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What is Free Evolution?
Free evolution is the idea that the natural processes of organisms can lead to their development over time. This includes the appearance and growth of new species.
(image: <a href="https://evolutionkr.kr/wp-content/uploads/2024/12/B4EAA0A7EC90B3EAB58BEA91B3EC80-97EBBCB3EC9D.png)Numerous examples have been offered of this, including different varieties of stickleback fish that can be found in fresh or salt water and walking stick insect varieties that prefer specific host plants. These reversible traits, however, cannot explain fundamental changes in body plans.
Evolution by Natural Selection
The development of the myriad living creatures on Earth is an enigma that has fascinated scientists for decades. The most widely accepted explanation is Darwin's natural selection process, a process that occurs when individuals that are better adapted survive and reproduce more effectively than those that are less well adapted. As time passes, the number of individuals who are well-adapted grows and eventually develops into an entirely new species.
Natural selection is an ongoing process that is characterized by the interaction of three factors that are inheritance, variation and reproduction. Sexual reproduction and mutations increase the genetic diversity of a species. Inheritance refers the transmission of genetic traits, which include recessive and dominant genes, to their offspring. Reproduction is the process of creating viable, fertile offspring. This can be done through sexual or asexual methods.
All of these elements must be in balance to allow natural selection to take place. For example, if an allele that is dominant at one gene can cause an organism to live and reproduce more frequently than the recessive one, the dominant allele will become more prominent in the population. However, if the allele confers a disadvantage in survival or reduces fertility, it will be eliminated from the population. The process is self-reinforcing, which means that an organism with a beneficial characteristic is more likely to survive and reproduce than one with an unadaptive characteristic. The more offspring that an organism has, the greater its fitness that is determined by its ability to reproduce and survive. Individuals with favorable traits, like having a longer neck in giraffes or bright white color patterns in male peacocks are more likely survive and have offspring, and thus will become the majority of the population over time.
Natural selection only acts on populations, not individuals. This is a significant distinction from the Lamarckian theory of evolution that states that animals acquire traits either through usage or inaction. For instance, if the Giraffe's neck grows longer due to stretching to reach prey its offspring will inherit a more long neck. The length difference between generations will persist until the neck of the giraffe becomes too long to not breed with other giraffes.
Evolution through Genetic Drift
Genetic drift occurs when alleles from a gene are randomly distributed in a population. At some point, one will reach fixation (become so widespread that it cannot be removed through natural selection), while other alleles fall to lower frequencies. This can lead to an allele that is dominant in extreme. The other alleles are eliminated, and heterozygosity decreases to zero. In a small number of people, this could lead to the total elimination of recessive allele. Such a scenario would be known as a bottleneck effect and it is typical of evolutionary process that occurs when a lot of individuals move to form a new group.
A phenotypic bottleneck may occur when survivors of a disaster such as an epidemic or a massive hunt, are confined into a small area. The surviving individuals will be largely homozygous for the dominant allele which means they will all share the same phenotype, and consequently have the same fitness traits. This may be caused by conflict, earthquake or even a disease. Regardless of the cause, the genetically distinct population that remains is susceptible to genetic drift.
Walsh, Lewens and Ariew define drift as a departure from the expected value due to differences in fitness. They give the famous example of twins who are genetically identical and have exactly the same phenotype. However one is struck by lightning and dies, but the other is able to reproduce.
This kind of drift could be vital to the evolution of a species. It is not the only method for evolution. Natural selection is the primary alternative, where mutations and migration maintain the phenotypic diversity in the population.
Stephens argues there is a vast difference between treating drift like an agent or cause and treating other causes like migration and selection mutation as causes and forces. He argues that a causal process explanation of drift permits us to differentiate it from these other forces, and this distinction is crucial. He further argues that drift has a direction: that is, it tends to eliminate heterozygosity, and that it also has a magnitude, which is determined by the size of population.
Evolution by Lamarckism
Students of biology in high school are often introduced to Jean-Baptiste Lemarck's (1744-1829) work. His theory of evolution is often known as "Lamarckism" and it states that simple organisms grow into more complex organisms via the inherited characteristics that are a result of the natural activities of an organism use and misuse. Lamarckism can be demonstrated by a giraffe extending its neck to reach higher levels of leaves in the trees. This causes the longer necks of giraffes to be passed onto their offspring who would then become taller.
Lamarck the French zoologist, presented an idea that was revolutionary in his opening lecture at the Museum of Natural History of Paris. He challenged traditional thinking about organic transformation. According Lamarck, living organisms evolved from inanimate material through a series of gradual steps. Lamarck was not the first to propose this but he was thought of as the first to offer the subject a comprehensive and general explanation.
The most popular story is that Charles Darwin's theory on evolution by natural selection and Lamarckism were rivals in the 19th century. Darwinism eventually prevailed and led to the creation of what biologists refer to as the Modern Synthesis. The Modern Synthesis theory denies that traits acquired through evolution can be acquired through inheritance and instead, it argues that organisms develop by the symbiosis of environmental factors, like natural selection.
While Lamarck supported the notion of inheritance through acquired characters, and his contemporaries also spoke of this idea however, it was not a major feature in any of their evolutionary theorizing. This is due in part to the fact that it was never validated scientifically.
It's been more than 200 years since the birth of Lamarck and in the field of age genomics, there is an increasing evidence-based body of evidence to support the heritability of acquired traits. This is sometimes called "neo-Lamarckism" or, more often epigenetic inheritance. This is a model that is just as valid as the popular Neodarwinian model.
Evolution through adaptation
One of the most common misconceptions about evolution is that it is a result of a kind of struggle for survival. In fact, this view misrepresents natural selection and ignores the other forces that determine the rate of evolution. The struggle for existence is better described as a struggle to survive in a particular environment. This may include not only other organisms but also the physical surroundings themselves.
Understanding how adaptation works is essential to understand evolution. Adaptation refers to any particular characteristic that allows an organism to live and reproduce within its environment. It can be a physiological structure, such as feathers or fur or a behavioral characteristic, such as moving into shade in hot weather or coming out at night to avoid cold.
The capacity of an organism to extract energy from its surroundings and interact with other organisms and their physical environment, is crucial to its survival. The organism must have the right genes to generate offspring, and it should be able to locate sufficient food and other resources. The organism should also be able reproduce itself at the rate that is suitable for its niche.
These elements, along with mutations and gene flow can result in an alteration in the ratio of different alleles within a population’s gene pool. This shift in the frequency of alleles can result in the emergence of novel traits and eventually new species in the course of time.
A lot of the traits we admire in animals and plants are adaptations, such as lung or gills for removing oxygen from the air, feathers or fur to protect themselves long legs to run away from predators, and camouflage for hiding. However, a thorough understanding of adaptation requires a keen eye to the distinction between the physiological and behavioral traits.
Physical characteristics like the thick fur and gills are physical traits. The behavioral adaptations aren't, such as the tendency of animals to seek out companionship or to retreat into the shade during hot temperatures. It is also important to keep in mind that lack of planning does not make an adaptation. In fact, a failure to think about the consequences of a behavior can make it unadaptable despite the fact that it may appear to be reasonable or even essential. (image: https://evolutionkr.kr/wp-content/uploads/2022/04/Depositphotos_218520288_XL-scaled.jpg)
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