What is Free Evolution?
Free evolution is the notion that natural processes can lead to the development of organisms over time. This includes the emergence and development of new species.
This has been demonstrated by many examples of stickleback fish species that can live in saltwater or fresh water and walking stick insect varieties that are apprehensive about particular host plants. These are mostly reversible traits can't, however, be the reason for fundamental changes in body plans.
Evolution by Natural Selection
Scientists have been fascinated by the evolution of all living organisms that inhabit our planet for ages. 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. As time passes, the number of well-adapted individuals grows and eventually creates a new species.
Natural selection is a cyclical process that involves the interaction of three elements: variation, inheritance and reproduction. Variation is caused by mutations and sexual reproduction, both of which increase the genetic diversity of the species. Inheritance is the term used to describe the transmission of a person's genetic traits, including recessive and dominant genes and their offspring. Reproduction is the process of generating fertile, viable offspring. This can be accomplished by both asexual or sexual methods.
Natural selection only occurs when all of these factors are in balance. If, for example an allele of a dominant gene allows an organism to reproduce and last longer than the recessive gene allele, then the dominant allele becomes more prevalent in a group. However, if the gene confers an unfavorable survival advantage or decreases fertility, it will disappear from the population. The process is self-reinforcing, meaning that an organism with a beneficial characteristic is more likely to survive and reproduce than an individual with an inadaptive characteristic. The greater an organism's fitness as measured by its capacity to reproduce and endure, is the higher number of offspring it will produce. Individuals with favorable traits, like longer necks in giraffes or bright white patterns of color in male peacocks, are more likely to survive and produce offspring, and thus 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 which states that animals acquire characteristics through use or disuse. If a giraffe stretches its neck to reach prey and the neck grows longer, then the offspring will inherit this trait. The differences in neck length between generations will persist until the giraffe's neck becomes too long to not breed with other giraffes.
Evolution by Genetic Drift
Genetic drift occurs when alleles from one gene are distributed randomly in a population. Eventually, only one will be fixed (become widespread enough to not longer be eliminated through natural selection) and the other alleles drop in frequency. This could lead to a dominant allele at the extreme. The other alleles have been essentially eliminated and heterozygosity has decreased to zero. In a small group, this could result in the complete elimination of the recessive gene. This scenario is called a bottleneck effect, and it is typical of evolutionary process when a lot of people migrate to form a new group.
A phenotypic bottleneck may also occur when survivors of a disaster such as an outbreak or a mass hunting event are confined to a small area. The remaining individuals will be mostly homozygous for the dominant allele meaning that they all share the same phenotype and consequently have the same fitness characteristics. This could be the result of a conflict, earthquake, or even a plague. The genetically distinct population, if it remains, 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 of differences in fitness. They give the famous example of twins who are both genetically identical and have exactly the same phenotype. However one is struck by lightning and dies, whereas the other lives to reproduce.
This kind of drift can play a crucial part in the evolution of an organism. But, it's not the only method to evolve. The primary alternative is a process known as natural selection, in which the phenotypic diversity of a population is maintained by mutation and migration.
Stephens argues there is a vast difference between treating drift like a force or cause, and considering other causes, such as migration and selection mutation as forces and causes. Stephens claims that a causal process explanation of drift allows us to distinguish it from the other forces, and that this distinction is crucial. He also argues that drift has both a 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
Biology students in high school are often introduced to Jean-Baptiste Lemarck's (1744-1829) work. His theory of evolution is often known as "Lamarckism" and it states that simple organisms grow into more complex organisms through the inheritance of traits that result from an organism's natural activities usage, use and disuse. Lamarckism can be demonstrated by a giraffe extending its neck to reach higher levels of leaves in the trees. This causes giraffes' longer necks to be passed to their offspring, who would then grow even taller.
Lamarck was a French Zoologist. In his opening lecture for his course on invertebrate zoology held at the Museum of Natural History in Paris on the 17th May 1802, he presented an original idea that fundamentally challenged the conventional wisdom about organic transformation. According to Lamarck, living things evolved from inanimate materials through a series of gradual steps. Lamarck was not the only one to suggest that this might be the case but his reputation is widely regarded as being the one who gave the subject its first general and comprehensive treatment.
The popular narrative is that Lamarckism became an opponent to Charles Darwin's theory of evolution by natural selection, and that the two theories battled it out in the 19th century. Darwinism eventually prevailed, leading to the development of what biologists call the Modern Synthesis. This theory denies acquired characteristics can be passed down and instead argues that organisms evolve through the selective influence of environmental elements, like Natural Selection.
Lamarck and his contemporaries endorsed the idea that acquired characters could be passed down to the next generation. However, this notion was never a major part of any of their evolutionary theories. This is due to the fact that it was never tested scientifically.
It's been over 200 years since the birth of Lamarck and in the field of genomics, there is an increasing body of evidence that supports the heritability acquired characteristics. It is sometimes called "neo-Lamarckism" or, more frequently epigenetic inheritance. This is a model that is just as valid as the popular neodarwinian model.
Evolution through adaptation
One of the most commonly-held misconceptions about evolution is its being driven by a struggle to survive. In reality, this notion misrepresents natural selection and ignores the other forces that determine the rate of evolution. 에볼루션 for survival can be more precisely described as a fight to survive within a particular environment, which can involve not only other organisms, but as well the physical environment.
Understanding the concept of adaptation is crucial to comprehend evolution. It refers to a specific characteristic that allows an organism to live and reproduce within its environment. It could be a physiological structure, like feathers or fur or a behavioral characteristic such as a tendency to move to the shade during hot weather or coming out at night to avoid cold.
The capacity of an organism to extract energy from its environment and interact with other organisms, as well as their physical environment is essential to its survival. The organism must possess the right genes for producing offspring and to be able to access sufficient food and resources. The organism must also be able to reproduce at a rate that is optimal for its specific niche.
These factors, together with gene flow and mutation result in changes in the ratio of alleles (different types of a gene) in the gene pool of a population. The change in frequency of alleles can lead to the emergence of novel traits and eventually new species over time.
Many of the characteristics we admire about animals and plants are adaptations, such as lung or gills for removing oxygen from the air, feathers or fur to provide insulation, long legs for running away from predators and camouflage for hiding. However, a thorough understanding of adaptation requires paying attention to the distinction between physiological and behavioral characteristics.
Physiological traits like large gills and thick fur are physical traits. Behavioral adaptations are not like the tendency of animals to seek companionship or move into the shade during hot weather. In addition, it is important to remember that lack of planning is not a reason to make something an adaptation. In fact, failure to think about the consequences of a decision can render it unadaptable, despite the fact that it appears to be sensible or even necessary.