Spatial heterogeneity and evolution of fecundity-affecting traits

Area of Science:

• Evolutionary biology
• Population genetics
• Ecological dynamics

Background:

• Spatial structure significantly impacts population dynamics.
• Homogeneous models (Wright's island model) show spatial structure does not alter fitness gradients for fecundity traits.
• Evolutionary branching is often inhibited in spatially homogeneous populations.

Purpose of the Study:

• To investigate the impact of spatial heterogeneity on evolutionary dynamics.
• To analyze evolutionary branching in heterogeneous metapopulations.
• To understand how varying island capacities and fecundities influence evolutionary trajectories.

Main Methods:

• Analysis of metapopulation fitness in an infinite Wright's island model with heterogeneous patches.
• Derivation of first-order and second-order derivatives of metapopulation fitness.
• Representation of selection gradients as biased averages of local selection pressures.

Main Results:

• Spatial heterogeneity generally favors evolutionary branching.
• The selection gradient is a weighted average of local selection pressures across different patch types.
• A specific condition is identified that particularly favors evolutionary branching.

Conclusions:

• Spatial heterogeneity is a key driver for evolutionary branching.
• This framework can explain emergent evolutionary patterns in public-goods games, including cooperation and defection.
• The findings challenge previous assumptions about the role of spatial structure in evolutionary dynamics.