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What is 에볼루션 무료체험 ? Free evolution is the idea that the natural processes of organisms can lead them to evolve over time. This includes the appearance and growth of new species. This has been demonstrated by numerous examples such as the stickleback fish species that can be found in fresh or saltwater and walking stick insect varieties that have a preference for specific host plants. These reversible traits however, are not able to be the reason for fundamental changes in body plans. Evolution by Natural Selection The evolution of the myriad living creatures on Earth is a mystery that has intrigued scientists for many centuries. Charles Darwin's natural selectivity is the most well-known explanation. This process occurs when people who are more well-adapted have more success in reproduction and survival than those who are less well-adapted. Over time, the population of well-adapted individuals grows and eventually creates an entirely new species. Natural selection is an ongoing process and involves the interaction of three factors that are: reproduction, variation and inheritance. Sexual reproduction and mutation increase the genetic diversity of an animal species. Inheritance is the transfer of a person's genetic traits to his or her offspring, which includes both dominant and recessive alleles. Reproduction is the process of generating fertile, viable offspring. This can be done through sexual or asexual methods. All of these elements have to be in equilibrium to allow natural selection to take place. For instance, if the dominant allele of one gene allows an organism to live and reproduce more frequently than the recessive one, the dominant allele will become more prevalent within the population. If the allele confers a negative survival advantage or decreases the fertility of the population, it will disappear. This process is self-reinforcing, which means that the organism with an adaptive trait will survive and reproduce much more than those with a maladaptive feature. The more offspring an organism can produce the more fit it is, which is measured by its ability to reproduce itself and live. People with desirable traits, like a long neck in giraffes, or bright white color patterns on male peacocks are more likely to others to reproduce and survive, which will eventually lead to them becoming the majority. Natural selection is only an element in the population and not on individuals. This is a major distinction from the Lamarckian theory of evolution which claims that animals acquire characteristics by use or inactivity. For instance, if the animal's neck is lengthened by 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 no longer able to breed with other giraffes. Evolution by Genetic Drift Genetic drift occurs when alleles of a gene are randomly distributed in a group. At some point, one will attain fixation (become so widespread that it is unable to be eliminated through natural selection) and the other alleles drop to lower frequency. This can lead to dominance in extreme. The other alleles are virtually eliminated and heterozygosity decreased to a minimum. In a small population it could lead to the complete elimination of recessive alleles. This is known as the bottleneck effect and is typical of the evolution process that occurs when an enormous number of individuals move to form a population. A phenotypic bottleneck can also occur when survivors of a catastrophe such as an epidemic or mass hunting event, are condensed into a small area. The survivors will be mostly homozygous for the dominant allele which means they will all have the same phenotype, and consequently have the same fitness characteristics. This could be caused by war, earthquakes or even plagues. Whatever the reason, the genetically distinct population that remains is prone to genetic drift. Walsh Lewens, Walsh, 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 both genetically identical and have exactly the same phenotype. However one is struck by lightning and dies, whereas the other lives to reproduce. This kind of drift can be crucial in the evolution of an entire species. It is not the only method for evolution. The most common alternative is a process known as natural selection, in which the phenotypic variation of an individual is maintained through mutation and migration. Stephens claims that there is a huge difference between treating the phenomenon of drift as a force or cause, and treating other causes like selection mutation and migration as forces and causes. Stephens claims that a causal process account of drift permits us to differentiate it from the other forces, and this distinction is crucial. He also argues that drift is a directional force: that is, it tends to eliminate heterozygosity, and that it also has a size, which is determined by population size. Evolution through 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 generally referred to as “Lamarckism” and it states that simple organisms develop into more complex organisms through the inherited characteristics that are a result of the organism's natural actions use and misuse. Lamarckism can be illustrated by a giraffe extending its neck to reach higher branches in the trees. This would cause the necks of giraffes that are longer to be passed to their offspring, who would then become taller. Lamarck was a French zoologist and, in his inaugural lecture for his course on invertebrate Zoology at the Museum of Natural History in Paris on 17 May 1802, he presented a groundbreaking concept that radically challenged previous thinking about organic transformation. According to Lamarck, living things evolved from inanimate materials by a series of gradual steps. Lamarck was not the first to suggest that this could be the case but he is widely seen as having given the subject its first general and comprehensive analysis. The most popular story is that Charles Darwin's theory of evolution by natural selection and Lamarckism fought in the 19th century. Darwinism eventually prevailed which led to what biologists call the Modern Synthesis. This theory denies the possibility that acquired traits can be inherited and instead argues that organisms evolve through the selective action of environmental factors, such as natural selection. Lamarck and his contemporaries believed in the notion that acquired characters could be passed down to future generations. However, this notion was never a central part of any of their theories about evolution. This is due in part to the fact that it was never validated scientifically. But it is now more than 200 years since Lamarck was born and in the age genomics there is a vast amount of evidence to support the heritability of acquired traits. This is sometimes called “neo-Lamarckism” or, more frequently, epigenetic inheritance. This is a model that is as valid as the popular neodarwinian model. Evolution through Adaptation One of the most widespread misconceptions about evolution is that it is a result of a kind of struggle to survive. In fact, this view is inaccurate and overlooks the other forces that are driving evolution. The fight for survival can be more accurately described as a struggle to survive in a certain environment. This can be a challenge for not just other living things, but also the physical environment itself. To understand how evolution functions it is important to think about what adaptation is. It refers to a specific feature that allows an organism to survive and reproduce in its environment. It can be a physiological structure such as feathers or fur or a behavioral characteristic, such as moving into the shade in hot weather or stepping out at night to avoid the cold. The capacity of an organism to extract energy from its environment and interact with other organisms, as well as their physical environments is essential to its survival. The organism must possess the right genes to create offspring, and must be able to find sufficient food and other resources. Furthermore, the organism needs to be able to reproduce itself at a high rate within its environmental niche. 에볼루션 바카라 무료체험 , in conjunction with gene flow and mutation result in a change in the proportion of alleles (different types of a gene) in the gene pool of a population. This shift in the frequency of alleles can lead to the emergence of new traits, and eventually, new species over time. Many of the characteristics we admire in animals and plants are adaptations. For instance 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 proper understanding of adaptation requires attention to the distinction between physiological and behavioral characteristics. Physical traits such as thick fur and gills are physical characteristics. The behavioral adaptations aren't an exception, for instance, the tendency of animals to seek out companionship or to retreat into the shade in hot temperatures. It is also important to keep in mind that the absence of planning doesn't cause an adaptation. A failure to consider the effects of a behavior even if it appears to be rational, may make it unadaptive.