What is Free Evolution?
Free evolution is the notion that the natural processes that organisms go through can cause them to develop over time. This includes the creation of new species and transformation of the appearance of existing species.
Many examples have been given of this, including different kinds of stickleback fish that can live in fresh or salt water and walking stick insect varieties that favor specific host plants. These reversible traits cannot explain fundamental changes to basic body plans.
Evolution by Natural Selection
Scientists have been fascinated by the development of all living creatures that live on our planet for centuries. Charles Darwin's natural selectivity is the most well-known explanation. This is because individuals who are better-adapted have more success in reproduction and survival than those who are less well-adapted. Over time, the population of individuals who are well-adapted grows and eventually creates a new species.
Natural selection is a process that is cyclical and involves the interaction of 3 factors that are: reproduction, variation and inheritance. Variation is caused by mutations and sexual reproduction both of which enhance the genetic diversity within an animal species. Inheritance is the passing of a person's genetic characteristics to his or her offspring that includes recessive and dominant alleles. Reproduction is the process of producing viable, fertile offspring, which includes both asexual and sexual methods.
All of these elements must be in balance to allow natural selection to take place. If, for instance an allele of a dominant gene allows an organism to reproduce and live longer than the recessive gene The dominant allele is more prevalent in a population. If the allele confers a negative survival advantage or lowers the fertility of the population, it will be eliminated. This process is self-reinforcing meaning that an organism that has an adaptive trait will survive and reproduce far more effectively than those with a maladaptive trait. The greater an organism's fitness, measured by its ability reproduce and endure, is the higher number of offspring it can produce. People with desirable traits, like having a longer neck in giraffes, or bright white patterns of color in male peacocks are more likely survive and produce offspring, so they will become the majority of the population in the future.
Natural selection is only a factor in populations and not on individuals. This is a major distinction from the Lamarckian theory of evolution, which states that animals acquire characteristics through use or disuse. If a giraffe stretches its neck to catch prey, and the neck becomes longer, then its children will inherit this characteristic. The differences in neck length between generations will persist until the neck of the giraffe becomes so long that it can no longer breed with other giraffes.
Evolution by Genetic Drift
In genetic drift, the alleles within a gene can reach different frequencies in a population due to random events. At some point, one will attain fixation (become so common that it cannot be removed by natural selection) and other alleles will fall to lower frequency. In extreme cases, this leads to a single allele dominance. The other alleles are essentially eliminated, and heterozygosity falls to zero. In a small population it could result in the complete elimination of recessive gene. This scenario is known as a bottleneck effect and it is typical of the kind of evolutionary process when a large amount of individuals migrate to form a new group.
A phenotypic bottleneck could happen when the survivors of a catastrophe such as an epidemic or a mass hunting event, are condensed into a small area. The survivors will be mostly homozygous for the dominant allele, meaning that they all have the same phenotype and will thus have the same fitness characteristics. This situation could be caused by war, earthquakes or even a plague. Whatever the reason the genetically distinct group that remains could be prone to genetic drift.
Walsh, Lewens, and Ariew employ Lewens, Walsh, and Ariew use a "purely outcome-oriented" definition of drift as any deviation from the expected values of variations in fitness. They cite the famous example of twins that are genetically identical and share the same phenotype, but one is struck by lightning and dies, whereas the other continues to reproduce.
This kind of drift could play a crucial part in the evolution of an organism. However, it is not the only way to progress. Natural selection is the main alternative, in which mutations and migration maintain the phenotypic diversity in the population.
Stephens asserts that there is a major difference between treating drift as a force, or an underlying cause, and considering other causes of evolution like mutation, selection and migration as forces or causes. He argues that a causal mechanism account of drift permits us to differentiate it from other forces, and that this distinction is essential. He argues further that drift is both direction, i.e., it tends to reduce heterozygosity. It also has a size which is determined by the size of the population.
Evolution by Lamarckism
Biology students in high school are often introduced to Jean-Baptiste Lemarck's (1744-1829) work. His theory of evolution, commonly called "Lamarckism is based on the idea that simple organisms transform into more complex organisms inheriting characteristics that result from an organism's use and disuse. Lamarckism can be illustrated by a giraffe extending its neck to reach higher branches in the trees. This would cause giraffes to give their longer necks to their offspring, which then become taller.
Lamarck, a French Zoologist from France, presented an innovative idea in his 17 May 1802 opening lecture at the Museum of Natural History of Paris. He challenged conventional wisdom on organic transformation. According to Lamarck, living creatures evolved from inanimate materials through a series gradual steps. Lamarck was not the first to make this claim however he was widely considered to be the first to provide the subject a comprehensive and general overview.
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 battled each other in the 19th century. Darwinism ultimately won and led to what biologists call the Modern Synthesis. This theory denies that acquired characteristics can be inherited, and instead, it argues that organisms develop through the selective action of environmental factors, such as natural selection.
Although Lamarck supported the notion of inheritance through acquired characters, and his contemporaries also spoke of this idea however, it was not a major feature in any of their evolutionary theories. This is largely due to the fact that it was never validated scientifically.
It has been more than 200 year since Lamarck's birth and in the field of age genomics there is a growing evidence base that supports the heritability-acquired characteristics. This is often called "neo-Lamarckism" or more frequently epigenetic inheritance. This is a version that is as valid as the popular Neodarwinian model.
Evolution through Adaptation
One of the most popular misconceptions about evolution is being driven by a struggle for survival. In reality, this notion is a misrepresentation of natural selection and ignores the other forces that drive evolution. 에볼루션 게이밍 for survival is more precisely described as a fight to survive within a particular environment, which may include not just other organisms but as well the physical environment.
To understand how evolution operates it is important to consider what adaptation is. Adaptation is any feature that allows a living organism to live in its environment and reproduce. It could be a physiological structure, like feathers or fur or a behavioral characteristic like moving into shade in the heat or leaving at night to avoid cold.
The ability of an organism to extract energy from its environment and interact with other organisms and their physical environments, is crucial to its survival. The organism must possess the right genes to produce offspring, and must be able to access sufficient food and other resources. The organism must be able to reproduce itself at the rate that is suitable for its specific niche.
These factors, in conjunction with mutations and gene flow can result in changes in the proportion of different alleles in the gene pool of a population. Over time, this change in allele frequencies can lead to the emergence of new traits and eventually new species.
Many of the features that we admire about animals and plants are adaptations, for example, lung or gills for removing oxygen from the air, feathers or fur for insulation long legs to run away from predators, and camouflage to hide. However, a thorough understanding of adaptation requires paying attention to the distinction between physiological and behavioral characteristics.
Physiological adaptations, such as the thick fur or gills are physical characteristics, whereas behavioral adaptations, such as the tendency to search for companions or to retreat to shade in hot weather, aren't. Furthermore, it is important to note that a lack of forethought is not a reason to make something an adaptation. A failure to consider the implications of a choice even if it seems to be logical, can cause it to be unadaptive.