What is 에볼루션 무료체험 ?
Free evolution is the notion that the natural processes that organisms go through can cause them to develop over time. This includes the development of new species and alteration of the appearance of existing species.
This has been proven by numerous examples, including stickleback fish varieties that can be found in fresh or saltwater and walking stick insect types that prefer particular host plants. These mostly reversible traits permutations do not explain the fundamental changes in the body's basic plans.
Evolution by Natural Selection
The development of the myriad living organisms on Earth is a mystery that has intrigued scientists for many centuries. Charles Darwin's natural selectivity is the most well-known explanation. This is because people who are more well-adapted have more success in reproduction and survival than those who are less well-adapted. Over time, a community of well-adapted individuals expands and eventually forms a whole new species.
Natural selection is a cyclical process that involves the interaction of three elements including inheritance, variation, and reproduction. Variation is caused by mutations and sexual reproduction both of which enhance the genetic diversity within the species. Inheritance refers to the transmission of a person's genetic traits, which include recessive and dominant genes and their offspring. Reproduction is the process of creating viable, fertile offspring. This can be achieved by both asexual or sexual methods.
All of these variables must be in balance for natural selection to occur. If, for example, a dominant gene allele makes an organism reproduce and live longer than the recessive gene, then the dominant allele is more prevalent in a group. But if the allele confers a disadvantage in survival or reduces fertility, it will disappear from the population. The process is self-reinforced, meaning that an organism that has a beneficial trait is more likely to survive and reproduce than an individual with a maladaptive characteristic. The higher the level of fitness an organism has which is measured by its ability to reproduce and survive, is the greater number of offspring it can produce. People with good traits, such as a longer neck in giraffes and bright white colors in male peacocks are more likely be able to survive and create offspring, and thus will eventually make up the majority of the population in the future.
Natural selection is only a force for populations, not individual organisms. This is an important distinction from the Lamarckian theory of evolution which states that animals acquire characteristics through use or disuse. If a giraffe stretches its neck to reach prey, and the neck becomes longer, then the offspring will inherit this trait. The differences in neck length between generations will continue until the giraffe's neck gets so long that it can no longer breed with other giraffes.
Evolution by Genetic Drift
In the process of genetic drift, alleles at a gene may attain different frequencies in a population due to random events. Eventually, one of them will reach fixation (become so widespread that it can no longer be eliminated through natural selection) and the other alleles drop to lower frequencies. This can result in a dominant allele in extreme. The other alleles have been essentially eliminated and heterozygosity has decreased to zero. In a small population it could lead to the complete elimination of recessive alleles. This is known as the bottleneck effect. It is typical of an evolutionary process that occurs whenever an enormous number of individuals move to form a group.
A phenotypic bottleneck could happen when the survivors of a catastrophe like an epidemic or a massive hunting event, are concentrated in a limited area. The survivors will have a dominant allele and thus will have the same phenotype. This situation could be caused by war, earthquakes, or even plagues. The genetically distinct population, if it remains, could be susceptible to genetic drift.
Walsh, Lewens and Ariew define drift as a deviation from the expected values due to differences in fitness. They cite a famous instance of twins who are genetically identical, have identical phenotypes, and yet one is struck by lightning and dies, while the other lives and reproduces.
This kind of drift could play a very important part in the evolution of an organism. But, it's not the only method to progress. The primary alternative is a process called natural selection, where phenotypic variation in the population is maintained through mutation and migration.
Stephens asserts that there is a significant difference between treating drift like a force or cause, and considering other causes, such as migration and selection mutation as forces and causes. He claims that a causal-process model of drift allows us to separate it from other forces, and this differentiation is crucial. He also argues that drift has both an orientation, i.e., it tends to eliminate heterozygosity. It also has a size, that 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 which means that simple organisms develop into more complex organisms adopting traits that result from the organism's use and misuse. Lamarckism is typically illustrated by the image of a giraffe stretching its neck further to reach the higher branches in the trees. This could cause giraffes to give their longer necks to offspring, who then become 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. He challenged previous thinking on organic transformation. According to Lamarck, living things evolved from inanimate materials through a series gradual steps. Lamarck was not the first to make this claim but he was thought of as the first to provide the subject a thorough and general treatment.
The most popular story is that Lamarckism was an opponent to Charles Darwin's theory of evolution through natural selection, and both theories battled it out in the 19th century. Darwinism eventually won and led to the creation of what biologists now refer to as the Modern Synthesis. The theory argues that acquired traits can be passed down and instead, it claims that organisms evolve through the influence of environment factors, such as Natural Selection.
Although Lamarck supported the notion of inheritance through acquired characters and his contemporaries offered a few words about this idea but it was not a major feature in any of their evolutionary theories. This is due in part to the fact that it was never validated scientifically.
It has been more than 200 years since the birth of Lamarck, and in the age genomics, there is a growing evidence-based body of evidence to support the heritability-acquired characteristics. It is sometimes referred to as "neo-Lamarckism" or more often epigenetic inheritance. It is a variant of evolution that is as valid as the more popular Neo-Darwinian model.
Evolution by adaptation
One of the most popular misconceptions about evolution is being driven by a fight for survival. In fact, this view misrepresents natural selection and ignores the other forces that determine the rate of evolution. The fight for survival can be more accurately described as a struggle to survive within a particular environment, which could involve not only other organisms, but also the physical environment itself.
Understanding the concept of adaptation is crucial to comprehend evolution. It refers to a specific feature that allows an organism to survive and reproduce in its environment. It can be a physical structure, like fur or feathers. It could also be a characteristic of behavior such as moving into the shade during hot weather or moving out to avoid the cold at night.
The ability of an organism to extract energy from its surroundings and interact with other organisms, as well as their physical environment, is crucial to its survival. The organism must possess the right genes for producing offspring and be able find enough food and resources. The organism should also be able reproduce itself at a rate that is optimal for its specific niche.
These factors, along with gene flow and mutation, lead to a change in the proportion of alleles (different types of a gene) in the gene pool of a population. This change in allele frequency can result in the emergence of new traits, and eventually new species in the course of time.
Many of the features that we admire about animals and plants are adaptations, such as lungs or gills to extract oxygen from the air, feathers or fur for insulation and long legs for running away from predators and camouflage to hide. To comprehend adaptation, it is important to differentiate between physiological and behavioral characteristics.
Physiological adaptations, such as the thick fur or gills are physical characteristics, whereas behavioral adaptations, like the tendency to seek out companions or to move into the shade in hot weather, are not. In addition, it is important to note that a lack of forethought does not make something an adaptation. Failure to consider the implications of a choice even if it appears to be rational, could cause it to be unadaptive.