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What is Free Evolution? Free evolution is the notion that the natural processes of organisms can lead them to evolve over time. This includes the evolution of new species and the transformation of the appearance of existing ones. This has been demonstrated by many examples such as the stickleback fish species that can live in fresh or saltwater and walking stick insect species that prefer specific host plants. These typically reversible traits do not explain the fundamental changes in the body's basic plans. Evolution by Natural Selection The development of the myriad of living creatures on Earth is an enigma that has fascinated scientists for decades. Charles Darwin's natural selection theory is the best-established explanation. This process occurs when people who are more well-adapted survive and reproduce more than those who are less well-adapted. As time passes, a group of well-adapted individuals increases and eventually forms a whole new species. Natural selection is a cyclical process that is characterized by the interaction of three elements: variation, inheritance and reproduction. Variation is caused by mutation and sexual reproduction both of which enhance the genetic diversity within the species. Inheritance is the passing of a person's genetic traits to the offspring of that person that includes recessive and dominant alleles. Reproduction is the process of producing viable, fertile offspring. This can be achieved through sexual or asexual methods. All of these elements have to be in equilibrium for natural selection to occur. If, for example, a dominant gene allele causes an organism reproduce and survive more than the recessive gene allele, then the dominant allele is more common in a population. But if the allele confers an unfavorable survival advantage or reduces fertility, it will be eliminated from the population. This process is self-reinforcing meaning that an organism with a beneficial characteristic can reproduce and survive longer than one with an unadaptive characteristic. The more offspring an organism produces the better its fitness which is measured by its ability to reproduce itself and survive. 에볼루션바카라사이트 with favorable traits, like longer necks in giraffes, or bright white patterns of color in male peacocks are more likely survive and produce offspring, and thus will make up the majority of the population in the future. Natural selection is an aspect of populations and not on individuals. This is an important distinction from the Lamarckian theory of evolution, which argues that animals acquire traits through use or neglect. For instance, if the Giraffe's neck grows longer due to stretching to reach prey its offspring will inherit a longer neck. The differences in neck size between generations will continue to grow until the giraffe becomes unable to reproduce with other giraffes. Evolution through Genetic Drift In genetic drift, alleles at a gene may reach different frequencies in a population by chance events. Eventually, only one will be fixed (become widespread enough to not more be eliminated through natural selection), and the other alleles decrease in frequency. In extreme cases it can lead to one allele dominance. Other alleles have been basically eliminated and heterozygosity has been reduced to zero. In a small population, this could lead to the total elimination of recessive allele. This is called a bottleneck effect, and it is typical of the kind of evolutionary process that occurs when a large amount of individuals migrate to form a new group. A phenotypic bottleneck may occur when the survivors of a disaster, such as an epidemic or a mass hunt, are confined into a small area. The survivors are likely to be homozygous for the dominant allele, which means they will all have the same phenotype, and therefore have the same fitness characteristics. This may be the result of a war, earthquake or even a disease. Regardless of the cause the genetically distinct population that remains could be susceptible to genetic drift. Walsh, Lewens and Ariew define drift as a departure from expected values due to differences in fitness. They provide the famous case of twins that are genetically identical and have exactly the same phenotype. However, one is struck by lightning and dies, but the other continues to reproduce. 에볼루션 바카라 of drift is crucial in the evolution of an entire species. It is not the only method of evolution. Natural selection is the most common alternative, in which mutations and migration maintain the phenotypic diversity of a population. Stephens asserts that there is a significant difference between treating the phenomenon of drift as an actual cause or force, and considering other causes, such as selection mutation and migration as causes and forces. He claims that a causal-process model of drift allows us to separate it from other forces and this differentiation is crucial. He also argues that drift has both direction, i.e., it tends to eliminate heterozygosity. It also has a size that is determined by population size. Evolution through 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, commonly referred to as “Lamarckism is based on the idea that simple organisms evolve into more complex organisms through taking on traits that are a product of the use and abuse of an organism. Lamarckism can be demonstrated by the giraffe's neck being extended to reach higher branches in the trees. This could cause giraffes' longer necks to be passed to their offspring, who would then become taller. Lamarck Lamarck, a French Zoologist, introduced 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 to Lamarck, living things evolved from inanimate materials by a series of gradual steps. Lamarck wasn't the only one to make this claim, but he was widely thought of as the first to offer the subject a comprehensive and general explanation. The most popular story is that Lamarckism was a rival to Charles Darwin's theory of evolution by natural selection and both theories battled each other in the 19th century. Darwinism eventually won and led to the creation of what biologists now call the Modern Synthesis. The theory denies that acquired characteristics can be passed down through generations and instead, it claims that organisms evolve through the influence of environment elements, like Natural Selection. Although Lamarck supported the notion of inheritance by acquired characters and his contemporaries spoke of this idea, it was never an integral part of any of their evolutionary theories. This is partly because it was never scientifically tested. It's been more than 200 years since the birth of Lamarck, and in the age genomics, there is an increasing evidence base that supports the heritability-acquired characteristics. It is sometimes referred to as “neo-Lamarckism” or more frequently, epigenetic inheritance. It is a version of evolution that is just as valid as the more well-known Neo-Darwinian model. Evolution through the process of adaptation One of the most commonly-held misconceptions about evolution is that it is being driven by a struggle to survive. This is a false assumption and ignores other forces driving evolution. The struggle for survival is more precisely described as a fight to survive within a specific environment, which could be a struggle that involves not only other organisms, but also the physical environment. To understand how evolution functions it is beneficial to understand what is adaptation. The term “adaptation” refers to any specific feature 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 like moving into the shade in hot weather or stepping out at night to avoid the cold. An organism's survival depends on its ability to extract energy from the surrounding environment and interact with other living organisms and their physical surroundings. The organism must possess the right genes to produce offspring, and it should be able to find sufficient food and other resources. In addition, the organism should be capable of reproducing at a high rate within its environment. These factors, in conjunction with gene flow and mutations, can lead to an alteration in the ratio of different alleles within a population’s gene pool. As time passes, this shift in allele frequency can result in the emergence of new traits, and eventually new species. A lot of the traits we appreciate in animals and plants are adaptations. For instance the lungs or gills which extract oxygen from air feathers and fur as insulation, long legs to run away from predators, and camouflage to hide. To understand adaptation it is essential to differentiate between physiological and behavioral traits. Physiological adaptations, like thick fur or gills, are physical characteristics, whereas behavioral adaptations, such as the tendency to search for companions or to move to the shade during hot weather, are not. It is also important to keep in mind that insufficient planning does not make an adaptation. In fact, failing to consider the consequences of a choice can render it unadaptable despite the fact that it appears to be sensible or even necessary.