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What is Free Evolution? Free evolution is the notion that the natural processes of organisms can lead to their development over time. This includes the evolution of new species and alteration of the appearance of existing ones. A variety of examples have been provided of this, such as different kinds of stickleback fish that can be found in salt or fresh water, and walking stick insect varieties that prefer specific host plants. These mostly reversible trait permutations, however, cannot be the reason for fundamental changes in body plans. Evolution by Natural Selection Scientists have been fascinated by the development of all living creatures that live on our planet for ages. The most well-known explanation is that of Charles Darwin's natural selection, a process that occurs when individuals that are better adapted survive and reproduce more effectively than those who are less well adapted. Over time, the population of individuals who are well-adapted grows and eventually creates a new species. Natural selection is a process that is cyclical and involves the interaction of three factors including reproduction, variation and inheritance. Variation is caused by mutations and sexual reproduction both of which increase the genetic diversity of a species. Inheritance refers the transmission of a person's genetic traits, which include both dominant and recessive genes, to their offspring. Reproduction is the process of producing viable, fertile offspring. This can be accomplished through sexual or asexual methods. Natural selection only occurs when all the factors are in balance. If, for example an allele of a dominant gene causes an organism reproduce and survive more than the recessive gene then the dominant allele will become more prevalent in a population. If the allele confers a negative advantage to survival or decreases the fertility of the population, it will disappear. This process is self-reinforcing meaning that a species with a beneficial trait can reproduce and survive longer than an individual with a maladaptive trait. The more offspring an organism produces the better its fitness that is determined by its capacity to reproduce and survive. People with desirable traits, like a longer neck in giraffes and bright white color patterns in male peacocks, are more likely to survive and have offspring, and thus will become the majority of the population in the future. Natural selection is only an element in the population and not on individuals. This is an important distinction from the Lamarckian theory of evolution, which claims that animals acquire characteristics through use or neglect. For instance, if the giraffe's neck gets longer through stretching to reach for prey, its offspring will inherit a more long neck. The difference in neck size between generations will increase until the giraffe is unable to reproduce with other giraffes. Evolution through Genetic Drift Genetic drift occurs when alleles from a gene are randomly distributed in a group. At some point, only one of them will be fixed (become widespread enough to not longer be eliminated through natural selection), and the rest of the alleles will decrease in frequency. In extreme cases it can lead to a single allele dominance. The other alleles have been basically eliminated and heterozygosity has been reduced to a minimum. In a small group it could result in the complete elimination of recessive gene. Such a scenario would be known as a bottleneck effect and it is typical of the kind of evolutionary process when a large number of people migrate to form a new group. A phenotypic bottleneck could occur when the survivors of a catastrophe, such as an epidemic or a massive hunt, are confined in a limited area. The survivors will have a dominant allele and thus will share the same phenotype. This could be the result of a conflict, earthquake or even a cholera outbreak. The genetically distinct population, if it remains, could be susceptible to genetic drift. Walsh, Lewens, and Ariew utilize a “purely outcome-oriented” definition of drift as any departure from the expected values of different fitness levels. They provide a well-known instance of twins who are genetically identical and have identical phenotypes, but one is struck by lightning and dies, whereas the other lives and reproduces. This type of drift can play a very important role in the evolution of an organism. This isn't the only method for evolution. The most common alternative is a process called natural selection, in which the phenotypic variation of a population is maintained by mutation and migration. Stephens argues that there is a major difference between treating drift as a force or as a cause and considering other causes of evolution, such as selection, mutation and migration as forces or causes. He claims that a causal-process model of drift allows us to differentiate it from other forces and that this differentiation is crucial. He further argues that drift has a direction: that is it tends to eliminate heterozygosity. It also has a magnitude, that is determined by population size. Evolution by Lamarckism When students in high school study biology, they are often introduced to the work of Jean-Baptiste Lamarck (1744 – 1829). His theory of evolution is often called “Lamarckism” and it states that simple organisms develop into more complex organisms via the inheritance of characteristics that are a result of the organism's natural actions usage, use and disuse. Lamarckism is usually illustrated with a picture of a giraffe extending its neck longer to reach higher up in the trees. This could cause the necks of giraffes that are longer to be passed on to their offspring who would then grow even taller. Lamarck, a French zoologist, presented an innovative idea in his opening lecture at the Museum of Natural History of Paris. He challenged the traditional thinking about organic transformation. According to him, living things had evolved from inanimate matter through a series of gradual steps. Lamarck wasn't the only one to make this claim but he was thought of as the first to give the subject a comprehensive and general overview. The popular narrative is that Lamarckism became an opponent to Charles Darwin's theory of evolution through natural selection and both theories battled out in the 19th century. Darwinism ultimately won, leading to what biologists call the Modern Synthesis. The theory argues the possibility that acquired traits can be inherited, and instead argues that organisms evolve by the symbiosis of environmental factors, such as natural selection. While Lamarck endorsed the idea of inheritance by acquired characters, and his contemporaries also spoke of this idea but it was not a central element 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 Lamarck was born and in the age genomics, there is a large amount of evidence that supports the heritability of acquired characteristics. This is sometimes called “neo-Lamarckism” or, more frequently, epigenetic inheritance. This is a variant that is as reliable as the popular neodarwinian model. Evolution through adaptation One of the most commonly-held misconceptions about evolution is that it is being driven by a fight for survival. In fact, this view is a misrepresentation of natural selection and ignores the other forces that are driving evolution. The struggle for existence is better described as a struggle to survive in a certain environment. This could include not only other organisms but also the physical surroundings themselves. To understand how evolution operates it is important to understand what is adaptation. 에볼루션 슬롯 refers to any particular feature that allows an organism to live and reproduce within its environment. It can be a physical structure, like fur or feathers. It could also be a trait of behavior, like moving into the shade during hot weather, or moving out to avoid the cold at night. The capacity of an organism to extract energy from its surroundings and interact with other organisms, as well as their physical environment is essential to its survival. The organism needs to have the right genes to generate offspring, and must be able to find sufficient food and other resources. The organism must be able to reproduce at the rate that is suitable for its particular niche. These factors, along with gene flow and mutation result in changes in the ratio of alleles (different forms of a gene) in the gene pool of a population. The change in frequency of alleles can lead to the emergence of novel traits and eventually, new species over time. Many of the features we find appealing in plants and animals are adaptations. For example the lungs or gills which draw oxygen from air feathers and fur as insulation, long legs to run away from predators, and camouflage to hide. However, a thorough understanding of adaptation requires attention to the distinction between the physiological and behavioral characteristics. Physiological adaptations like thick fur or gills, are physical traits, whereas behavioral adaptations, like the desire to find companions or to move to shade in hot weather, aren't. It is important to keep in mind that insufficient planning does not result in an adaptation. A failure to consider the effects of a behavior even if it seems to be logical, can make it unadaptive.