Linyun Wang1* and Taoran Du, Ph.D2

Species variation is a biological phenomenon. When organisms reproduce, they produce offspring, and during the reproduction process of successive generations, variations occur. However, many people are unaware of or have disputes about this, believing that biological species do not vary during their generations. Scientists believe that life already existed on Earth 3.8 billion years ago. Over the past 500 million years, due to various reasons, at least five major mass extinctions (referred to as major extinctions) have occurred on Earth. After each major extinction, the remaining organisms would recover and thrive. Up to now, there are 500,000 to 300 million species of various organisms on Earth. Where did the original species come from? How did the species inherit and continue from generation to generation? What are the causes of biological variation? After the mass extinction, how did living beings reproduce and recover, and why did the number of species become increasingly larger and more complex, forming the biodiversity of the Earth? Up to now, there is still no satisfactory theory to explain it. Human beings have gradually come to understand the causes of biological variation. From the superstition of “God created all things” to Darwin’s first proposal in 1859 that a species could evolve from other species. From Morgan’s speculation in 1928 that there are paired genetic elements (genes) within the reproductive material of organisms to the confirmation of biological genetic material DNA in 1953. Human understanding of biological variation has entered the era of molecular biology. Over the past 70 years, human understanding of biological variation has continued to increase. Among them, the most important is: it is believed that the genetic material genome of organisms undergoes mutations and recombination during the continuation of generations. Mutations and recombination are the key processes causing changes in the genome. The heterozygous effect produced within a species during its continuation is the main driving force for species variation and evolution. This can be found in the history of variation and evolution of humans, animals, plants, and microorganisms. Some of the main rules of genetic heterogeneity effects are as follows: 4.1 Heterogeneity effect is not the replacement of one gene particle by another. The influence of parental traits on offspring traits is not symmetrical. The offspring traits are not the sum of the related traits of the two parents minus 2. It cannot be expressed as 50% of the father: 50% of the mother; it should be expressed as 50 ±% of the father: 50 ±% of the mother. The heterogeneity effect also varies depending on the degree of heterogeneity of the parents themselves. The F1 generation self-crossing results in the F2 generation, which will separate. The situation is even more complex. 4.2 The variation between the offspring and the parents shows microscopicality, gradualness, and multiplicity. 4.3 The variation between the offspring and the parents is random, without directionality. Without human intervention, it is not subject to the will of the organism itself. 4.4 The nucleotide sequences of the offspring after biological mutations can be inherited or separated again. The newly generated nucleotide sequences in the offspring can be fixed and passed on through appropriate inbreeding. Both good and bad traits can accumulate and be passed down from generation to generation. However, some nucleotide sequences are very conservative and do not change, while others may undergo re-separation or mutation, and the traits will also change accordingly. 4.5 The speed of various biological mutations varies. 4.6 Molecular genetics holds that genes do not have dominant and recessive traits, but there are DNA methylation and demethylation, as well as epigenetic phenomena. 4.7 Biological genomic variations are generally irreversible. 4.8 The same biological species will undergo nucleotide sequence variations in different living environments. The same species will have nucleotide sequence variations during their generations when they are in different altitudes and under different environmental conditions on Earth. The theory of species variation has extensive applications in the evolution of living beings. 5.1 It can provide a reasonable explanation for the causes of biodiversity on Earth. 5.2 During the 4.5 million-year evolution of humans, through hybridization, they have continuously changed their genetic structure to adapt to survival on Earth and to better adapt to the environment on Earth, resulting in longer life spans. 5.3 Humans have applied the theory of species variation not only to domesticate wild plants and animals into crops and livestock, changing their genetic structure, but also to continuously improve their yield and quality. 5.4 Microorganisms on Earth are also constantly undergoing variations. Studying the variations of harmful microorganisms to humans can enable humans to take preventive measures against them in advance, while studying the variations of beneficial microorganisms to humans can make them better serve humanity. 5.5 Applying the theory of biological hybridization to the variations of other lower species under lunar conditions is also very promising. It can accumulate data for humans to live on the moon. The issue of species variation and whether there will be a biological extinction on the Earth are two distinct matters.

Keywords: Species variation Genetics Gene Nucleotide Biodiversity.

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Citation: Wang, L. & Du, T. (2025). Species Variation is Irresistible. Adv Earth & Env Sci; 6(4):1-13.
DOI : https://doi.org/10.47485/2766-2624.1073