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What is Free Evolution? Free evolution is the idea that the natural processes of organisms can lead them to evolve over time. This includes the evolution of new species and transformation of the appearance of existing species. This has been demonstrated by many examples, including stickleback fish varieties that can thrive in fresh or saltwater and walking stick insect varieties that are apprehensive about particular host plants. These reversible traits however, are not able to explain fundamental changes in body plans. Evolution by Natural Selection The development of the myriad living creatures on Earth is a mystery that has fascinated scientists for decades. The most widely accepted explanation is that of Charles Darwin's natural selection process, a process that occurs when better-adapted individuals survive and reproduce more effectively than those that are less well adapted. As time passes, a group of well-adapted individuals increases and eventually becomes a new species. Natural selection is an ongoing process that is characterized by the interaction of three elements that are inheritance, variation and reproduction. Sexual reproduction and mutations increase genetic diversity in an animal species. Inheritance is the passing of a person's genetic characteristics to his or her offspring that includes dominant and recessive alleles. Reproduction is the process of generating viable, fertile offspring. This can be accomplished by both asexual or sexual methods. All of these elements have to be in equilibrium for natural selection to occur. For example when an allele that is dominant at a gene causes an organism to survive and reproduce more often than the recessive allele, the dominant allele will be more common in the population. However, if the gene confers a disadvantage in survival or reduces fertility, it will be eliminated from the population. This process is self-reinforcing meaning that a species with a beneficial characteristic can reproduce and survive longer than an individual with a maladaptive trait. The more offspring an organism produces the better its fitness which is measured by its capacity to reproduce itself and survive. Individuals with favorable traits, like having a longer neck in giraffes, or bright white patterns of color in male peacocks are more likely be able to survive and create offspring, so they will become the majority of the population in the future. Natural selection is only 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. For instance, if a animal's neck is lengthened by stretching to reach for prey, its offspring will inherit a longer neck. The differences in neck size between generations will increase until the giraffe is unable to breed with other giraffes. Evolution through Genetic Drift Genetic drift occurs when the alleles of one gene are distributed randomly in a population. Eventually, only one will be fixed (become common enough that it can no longer be eliminated through natural selection), and the rest of the alleles will diminish in frequency. This can result in a dominant allele in the extreme. The other alleles are essentially eliminated, and heterozygosity decreases to zero. In a small group this could lead to the complete elimination the 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 individuals migrate to form a new group. A phenotypic bottleneck can also occur when survivors of a disaster such as an outbreak or mass hunting incident are concentrated in an area of a limited size. The survivors will share a dominant allele and thus will share the same phenotype. This could be caused by war, earthquakes, or even plagues. The genetically distinct population, if left vulnerable to genetic drift. Walsh, Lewens, and Ariew utilize a “purely outcome-oriented” definition of drift as any deviation from expected values for different fitness levels. They give the famous example of twins who are genetically identical and have exactly the same phenotype, but one is struck by lightning and dies, whereas the other is able to reproduce. This type of drift is vital to the evolution of the species. However, it is not the only method to develop. Natural selection is the most common alternative, in which mutations and migrations maintain phenotypic diversity within a population. Stephens claims that there is a significant distinction between treating drift as a force, or a cause and considering other causes of evolution such as selection, mutation and migration as causes or causes. Stephens claims that a causal process explanation of drift lets us separate it from other forces and this distinction is crucial. He argues further that drift has both an orientation, i.e., it tends towards eliminating heterozygosity. It also has a size 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, often referred to as “Lamarckism which means that simple organisms develop into more complex organisms through adopting traits that are a product of the organism's use and misuse. Lamarckism is typically illustrated with an image of a giraffe stretching its neck to reach the higher branches in the trees. This causes the longer necks of giraffes to be passed on to their offspring who would then become taller. Lamarck Lamarck, a French zoologist, presented an innovative idea in his 17 May 1802 opening lecture at the Museum of Natural History of Paris. He challenged previous thinking on organic transformation. In his view living things evolved from inanimate matter through the gradual progression of events. Lamarck was not the only one to suggest that this could be the case but he is widely seen as having given the subject his first comprehensive and comprehensive analysis. The popular narrative is that Lamarckism was a rival to Charles Darwin's theory of evolution by natural selection and that the two theories battled it out 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 the possibility that acquired traits can be inherited, and instead suggests that organisms evolve through the selective action of environmental factors, like natural selection. Although Lamarck believed in the concept of inheritance through acquired characters and his contemporaries also paid lip-service to this notion however, it was not an integral part of any of their evolutionary theories. This is due to the fact that it was never scientifically validated. However, it has been more than 200 years since Lamarck was born and in the age of genomics there is a vast body of evidence supporting the possibility of inheritance of acquired traits. This is also known as “neo Lamarckism”, or more often epigenetic inheritance. This is a version that is just 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. This notion is not true and overlooks other forces that drive evolution. The struggle for survival is more precisely described as a fight to survive in a specific environment, which could be a struggle that involves not only other organisms but also the physical environment. Understanding how adaptation works is essential to understand evolution. Adaptation is any feature that allows a living thing to live in its environment and reproduce. It could 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 the cold. An organism's survival depends on its ability to draw energy from the environment and interact with other organisms and their physical environments. The organism must possess the right genes for producing offspring and to be able to access enough food and resources. In addition, the organism should be capable of reproducing at a high rate within its environmental niche. These factors, together with gene flow and mutations, can lead to changes in the proportion of different alleles within the gene pool of a population. As time passes, this shift in allele frequencies could result in the emergence of new traits and ultimately new species. Many of the characteristics we find appealing in plants and animals are adaptations. For example lung or gills that draw oxygen from air feathers and fur for insulation, long legs to run away from predators and camouflage for hiding. However, a proper understanding of adaptation requires attention to the distinction between physiological and behavioral traits. Physiological adaptations, such as the thick fur or gills are physical traits, whereas behavioral adaptations, like the tendency to search for companions or to move to the shade during hot weather, are not. It is important to keep in mind that the absence of planning doesn't make an adaptation. 에볼루션 to consider the consequences of a decision even if it appears to be rational, may cause it to be unadaptive.