What is Free Evolution? Free evolution is the concept that natural processes can cause organisms to evolve over time. This includes the emergence and development of new species. Many examples have been given of this, such as different varieties of stickleback fish that can live in either salt or fresh water, and walking stick insect varieties that favor particular host plants. These reversible traits can't, however, explain fundamental changes in body plans. Evolution by Natural Selection The evolution of the myriad living organisms on Earth is an enigma that has intrigued scientists for decades. The most well-known explanation is that of Charles Darwin's natural selection process, a process that is triggered when more well-adapted individuals live longer and reproduce more effectively than those who are less well-adapted. Over time, a community of well-adapted individuals increases and eventually forms a whole new species. Natural selection is an ongoing process that involves the interaction of three factors that are inheritance, variation and reproduction. Mutation and sexual reproduction increase genetic diversity in an animal species. Inheritance is the passing of a person's genetic traits to his or her offspring, which includes both recessive and dominant alleles. Reproduction is the process of producing viable, fertile offspring, which includes both asexual and sexual methods. Natural selection can only occur when all these elements are in harmony. For example, if a dominant allele at one gene allows an organism to live and reproduce more frequently than the recessive allele the dominant allele will become more common in the population. However, if the gene confers an unfavorable survival advantage or decreases fertility, it will be eliminated from the population. The process is self reinforcing meaning that the organism with an adaptive trait will live and reproduce much more than those with a maladaptive feature. The more offspring an organism can produce the better its fitness which is measured by its ability to reproduce itself and live. Individuals with favorable characteristics, like longer necks in giraffes or bright white color patterns in male peacocks are more likely survive and produce offspring, so they will make up the majority of the population over time. Natural selection is only an aspect of populations and not on individuals. This is an important distinction from the Lamarckian theory of evolution which argues that animals acquire characteristics by use or inactivity. For example, if a Giraffe's neck grows longer due to stretching to reach for prey and its offspring will inherit a larger neck. The differences in neck length between generations will persist until the giraffe's neck gets too long that it can not breed with other giraffes. Evolution through Genetic Drift Genetic drift occurs when the alleles of a gene are randomly distributed within a population. Eventually, only one will be fixed (become common enough to no more be eliminated through natural selection), and the other alleles will decrease in frequency. This can result in dominance in extreme. Other alleles have been essentially eliminated and heterozygosity has been reduced to a minimum. In a small population it could result in the complete elimination the recessive gene. This scenario is known as a bottleneck effect and it is typical of evolutionary process that takes place when a lot of individuals migrate to form a new group. A phenotypic bottleneck can also occur when the survivors of a catastrophe such as an outbreak or mass hunt incident are concentrated in the same area. The survivors will have a dominant allele and thus will share the same phenotype. This could be caused by earthquakes, war or even plagues. The genetically distinct population, if it remains 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 who are both genetically identical and share the same phenotype. However, one is struck by lightning and dies, while the other is able to reproduce. This kind of drift could be very important in the evolution of a species. But, it's not the only method to evolve. The main alternative is to use a process known as natural selection, in which the phenotypic variation of the population is maintained through mutation and migration. Stephens claims that there is a huge distinction between treating drift as a force or cause, and treating other causes like migration and selection as causes and forces. He claims that a causal process account of drift allows us to distinguish it from these other forces, and this distinction is crucial. He also argues that drift has a direction, that is it tends to reduce heterozygosity. It also has a specific magnitude that is determined by the size of the population. Evolution by Lamarckism When high school students study biology they are often introduced to the work of Jean-Baptiste Lamarck (1744 - 1829). His theory of evolution, also called "Lamarckism, states that simple organisms transform into more complex organisms through inheriting characteristics that are a product of the use and abuse of an organism. Lamarckism is typically illustrated with an image of a giraffe stretching its neck to reach the higher branches in the trees. This process would cause giraffes to give their longer necks to offspring, who would then get taller. Lamarck was a French zoologist and, in his lecture to begin his course on invertebrate Zoology at the Museum of Natural History in Paris on 17 May 1802, he introduced an innovative concept that completely challenged previous thinking about 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 might be the case, but he is widely seen as having given the subject its first general and comprehensive analysis. The most popular story is that Lamarckism grew into a rival to Charles Darwin's theory of evolution through natural selection, and that the two theories fought each other in the 19th century. Darwinism ultimately prevailed and led to what biologists call the Modern Synthesis. The Modern Synthesis theory denies that acquired characteristics can be acquired through inheritance and instead suggests that organisms evolve through the selective action of environmental factors, such as natural selection. Lamarck and his contemporaries endorsed the notion that acquired characters could be passed on to future generations. However, this notion was never a key element of any of their theories on evolution. This is due in part to the fact that it was never validated scientifically. But it is now more than 200 years since Lamarck was born and in the age genomics there is a vast body of evidence supporting the heritability of acquired traits. This is referred to as "neo Lamarckism", or more commonly epigenetic inheritance. It is a variant of evolution that is just as relevant as the more popular Neo-Darwinian theory. Evolution through the process of adaptation One of the most commonly-held misconceptions about evolution is its being driven by a struggle for survival. In fact, this view is inaccurate and overlooks the other forces that drive evolution. The fight for survival is better described as a fight to survive in a specific environment. click through the following post can include not only other organisms as well as the physical surroundings themselves. To understand how evolution works it is beneficial to think about what adaptation is. It refers to a specific feature that allows an organism to survive and reproduce in its environment. It can be a physical feature, like fur or feathers. Or it can be a trait of behavior that allows you to move to the shade during hot weather, or moving out to avoid the cold at night. The ability of an organism to draw energy from its surroundings and interact with other organisms as well as their physical environment, is crucial to its survival. The organism needs to have the right genes to produce offspring, and must be able to access sufficient food and other resources. Moreover, the organism must be capable of reproducing in a way that is optimally within its environment. These factors, together with mutation and gene flow result in an alteration in the percentage of alleles (different forms of a gene) in the population's gene pool. The change in frequency of alleles can lead to the emergence of new traits and eventually, new species as time passes. Many of the characteristics we admire in animals and plants are adaptations. For example the lungs or gills which draw oxygen from air, fur and feathers as insulation long legs to run away from predators and camouflage to conceal. To comprehend adaptation, it is important to differentiate between physiological and behavioral characteristics. Physiological adaptations, such as thick fur or gills are physical characteristics, whereas behavioral adaptations, like the tendency to search for friends or to move to shade in hot weather, are not. It is also important to note that the absence of planning doesn't result in an adaptation. A failure to consider the implications of a choice even if it seems to be rational, may make it inflexible.
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