental conditions impacting population fitness.
• This interpretation assumes dormancy is solely a response to external environmental unpredictability.

Purpose of the Study:

• To investigate whether intrinsic population dynamics, independent of environmental variance, can drive the evolution of dormancy.
• To explore the role of chaotic population dynamics in selecting for dormancy strategies.
• To determine if dormancy can stabilize populations exhibiting chaotic fluctuations.

Main Methods:

• Utilized a Ricker-type population model incorporating heritable variation in dormancy.
• Simulated population dynamics under conditions with and without environmental variance.
• Analyzed the selective pressures on dormancy strategies arising from intrinsic chaotic dynamics.

Main Results:

• Intrinsic population dynamics can generate chaotic fluctuations without environmental variance.
• Chaotic dynamics favor a higher frequency of dormant strategists, even with significant dormancy mortality.
• The buffering effect of a high frequency of dormant individuals can stabilize chaotic dynamics or lead to low-amplitude periodic orbits.

Conclusions:

• Dormancy does not exclusively indicate environmental variance; intrinsic population dynamics can also drive its evolution.
• Chaotic dynamics can promote the selection and maintenance of dormancy as a stabilizing mechanism.
• Stabilized populations can harbor a substantial proportion of dormant individuals with varied dormancy propensities.