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What is Free Evolution? Free evolution is the concept that natural processes can cause organisms to develop over time. This includes the evolution of new species as well as the transformation of the appearance of existing ones. This is evident in numerous examples of stickleback fish species that can live in salt or fresh water, and walking stick insect species that prefer particular host plants. These are mostly reversible traits, however, cannot explain fundamental changes in basic body plans. Evolution by Natural Selection Scientists have been fascinated by the development of all living creatures that inhabit our planet for ages. Charles Darwin's natural selectivity is the best-established explanation. This happens when individuals who are better-adapted survive and reproduce more than those who are less well-adapted. As time passes, a group of well-adapted individuals increases and eventually becomes a new species. Natural selection is a process that is cyclical and involves the interaction of 3 factors: variation, reproduction and inheritance. Sexual reproduction and mutation increase the genetic diversity of a species. Inheritance is the term used to describe the transmission of a person's genetic characteristics, which includes recessive and dominant genes and their offspring. Reproduction is the process of creating viable, fertile offspring. This can be accomplished through sexual or asexual methods. Natural selection can only occur when all these elements are in equilibrium. For example when the dominant allele of a gene can cause an organism to live and reproduce more frequently than the recessive allele the dominant allele will become more common within the population. But if the allele confers an unfavorable survival advantage or reduces fertility, it will disappear from the population. This process is self-reinforcing which means that an organism with a beneficial trait is more likely to survive and reproduce than an individual with an inadaptive characteristic. The higher the level of fitness an organism has as measured by its capacity to reproduce and survive, is the more offspring it will produce. Individuals with favorable characteristics, such as having a long neck in the giraffe, or bright white color patterns on male peacocks, are more likely than others to live and reproduce and eventually lead to them becoming the majority. Natural selection is an aspect of populations and not on individuals. This is a major distinction from the Lamarckian theory of evolution, which claims that animals acquire traits through use or disuse. If a giraffe stretches its neck to reach prey, and the neck becomes longer, then the offspring will inherit this characteristic. The length difference between generations will persist until the giraffe's neck becomes so long that it can no longer breed with other giraffes. Evolution through Genetic Drift In genetic drift, alleles of a gene could reach different frequencies within a population due to random events. In the end, only one will be fixed (become widespread enough to not longer be eliminated by natural selection), and the other alleles will decrease in frequency. In extreme cases it can lead to dominance of a single allele. The other alleles are essentially eliminated and heterozygosity has decreased to a minimum. In a small number of people it could result in the complete elimination of the recessive gene. This scenario is called a bottleneck effect, and it is typical of the kind of evolutionary process that occurs when a large number of individuals move to form a new group. A phenotypic bottleneck can also happen when the survivors of a disaster such as an epidemic or mass hunt, are confined in a limited area. The surviving individuals will be largely homozygous for the dominant allele, which means they will all share the same phenotype and will thus have the same fitness characteristics. This may be the result of a war, earthquake, or even a plague. The genetically distinct population, if it remains susceptible to genetic drift. 에볼루션 사이트 , Walsh, and Ariew define drift as a departure from the expected value due to differences in fitness. They provide a well-known instance of twins who are genetically identical and have identical phenotypes, and yet one is struck by lightning and dies, whereas the other lives and reproduces. This type of drift can play a crucial part in the evolution of an organism. This isn't the only method for evolution. Natural selection is the most common alternative, in which mutations and migration keep the phenotypic diversity in a population. Stephens claims that there is a huge difference between treating the phenomenon of drift as a force or cause, and treating other causes like migration and selection mutation as forces and causes. He claims that a causal-process account of drift allows us distinguish it from other forces and that this distinction is essential. He argues further that drift has a direction, i.e., it tends to reduce heterozygosity. It also has a size that is determined by the size of the population. Evolution by Lamarckism In high school, students study biology they are often introduced to the work of Jean-Baptiste Lamarck (1744 – 1829). His theory of evolution is commonly called “Lamarckism” and it states that simple organisms develop into more complex organisms via the inheritance of traits that result from the natural activities of an organism use and misuse. Lamarckism is illustrated through an giraffe's neck stretching to reach higher branches in the trees. This could result in giraffes passing on their longer necks to their offspring, which then become taller. Lamarck was a French Zoologist. In his lecture to begin his course on invertebrate Zoology at the Museum of Natural History in Paris on the 17th May 1802, he presented an innovative concept that completely challenged the conventional wisdom about organic transformation. According to Lamarck, living things evolved from inanimate material through a series of gradual steps. Lamarck was not the first to suggest that this could be the case but the general consensus is that he was the one being the one who gave the subject its first broad and comprehensive treatment. The predominant story is that Charles Darwin's theory on natural selection and Lamarckism were rivals in the 19th century. Darwinism ultimately won which led to what biologists call the Modern Synthesis. This theory denies that acquired characteristics can be inherited, and instead, it argues that organisms develop by the symbiosis of environmental factors, like natural selection. Although Lamarck supported the notion of inheritance through acquired characters and his contemporaries also paid lip-service to this notion but it was not an integral part of any of their theories about evolution. This is largely due to the fact that it was never tested scientifically. It has been more than 200 year since Lamarck's birth and in the field of genomics there is a growing evidence-based body of evidence to support the heritability of acquired traits. This is referred to as “neo Lamarckism”, or more generally epigenetic inheritance. This is a variant that is as reliable as the popular Neodarwinian model. Evolution through adaptation One of the most widespread misconceptions about evolution is that it is driven by a sort of struggle to survive. This is a false assumption and ignores other forces driving evolution. The struggle for existence is more accurately described as a struggle to survive in a particular environment. This could include not just other organisms as well as the physical surroundings themselves. To understand how evolution works, it is helpful to consider what adaptation is. The term “adaptation” refers to any specific feature that allows an organism to live and reproduce in its environment. It can be a physiological structure, such as fur or feathers or a behavioral characteristic like moving into the shade in the heat or leaving at night to avoid cold. The capacity of an organism to extract energy from its surroundings and interact with other organisms as well as their physical environment, is crucial to its survival. The organism should possess the right genes to create offspring and to be able to access sufficient food and resources. The organism should also be able reproduce at the rate that is suitable for its specific niche. These factors, in conjunction with gene flow and mutations can result in an alteration in the ratio of different alleles in a population’s gene pool. This change in allele frequency can lead to the emergence of new traits, and eventually, new species as time passes. A lot of the traits we admire about animals and plants are adaptations, like lungs or gills to extract oxygen from the air, feathers or fur to provide insulation, long legs for running away from predators, and camouflage for hiding. To understand adaptation, it is important to differentiate between physiological and behavioral traits. Physiological adaptations like the thick fur or gills are physical traits, while behavioral adaptations, such as the tendency to search for companions or to retreat into the shade in hot weather, are not. In addition it is important to note that a lack of forethought does not mean that something is an adaptation. In fact, a failure to think about the consequences of a decision can render it ineffective despite the fact that it appears to be sensible or even necessary.