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Dobzhansky-Muller incompatibilities and adaptation to a shared environment.
1Department of Biology, University of Rochester, Rochester, NY 14627, USA. runckles@mail.rochester.edu
Heredity
|January 15, 2009
Summary
Natural selection can drive reproductive isolation between populations adapting to similar environments. However, identical environmental adaptation often leads to the same genetic changes, preventing the evolution of Dobzhansky-Muller incompatibilities (DMIs).
Area of Science:
- Evolutionary Biology
- Population Genetics
- Speciation
Background:
- Muller's (1942) hypothesis suggested natural selection could cause reproductive isolation in allopatric populations adapting to identical environments.
- Dobzhansky-Muller incompatibilities (DMIs) are genetic incompatibilities arising between diverging populations, a key mechanism in speciation.
Purpose of the Study:
- To mathematically analyze the conditions under which natural selection drives the evolution of DMIs in populations adapting to identical environments.
- To investigate potential limitations of Muller's scenario regarding DMI formation under congruent adaptation.
Main Methods:
- Mathematical modeling of allele substitutions at two loci under natural selection in allopatric populations.
- Analysis of the impact of varying selection coefficients on the probability of DMI evolution.
Main Results:
- Adaptation to identical environments can lead to the substitution of the same alleles in both populations, hindering DMI formation.
- The probability of evolving a DMI decreases as selection coefficients for beneficial alleles become more similar between loci.
- Stronger selection on one locus increases the likelihood of its substitution in both populations, preventing the necessary divergent substitutions for a DMI.
Conclusions:
- Muller's scenario faces challenges when populations adapt to identical environments due to congruent allele substitutions.
- Divergence in selection pressures across loci is crucial for the evolution of DMIs, even under similar environmental conditions.
- The study highlights the importance of differential selection strengths in the process of reproductive isolation and speciation.
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