Population density, bottom-up and top-down control as an interactive triplet to trigger dispersal

Area of Science:

• Behavioral Ecology
• Animal Movement
• Population Dynamics

Background:

• Dispersal is a crucial life-history strategy influenced by habitat costs and fitness benefits.
• Field studies on dispersal triggers are limited by controllability, necessitating laboratory investigations.
• Understanding dispersal mechanisms is vital for modeling animal behavior in dynamic landscapes.

Purpose of the Study:

• To investigate the influence of population density, bottom-up (food availability), and top-down (predation) control on nematode dispersal.
• To determine if environmental factors trigger non-random dispersal in Caenorhabditis elegans.
• To explore the interactive effects of these factors on emigration.

Main Methods:

• Experiments utilized two-chamber arenas to manipulate population density and food availability.
• The predatory flatworm Polycelis tenuis was introduced to simulate top-down control.
• Nematode movement and emigration rates were quantified under varied conditions.

Main Results:

• Decreasing food availability significantly increased nematode dispersal.
• Increasing population density also positively influenced nematode emigration.
• Predation by P. tenuis had inconsistent effects but amplified density-dependent dispersal under specific food conditions.

Conclusions:

• Nematode dispersal is a non-random, context-dependent decision influenced by environmental information.
• Population density and food availability are key drivers of small-scale dispersal in C. elegans.
• This research enhances the understanding of dispersal triggers and traits for improved ecological modeling.