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Successful biological invasion despite a severe genetic load
Amro Zayed1, Serban A Constantin, Laurence Packer
1Department of Biology, York University, Toronto, Ontario, Canada. azayed@life.uiuc.edu
Plos One
|September 13, 2007
Summary
Biological invasions can succeed with small founding populations, challenging the propagule pressure hypothesis. Chance events and species traits, not just propagule numbers, drive invasion success.
Area of Science:
- Ecology
- Evolutionary Biology
- Genetics
Background:
- Biological invasions pose significant ecological and economic threats.
- Invasive species often maintain high genetic diversity, supporting the propagule pressure hypothesis.
- This hypothesis suggests large founding populations or multiple introductions are key to invasion success.
Purpose of the Study:
- To investigate the genetic diversity and invasion dynamics of the solitary bee Lasioglossum leucozonium.
- To test the role of propagule pressure versus other factors in invasion success.
- To understand the genetic basis for the success of L. leucozonium in North America.
Main Methods:
- Population genetic analysis using neutral microsatellite markers.
- Analysis of a gene under balancing selection.
- Stochastic modeling to simulate invasion scenarios.
Main Results:
- Lasioglossum leucozonium experienced a severe genetic bottleneck during introduction from Europe.
- Invasion success occurred despite a high genetic load (30% sterile diploid males).
- Stochastic modeling indicated invasion by a single, likely mated, female, contradicting the propagule pressure hypothesis.
Conclusions:
- Invasion success is influenced more by chance events and invader ecological traits than propagule pressure.
- Vigilance against biological invasions may need to be significantly enhanced.
- The study highlights the complex factors governing biological invasion dynamics.
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