What is Free Evolution?
Free evolution is the idea that the natural processes that organisms go through can cause them to develop over time. This includes the creation of new species and the transformation of the appearance of existing ones.
This has been demonstrated by numerous examples such as the stickleback fish species that can thrive in salt or fresh water, and walking stick insect species that are apprehensive about specific host plants. These are mostly reversible traits, however, cannot be the reason for fundamental changes in body plans.
Evolution by Natural Selection
Scientists have been fascinated by the evolution of all living creatures that inhabit our planet for ages. The most widely accepted explanation is Charles Darwin's natural selection, 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 grows and eventually becomes a new species.
Natural selection is a process that is cyclical and involves the interaction of three factors that are: reproduction, variation and inheritance. Variation is caused by mutations and sexual reproduction both of which increase the genetic diversity of an animal species. Inheritance refers to the passing of a person's genetic traits to the offspring of that person, which includes both dominant and recessive alleles. Reproduction is the production of fertile, viable offspring, which includes both asexual and sexual methods.
Natural selection can only occur when all of these factors are in balance. If, for example the dominant gene allele allows an organism to reproduce and last longer than the recessive gene allele then the dominant allele will become more prevalent in a population. But if the allele confers an unfavorable survival advantage or decreases fertility, it will be eliminated from the population. The process is self-reinforcing which means that an organism that has an adaptive trait will survive and reproduce far more effectively than those with a maladaptive feature. The greater an organism's fitness which is measured by its ability to reproduce and survive, is the greater number of offspring it produces. People with desirable characteristics, like having a longer neck in giraffes or bright white colors in male peacocks are more likely be able to survive and create offspring, which means they will eventually make up the majority of the population in the future.
Natural selection only affects populations, not on individuals. This is a crucial distinction from the Lamarckian evolution theory which holds that animals acquire traits through use or lack of use. If a giraffe extends its neck in order to catch prey and its neck gets larger, then its children will inherit this characteristic. The length difference between generations will continue until the giraffe's neck becomes too long that it can not breed with other giraffes.
Evolution through Genetic Drift
Genetic drift occurs when alleles from the same gene are randomly distributed in a group. In the end, only one will be fixed (become common enough that it can no longer be eliminated by natural selection) and the rest of the alleles will diminish in frequency. In extreme cases this, it leads to dominance of a single allele. The other alleles are essentially eliminated, and heterozygosity falls to zero. In a small group it could lead to the complete elimination of recessive alleles. Such a scenario would be called a bottleneck effect, and it is typical of evolutionary process when a large number of people migrate to form a new population.
A phenotypic bottleneck can also occur when the survivors of a disaster such as an epidemic or a massive hunting event, are condensed into a small area. The survivors will carry an allele that is dominant and will share the same phenotype. This situation could be caused by war, earthquakes, or even plagues. Whatever the reason the genetically distinct population that is left might be susceptible to genetic drift.
Walsh Lewens and Ariew use Lewens, Walsh and Ariew employ a "purely outcome-oriented" definition of drift as any departure from expected values for different fitness levels. They cite the famous example of twins who are both genetically identical and have exactly the same phenotype, but one is struck by lightning and dies, but the other is able to reproduce.
This kind of drift could play a crucial role in the evolution of an organism. It is not the only method of evolution. The most common alternative is to use a process known as natural selection, where the phenotypic variation of the population is maintained through mutation and migration.
Stephens asserts that there is a major difference between treating the phenomenon of drift as a force or a cause and treating other causes of evolution such as mutation, selection and migration as forces or causes. He argues that a causal-process explanation of drift lets us differentiate it from other forces and that this differentiation is crucial. He further argues that drift is both an orientation, i.e., it tends towards eliminating heterozygosity. It also has a size that 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 generally known as "Lamarckism" and it states that simple organisms develop into more complex organisms through the inheritance of characteristics which result from the natural activities of an organism usage, use and disuse. Lamarckism is typically illustrated by an image of a giraffe that extends its neck longer to reach higher up in the trees. This would cause the longer necks of giraffes to be passed to their offspring, who would grow taller.
Lamarck was a French zoologist and, in his inaugural lecture for his course on invertebrate Zoology at the Museum of Natural History in Paris on the 17th May 1802, he introduced a groundbreaking concept that radically challenged the conventional wisdom about organic transformation. According Lamarck, living organisms evolved from inanimate material through a series of gradual steps. Lamarck was not the first to suggest that this might be the case, but he is widely seen as having given the subject its first broad and comprehensive treatment.
The most popular story is that Charles Darwin's theory of evolution by natural selection and Lamarckism were competing during the 19th century. Darwinism ultimately won which led to what biologists call the Modern Synthesis. The theory argues that traits acquired through evolution can be acquired through inheritance and instead, it argues that organisms develop through the action of environmental factors, including natural selection.
Although Lamarck supported the notion of inheritance through acquired characters, and his contemporaries also offered a few words about this idea, it was never a central element in any of their evolutionary theorizing. This is due to the fact that it was never scientifically validated.
However, it has been more than 200 years since Lamarck was born and, in the age of genomics, there is a large amount of evidence to support the heritability of acquired traits. This is sometimes referred to as "neo-Lamarckism" or, more frequently, epigenetic inheritance. This is a variant that is as valid as the popular Neodarwinian model.
Evolution through the process of adaptation
One of the most commonly-held misconceptions about evolution is that it is being driven by a struggle for survival. In fact, this view is a misrepresentation of natural selection and ignores the other forces that are driving evolution. The struggle for survival is more accurately described as a struggle to survive within a specific environment, which can be a struggle that involves not only other organisms, but also the physical environment.
Understanding adaptation is important to understand evolution. The term "adaptation" refers to any characteristic that allows a living organism to survive in its environment and reproduce. It could be a physical structure, such as feathers or fur. Or it can be a characteristic of behavior that allows you to move towards shade during the heat, or escaping the cold at night.
An organism's survival depends on its ability to obtain energy from the environment and to interact with other living organisms and their physical surroundings. The organism must possess the right genes to create offspring, and it should be able to access sufficient food and other resources. The organism should be able to reproduce itself at an amount that is appropriate for its niche.
These factors, along with gene flow and mutation result in a change in the proportion of alleles (different varieties of a particular gene) in the population's gene pool. Over time, this change in allele frequencies can result in the development of new traits and eventually new species.
Many of the features that we admire about animals and plants are adaptations, for example, lungs or gills to extract oxygen from the air, fur or feathers to protect themselves and long legs for running away from predators and camouflage for hiding. To understand the concept of adaptation, it is important to discern between physiological and behavioral traits.
Physical traits such as large gills and thick fur are physical characteristics. The behavioral adaptations aren't an exception, for instance, the tendency of animals to seek companionship or retreat into shade in hot weather. Furthermore, visit this site is important to understand that lack of planning does not make something an adaptation. In visit the next internet site , failure to think about the consequences of a choice can render it ineffective despite the fact that it appears to be sensible or even necessary.