What is Free Evolution?
Free evolution is the concept that natural processes can lead to the development of organisms over time. This includes the evolution of new species and the change in appearance of existing species.
Numerous examples have been offered of this, including various kinds of stickleback fish that can be found in salt or fresh water, and walking stick insect varieties that prefer particular host plants. These are mostly reversible traits however, are not able to explain fundamental changes in basic body plans.
Evolution by Natural Selection
The evolution of the myriad living organisms on Earth is an enigma that has fascinated scientists for decades. The best-established explanation is that of Charles Darwin's natural selection process, a process that occurs when individuals that are better adapted survive and reproduce more effectively than those that are less well adapted. Over time, a community of well-adapted individuals expands and eventually becomes a new species.
Natural selection is an ongoing process and involves the interaction of three factors including reproduction, variation and inheritance. Sexual reproduction and mutations increase the genetic diversity of a species. Inheritance is the passing of a person's genetic characteristics to the offspring of that person which includes both recessive and dominant alleles. Reproduction is the process of creating fertile, viable offspring. This can be done through sexual or asexual methods.
All of these factors have to be in equilibrium to allow natural selection to take place. If, for example, a dominant gene allele allows an organism to reproduce and last longer than the recessive gene allele, then the dominant allele is more common in a population. However, if the allele confers a disadvantage in survival or reduces fertility, it will be eliminated from the population. The process is self-reinforced, meaning that an organism with a beneficial characteristic is more likely to survive and reproduce than one with an unadaptive trait. 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 good traits, like a long neck in giraffes, or bright white color patterns on male peacocks are more likely to others to reproduce and survive, which will eventually lead to them becoming the majority.
Natural selection is an aspect of populations and not on individuals. This is a significant distinction from the Lamarckian theory of evolution which claims that animals acquire traits by use or inactivity. For instance, if the Giraffe's neck grows longer due to reaching out to catch prey and its offspring will inherit a longer neck. The differences in neck size between generations will continue to grow until the giraffe becomes unable to reproduce with other giraffes.
Evolution through Genetic Drift
In genetic drift, the alleles at a gene may be at different frequencies in a population by chance events. At some point, only one of them will be fixed (become widespread enough to not more be eliminated through natural selection) and the other alleles drop in frequency. This could lead to dominance in the extreme. The other alleles are essentially eliminated, and heterozygosity falls to zero. In a small group this could lead to the complete elimination the recessive gene. This scenario is called the bottleneck effect. It is typical of an evolution process that occurs when a large number individuals migrate to form a population.
A phenotypic bottleneck can also occur when the survivors of a disaster such as an outbreak or mass hunting event are confined to the same area. The surviving individuals will be largely homozygous for the dominant allele which means they will all have the same phenotype, and thus have the same fitness characteristics. This could be caused by a war, an earthquake, or even a plague. The genetically distinct population, if it is left susceptible to genetic drift.
Walsh Lewens, Walsh, and Ariew define drift as a departure from expected values due to differences in fitness. They give a famous instance of twins who are genetically identical and have identical phenotypes but one is struck by lightning and dies, whereas the other lives and reproduces.
에볼루션 게이밍 of drift can be crucial in the evolution of an entire species. This isn't the only method for evolution. The primary alternative is a process called natural selection, where the phenotypic variation of a population is maintained by mutation and migration.
Stephens asserts that there is a significant difference between treating the phenomenon of drift as an agent or cause and treating other causes such as selection mutation and migration as forces and causes. He argues that a causal process explanation of drift permits us to differentiate it from the other forces, and this distinction is vital. He also argues that drift has a direction: that is it tends to reduce heterozygosity. It also has a specific magnitude that is determined by population size.
Evolution by Lamarckism
When students in high school study biology they are often introduced to the work of Jean-Baptiste Lamarck (1744 - 1829). His theory of evolution is often known as "Lamarckism" and it states that simple organisms grow into more complex organisms by the inherited characteristics that result from the natural activities of an organism use and misuse. Lamarckism is usually illustrated with a picture of a giraffe that extends its neck further to reach the higher branches in the trees. This would cause giraffes to give their longer necks to offspring, who then get taller.
Lamarck was a French Zoologist. In his lecture to begin his course on invertebrate zoology held at the Museum of Natural History in Paris on 17 May 1802, he introduced an original idea that fundamentally challenged the conventional wisdom about organic transformation. According to Lamarck, living creatures evolved from inanimate matter through a series gradual steps. Lamarck was not the first to propose this, but he was widely thought of as the first to provide the subject a comprehensive and general treatment.
The dominant story is that Charles Darwin's theory of natural selection and Lamarckism were competing in the 19th Century. Darwinism ultimately prevailed and led to what biologists call the Modern Synthesis. The theory denies that acquired characteristics can be passed down and instead argues organisms evolve by the selective influence of environmental factors, such as Natural Selection.
Although Lamarck supported the notion of inheritance through acquired characters and his contemporaries spoke of this idea, it was never an integral part of any of their evolutionary theories. This is due to the fact that it was never scientifically tested.
However, it has been more than 200 years since Lamarck was born and, in the age of genomics there is a huge amount of evidence that supports the heritability of acquired characteristics. It is sometimes called "neo-Lamarckism" or, more commonly epigenetic inheritance. It is a variant of evolution that is as valid as the more well-known Neo-Darwinian model.
Evolution by adaptation
One of the most popular misconceptions about evolution is that it is driven by a type of struggle for survival. In reality, this notion is a misrepresentation of natural selection and ignores the other forces that drive evolution. The fight for survival can be more effectively described as a struggle to survive in a specific environment, which may involve not only other organisms, but also the physical environment.
Understanding the concept of adaptation is crucial to understand evolution. The term "adaptation" refers to any specific characteristic that allows an organism to live and reproduce within its environment. It could be a physiological structure, such as feathers or fur or a behavioral characteristic, such as moving into the shade in hot weather or coming out at night to avoid the 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 it should be able to access enough food and other resources. The organism must be able to reproduce itself at an amount that is appropriate for its specific niche.
These factors, together 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 new traits and eventually new species in the course of time.
Many of the features that we admire in 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 for hiding. To comprehend adaptation it is crucial to differentiate between physiological and behavioral traits.
Physiological adaptations, like thick fur or gills are physical traits, while behavioral adaptations, such as the tendency to search for friends or to move to the shade during hot weather, are not. In addition, it is important to note that lack of planning does not make something an adaptation. Failure to consider the implications of a choice even if it appears to be rational, may cause it to be unadaptive.