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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. Many examples have been given of this, including different varieties of stickleback fish that can be found in fresh or salt water and walking stick insect varieties that prefer specific host plants. These reversible traits cannot explain fundamental changes to the basic body plan. Evolution by Natural Selection The evolution of the myriad living creatures on Earth is a mystery that has fascinated scientists for centuries. Charles Darwin's natural selectivity is the best-established 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 grows and eventually creates a new species. Natural selection is an ongoing process and involves the interaction of three factors: variation, reproduction and inheritance. Mutation and sexual reproduction increase the genetic diversity of an animal species. Inheritance refers to the passing of a person's genetic traits to their offspring which includes both dominant and recessive alleles. Reproduction is the process of generating viable, fertile offspring. This can be achieved via sexual or asexual methods. All of these elements must be in harmony to allow natural selection to take place. For example the case where a dominant allele at the gene can cause an organism to live and reproduce more frequently than the recessive allele, the dominant allele will become more common in the population. If the allele confers a negative survival advantage or decreases the fertility of the population, it will disappear. The process is self-reinforcing meaning that an organism that has an adaptive trait will survive and reproduce more quickly than those with a maladaptive trait. The more offspring an organism can produce the better its fitness which is measured by its capacity to reproduce itself and live. People with good characteristics, such as a long neck in the giraffe, or bright white patterns on male peacocks, are more likely than others to survive and reproduce, which will eventually lead to them becoming the majority. Natural selection is an element in the population and not on individuals. This is a significant distinction from the Lamarckian theory of evolution, which states that animals acquire characteristics through use or disuse. If a giraffe expands its neck to catch prey and its neck gets longer, then its offspring will inherit this characteristic. The difference in neck length between generations will continue until the neck of the giraffe becomes too long to no longer breed with other giraffes. Evolution through Genetic Drift Genetic drift occurs when alleles from one gene are distributed randomly in a group. At some point, only one of them will be fixed (become common enough that it can no longer be eliminated by natural selection), and the other alleles decrease in frequency. In extreme cases, this leads to dominance of a single allele. The other alleles are essentially eliminated, and heterozygosity falls to zero. In a small group this could lead to the complete elimination the recessive gene. This is known as the bottleneck effect. It is typical of an evolutionary process that occurs whenever a large number individuals migrate to form a population. A phenotypic 'bottleneck' can also occur when the survivors of a disaster like an outbreak or a mass hunting event are concentrated in the same area. The survivors will have a dominant allele and thus will share the same phenotype. This can be caused by war, earthquakes or even plagues. The genetically distinct population, if left vulnerable 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 who are both genetically identical and have exactly the same phenotype, but one is struck by lightning and dies, but the other continues to reproduce. This kind of drift could be crucial in the evolution of an entire species. However, it is not the only method to progress. The most common alternative is to use a process known as natural selection, where the phenotypic diversity of a population is maintained by mutation and migration. Stephens asserts that there is a big difference between treating drift as a force or as an underlying cause, and considering other causes of evolution such as selection, mutation, and migration as forces or causes. He argues that a causal-process model of drift allows us to distinguish it from other forces and this differentiation is crucial. He further argues that drift has direction, i.e., it tends towards eliminating heterozygosity. It also has a size, which is determined based on population size. Evolution by Lamarckism Biology students in high school are frequently introduced to Jean-Baptiste Lamarck's (1744-1829) work. His theory of evolution, also referred to as “Lamarckism” which means that simple organisms develop into more complex organisms adopting traits that result from an organism's use and disuse. Lamarckism is illustrated through an giraffe's neck stretching to reach higher branches in the trees. This could cause giraffes to pass on their longer necks to offspring, who then grow even taller. Lamarck Lamarck, a French zoologist, presented a revolutionary concept in his opening lecture at the Museum of Natural History of Paris. He challenged conventional wisdom on organic transformation. In Going In this article living things had evolved from inanimate matter through a series of gradual steps. Lamarck was not the first to suggest this, but he was widely regarded as the first to provide the subject a comprehensive and general overview. The popular narrative is that Lamarckism grew into a rival to Charles Darwin's theory of evolution by natural selection, and both theories battled each other in the 19th century. Darwinism eventually triumphed, leading to the development of what biologists today refer to as the Modern Synthesis. This theory denies acquired characteristics can be passed down through generations and instead argues organisms evolve by the influence of environment elements, like Natural Selection. While Lamarck endorsed the idea of inheritance by acquired characters and his contemporaries spoke of this idea but it was not an integral part of any of their theories about evolution. This is due in part to the fact that it was never validated scientifically. However, it has been more than 200 years since Lamarck was born and in the age genomics there is a huge body of evidence supporting the possibility of inheritance of acquired traits. This is also known as “neo Lamarckism”, or more generally epigenetic inheritance. This is a version that is as valid as the popular neodarwinian model. Evolution by adaptation One of the most commonly-held misconceptions about evolution is that it is being driven by a fight for survival. This view misrepresents natural selection and ignores the other forces that are driving evolution. The struggle for survival is more accurately described as a struggle to survive within a particular environment, which could be a struggle that involves not only other organisms, but also the physical environment. To understand how evolution operates it is important to consider what adaptation is. The term “adaptation” refers to any specific feature that allows an organism to survive and reproduce within its environment. It could be a physiological structure, such as feathers or fur or a behavior such as a tendency to move into shade in the heat or leaving at night to avoid the cold. The capacity of an organism to extract energy from its environment and interact with other organisms and their physical environment is essential to its survival. The organism must possess the right genes to generate offspring, and must be able to locate sufficient food and other resources. The organism should also be able reproduce at an amount that is appropriate for its niche. These factors, together with gene flow and mutations can result in changes in the proportion of different alleles within the gene pool of a population. Over time, this change in allele frequencies could result in the emergence of new traits, and eventually new species. Many of the features we find appealing in plants and animals are adaptations. For instance lung or gills that extract oxygen from air feathers and fur as insulation long legs to run away from predators and camouflage for hiding. However, a thorough understanding of adaptation requires attention to the distinction between the physiological and behavioral traits. Physiological adaptations like thick fur or gills are physical characteristics, whereas behavioral adaptations, like the tendency to seek out friends or to move into the shade in hot weather, are not. In addition, it is important to note that a lack of thought is not a reason to make something an adaptation. A failure to consider the consequences of a decision, even if it appears to be rational, may cause it to be unadaptive.