Network topology and patch connectivity affect dynamics in experimental and model metapopulations.

Area of Science:

• Ecology
• Population Dynamics
• Network Theory

Background:

• Biological populations exist as interconnected metapopulations, influenced by dispersal and network structure.
• Theoretical models suggest scale-free networks enhance robustness, but experimental data on metapopulation dynamics is scarce.

Purpose of the Study:

• To experimentally investigate how different network topologies (random vs. scale-free) affect population dynamics and occupancy in a metapopulation framework.
• To compare experimental findings with simulation results for robust conclusions on network effects.

Main Methods:

• Utilized experimental metapopulations of the aquatic protist Paramecium tetraurelia.
• Engineered metapopulations with comparable linkage density but varying degree distributions (random vs. scale-free networks).
• Monitored local population occupancy and abundance over 18-30 generations, complemented by simulation studies.

Main Results:

• Under low dispersal, random networks exhibited higher protist abundance and patch occupancy than scale-free networks.
• High dispersal rates eliminated significant differences in occupancy and abundance between network types.
• Increased patch connectivity (degree) consistently reduced local extinction probability across both network types.

Conclusions:

• The interplay between dispersal, extinction rates, and network topology critically influences metapopulation dynamics, particularly rescue effects.
• Network structure, not just connectivity density, plays a key role in maintaining population occupancy and abundance.
• Experimental evidence demonstrates that random networks can be more effective than scale-free networks in certain metapopulation scenarios.