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The origin of chromosomes. I. Selection for linkage
1School of Biological Sciences, University of Sussex, Brighton, U.K.
Journal of Theoretical Biology
|October 21, 1993
Summary
Linked genes on a primitive chromosome can increase in frequency within cells. This occurs when genes provide a synergistic growth advantage and are present in small numbers, even with slower replication.
Area of Science:
- Evolutionary genetics
- Systems biology
- Molecular evolution
Background:
- Cells contain independently replicating genes that segregate randomly during division.
- Understanding gene linkage and its evolutionary implications is crucial for cellular evolution models.
Purpose of the Study:
- To analyze a model of cells with independently replicating genes and linked genes on a primitive chromosome.
- To determine the conditions under which a linked gene chromosome increases in frequency within a cell population.
Main Methods:
- Mathematical modeling of gene replication and segregation in a cellular population.
- Analysis of a primitive chromosome model where two genes are linked, replicating and segregating together.
- Investigating the impact of synergistic gene action and gene copy number on chromosome frequency.
Main Results:
- A linked gene chromosome increases in frequency if the genes act synergistically, enhancing cell growth.
- This increase is favored when the number of genes per cell is small.
- The linked chromosome can outcompete individual genes even with a two-fold replication time disadvantage.
Conclusions:
- Gene linkage can be evolutionarily advantageous under specific conditions, promoting the co-transmission of beneficial genes.
- Synergistic gene interactions and limited gene copy numbers are key drivers for the spread of linked genes.
- This mechanism explains how primitive chromosomes could evolve and persist despite potential replication costs.