A Century of Bias in Genetics and Evolution - review

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The same intimate link between genetics and evolution is for the most part ignored in UK school teaching. Understanding of the role of bias in transmission is, I suggest, a helpful way of explaining the relationship between the two, so overcoming psychological biases that can be an impediment to learning owing to cognitive dissonance.


segregation distortion


Article “A Century of Bias in Genetics and Evolution”: Laurence Hurst, Heredity (6/19)

Introduction

In his thought-provoking article Hurst challenges the prevailing assumption of Mendelian segregation ratios, arguing that biased transmission of genetic material can significantly influence evolutionary processes. Hurst traces the historical development of this concept, highlighting the early recognition of segregation distortion and its subsequent neglect in mainstream evolutionary genetics. He then presents a compelling case for the widespread occurrence of biased transmission and its potential impact on various evolutionary phenomena.

A Historical Perspective: Segregation Distortion and Its Downplaying

Hurst begins by revisiting the early days of genetics, when segregation distortion, a deviation from the expected 1:1 ratio of parental alleles in offspring, was first observed. Despite its intriguing implications, segregation distortion received limited attention during the mid-20th century, primarily due to the dominance of Fisherian and neo-Darwinian models that emphasized natural selection as the primary driving force of evolution. These models assumed Mendelian segregation, implying unbiased transmission of genetic material.

Revisiting Segregation Distortion: A Neglected Evolutionary Mechanism

Hurst argues that the neglect of segregation distortion has led to an incomplete understanding of evolutionary processes. He provides numerous examples of genetic systems that exhibit biased transmission, demonstrating its prevalence across various organisms and environments. These examples illustrate how biased transmission can influence evolutionary trajectories, affecting phenomena such as speciation, adaptation, and disease susceptibility.

Impacts of Biased Transmission: Speciation, Adaptation, and Disease

Hurst delves into the specific impacts of biased transmission on various evolutionary processes. He discusses how biased transmission can contribute to speciation by driving the accumulation of reproductive isolation between populations. He also demonstrates how biased transmission can facilitate adaptation by promoting the spread of beneficial alleles and hindering the spread of deleterious alleles. Additionally, he highlights the role of biased transmission in disease susceptibility, as it can influence the transmission of disease-causing alleles.

Moving Beyond the Mendelian Paradigm: A Broader Evolutionary Framework

Hurst calls for a broader evolutionary framework that encompasses biased transmission alongside natural selection. He emphasizes the need to integrate molecular and transmission genetics into evolutionary biology, recognizing the interplay between genetic mechanisms and evolutionary outcomes. This integrative approach promises a more comprehensive understanding of evolutionary processes and their underlying mechanisms.

Conclusion: A Paradigm Shift in Evolutionary Genetics

Hurst's article challenges the long-held assumption of unbiased transmission in genetics and evolution. His compelling arguments and extensive evidence highlight the widespread occurrence of biased transmission and its significant impact on evolutionary processes. By advocating for a broader evolutionary framework that incorporates biased transmission, Hurst paves the way for a more nuanced and comprehensive understanding of evolutionary biology.

The paper challenges neo-Darwinism in several ways.

First, the paper argues that neo-Darwinism has been biased against the recognition of biased transmission genetics. Biased transmission genetics is the study of how genetic variants can be transmitted to offspring in a non-random fashion. This can happen for a variety of reasons, such as meiotic drive or selfish genetic elements. The paper argues that biased transmission genetics has been neglected by neo-Darwinists because it challenges the central neo-Darwinian assumption that natural selection is the only major force driving evolution.

Second, the paper argues that neo-Darwinism has been biased against the recognition of non-adaptive evolution. Non-adaptive evolution is evolution that is not driven by natural selection. This can happen for a variety of reasons, such as mutation bias. The paper argues that non-adaptive evolution has been neglected by neo-Darwinists because it challenges the central neo-Darwinian assumption that adaptation is the goal of evolution.

Third, the paper argues that neo-Darwinism has been biased against the recognition of the importance of the genetic architecture of populations. The genetic architecture of a population is the arrangement of genes in the population. The paper argues that the genetic architecture of a population can have a major impact on how evolution proceeds. This is because the genetic architecture of a population can affect things like the rate of mutation, the rate of recombination, and the strength of selection. The paper argues that neo-Darwinists have neglected the importance of the genetic architecture of populations because it challenges the central neo-Darwinian assumption that evolution is a predictable process.

In conclusion, the paper "A Century of Bias in Genetics and Evolution" argues that neo-Darwinism has been biased against the recognition of biased transmission genetics, non-adaptive evolution, and the importance of the genetic architecture of populations. These challenges suggest that neo-Darwinism may need to be revised or replaced in order to provide a more accurate and comprehensive understanding of evolution.

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