What is Free Evolution?
Free evolution is the concept that the natural processes of living organisms can lead to their development over time. This includes the evolution of new species as well as the alteration of the appearance of existing ones.
This is evident in many examples of stickleback fish species that can live in salt or fresh water, and walking stick insect varieties that are apprehensive about particular host plants. These mostly reversible trait permutations can't, however, explain fundamental changes in body plans.
Evolution through Natural Selection
The development of the myriad of living creatures on Earth is a mystery that has intrigued scientists for centuries. Charles Darwin's natural selection is the best-established explanation. This process occurs when individuals who are better-adapted survive and reproduce more 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 factors: variation, inheritance and reproduction. Variation is caused by mutations and sexual reproduction both of which enhance the genetic diversity within an animal species. Inheritance refers to the transmission of a person’s genetic characteristics, which includes recessive and dominant genes and their offspring. Reproduction is the process of producing fertile, viable offspring which includes both asexual and sexual methods.
All of these factors must be in balance to allow natural selection to take place. For instance when the dominant allele of the gene can cause an organism to live and reproduce more frequently than the recessive allele the dominant allele will become more common within the population. But if the allele confers an unfavorable survival advantage or decreases fertility, it will be eliminated from the population. The process is self-reinforcing, meaning that an organism with a beneficial trait will survive and reproduce more than an individual with an unadaptive characteristic. The more offspring an organism can produce the more fit it is, which is measured by its ability to reproduce itself and survive. Individuals with favorable traits, such as having a longer neck in giraffes or bright white patterns of color in male peacocks, are more likely to survive and have offspring, so they will make up the majority of the population over time.
Natural selection only affects populations, not individuals. This is a significant distinction from the Lamarckian theory of evolution that states that animals acquire traits either through the use or absence of use. If a giraffe extends its neck to reach prey, and the neck becomes longer, then the children will inherit this characteristic. The difference in neck size between generations will continue to grow until the giraffe becomes unable to reproduce with other giraffes.
Evolution by Genetic Drift
In genetic drift, alleles at a gene may reach different frequencies in a population by chance events. In the end, only one will be fixed (become common enough to no longer be eliminated through natural selection), and the other alleles drop in frequency. In extreme cases it can lead to dominance of a single allele. Other alleles have been basically eliminated and heterozygosity has diminished to a minimum. In a small group this could result in the total elimination of recessive allele. This scenario is called a bottleneck effect, and it is typical of the kind of evolutionary process that takes place when a large amount of people migrate to form a new group.
A phenotypic bottleneck could happen when the survivors of a disaster such as an epidemic or a massive hunt, are confined within a narrow area. The survivors will share a dominant allele and thus will share the same phenotype. This situation could be caused by earthquakes, war or even plagues. The genetically distinct population, if it is left, could be susceptible 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 for differences in fitness. They cite a famous example of twins that are genetically identical and have the exact same phenotype but 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. It is not the only method for evolution. Natural selection is the most common alternative, where mutations and migration keep the phenotypic diversity in a population.
Stephens argues there is a huge difference between treating drift like an agent or cause and treating other causes such as migration and selection mutation as forces and causes. He argues that a causal process explanation of drift allows us to distinguish it from other forces, and this distinction is essential. He also argues that drift has a direction, that is it tends to eliminate heterozygosity, and that it also has a magnitude, which is determined by the size of population.
Evolution through Lamarckism
In high school, students take biology classes, they are frequently introduced to the work of Jean-Baptiste Lamarck (1744 - 1829). His theory of evolution, often referred to as “Lamarckism”, states that simple organisms develop into more complex organisms inheriting characteristics that result from an organism's use and disuse. Lamarckism is usually illustrated with an image of a giraffe stretching its neck longer to reach leaves higher up in the trees. This would cause giraffes' longer necks to be passed on to their offspring who would then become taller.
Lamarck was a French zoologist and, in his opening lecture for his course on invertebrate Zoology at the Museum of Natural History in Paris on the 17th May 1802, he presented a groundbreaking concept that radically challenged the previous understanding of organic transformation. According to Lamarck, living creatures evolved from inanimate material through a series gradual steps. Lamarck was not the only one to suggest that this might be the case but the general consensus is that he was the one giving the subject its first broad and comprehensive treatment.
The popular narrative is that Lamarckism was an opponent 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 which led to what biologists refer to as the Modern Synthesis. 무료에볼루션 argues that acquired characteristics can be acquired through inheritance and instead suggests that organisms evolve through the action of environmental factors, like natural selection.
Although Lamarck endorsed the idea of inheritance by acquired characters and his contemporaries also spoke of this idea, it was never an integral part of any of their evolutionary theorizing. This is due to the fact that it was never tested scientifically.
It's been more than 200 years since Lamarck was born and, in the age of genomics there is a vast body of evidence supporting the possibility of inheritance of acquired traits. This is sometimes called "neo-Lamarckism" or more frequently epigenetic inheritance. It is a variant of evolution that is as valid as the more well-known Neo-Darwinian model.
Evolution through Adaptation
One of the most widespread misconceptions about evolution is that it is driven by a type of struggle for survival. This notion is not true and overlooks other forces that drive evolution. The fight for survival can be better described as a struggle to survive in a specific environment. This could be a challenge for not just other living things as well as the physical environment itself.
To understand how evolution operates, it is helpful to think about what adaptation is. Adaptation refers to any particular characteristic that allows an organism to survive and reproduce in its environment. It can be a physiological feature, such as fur or feathers, or a behavioral trait such as a tendency to move to the shade during the heat or leaving at night to avoid cold.
The survival of an organism is dependent on its ability to draw energy from the environment and interact with other organisms and their physical environments. The organism must possess the right genes to produce offspring, and be able to find sufficient food and resources. The organism must also be able reproduce at an amount that is appropriate for its particular niche.
These elements, along with mutations and gene flow can result in an alteration in the ratio of different alleles within the gene pool of a population. This change in allele frequency could lead to the development of novel traits and eventually, new species as time passes.
A lot of the traits we admire in animals and plants are adaptations, like the lungs or gills that extract oxygen from the air, fur or feathers for insulation, long legs for running away from predators and camouflage to hide. To understand adaptation it is crucial to distinguish between behavioral and physiological characteristics.
Physiological adaptations like thick fur or gills, are physical traits, while behavioral adaptations, like the tendency to search for companions or to retreat to shade in hot weather, aren't. It is important to remember that a insufficient planning does not make an adaptation. Inability to think about the implications of a choice, even if it appears to be rational, could make it unadaptive.