What is Free Evolution?
Free evolution is the notion that natural processes can cause organisms to develop over time. This includes the emergence and development of new species.
This has been proven by numerous examples, including stickleback fish varieties that can be found in saltwater or fresh water and walking stick insect species that are apprehensive about specific host plants. These are mostly reversible traits, however, cannot explain fundamental changes in basic body plans.
Evolution by Natural Selection
The development of the myriad living creatures on Earth is a mystery that has intrigued scientists for centuries. 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 successfully than those who are less well adapted. Over time, a population of well-adapted individuals expands and eventually becomes a new species.
Natural selection is an ongoing process that involves the interaction of three elements including inheritance, variation, and reproduction. Mutation and sexual reproduction increase the genetic diversity of a species. Inheritance refers to the passing of a person's genetic traits to the offspring of that person, which includes both recessive and dominant alleles. Reproduction is the process of producing fertile, viable offspring. This can be achieved by both asexual or sexual methods.
All of these factors must be in harmony to allow natural selection to take place. For instance the case where the dominant allele of the gene can cause an organism to live and reproduce more often than the recessive allele the dominant allele will become more common within the population. If the allele confers a negative advantage to survival or decreases the fertility of the population, it will disappear. This process is self-reinforcing which means that the organism with an adaptive trait will live and reproduce much more than those with a maladaptive feature. The more offspring an organism produces, the greater its fitness that is determined by its ability to reproduce itself and live. Individuals with favorable traits, like the long neck of the giraffe, or bright white patterns on male peacocks, are more likely than others to live and reproduce, which will eventually lead to them becoming the majority.
Natural selection is a factor in populations and not on individuals. This is a crucial distinction from the Lamarckian theory of evolution that states that animals acquire traits through use or lack of use. If a giraffe expands its neck in order to catch prey and the neck grows longer, then the offspring will inherit this characteristic. The differences in neck length between generations will persist until the giraffe's neck becomes so long that it can no longer breed with other giraffes.
Evolution through Genetic Drift
In genetic drift, alleles within a gene can reach different frequencies in a population due to random events. In the end, one will attain fixation (become so widespread that it can no longer be removed through natural selection) and other alleles will fall to lower frequency. In the extreme this, it leads to one allele dominance. Other alleles have been virtually eliminated and heterozygosity diminished to a minimum. In a small number of people, this could result in the complete elimination of the recessive gene. This is known as the bottleneck effect and is typical of the evolutionary process that occurs when the number of individuals migrate to form a population.
A phenotypic bottleneck can also occur when the survivors of a disaster like an epidemic or a massive hunting event, are concentrated into a small area. The surviving individuals will be mostly homozygous for the dominant allele meaning that they all have the same phenotype and will consequently have the same fitness characteristics. This situation might be the result of a war, earthquake or even a disease. Whatever the reason the genetically distinct group that remains could be susceptible to genetic drift.
Walsh, Lewens and Ariew define drift as a deviation from the expected values due to differences in fitness. They cite a famous example of twins that are genetically identical and have identical phenotypes but one is struck by lightning and dies, while the other lives and reproduces.
This type of drift can play a significant part in the evolution of an organism. It is not the only method of evolution. The most common alternative is a process called natural selection, in which the phenotypic variation of an individual is maintained through mutation and migration.
Stephens argues that there is a big difference between treating the phenomenon of drift as a force or an underlying cause, and treating other causes of evolution such as mutation, selection and migration as forces or causes. Stephens claims that a causal process account of drift allows us to distinguish it from the other forces, and this distinction is crucial. 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 the size of population.
Evolution through Lamarckism
Students of biology in high school are frequently exposed to Jean-Baptiste lamarck's (1744-1829) work. His theory of evolution, often referred to as “Lamarckism”, states that simple organisms transform into more complex organisms adopting traits that are a product of an organism's use and disuse. Lamarckism can be demonstrated by a giraffe extending its neck to reach higher leaves in the trees. This process would cause giraffes to pass on their longer necks 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 presented an original idea that fundamentally challenged previous thinking about organic transformation. According to Lamarck, living things evolved from inanimate material through a series of gradual steps. Lamarck was not the first to suggest that this could be the case, but the general consensus is that he was the one being the one who gave the subject its first general and comprehensive treatment.
The prevailing story is that Lamarckism grew into a rival to Charles Darwin's theory of evolutionary natural selection, and both theories battled each other in the 19th century. Darwinism eventually triumphed and led to the development of what biologists now refer to as the Modern Synthesis. The Modern Synthesis theory denies that acquired characteristics can be inherited, and instead, it argues that organisms develop by the symbiosis of environmental factors, including natural selection.
Lamarck and his contemporaries endorsed the notion that acquired characters could be passed on to future generations. However, this idea was never a central part of any of their theories about evolution. This is largely due to the fact that it was never validated scientifically.
It has been more than 200 years since the birth of Lamarck, and in the age genomics, there is a growing evidence base that supports the heritability of acquired traits. This is also referred to as "neo Lamarckism", or more generally epigenetic inheritance. It is a version of evolution that is just as valid as the more well-known neo-Darwinian model.
Evolution by the process of adaptation
One of the most widespread misconceptions about evolution is that it is a result of a kind of struggle for survival. This view is inaccurate and ignores other forces driving evolution. The struggle for survival is more effectively described as a struggle to survive in a specific environment, which can be a struggle that involves not only other organisms but also the physical environment.
To understand how evolution functions it is important to understand what is adaptation. It refers to a specific characteristic that allows an organism to live and reproduce within its environment. It can be a physiological structure, such as feathers or fur or a behavioral characteristic, such as moving to the shade during hot weather or stepping out at night to avoid the cold.
The capacity of an organism to extract energy from its surroundings and interact with other organisms as well as their physical environment is essential to its survival. The organism needs to have the right genes to generate offspring, and it must be able to find enough food and other resources. In addition, the organism should be capable of reproducing at an optimal rate within its niche.
These factors, together with gene flow and mutations can cause changes in the proportion of different alleles within a population’s gene pool. The change in frequency of alleles can lead to the emergence of new traits, and eventually, new species over time.
A lot of the traits we admire about animals and plants are adaptations, for example, the lungs or gills that extract oxygen from the air, fur or feathers to protect themselves and long legs for running away from predators, and camouflage to hide. However, a proper understanding of adaptation requires attention to the distinction between the physiological and behavioral traits.
에볼루션 슬롯 like the thick fur and gills are physical traits. Behavioral adaptations are not, such as the tendency of animals to seek companionship or retreat into shade in hot weather. In addition it is important to understand that a lack of thought does not mean that something is an adaptation. In fact, failing to consider the consequences of a decision can render it unadaptive, despite the fact that it might appear sensible or even necessary.