What is Free Evolution?
Free evolution is the concept that natural processes can lead to the development of organisms 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 live in fresh or salt water and walking stick insect varieties that favor particular host plants. These are mostly reversible traits however, are not able to be the reason for fundamental changes in body plans.
Evolution by Natural Selection
The development of the myriad living organisms on Earth is an enigma that has intrigued scientists for centuries. Charles Darwin's natural selection is the best-established explanation. This happens when those who are better adapted survive and reproduce more than those who are less well-adapted. Over time, a population of well-adapted individuals increases and eventually creates a new species.
Natural selection is an ongoing process and involves the interaction of 3 factors: variation, reproduction and inheritance. Variation is caused by mutation and sexual reproduction, both of which increase the genetic diversity within an animal species. Inheritance refers to the passing of a person's genetic characteristics to his or her offspring, which includes both recessive and dominant alleles. Reproduction is the production of fertile, viable offspring, which includes both sexual and asexual methods.
All of these factors must be in harmony for natural selection to occur. For instance, if a dominant allele at the gene allows an organism to live and reproduce more often than the recessive one, the dominant allele will become more prominent within the population. But if the allele confers a disadvantage in survival or decreases fertility, it will disappear from the population. The process is self-reinforced, which means that an organism with a beneficial trait is more likely to survive and reproduce than an individual with an inadaptive characteristic. The more offspring that an organism has the more fit it is which is measured by its ability to reproduce and survive. People with good characteristics, like a longer neck in giraffes or bright white colors in male peacocks are more likely survive and produce offspring, and thus will eventually make up the majority of the population over time.
Natural selection only acts on populations, not individuals. This is a significant distinction from the Lamarckian theory of evolution, which states that animals acquire traits either through usage or inaction. If a giraffe extends its neck to catch prey and the neck grows longer, then the offspring will inherit this characteristic. The difference in neck length between generations will continue until the giraffe's neck gets too long to not breed with other giraffes.
Evolution by Genetic Drift
In genetic drift, alleles within a gene can reach different frequencies in a group through random events. Eventually, only one will be fixed (become common enough to no longer be eliminated by natural selection), and the other alleles will diminish in frequency. In extreme cases, this leads to dominance of a single allele. Other alleles have been essentially eliminated and heterozygosity has decreased to a minimum. In a small group, this could lead to the total elimination of the recessive allele. Such a scenario would be called a bottleneck effect, and it is typical of the kind of evolutionary process when a lot of individuals move to form a new population.
에볼루션 사이트 can also occur when survivors of a disaster like an outbreak or a mass hunting event are concentrated in a small area. The surviving individuals will be largely homozygous for the dominant allele, meaning that they all have the same phenotype, and therefore have the same fitness traits. This may be caused by a war, earthquake or even a disease. Whatever the reason the genetically distinct population that remains is susceptible to genetic drift.
Walsh Lewens, Lewens, and Ariew use Lewens, Walsh, and Ariew use a "purely outcome-oriented" definition of drift as any deviation from the expected values for different fitness levels. They give the famous example of twins that are genetically identical and share the same phenotype. However, one is struck by lightning and dies, while the other lives to reproduce.
This type of drift is very important in the evolution of an entire species. It is not the only method of evolution. Natural selection is the most common alternative, where mutations and migration keep the phenotypic diversity of the population.
Stephens claims that there is a huge distinction between treating drift as an actual cause or force, and considering other causes, such as migration and selection mutation as forces and causes. He argues that a causal-process model of drift allows us to distinguish it from other forces and that this distinction is crucial. He argues further that drift has both an orientation, i.e., it tends to eliminate heterozygosity. It also has a size which is determined by the size of the population.
Evolution through Lamarckism
Students of biology in high school are frequently introduced to Jean-Baptiste Lamarck's (1744-1829) work. His theory of evolution is commonly known as "Lamarckism" and it asserts that simple organisms evolve into more complex organisms via the inheritance of characteristics which result from an organism's natural activities use and misuse. Lamarckism can be illustrated by an giraffe's neck stretching to reach higher levels of leaves in the trees. This could result in giraffes passing on their longer necks to offspring, who then get taller.
Lamarck, a French Zoologist from France, presented a revolutionary concept in his 17 May 1802 opening lecture at the Museum of Natural History of Paris. He challenged the previous thinking on organic transformation. According to him, living things had evolved from inanimate matter through an escalating series of steps. Lamarck wasn't the first to make this claim, but he was widely thought of as the first to provide the subject a comprehensive and general treatment.
The most popular story is that Charles Darwin's theory of evolution by natural selection and Lamarckism were rivals during the 19th century. Darwinism ultimately won which led to what biologists call the Modern Synthesis. The theory argues that acquired traits can be passed down through generations and instead argues that organisms evolve through the selective action of environment factors, including Natural Selection.
Lamarck and his contemporaries believed in the notion that acquired characters could be passed down to the next generation. However, this concept was never a central part of any of their theories about evolution. This is due to the fact that it was never tested 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. This is sometimes referred to as "neo-Lamarckism" or more commonly, epigenetic inheritance. This is a version that is as reliable as the popular neodarwinian model.
Evolution by Adaptation
One of the most common misconceptions about evolution is being driven by a fight for survival. This is a false assumption and ignores other forces driving evolution. The fight for survival is better described as a fight to survive in a specific environment. This can include not just other organisms as well as the physical environment.
Understanding the concept of adaptation is crucial to understand evolution. Adaptation refers to any particular characteristic that allows an organism to survive and reproduce in its environment. It could be a physical structure, like feathers or fur. It could also be a trait of behavior, like moving to the shade during hot weather or escaping the cold at night.
The survival of an organism is dependent on its ability to draw energy from the environment and to interact with other living organisms and their physical surroundings. The organism must have the right genes to produce offspring and to be able to access enough food and resources. Moreover, the organism must be able to reproduce itself at a high rate within its niche.
These factors, together with gene flow and mutation can result in an alteration in the percentage of alleles (different varieties of a particular gene) in a population's gene pool. The change in frequency of alleles could lead to the development of new traits and eventually new species over time.
Many of the characteristics we admire in plants and animals are adaptations. For example, lungs or gills that extract oxygen from the air feathers and fur as insulation and long legs to get away from predators, and camouflage to hide. To comprehend adaptation it is essential to discern between physiological and behavioral characteristics.
Physiological traits like thick fur and gills are physical traits. Behavioral adaptations are not an exception, for instance, the tendency of animals to seek out companionship or to retreat into the shade during hot temperatures. Additionally, it is important to remember that a lack of forethought does not mean that something is an adaptation. In fact, a failure to consider the consequences of a decision can render it unadaptive despite the fact that it may appear to be logical or even necessary.