What is Free Evolution?
Free evolution is the idea that natural processes can cause organisms to develop over time. This includes the appearance and development of new species.
This is evident in many examples such as the stickleback fish species that can thrive in fresh or saltwater and walking stick insect varieties that are apprehensive about particular host plants. These are mostly reversible traits however, are not able to be the reason for fundamental changes in body plans.
Evolution through Natural Selection
Scientists have been fascinated by the development of all living creatures that inhabit our planet for many centuries. Charles Darwin's natural selection is the best-established explanation. This is because those who are better adapted have more success in reproduction and survival 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 a cyclical process that is characterized by the interaction of three elements including inheritance, variation, and reproduction. Variation is caused by mutations and sexual reproduction, both of which increase the genetic diversity of the species. Inheritance refers to the passing of a person's genetic traits to their offspring, which includes both recessive and dominant alleles. Reproduction is the process of creating viable, fertile offspring. This can be achieved through sexual or asexual methods.
All of these elements have to be in equilibrium to allow natural selection to take place. For instance when a dominant allele at the gene causes an organism to survive and reproduce more often than the recessive allele the dominant allele will be more prevalent in the population. If the allele confers a negative survival advantage or decreases the fertility of the population, it will be eliminated. This process is self-reinforcing meaning that the organism with an adaptive trait 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 more offspring it can produce. People with desirable traits, like longer necks in giraffes and bright white color patterns in male peacocks, are more likely to be able to survive and create offspring, and thus will become the majority of the population in the future.
Natural selection is an element in the population and not on individuals. This is a crucial distinction from the Lamarckian evolution theory which holds that animals acquire traits through usage or inaction. If a giraffe extends its neck to reach prey and its neck gets longer, then the children will inherit this characteristic. The difference in neck length between generations will persist 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. Eventually, one of them will attain fixation (become so widespread that it cannot be removed by natural selection) and the other alleles drop to lower frequency. This can lead to an allele that is dominant in extreme. The other alleles are essentially eliminated, and heterozygosity is reduced to zero. In a small population this could result in the complete elimination of the recessive allele. This scenario is called the bottleneck effect. It is typical of the evolutionary process that occurs whenever the number of individuals migrate to form a population.
A phenotypic bottleneck may occur when survivors of a catastrophe such as an epidemic or a massive hunt, are confined into a small area. The survivors will carry an dominant allele, and will share the same phenotype. This may be caused by war, earthquake or even a disease. The genetically distinct population, if left susceptible to genetic drift.
Walsh Lewens, Walsh and Ariew define drift as a deviation from the expected values due to differences in fitness. 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, but the other lives to reproduce.
This type of drift can play a crucial part in the evolution of an organism. It's not the only method for evolution. The most common alternative is a process called natural selection, where phenotypic variation in a population is maintained by mutation and migration.
Stephens asserts that there is a vast difference between treating the phenomenon of drift as an actual cause or force, and treating other causes such as migration and selection mutation as forces and causes. He argues that a causal-process model of drift allows us to distinguish 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, and that it also has a specific magnitude that is determined by the size of population.
Evolution by Lamarckism
Biology students in high school are often exposed to Jean-Baptiste lamarck's (1744-1829) work. His theory of evolution, often referred to as “Lamarckism” is based on the idea that simple organisms evolve into more complex organisms by inheriting characteristics that are a product of an organism's use and disuse. Lamarckism is typically illustrated with a picture of a giraffe stretching its neck further to reach leaves higher up in the trees. This could cause giraffes to pass on their longer necks to offspring, who would then grow even taller.
Lamarck was a French Zoologist. In his lecture to begin his course on invertebrate Zoology at the Museum of Natural History in Paris on the 17th of May in 1802, he introduced an original idea that fundamentally challenged the previous understanding of organic transformation. According to Lamarck, living creatures evolved from inanimate material by a series of gradual steps. 에볼루션바카라사이트 Evolution KR was not the first to propose this, but he was widely thought of as the first to give the subject a thorough and general overview.
The most popular story is that Lamarckism became an opponent to Charles Darwin's theory of evolution by natural selection, and both theories battled it out in the 19th century. Darwinism ultimately won which led to what biologists call the Modern Synthesis. The theory argues the possibility that acquired traits can be acquired through inheritance and instead suggests that organisms evolve through the action of environmental factors, including natural selection.
Although Lamarck supported the notion of inheritance through acquired characters and his contemporaries also spoke of this idea, it was never an integral part of any of their evolutionary theories. 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 field of genomics, there is a growing body of evidence that supports the heritability of acquired traits. This is sometimes referred to as "neo-Lamarckism" or more frequently, epigenetic inheritance. It is a form of evolution that is as valid as the more popular Neo-Darwinian model.
Evolution by adaptation
One of the most widespread misconceptions about evolution is that it is a result of a kind of struggle to survive. In fact, this view misrepresents natural selection and ignores the other forces that drive evolution. The struggle for existence is more accurately described as a struggle to survive in a specific environment. This can include not just other organisms but also the physical surroundings themselves.
To understand how evolution works it is important to understand what is adaptation. It is a feature that allows a living organism to live in its environment and reproduce. It could be a physical structure like feathers or fur. Or it can be a trait of behavior that allows you to move into the shade during hot weather or escaping the cold at night.
The capacity of an organism to draw energy from its environment and interact with other organisms, as well as their physical environment, is crucial to its survival. The organism must have the right genes to create offspring and be able find sufficient food and resources. Moreover, the organism must be capable of reproducing at a high rate within its niche.
These factors, in conjunction with gene flow and mutations can result in changes in the proportion of different alleles in a population’s gene pool. This shift in the frequency of alleles could lead to the development of novel traits and eventually new species as time passes.
Many of the features that we admire in animals and plants are adaptations, like lungs or gills to extract oxygen from the air, feathers or fur to provide insulation, long legs for running away from predators, and camouflage to hide. To understand adaptation it is crucial to discern between physiological and behavioral characteristics.
Physiological traits like the thick fur and gills are physical traits. Behavioral adaptations are not, such as the tendency of animals to seek out companionship or move into the shade in hot temperatures. In addition it is important to note that lack of planning is not a reason to make something an adaptation. Inability to think about the effects of a behavior even if it seems to be logical, can make it inflexible.