What is Free Evolution?
Free evolution is the idea that the natural processes of living organisms can lead to their development over time. This includes the appearance and development of new species.
Many examples have been given of this, including different varieties of fish called sticklebacks that can live in fresh or salt water and walking stick insect varieties that prefer particular host plants. These mostly reversible trait permutations, however, cannot be the reason for fundamental changes in body plans.
Evolution through Natural Selection
Scientists have been fascinated by the development of all the living creatures that live on our planet for centuries. The most widely accepted explanation is that of Charles Darwin's natural selection, a process that is triggered when more well-adapted individuals live longer and reproduce more effectively than those less well-adapted. Over time, the population of well-adapted individuals grows and eventually creates an entirely new species.
Natural selection is a cyclical process that is characterized by the interaction of three elements including inheritance, variation, and reproduction. Variation is caused by mutation and sexual reproduction both of which enhance the genetic diversity within an animal species. Inheritance refers to the passing of a person's genetic traits to their offspring, which includes both dominant and recessive alleles. Reproduction is the generation of fertile, viable offspring which includes both asexual and sexual methods.
All of these factors must be in harmony for natural selection to occur. If, for instance the dominant gene allele makes an organism reproduce and live longer than the recessive gene allele, then the dominant allele becomes more prevalent in a group. If the allele confers a negative survival advantage or decreases the fertility of the population, it will be eliminated. The process is self-reinforcing, which means 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 that is determined by its capacity to reproduce and survive. People with desirable characteristics, such as the long neck of giraffes, or bright white patterns on male peacocks are more likely than others to survive and reproduce, which will eventually lead to them becoming the majority.
Natural selection only acts on populations, not on individuals. This is a major distinction from the Lamarckian evolution theory, which states that animals acquire traits either through usage or inaction. For instance, if the Giraffe's neck grows longer due to stretching to reach for prey its offspring will inherit a larger neck. The length difference between generations will continue until the neck of the giraffe becomes so long that it can not breed with other giraffes.
Evolution through Genetic Drift
Genetic drift occurs when the alleles of one gene are distributed randomly in a group. At some point, only one of them will be fixed (become common enough to no more be eliminated through natural selection), and the rest of the alleles will drop in frequency. This can result in a dominant allele at the extreme. The other alleles have been basically eliminated and heterozygosity has been reduced to a minimum. In a small number of people it could lead to the complete elimination of recessive allele. This is known as the bottleneck effect and is typical of the evolution process that occurs when a large number individuals migrate to form a population.
A phenotypic bottleneck could happen when the survivors of a disaster, such as an epidemic or a mass hunting event, are condensed within a narrow area. The survivors will share a dominant allele and thus will share the same phenotype. This situation might be caused by war, earthquake or even a disease. Regardless of the cause the genetically distinct group that remains could be prone to genetic drift.
Walsh Lewens and Ariew utilize a "purely outcome-oriented" definition of drift as any deviation from the expected values of different fitness levels. They cite the famous example of twins who are both genetically identical and have exactly the same phenotype. However, one is struck by lightning and dies, while the other lives to reproduce.
에볼루션 무료체험 of drift could be crucial in the evolution of an entire species. This isn't the only method of evolution. The main alternative is a process known as natural selection, where phenotypic variation in a population is maintained by mutation and migration.
Stephens claims that there is a major difference between treating the phenomenon of drift as a force, or a cause and considering other causes of evolution like selection, mutation, and migration as forces or causes. Stephens claims that a causal process account of drift allows us separate it from other forces, and this differentiation is crucial. He argues further that drift is both direction, i.e., it tends to eliminate heterozygosity. It also has a size, which is determined by the size of the population.
Evolution through Lamarckism
When students in high school study biology they are often introduced to the work of Jean-Baptiste Lamarck (1744 - 1829). 에볼루션 게이밍 of evolution, often referred to as "Lamarckism is based on the idea that simple organisms evolve into more complex organisms taking on traits that are a product of the organism's use and misuse. Lamarckism is typically illustrated by an image of a giraffe stretching its neck further to reach the higher branches in the trees. This would cause the longer necks of giraffes to be passed to their offspring, who would then become taller.
Lamarck Lamarck, a French zoologist, presented an innovative idea in his 17 May 1802 opening lecture at the Museum of Natural History of Paris. He challenged the conventional wisdom on organic transformation. According to Lamarck, living creatures evolved from inanimate matter by a series of gradual steps. Lamarck wasn't the only one to propose this but he was considered to be the first to give the subject a comprehensive and general overview.
The prevailing story is that Lamarckism became a rival to Charles Darwin's theory of evolutionary natural selection, and that the two theories battled out in the 19th century. Darwinism eventually prevailed, leading to the development of what biologists today refer to as the Modern Synthesis. This theory denies acquired characteristics can be passed down through generations and instead argues that organisms evolve through the selective influence of environmental factors, such as Natural Selection.
Lamarck and his contemporaries endorsed the notion that acquired characters could be passed down to future generations. However, this idea was never a central part of any of their theories on evolution. This is due to the fact that it was never tested scientifically.
But it is now more than 200 years since Lamarck was born and, in the age of genomics there is a vast amount of evidence that supports the heritability of acquired characteristics. This is often called "neo-Lamarckism" or, more often, epigenetic inheritance. It is a form of evolution that is as valid as the more popular neo-Darwinian model.
Evolution through Adaptation
One of the most commonly-held misconceptions about evolution is being driven by a struggle to survive. In fact, this view is a misrepresentation of natural selection and ignores the other forces that are driving evolution. The fight for survival is better described as a struggle to survive in a certain environment. This can be a challenge for not just other living things as well as the physical environment itself.
Understanding how adaptation works is essential to comprehend evolution. It refers to a specific feature that allows an organism to survive and reproduce within its environment. It could be a physical structure, like fur or feathers. It could also be a trait of behavior, like moving towards shade during the heat, or escaping the cold at night.
The ability of a living thing to extract energy from its surroundings and interact with other organisms, as well as their physical environments is essential to its survival. The organism must have the right genes to produce offspring, and must be able to access enough food and other resources. The organism should also be able to reproduce at the rate that is suitable for its particular niche.
These elements, in conjunction with gene flow and mutation result in a change in the proportion of alleles (different forms of a gene) in the gene pool of a population. This shift in the frequency of alleles can lead to the emergence of novel traits and eventually, new species in the course of time.
Many of the characteristics we appreciate in animals and plants are adaptations. For instance, lungs or gills that extract oxygen from air, fur and feathers as insulation and long legs to get away from predators and camouflage to conceal. However, a thorough understanding of adaptation requires attention to the distinction between physiological and behavioral characteristics.
Physiological traits like the thick fur and gills are physical characteristics. Behavioral adaptations are not like the tendency of animals to seek companionship or to retreat into the shade during hot temperatures. It is important to remember that a insufficient planning does not cause an adaptation. A failure to consider the implications of a choice even if it seems to be rational, could cause it to be unadaptive.