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The secrets of genetics: How does population genetics reveal the mysteries of species evolution?
In the scientific world, the first place where genetics and evolutionary biology intersect is in "population genetics." This field focuses on genetic differences between and within populations, exploring phenomena such as adaptation, speciation, and population structure. Founded by scientists such as Sewall Wright, J.B.S. Haldane, and Ronald Fisher, population genetics became the core of modern evolutionary theory, using statistics, data, and Field experiments to explain how species evolve over time.
"The evolution of population genetics is not just about looking at genes, but also about developing a deeper understanding of how genes affect the entire ecosystem."
One hypothesis in the past was "admixture inheritance", but this causes genetic variation to disappear quickly, making evolution based on natural selection or sexual selection unrealistic. An explanation for stable genetic variation is provided by the Hardy–Weinberg principle, which states that in the absence of selection, mutation, migration, and genetic drift, genotype frequencies will remain constant.
In his famous book "The Genetic Theory of Natural Selection", Ronald Fisher demonstrated that the continuous variation of many separate genes can change in the population through natural selection, which promoted the development of the theory of evolution. J.B.S. Haldane focused on the mathematical study of single genetic loci and applied these mathematical concepts to real-world examples of natural selection, such as the evolution of the peppered moth. Wright introduced the concept of "adaptive landscape" to explore how genetic drift in small populations affects their movement toward adaptive peaks.
“It is population genetics that has enabled scientists to combine natural selection with Mendelian genetics, breaking the limitations of previous understanding of evolution.”
Entering the modern synthesis period, scientists began to clear out theories such as Lamarckism and forward evolution that did not conform to observed facts. The genetic diversity studies of Russian geneticists such as Sergey Chetverikov led the American biologist Theodosius Dobzhansky to connect the concept of microevolution with actual macroevolutionary models. Combined, they provide new perspectives for understanding the evolutionary dynamics of species.
The core of population genetics lies in understanding the major processes by which gene frequencies change - natural selection, genetic drift, gene flow and mutation. Natural selection drives changes in the gene pool by increasing the chances of survival and reproduction of certain traits.
"Population genetics is an effective tool for explaining why certain traits flourish in certain environments while others are eliminated."
This process is not limited to natural selection. For example, gene mutations play a crucial role in genetic variation, but most mutations are harmful. Studies have shown that when mutations affect gene products, about 70% result in harmful consequences. This has made scientists more aware that the existence of mutations is the key to potential future changes in evolution.
"Gene flow refers to the exchange of genes between different populations, which promotes the formation of biodiversity."
Scientists have also proposed the influence of genetic drift, a process by which gene frequencies change due to random sampling. Although it does not have the clear adaptive significance that natural selection does, it can have a huge impact on small populations and in some cases can lead to the extinction of species.
With the advancement of molecular biology, the proposal of the neutral theory has also added a new perspective to population genetics. The theory holds that most genetic variations are neutral and driven by random drift. This makes us rethink the relationship between randomness and selectivity in the evolutionary process.
Finally, with the acceleration of globalization and ecological change, the role of gene flow in the evolution of current species is becoming increasingly important. The impact of different environments on organisms is transformed into complex interactions between genes, which in turn promotes the exploration of new species.
