Related Experiment Video
Updated: Jul 11, 2026
20:36
Predicting the Effectiveness of Population Replacement Strategy Using Mathematical Modeling
Published on: July 4, 2007
Metapopulation extinction risk is increased by environmental stochasticity and assemblage complexity
James C Bull1, Nicola J Pickup, Brian Pickett
1Division of Biology, Imperial College London, Silwood Park Campus, Ascot, Berkshire SL5 7PY, UK.
Proceedings. Biological Sciences
|October 5, 2006
Summary
Environmental fluctuations increase extinction risk in simple ecological systems. However, complex communities show that trophic interactions dominate, reducing persistence regardless of resource changes.
Area of Science:
- Ecology
- Conservation Biology
- Theoretical Ecology
Background:
- Extinction risk is a critical focus for ecologists and conservationists.
- Understanding ecological processes is vital for species conservation.
- Environmental heterogeneity and demographic processes influence species persistence.
Purpose of the Study:
- To test the effects of fluctuating resource levels on experimental multispecies metapopulations.
- To compare a three-species host-parasitoid assemblage with pairwise interactions.
- To investigate how assemblage complexity affects extinction risk and persistence.
Main Methods:
- Laboratory microcosm experiments using multispecies metapopulations.
- Manipulation of resource levels to simulate environmental fluctuations.
- Comparison of three-species host-parasitoid dynamics with pairwise interactions.
Main Results:
- Environmental stochasticity reduced persistence time in two-species assemblages.
- Metapopulation structure increased persistence time in two-species assemblages.
- In complex three-species assemblages, trophic interactions masked environmental impacts, reducing persistence.
Conclusions:
- Theory on environmental heterogeneity and extinction risk is supported in simple systems.
- Assemblage complexity alters the dynamics of resource-consumer interactions.
- Both intrinsic and extrinsic factors across spatial scales are crucial for understanding persistence.
Related Concept Videos
00:30What are Populations and Communities?
Populations are groups of individuals of the same species that inhabit a shared environment. Communities include multiple co-existing, interacting populations of different species. Metapopulations span multiple populations of the same species that occupy different areas. Metapopulations interact through immigration and emigration, providing genetic diversity that lends resilience to harsh environments. Population size and density can be estimated using quadrat and mark and recapture...
01:50Threats to Biodiversity
There have been five major extinction events throughout geological history, resulting in the elimination of biodiversity, followed by a rebound of species that adapted to the new conditions. In the current geological epoch, the Holocene, there is a sixth extinction event in progress. This mass extinction has been attributed to human activities and is thus provisionally called the Anthropocene. In 2019 the human population reached 7.7 billion people and is projected to comprise 10 billion by...
02:04Conservation of Small Populations
Small population sizes put a species at extreme risk of extinction due to a lack of variation, and a consequent decrease in adaptability. This weakens the chances of survival under pressures such as climate change, competition from other species, or new diseases. Large populations are more likely to survive pressures such as these, as such populations are more likely to harbor individuals that have genetic variants that are adaptive under new stresses. Small populations are much less likely to...
02:07Conservation of Declining Populations
Conservation of declining population focuses on ways of detecting, diagnosing, and halting a population decline. The approach uses methods to prevent populations from going extinct.
02:31Habitat Fragmentation
Habitat fragmentation describes the division of a more extensive, continuous habitat into smaller, discontinuous areas. Human activities such as land conversion, as well as slower geological processes leading to changes in the physical environment, are the two leading causes of habitat fragmentation. The fragmentation process typically follows the same steps: perforation, dissection, fragmentation, shrinkage, and attrition.
03:33Genetic Drift
Natural selection—probably the most well-known evolutionary mechanism—increases the prevalence of traits that enhance survival and reproduction. However, evolution does not merely propagate favorable traits, nor does it always benefit populations.Life is not fair. A deer grazing contentedly in a field can have her meal cut tragically short by a bolt of lightning. If the doomed doe is one of only three in the population, 1/3 of the population’s gene pool is lost. Random events like this can...