What is Free Evolution?
Free evolution is the notion that the natural processes of living organisms can lead them to evolve over time. This includes the evolution of new species and transformation of the appearance of existing species.
Numerous examples have been offered of this, including various varieties of fish called sticklebacks that can be found in fresh or salt water and walking stick insect varieties that prefer particular host plants. 에볼루션사이트 , however, cannot explain fundamental changes in basic body plans.
Evolution by Natural Selection
The development of the myriad living organisms on Earth is a mystery that has intrigued scientists for centuries. The most widely accepted explanation is Darwin's natural selection process, an evolutionary process that occurs when individuals that are better adapted survive and reproduce more effectively than those who are less well adapted. As time passes, the number of well-adapted individuals grows and eventually creates an entirely new species.
Natural selection is a cyclical process that involves the interaction of three elements: variation, inheritance and reproduction. Mutation and sexual reproduction increase the genetic diversity of a species. Inheritance refers to the transmission of a person’s genetic characteristics, which includes both dominant and recessive genes and their offspring. Reproduction is the process of producing fertile, viable offspring which includes both sexual and asexual methods.
Natural selection only occurs when all these elements are in equilibrium. If, for instance an allele of a dominant gene allows an organism to reproduce and survive more than the recessive gene The dominant allele will become more prevalent in a population. If the allele confers a negative advantage to survival or reduces the fertility of the population, it will be eliminated. This process is self-reinforcing meaning that an organism that has a beneficial trait can reproduce and survive longer than one with an inadaptive trait. 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 traits, like a longer neck in giraffes, or bright white colors in male peacocks are more likely be able to survive and create offspring, and thus will become the majority of the population in the future.
Natural selection is only a force for populations, not on individual organisms. This is an important distinction from the Lamarckian theory of evolution which argues that animals acquire traits through use or disuse. For example, if a Giraffe's neck grows longer due to stretching to reach prey its offspring will inherit a longer neck. The length difference between generations will continue until the neck of the giraffe becomes too long to no longer breed with other giraffes.
Evolution by Genetic Drift
Genetic drift occurs when the alleles of a gene are randomly distributed in a group. At some point, one will attain fixation (become so widespread that it can no longer be eliminated through natural selection) and the other alleles drop to lower frequency. In the extreme, this leads to dominance of a single allele. The other alleles are eliminated, and heterozygosity is reduced to zero. In a small population this could result in the total elimination of the recessive allele. This is called a bottleneck effect, and it is typical of evolutionary process that takes place when a lot of people migrate to form a new population.
A phenotypic bottleneck can also occur when the survivors of a catastrophe like an epidemic or a mass hunting event, are concentrated in a limited area. The survivors will share a dominant allele and thus will share the same phenotype. This situation might be caused by a conflict, earthquake or even a cholera outbreak. The genetically distinct population, if left vulnerable to genetic drift.
Walsh Lewens, Walsh, and Ariew define drift as a deviation from expected values due to differences in fitness. They give a famous example of twins that are genetically identical, share identical phenotypes, but one is struck by lightning and dies, whereas the other lives and reproduces.
This type of drift is vital to the evolution of the species. However, it's not the only method to progress. The most common alternative is to use a process known as natural selection, where the phenotypic variation of a population is maintained by mutation and migration.
Stephens argues there is a huge difference between treating drift like a force or cause, and treating other causes like migration and selection as causes and forces. click through the following post claims that a causal-process model of drift allows us to separate it from other forces and this differentiation is crucial. He further argues that drift has a direction: that is it tends to eliminate heterozygosity, and that it also has a magnitude, that is determined by population size.
Evolution by Lamarckism
Students of biology in high school are often introduced to Jean-Baptiste Lamarck's (1744-1829) work. His theory of evolution, also called "Lamarckism which means that simple organisms transform into more complex organisms through adopting traits that result from an organism's use and disuse. Lamarckism is typically illustrated by the image of a giraffe extending its neck longer to reach leaves higher up in the trees. This process would result in giraffes passing on their longer necks to their offspring, who would then get 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 the 17th May 1802, he introduced a groundbreaking concept that radically challenged previous thinking about organic transformation. According to Lamarck, living creatures evolved from inanimate materials by a series of gradual steps. Lamarck was not the first to suggest that this could be the case, but he is widely seen as giving the subject his first comprehensive and comprehensive treatment.
The most popular story is that Lamarckism grew into an opponent to Charles Darwin's theory of evolutionary natural selection and both theories battled out in the 19th century. Darwinism eventually prevailed, leading to the development of what biologists now call the Modern Synthesis. The Modern Synthesis theory denies that traits acquired through evolution can be inherited, and instead suggests that organisms evolve through the action of environmental factors, such as natural selection.
Lamarck and his contemporaries supported the idea that acquired characters could be passed on to the next generation. However, this idea 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 more than 200 year since Lamarck's birth and in the field of genomics, there is a growing evidence-based body of evidence to support the heritability acquired characteristics. This is often called "neo-Lamarckism" or, more frequently, epigenetic inheritance. This is a variant that is as reliable as the popular neodarwinian model.
Evolution by adaptation
One of the most commonly-held misconceptions about evolution is its being driven by a struggle for survival. In fact, this view is inaccurate and overlooks the other forces that are driving evolution. The fight for survival can be more effectively described as a struggle to survive within a specific environment, which may involve not only other organisms but also the physical environment.
To understand how evolution operates it is important to consider what adaptation is. 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 trait like moving to the shade during the heat or leaving at night to avoid cold.
The capacity of an organism to draw 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 produce offspring, and it should be able to find enough food and other resources. In addition, the organism should be able to reproduce itself at a high rate within its environmental niche.
These factors, together with mutation and gene flow result in an alteration in the percentage of alleles (different varieties of a particular gene) in a population's gene pool. The change in frequency of alleles can result in the emergence of new traits and eventually new species over time.
Many of the features we find appealing in animals and plants are adaptations. For example, lungs or gills that extract oxygen from the air feathers and fur for insulation, long legs to run away from predators and camouflage to conceal. To understand the concept of adaptation it is essential to discern between physiological and behavioral characteristics.
Physiological adaptations, such as the thick fur or gills are physical traits, while behavioral adaptations, like the desire to find friends or to move into the shade in hot weather, are not. It is also important to keep in mind that insufficient planning does not make an adaptation. In fact, a failure to think about the implications of a behavior can make it ineffective despite the fact that it appears to be sensible or even necessary.