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What is Free Evolution? Free evolution is the idea that natural processes can cause organisms to develop over time. This includes the emergence and development of new species. Many examples have been given of this, including different varieties of stickleback fish that can live in either salt or fresh water, and walking stick insect varieties that are attracted to specific host plants. These reversible traits cannot explain fundamental changes to the body's basic plans. Evolution through Natural Selection Scientists have been fascinated by the development of all the living creatures that inhabit our planet for centuries. Charles Darwin's natural selection theory is the most well-known explanation. This process occurs when individuals who are better-adapted have more success in reproduction and survival than those who are less well-adapted. Over time, the population of well-adapted individuals becomes larger and eventually creates an entirely new species. Natural selection is a process that is cyclical and involves the interaction of three factors: variation, reproduction and inheritance. Variation is caused by mutations and sexual reproduction, both of which increase the genetic diversity of an animal species. Inheritance refers the transmission of a person’s genetic traits, which include both dominant and recessive genes, to their offspring. Reproduction is the generation of viable, fertile offspring, which includes both sexual and asexual methods. Natural selection can only occur when all the factors are in balance. If, for example an allele of a dominant gene makes an organism reproduce and live longer than the recessive gene The dominant allele becomes more prevalent in a population. If the allele confers a negative survival advantage or lowers the fertility of the population, it will disappear. The process is self-reinforcing, meaning that a species with a beneficial characteristic can reproduce and survive longer than an individual with an inadaptive characteristic. The more offspring that an organism has, the greater its fitness that is determined by its ability to reproduce itself and live. People with desirable traits, such as longer necks in giraffes, or bright white colors in male peacocks are more likely survive and have offspring, which means they will become the majority of the population in the future. Natural selection is only a force for populations, not on individual organisms. This is a major distinction from the Lamarckian theory of evolution which states that animals acquire traits through use or disuse. For example, if a Giraffe's neck grows longer due to stretching to reach for prey, its offspring will inherit a longer neck. The differences in neck size between generations will continue to increase until the giraffe is no longer able to reproduce with other giraffes. Evolution through Genetic Drift In genetic drift, the alleles at a gene may be at different frequencies in a group through random events. Eventually, 에볼루션 룰렛 of them will attain fixation (become so widespread that it is unable to be removed through natural selection), while other alleles will fall to lower frequencies. This can result in a dominant allele in the extreme. The other alleles are eliminated, and heterozygosity decreases to zero. In a small number of people this could result in the total elimination of recessive allele. This is called a bottleneck effect, and it is typical of the kind of evolutionary process when a large amount of individuals move to form a new population. A phenotypic 'bottleneck' can also occur when the survivors of a catastrophe such as an outbreak or mass hunting event are confined to an area of a limited size. The remaining individuals will be mostly homozygous for the dominant allele meaning that they all have the same phenotype, and thus have the same fitness characteristics. This may be caused by a conflict, earthquake or even a disease. The genetically distinct population, if it remains, could be susceptible to genetic drift. Walsh Lewens, Walsh, and Ariew define drift as a departure from the expected values due to differences in fitness. They provide the famous case of twins that are genetically identical and have exactly the same phenotype, but one is struck by lightning and dies, whereas the other lives to reproduce. This type of drift can play a significant role in the evolution of an organism. However, it is not the only method to progress. Natural selection is the primary alternative, in which mutations and migration maintain the phenotypic diversity of the population. Stephens claims that there is a major distinction between treating drift as a force or a cause and treating other causes of evolution like mutation, selection, and migration as forces or causes. Stephens claims that a causal process model of drift allows us to separate it from other forces and that this differentiation is crucial. He argues further that drift is both a direction, i.e., it tends to reduce 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 is generally known as “Lamarckism” and it states that simple organisms grow into more complex organisms via the inheritance of traits that are a result of the organism's natural actions, use and disuse. Lamarckism can be demonstrated by a giraffe extending its neck to reach higher branches in the trees. This would cause giraffes to give their longer necks to offspring, who would then grow even 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 an original idea that fundamentally challenged the conventional wisdom about organic transformation. In his opinion living things had evolved from inanimate matter via a series of gradual steps. Lamarck was not the first to suggest that this might be the case but the general consensus is that he was the one giving the subject its first general and comprehensive treatment. The popular narrative is that Lamarckism was an opponent to Charles Darwin's theory of evolution through natural selection and both theories battled it out in the 19th century. Darwinism eventually prevailed, leading to what biologists refer to as the Modern Synthesis. The theory argues that acquired traits can be passed down and instead, it claims that organisms evolve through the selective action of environment elements, like Natural Selection. Lamarck and his contemporaries supported the notion that acquired characters could be passed on to future generations. However, this concept was never a key element of any of their evolutionary theories. This is due to the fact that it was never scientifically tested. 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 acquired characteristics. This is often referred to as “neo-Lamarckism” or, more often epigenetic inheritance. This is a model that is just as valid as the popular neodarwinian model. Evolution by adaptation One of the most popular misconceptions about evolution is that it is driven by a type of struggle for survival. In reality, this notion is a misrepresentation of natural selection and ignores the other forces that are driving evolution. The fight for survival is more accurately described as a struggle to survive in a certain environment. This may be a challenge for not just other living things but also the physical environment itself. To understand how evolution works it is beneficial to think about what adaptation is. It refers to a specific characteristic that allows an organism to live and reproduce in its environment. It can be a physical structure like fur or feathers. Or it can be a behavior trait, like moving to the shade during hot weather or escaping the cold at night. The ability of an organism to extract energy from its surroundings and interact with other organisms, as well as their physical environments is essential to its survival. The organism must possess the right genes for producing offspring and be able find enough food and resources. The organism should also be able reproduce at a rate that is optimal for its niche. These factors, along with gene flow and mutation result in a change in the proportion of alleles (different types of a gene) in the population's gene pool. The change in frequency of alleles could lead to the development of new traits, and eventually, new species over time. Many of the features that we admire about animals and plants are adaptations, like the lungs or gills that extract oxygen from the air, feathers or fur for insulation long legs to run away from predators and camouflage for hiding. To comprehend adaptation, it is important to differentiate between physiological and behavioral characteristics. Physiological adaptations, such as thick fur or gills, are physical traits, whereas behavioral adaptations, like the tendency to seek out companions or to retreat to the shade during hot weather, are not. Furthermore, it is important to note that a lack of thought does not mean that something is an adaptation. In fact, failure to think about the implications of a behavior can make it unadaptable despite the fact that it might appear reasonable or even essential.