BGC overcomes the NeoDarwinian/Neutral theory duopoly of unbiased transmission for increased genetic diversity

Charles Darwin's theory of evolution by natural selection relies on the idea that there is variation in a population, and that some variants are more likely to survive and reproduce than others. This leads to the gradual accumulation of favorable traits in the population over time.

However, one early objection to Darwin's theory was that it did not explain how variation could be preserved in the absence of selection. For example, if all individuals in a population are equally fit, then there would be no reason for natural selection to favor any particular variant.

The assumption of unbiased transmission solves this problem. It states that the probability of an offspring inheriting a particular trait from its parents is the same regardless of whether the trait is beneficial, harmful, or neutral. This means that even if there is no selection for or against a particular trait, it can still be preserved in the population through random genetic drift.


The selectionist-neutralist duopoly was a theoretical framework in population genetics that dominated the field for many years. It proposed that the evolution of genes and genomes is driven by unbiased inheritance by either natural selection or genetic drift, with no significant contributions from other factors.

However, in recent years, it has become clear that biased gene conversion can also play a significant role in the evolution of genes and genomes. Biased gene conversion is a process in which the DNA sequence of one gene is copied onto another gene, even if the two genes are not identical. This can lead to the spread of advantageous mutations, or the elimination of deleterious mutations, in a population.

Mammalian isochore structures are regions of the genome that are characterized by different gene densities. For example, some regions of the genome may be very gene-rich, while other regions may be very gene-poor. These isochore structures are thought to be the result of biased gene conversion, which has preferentially copied genes from gene-rich regions to gene-poor regions.

The discovery that biased gene conversion can play a significant role in the evolution of genes and genomes has challenged the traditional selectionist-neutralist duopoly. It has opened up new possibilities for understanding how genes and genomes evolve, and it has led to a renewed interest in the study of non-selective processes in evolution.

Here are some other examples of phenomena that can be explained by biased gene conversion:

  • The evolution of sex chromosomes

  • The evolution of repetitive DNA

  • The evolution of gene duplications

  • The evolution of gene families

  • The evolution of regulatory sequences

Biased gene conversion is a complex process that is not fully understood. However, it is clear that it can play a significant role in the evolution of genes and genomes. The discovery of biased gene conversion has had a major impact on our understanding of evolution, and it is likely to continue to be an important area of research in the years to come.

The article "A Century of Bias in Genetics and Evolution" by Laurence Hurst is a comprehensive and insightful overview of the role of bias in genetics and evolution. Hurst begins by defining bias as "any deviation from Mendelian expectations of equal transmission of alleles from parents to offspring." He then traces the history of research on bias, from the early work of Fisher and Haldane to the more recent discoveries of biased gene conversion and epigenetic inheritance.

Hurst argues that bias is a fundamental force in evolution, and that it can have a significant impact on the distribution of genetic variation in populations. He notes that bias can be caused by a variety of factors.

One of the most important implications of bias is that it can lead to the spread of deleterious alleles. This is because even a weakly deleterious allele can become fixed in a population if it has a slight advantage in transmission. Hurst cites the example of the sickle cell allele, which is a mutation that causes sickle cell anemia. The sickle cell allele is harmful in most environments, but it confers resistance to malaria. In malaria-ridden regions, the sickle cell allele can become fixed, even though it is overall harmful.

Another important implication of bias is that it can lead to the maintenance of genetic diversity. This is because bias can prevent the fixation of beneficial alleles, which can help to maintain a diversity of genotypes in a population. Hurst cites the example of meiotic drive, which is a type of bias that can cause certain alleles to be transmitted more often than others. Meiotic drive can help to maintain genetic diversity by preventing the fixation of beneficial alleles that would otherwise become too common.

Hurst concludes by arguing that bias is a complex and fascinating phenomenon that has important implications for our understanding of genetics and evolution. He calls for more research on bias, so that we can better understand its role in shaping the genetic makeup of populations.

Despite the challenges of studying bias, it is clear that it is a fundamental force in genetics and evolution. By understanding bias, we can better understand how genetic variation is distributed in populations, and how evolution takes place.

Here are some additional thoughts on the article:

  • Bias can be a powerful force in evolution.

  • Bias can be difficult to study, but it is becoming increasingly possible with new technologies.

  • Bias can have both positive and negative consequences for populations. It is important to understand the potential consequences of bias in order to manage it effectively.

Overall, the article "A Century of Bias in Genetics and Evolution" is a valuable contribution to the field of evolutionary genetics. It provides a comprehensive overview of the research on bias, and it highlights the importance of this phenomenon for our understanding of evolution.

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