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What is Free Evolution? Free evolution is the idea that the natural processes that organisms go through can lead them to evolve over time. This includes the appearance and growth of new species. This is evident in many examples such as the stickleback fish species that can thrive in saltwater or fresh water and walking stick insect varieties that prefer particular host plants. These mostly reversible trait permutations, however, cannot explain fundamental changes in basic body plans. Evolution through Natural Selection Scientists have been fascinated by the development of all the living organisms that inhabit our planet for centuries. Charles Darwin's natural selectivity is the best-established explanation. This happens when individuals who are better-adapted survive and reproduce more than those who are less well-adapted. Over time, a population of well-adapted individuals increases and eventually becomes a new species. Natural selection is a process that is cyclical and involves the interaction of 3 factors including reproduction, variation and inheritance. Mutation and sexual reproduction increase genetic diversity in the species. Inheritance is the passing of a person's genetic characteristics to their offspring that includes dominant and recessive alleles. Reproduction is the process of producing viable, fertile offspring. This can be done via sexual or asexual methods. All of these variables have to be in equilibrium to allow natural selection to take place. If, for example the dominant gene allele allows an organism to reproduce and live longer than the recessive gene allele then the dominant allele is more prevalent in a group. But if the allele confers a disadvantage in survival or decreases fertility, it will disappear from the population. 에볼루션 바카라 체험 is self reinforcing, which means that an organism with an adaptive characteristic will live and reproduce far more effectively than one with a maladaptive characteristic. The higher the level of fitness an organism has as measured by its capacity to reproduce and survive, is the greater number of offspring it produces. People with desirable characteristics, such as the long neck of giraffes, or bright white patterns on male peacocks are more likely to others to survive and reproduce, which will eventually lead to them becoming the majority. Natural selection is only an aspect of populations and not on individuals. This is a crucial distinction from the Lamarckian evolution theory which holds that animals acquire traits through the use or absence of use. For example, if a animal's neck is lengthened by stretching to reach for prey and 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 reproduce with other giraffes. Evolution by Genetic Drift In genetic drift, the alleles within a gene can attain different frequencies in a population due to random events. In the end, only one will be fixed (become common enough to no longer be eliminated through natural selection), and the other alleles diminish in frequency. In extreme cases it can lead to a single allele dominance. The other alleles have been virtually eliminated and heterozygosity been reduced to zero. In a small number of people this could result in the complete elimination of recessive allele. This scenario is called the bottleneck effect and is typical of an evolutionary process that occurs when a large number individuals migrate to form a population. A phenotypic bottleneck could occur when the survivors of a catastrophe such as an epidemic or a massive hunt, are confined within a narrow area. The remaining individuals are likely to be homozygous for the dominant allele which means they will all have the same phenotype, and consequently have the same fitness characteristics. This situation might be the result of a war, earthquake, or even a plague. Whatever the reason, the genetically distinct population that is left might 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 cite 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 continues to reproduce. This type of drift can play a significant part in the evolution of an organism. However, it's not the only method to evolve. Natural selection is the primary alternative, in which mutations and migration maintain phenotypic diversity within the population. Stephens argues there is a significant difference between treating the phenomenon of drift as an agent or cause and treating other causes such as migration and selection as forces and causes. He claims that a causal process explanation of drift allows us to distinguish it from other forces, and this distinction is vital. He also argues that drift has a direction: that is it tends to reduce heterozygosity, and that it also has a size, that is determined by the size of population. Evolution by Lamarckism Students of biology in high school are often introduced to Jean-Baptiste Lemarck's (1744-1829) work. His theory of evolution, often referred to as “Lamarckism is based on the idea that simple organisms evolve into more complex organisms by inheriting characteristics that result from the organism's use and misuse. Lamarckism is typically illustrated by an image of a giraffe that extends its neck longer to reach the higher branches in the trees. This causes giraffes' longer necks to be passed on to their offspring who would then grow even taller. Lamarck, a French Zoologist from France, presented an idea that was revolutionary in his opening lecture at the Museum of Natural History of Paris. 에볼루션 바카라 체험 challenged previous thinking on organic transformation. According to Lamarck, living things evolved from inanimate matter through a series of gradual steps. Lamarck wasn't the first to make this claim however he was widely thought of as the first to provide the subject a thorough and general treatment. The popular narrative is that Lamarckism became an opponent to Charles Darwin's theory of evolutionary natural selection and that the two theories fought each other in the 19th century. Darwinism eventually prevailed and led to the creation of what biologists call the Modern Synthesis. This theory denies acquired characteristics can be passed down through generations and instead, it claims that organisms evolve through the influence of environment factors, including Natural Selection. Although Lamarck believed in the concept of inheritance by acquired characters, and his contemporaries also paid lip-service to this notion, it was never a major feature in any of their theories about evolution. This is due to the fact that it was never tested scientifically. However, it has been more than 200 years since Lamarck was born and, in the age of genomics, there is a large amount of evidence to support the heritability of acquired characteristics. It is sometimes referred to as “neo-Lamarckism” or more frequently, epigenetic inheritance. It is a variant of evolution that is just as relevant as the more popular neo-Darwinian model. Evolution by adaptation One of the most common misconceptions about evolution is that it is a result of a kind of struggle to survive. In reality, this notion is a misrepresentation of natural selection and ignores the other forces that are driving evolution. The struggle for existence is better described as a fight to survive in a certain environment. This may include not only other organisms as well as the physical environment itself. Understanding the concept of adaptation is crucial to comprehend evolution. Adaptation refers to any particular characteristic that allows an organism to survive and reproduce within its environment. It can be a physiological structure such as feathers or fur or a behavioral characteristic like moving to the shade during hot weather or stepping out at night to avoid the cold. An organism's survival depends on its ability to extract energy from the environment and to interact with other living organisms and their physical surroundings. The organism must possess the right genes to generate offspring, and it 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 niche. These elements, in conjunction with gene flow and mutation, lead to a change in the proportion of alleles (different forms of a gene) in the gene pool of a population. This shift in the frequency of alleles can result in the emergence of new traits and eventually, new species over time. Many of the features that we admire in animals and plants are adaptations, like lungs or gills to extract oxygen from the air, feathers or fur to protect themselves and long legs for running away from predators and camouflage for hiding. However, a complete understanding of adaptation requires attention to the distinction between physiological and behavioral characteristics. Physiological adaptations like the thick fur or gills are physical characteristics, whereas behavioral adaptations, like the tendency to seek out companions or to retreat to shade in hot weather, aren't. In addition, it is important to remember that a lack of thought does not mean that something is an adaptation. In fact, failure to consider the consequences of a behavior can make it ineffective, despite the fact that it may appear to be sensible or even necessary.