Related Experiment Videos
Dispersal in relation to carrying capacity
1Biology Department, McGill University, 1205 McGregor St., Montreal, Quebec H3A 1B1, Canada.
Summary
Herbivorous voles (Microtus pennsylvanicus) disperse when nutrient availability, not just energy, becomes scarce. This selective feeding behavior, driven by natural selection, helps populations avoid future food shortages.
Area of Science:
- Ecology
- Animal Behavior
- Population Dynamics
Background:
- Herbivore populations, like the meadow vole (Microtus pennsylvanicus), often disperse from their initial habitats.
- Understanding the drivers of this dispersal is crucial for ecological management and conservation efforts.
Purpose of the Study:
- To investigate the triggers for dispersal in Microtus pennsylvanicus from grassland to woodland habitats.
- To determine the role of energy versus nutrient availability in initiating herbivore dispersal.
Main Methods:
- An experimental field system was used to study vole dispersal over a spring-to-autumn period.
- Vole feeding behavior and resource availability (energy, sodium, phosphorus) were monitored.
Main Results:
- Dispersal was observed when available energy was 100 times greater than population requirements, indicating energy was not the primary limiting factor.
- Sodium and phosphorus were identified as key limiting nutrients, with voles feeding selectively to meet deficits.
- Selective feeding allowed voles to consume less than 10% of available resources, but potential for severe depletion existed for the upcoming winter.
Conclusions:
- Nutrient availability, rather than total energy, may be a more significant limiting factor for herbivore populations.
- Presaturation dispersal is likely driven by natural selection favoring individuals that respond to environmental cues of impending food shortages.
- Aggressive and interactive behaviors play a role in resource access and exclusion, inducing dispersal in non-tenured individuals.