What is Free Evolution?
Free evolution is the concept that natural processes can cause organisms to evolve over time. This includes the creation of new species and the change in appearance of existing species.
Numerous examples have been offered of this, including different kinds of stickleback fish that can live in either fresh or salt water and walking stick insect varieties that are attracted to 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 living organisms on Earth is an enigma that has fascinated scientists for centuries. The most well-known explanation is that of Charles Darwin's natural selection process, which is triggered when more well-adapted individuals live longer and reproduce more successfully than those less well adapted. Over time, a population of well-adapted individuals increases and eventually forms a whole new species.
Natural selection is a cyclical process that involves the interaction of three factors that are inheritance, variation and reproduction. Mutation and sexual reproduction increase the genetic diversity of the species. Inheritance refers to the transmission of genetic characteristics, which includes recessive and dominant genes to their offspring. 에볼루션 바카라 is the process of producing fertile, viable offspring which includes both asexual and sexual methods.
Natural selection can only occur when all the factors are in harmony. If, for instance, a dominant gene allele makes an organism reproduce and last longer than the recessive gene allele The dominant allele will become more prevalent in a population. If the allele confers a negative advantage to survival or reduces the fertility of the population, it will disappear. The process is self reinforcing meaning that the organism with an adaptive characteristic will live and reproduce much more than those with a maladaptive feature. The greater an organism's fitness as measured by its capacity to reproduce and survive, is the greater number of offspring it can produce. People with desirable traits, such as having a longer neck in giraffes, or bright white colors in male peacocks are more likely to survive and produce offspring, and thus will eventually make up the majority of the population in the future.
Natural selection is only a force for populations, not on individual organisms. This is a major distinction from the Lamarckian theory of evolution which holds that animals acquire traits due to usage or inaction. If a giraffe stretches its neck to reach prey and the neck grows larger, then its offspring will inherit this characteristic. The differences in neck size between generations will increase until the giraffe is unable to reproduce with other giraffes.
Evolution through Genetic Drift
Genetic drift occurs when the alleles of the same gene are randomly distributed in a group. At some point, one will attain fixation (become so common that it can no longer be removed by natural selection) and the other alleles drop to lower frequencies. In the extreme, this leads to dominance of a single allele. The other alleles are essentially eliminated, and heterozygosity falls to zero. In a small population this could result in the total elimination of recessive allele. This scenario is called the bottleneck effect. It is typical of the evolution process that occurs when the number of individuals migrate to form a population.
A phenotypic bottleneck can also occur when the survivors of a catastrophe such as an epidemic or a mass hunting event, are concentrated in a limited area. The remaining individuals will be mostly homozygous for the dominant allele meaning that they all have the same phenotype and therefore have the same fitness characteristics. This situation could be caused by war, earthquakes, or even plagues. The genetically distinct population, if it is left, could be susceptible to genetic drift.
Walsh, Lewens, and Ariew use a "purely outcome-oriented" definition of drift as any deviation from the expected values of 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 is able to reproduce.
This type of drift is crucial in the evolution of a species. However, it is not the only method to develop. Natural selection is the main alternative, where mutations and migration keep the phenotypic diversity in a population.
Stephens argues that there is a big difference between treating the phenomenon of drift as a force or a cause and treating other causes of evolution like mutation, selection and migration as forces or causes. He argues that a causal-process account of drift allows us separate it from other forces and that this distinction is essential. He also argues that drift has a direction: that is, it tends to eliminate heterozygosity. He also claims that it also has a magnitude, that is determined by population size.
Evolution by Lamarckism
In high school, students study biology they are often introduced to the work of Jean-Baptiste Lamarck (1744 - 1829). His theory of evolution, commonly called "Lamarckism, states that simple organisms evolve into more complex organisms through taking on traits that result from the use and abuse of an organism. Lamarckism is usually illustrated with the image of a giraffe that extends its neck to reach leaves higher up in the trees. This would cause giraffes' longer necks to be passed on to their offspring who would then grow even taller.
Lamarck was a French Zoologist. In his opening lecture for his course on invertebrate zoology at the Museum of Natural History in Paris on 17 May 1802, he introduced an original idea that fundamentally challenged the previous understanding of organic transformation. According to him, living things had evolved from inanimate matter through the gradual progression of events. Lamarck was not the only one to suggest that this could be the case but he is widely seen as giving the subject its first broad and thorough treatment.
The most popular story is that Charles Darwin's theory of natural selection and Lamarckism were competing during the 19th century. Darwinism ultimately prevailed, leading to what biologists refer to as the Modern Synthesis. This theory denies the possibility that acquired traits can be inherited, and instead suggests that organisms evolve by the symbiosis of environmental factors, such as natural selection.
While Lamarck endorsed the idea of inheritance through acquired characters and his contemporaries also offered a few words about this idea however, it was not a central element in any of their theories about evolution. This is partly because it was never tested scientifically.
However, it has been more than 200 years since Lamarck was born and in the age genomics, there is a large body of evidence supporting the heritability of acquired characteristics. This is also referred to as "neo Lamarckism", or more often epigenetic inheritance. This is a version that is as valid as the popular neodarwinian model.
Evolution by adaptation
One of the most popular misconceptions about evolution is its being driven by a fight for survival. In reality, this notion is inaccurate and overlooks the other forces that determine the rate of evolution. The struggle for survival is more precisely described as a fight to survive in a specific environment, which can involve not only other organisms, but also the physical environment itself.
Understanding how adaptation works is essential to understand evolution. Adaptation refers to any particular characteristic that allows an organism to survive and reproduce within its environment. It could be a physical feature, like fur or feathers. Or it can be a behavior trait such as moving towards 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 surrounding environment and interact with other living organisms and their physical surroundings. The organism must have the right genes to create offspring and to be able to access sufficient food and resources. The organism must be able to reproduce at an amount that is appropriate for its specific niche.
These elements, along with gene flow and mutations can cause a shift in the proportion of different alleles in the population's gene pool. The change in frequency of alleles could lead to the development of novel traits and eventually new species as time passes.
A lot of the traits we admire in plants and animals are adaptations. For instance the lungs or gills which extract oxygen from air feathers and fur for insulation long legs to run away from predators and camouflage to conceal. To comprehend adaptation, it is important to distinguish between behavioral and physiological characteristics.
Physiological adaptations like the thick fur or gills are physical characteristics, whereas behavioral adaptations, like the tendency to search for companions or to retreat to shade in hot weather, aren't. It is also important to keep in mind that insufficient planning does not result in an adaptation. In fact, failing to think about the consequences of a decision can render it ineffective even though it appears to be logical or even necessary.