Evolutionary and population dynamics: A coupled approach

We study the interplay of population growth and evolutionary
dynamics using a stochastic model based on birth and death events.
In contrast to the common assumption of an independent population
size, evolution can be strongly affected by population dynamics in
general. Especially for fast reproducing microbes which are subject
to selection, both types of dynamics are often closely intertwined.
We illustrate this by considering different growth scenarios.
Depending on whether microbes die or stop to reproduce (dormancy),
qualitatively different behaviors emerge. For cooperating bacteria,
a permanent increase of costly cooperation can occur. Even if not
permanent, cooperation can still increase transiently due to
demographic fluctuations. We validate our analysis via stochastic
simulations and analytic calculations. In particular, we derive a
condition for an increase in the level of cooperation.