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On the evolutionary stability of Mendelian segregation
1Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts 02138, USA. francisco.ubeda@sjc.ox.ac.uk
Genetics
|May 25, 2005
Summary
We modeled how genes can alter offspring ratios based on sex. Such genetic drive can lead to extreme segregation patterns, questioning the universality of standard Mendelian inheritance.
Area of Science:
- Evolutionary genetics
- Population genetics
Background:
- Mendelian segregation describes predictable inheritance patterns.
- Genomic imprinting can lead to differential viability of heterozygotes.
- Sex-specific segregation distortion is a known phenomenon.
Purpose of the Study:
- To model the evolution of sex-specific segregation distorters.
- To investigate the conditions under which segregation distorters can invade populations.
- To explore the evolutionary outcome of sex-specific segregation distortion.
Main Methods:
- Mathematical modeling of genetic loci.
- Analysis of selection and drift at linked and unlinked loci.
- Population genetics simulations.
Main Results:
- Modifier alleles causing sex-specific segregation biases can invade populations with balanced polymorphisms.
- This invasion is effective even without differences in heterozygote viability.
- The predicted evolutionary outcome is 'all-and-none' segregation, favoring heterozygotes.
Conclusions:
- Sex-specific segregation distorters can evolve towards extreme biases.
- 'All-and-none' segregation creates populations of maximally fit heterozygotes.
- This challenges the assumption of ubiquitous Mendelian segregation.