What is Free Evolution? Free evolution is the concept that natural processes can cause organisms to evolve over time. This includes the appearance and development of new species. This has been demonstrated by many examples, including stickleback fish varieties that can live in salt or fresh water, and walking stick insect species that are apprehensive about particular host plants. These are mostly reversible traits can't, however, explain fundamental changes in basic body plans. Evolution through Natural Selection The development of the myriad of living creatures on Earth is a mystery that has intrigued scientists for centuries. Charles Darwin's natural selectivity is the most well-known explanation. ???? ??? ?? is because those who are better adapted have more success in reproduction and survival than those who are less well-adapted. As time passes, the number of individuals who are well-adapted grows and eventually forms an entirely new species. Natural selection is a cyclical process that involves the interaction of three elements that are inheritance, variation and reproduction. Variation is caused by mutation and sexual reproduction both of which increase the genetic diversity of a species. Inheritance refers to the passing of a person's genetic traits to the offspring of that person, which includes both dominant and recessive alleles. 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 equilibrium. If, for instance, a dominant gene allele causes an organism reproduce and last longer than the recessive allele then the dominant allele becomes more prevalent in a population. However, if the gene confers an unfavorable survival advantage or decreases fertility, it will disappear from the population. This process is self-reinforcing meaning that an organism with a beneficial characteristic will survive and reproduce more than one with a maladaptive characteristic. The more offspring an organism produces the more fit it is, which is measured by its capacity to reproduce itself and live. People with good traits, like the long neck of the giraffe, or bright white color patterns on male peacocks are more likely than others to reproduce and survive and eventually lead to them becoming the majority. Natural selection is only a factor in populations and not on individuals. This is a major distinction from the Lamarckian evolution theory, which states that animals acquire traits either through use or lack of use. For example, if a Giraffe's neck grows longer due to stretching to reach prey, its offspring will inherit a larger neck. The difference in neck length between generations will continue until the giraffe's neck gets too long to no longer breed with other giraffes. Evolution through Genetic Drift Genetic drift occurs when the alleles of one gene are distributed randomly in a population. At some point, one will attain fixation (become so common that it is unable to be eliminated through natural selection), while the other alleles drop to lower frequencies. This can result in a dominant allele at the extreme. The other alleles are basically eliminated and heterozygosity has diminished to zero. In a small group this could lead to the complete elimination of the recessive gene. This is called a bottleneck effect, and it is typical of the kind of evolutionary process when a large number of people migrate to form a new population. A phenotypic bottleneck could occur when the survivors of a catastrophe, such as an epidemic or mass hunting event, are concentrated into a small area. The remaining individuals will be largely homozygous for the dominant allele which means that they will all have the same phenotype, and therefore have the same fitness characteristics. This may be caused by war, an earthquake or even a cholera outbreak. Whatever the reason, the genetically distinct population that is left might be prone to genetic drift. Walsh Lewens, Lewens, and Ariew use Lewens, Walsh, and Ariew use a "purely outcome-oriented" definition of drift as any departure from the expected values of 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, while the other is able to reproduce. This type of drift is vital to the evolution of an entire species. It is not the only method for evolution. Natural selection is the main alternative, where mutations and migrations maintain the phenotypic diversity of the population. Stephens asserts that there is a big difference between treating the phenomenon of drift as a force or an underlying cause, and considering other causes of evolution like selection, mutation, and migration as forces or causes. He claims that a causal-process account of drift allows us differentiate it from other forces, and this distinction is essential. He further argues that drift has a direction, that is it tends to reduce heterozygosity, and that it also has a specific magnitude which is determined by the size of the population. Evolution through Lamarckism Students of biology in high school are often introduced to Jean-Baptiste Lamarck's (1744-1829) work. His theory of evolution is commonly referred to as "Lamarckism" and it states that simple organisms develop into more complex organisms by the inheritance of characteristics that result from the organism's natural actions use and misuse. Lamarckism is typically illustrated with a picture of a giraffe stretching its neck further to reach higher up in the trees. This would cause giraffes' longer necks to be passed to their offspring, who would then grow even taller. Lamarck was a French zoologist and, in his opening lecture for his course on invertebrate Zoology at the Museum of Natural History in Paris on the 17th of May in 1802, he presented a groundbreaking concept that radically challenged the conventional wisdom about organic transformation. According to Lamarck, living things evolved from inanimate matter through a series gradual steps. Lamarck was not the first to make this claim but he was regarded as the first to provide the subject a comprehensive and general treatment. The popular narrative is that Lamarckism was a rival to Charles Darwin's theory of evolutionary natural selection and that the two theories fought it out in the 19th century. Darwinism eventually prevailed, leading to the development of what biologists refer to as the Modern Synthesis. The theory argues that acquired traits can be passed down and instead argues that organisms evolve through the influence of environment factors, such as Natural Selection. Lamarck and his contemporaries believed in the notion that acquired characters could be passed down to the next generation. However, this notion was never a central part of any of their evolutionary theories. This is due to the fact that it was never scientifically validated. It's been more than 200 years since Lamarck was born and in the age of genomics there is a vast amount of evidence that supports the heritability of acquired traits. This is also referred to as "neo Lamarckism", or more often epigenetic inheritance. This is a version 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. This is a false assumption and overlooks other forces that drive evolution. The fight for survival can be better described as a fight to survive in a particular environment. This may be a challenge for not just other living things, but also the physical environment itself. Understanding adaptation is important to understand evolution. The term "adaptation" refers to any specific feature that allows an organism to survive and reproduce in its environment. It could be a physical feature, like feathers or fur. It could also be a behavior trait that allows you to move into the shade during hot weather, or escaping the cold at night. The survival of an organism is dependent on its ability to draw energy from the environment and interact with other organisms and their physical environments. The organism should possess the right genes for producing offspring and be able find sufficient food and resources. The organism should also be able reproduce itself at an amount that is appropriate for its particular niche. These elements, in conjunction with gene flow and mutation result in a change in the proportion of alleles (different varieties of a particular gene) in the gene pool of a population. Over time, this change in allele frequencies could result in the development of new traits and ultimately new species. A lot of the traits we admire in animals and plants are adaptations, like lung or gills for removing oxygen from the air, feathers or fur for insulation, long legs for running away from predators and camouflage to hide. However, a proper understanding of adaptation requires attention to the distinction between the physiological and behavioral characteristics. Physiological adaptations, such as thick fur or gills are physical characteristics, whereas behavioral adaptations, like the tendency to seek out friends or to move to shade in hot weather, are not. It is also important to remember that a 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 cause it to be unadaptive.
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