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Hybrid populations selectively filter gene introgression between species
G D Martinsen1, T G Whitham, R J Turek
1Department of Biological Sciences and The Merriam-Powell Center for Environmental Research, Northern Arizona University, Flagstaff 86011, USA. gregory.martinsen@nau.edu
Evolution; International Journal of Organic Evolution
|August 30, 2001
Summary
Gene flow between cottonwood species shows selective introgression, with some genes crossing species boundaries over long distances. This selective process impacts evolution and conservation biology by filtering gene flow.
Area of Science:
- Genetics
- Evolutionary Biology
- Conservation Biology
Background:
- Hybridization is a known pathway for gene flow between species.
- Understanding the extent and mechanisms of introgression is crucial for evolutionary and conservation studies.
- Few studies have demonstrated broad-scale gene introgression between species.
Purpose of the Study:
- To investigate the extent and patterns of gene introgression between two cottonwood species.
- To analyze the genomic barriers and facilitators of introgression.
- To understand the evolutionary consequences of selective gene flow.
Main Methods:
- Utilized 35 genetically mapped restriction fragment length polymorphism (RFLP) markers.
- Analyzed 550 hybrid and parent trees of Populus fremontii and Populus angustifolia.
- Conducted a genome-wide analysis of introgression patterns.
Main Results:
- The majority of the genome showed barriers to introgression between species.
- Fremont cottonwood chloroplast and mitochondrial DNA introgressed widely into narrowleaf cottonwood.
- 20% of Fremont cottonwood nuclear markers introgressed into narrowleaf cottonwood, some exceeding 100 km.
Conclusions:
- Introgression between cottonwood species is selective, with genomic filtering acting on gene flow.
- Selective introgression can be adaptive, preventing genetic assimilation and stabilizing hybrid zones.
- Natural hybridization can provide significant genetic variation impacting ecological and evolutionary processes.