It Is The History Of Free Evolution In 10 Milestones
What is Free Evolution?
Free evolution is the notion that the natural processes of organisms can cause them to develop over time. This includes the evolution of new species and the change in appearance of existing ones.
This is evident in many examples of stickleback fish species that can thrive in fresh or saltwater and walking stick insect types that have a preference for specific host plants. These reversible traits can't, however, be the reason for fundamental changes in body plans.
Evolution through Natural Selection
Scientists have been fascinated by the development of all the living creatures that inhabit our planet for ages. Charles Darwin's natural selection is the most well-known explanation. This is because those who are better adapted survive and reproduce more than those who are less well-adapted. As time passes, a group of well-adapted individuals expands and eventually creates a new species.
Natural selection is an ongoing process and involves the interaction of 3 factors that are: reproduction, variation and inheritance. Mutation and sexual reproduction increase genetic diversity in a species. Inheritance refers the transmission of genetic characteristics, which includes recessive and dominant genes, to their offspring. Reproduction is the generation of fertile, viable offspring, which includes both asexual and sexual methods.
All of these factors must be in harmony for natural selection to occur. If, for instance the dominant gene allele causes an organism reproduce and live longer than the recessive allele, then the dominant allele will become more prevalent in a group. If the allele confers a negative advantage to survival or lowers the fertility of the population, it will go away. The process is self-reinforcing which means that an organism with an adaptive trait will survive and reproduce much more than one with a maladaptive characteristic. The more offspring that an organism has the better its fitness, which is measured by its capacity to reproduce and survive. People with desirable characteristics, like a longer neck in giraffes, or bright white patterns of color in male peacocks are more likely to be able to survive and create offspring, and thus will make up the majority of the population in the future.
Natural selection is only a factor in populations and not on individuals. This is an important distinction from the Lamarckian theory of evolution, which states that animals acquire traits through use or disuse. For example, if a giraffe's neck gets longer through stretching to reach for prey, its offspring will inherit a larger neck. The length difference between generations will persist 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 one gene are distributed randomly in a population. Eventually, one of them will attain fixation (become so widespread that it can no longer be removed through natural selection), while the other alleles drop to lower frequencies. In extreme cases it can lead to dominance of a single allele. The other alleles are essentially eliminated, and heterozygosity falls to zero. In a small group this could result in the total elimination of recessive allele. This scenario is called the bottleneck effect and is typical of the evolution process that occurs when an enormous number of individuals move to form a group.
A phenotypic bottleneck can also occur when survivors of a disaster like an outbreak or mass hunt event are concentrated in the same area. The survivors will carry an dominant allele, and will have the same phenotype. This situation could be caused by war, earthquakes or even a plague. Whatever 에볼루션게이밍 that remains could be susceptible to genetic drift.
Walsh Lewens, Lewens, and Ariew employ a "purely outcome-oriented" definition of drift as any deviation from the expected values of variations in fitness. They cite the famous example of twins that are genetically identical and share the same phenotype, but one is struck by lightning and dies, whereas the other is able to reproduce.
This type of drift can play a very important part in the evolution of an organism. It is not the only method for evolution. Natural selection is the main alternative, where mutations and migrations maintain phenotypic diversity within the population.
Stephens claims that there is a significant distinction between treating drift as a force or a cause and treating other causes of evolution, such as selection, mutation, 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 vital. He also claims that drift has a direction, that is it tends to eliminate heterozygosity, and that it also has a specific magnitude which is determined by the size of population.
Evolution through Lamarckism
In high school, students take biology classes, they are frequently introduced to the work of Jean-Baptiste Lamarck (1744 - 1829). His theory of evolution is often called "Lamarckism" and it asserts that simple organisms evolve into more complex organisms through the inheritance of characteristics that result from the natural activities of an organism, use and disuse. Lamarckism can be illustrated by an giraffe's neck stretching to reach higher leaves in the trees. This process would cause giraffes to pass on their longer necks to their offspring, who would then become taller.
Lamarck was a French Zoologist. In his inaugural 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 Lamarck, living organisms evolved from inanimate materials through a series of gradual steps. Lamarck was not the only one to suggest that this could be the case, but he is widely seen as having given the subject its first general and comprehensive treatment.
The predominant story is that Charles Darwin's theory of natural selection and Lamarckism were rivals during the 19th century. Darwinism eventually prevailed and led to the development of what biologists now call the Modern Synthesis. The theory denies that acquired characteristics can be passed down and instead argues that organisms evolve through the selective action of environment factors, such as Natural Selection.
Lamarck and his contemporaries believed in the idea that acquired characters could be passed on to future generations. However, this notion was never a central part of any of their evolutionary theories. This is due to the fact that it was never scientifically tested.
It's been more than 200 years since Lamarck was born and in the age genomics there is a vast amount of evidence that supports the possibility of inheritance of acquired traits. This is referred to as "neo Lamarckism", or more often epigenetic inheritance. This is a variant that is as reliable as the popular neodarwinian model.
Evolution by the process of adaptation
One of the most common misconceptions about evolution is that it is driven by a sort of struggle to survive. This is a false assumption and overlooks other forces that drive evolution. The struggle for survival is more precisely described as a fight to survive in a specific environment, which could include not just other organisms but also the physical environment itself.
Understanding the concept of adaptation is crucial to understand evolution. Adaptation refers to any particular characteristic that allows an organism to live and reproduce in its environment. It can be a physical structure, such as feathers or fur. Or it can be a trait of behavior, like moving to the shade during hot weather or escaping the cold at night.
An organism's survival depends on its ability to extract energy from the environment and to interact with other living organisms and their physical surroundings. The organism must possess the right genes to produce offspring, and must be able to access sufficient food and other resources. Furthermore, the organism needs to be capable of reproducing at a high rate within its environmental niche.
These factors, together with gene flow and mutations can result in changes in the proportion of different alleles in the population's gene pool. This change in allele frequency can lead to the emergence of novel traits and eventually, new species in the course of time.
A lot of the traits we admire about animals and plants are adaptations, like lung or gills for removing oxygen from the air, fur or feathers for insulation and long legs for running away from predators, and camouflage to hide. To comprehend adaptation it is essential to differentiate between physiological and behavioral characteristics.
Physical characteristics like thick fur and gills are physical traits. The behavioral adaptations aren't an exception, for instance, the tendency of animals to seek companionship or to retreat into the shade in hot weather. It is important to keep in mind that the absence of planning doesn't cause an adaptation. In fact, failing to consider the consequences of a decision can render it ineffective despite the fact that it might appear logical or even necessary.