What is Free Evolution?
Free evolution is the idea that the natural processes of living organisms can lead to their development over time. This includes the emergence and development of new species.
This has been demonstrated by many examples, including stickleback fish varieties that can live in fresh or saltwater and walking stick insect types that are apprehensive about particular host plants. These mostly reversible trait permutations, however, cannot explain fundamental changes in body plans.
Evolution through Natural Selection
Scientists have been fascinated by the evolution of all living organisms that inhabit our planet for many centuries. The most well-known explanation is Charles Darwin's natural selection process, which occurs when individuals that are better adapted survive and reproduce more successfully than those who are less well adapted. Over time, a community of well-adapted individuals increases and eventually forms a whole new species.
Natural selection is a cyclical process that involves the interaction of three factors that are inheritance, variation and reproduction. Variation is caused by mutations and sexual reproduction both of which enhance the genetic diversity of a species. Inheritance is the passing of a person's genetic traits to their offspring which includes both recessive and dominant alleles. Reproduction is the process of producing fertile, viable offspring, which includes both asexual and sexual methods.
All of these factors have to be in equilibrium to allow natural selection to take place. For instance when the dominant allele of one gene allows an organism to live and reproduce more frequently than the recessive allele, the dominant allele will become more common in the population. However, if the allele confers a disadvantage in survival or decreases fertility, it will disappear from the population. This process is self-reinforcing meaning that a species with a beneficial characteristic will survive and reproduce more than an individual with an unadaptive trait. The more fit an organism is, measured by its ability reproduce and survive, is the greater number of offspring it will produce. People with good traits, such as longer necks in giraffes, or bright white colors in male peacocks are more likely to be able to survive and create offspring, so they will become the majority of the population over time.
Natural selection is an element in the population and not on individuals. This is a major distinction from the Lamarckian theory of evolution which argues that animals acquire traits through use or disuse. For 에볼루션 블랙잭 , if the Giraffe's neck grows longer due to stretching to reach prey its offspring will inherit a more long neck. The length difference between generations will persist until the giraffe's neck becomes so long that it can not breed with other giraffes.
Evolution by Genetic Drift
In genetic drift, the alleles within a gene can reach different frequencies in a group due to random events. At some point, one will attain fixation (become so widespread that it can no longer be removed through natural selection), while other alleles will fall to lower frequency. This can result in an allele that is dominant at the extreme. The other alleles are essentially eliminated, and heterozygosity falls to zero. In a small group it could result in the complete elimination of recessive gene. This scenario is called the bottleneck effect and is typical of an 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 epidemic or a mass hunting event, are concentrated in a limited area. The survivors will have a dominant allele and thus will share the same phenotype. This situation could be caused by war, earthquakes, or even plagues. Regardless of the cause the genetically distinct group that is left might be prone 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, and yet one is struck by lightning and dies, while the other lives and reproduces.
This type of drift is crucial in the evolution of a species. It's not the only method for evolution. Natural selection is the most common alternative, in which mutations and migrations maintain phenotypic diversity within a population.
Stephens asserts that there is a huge difference between treating drift like a force or cause, and treating other causes such as migration and selection as forces and causes. Stephens claims that a causal process explanation of drift permits us to differentiate it from the other forces, and that this distinction is crucial. 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 population size.
Evolution by Lamarckism
Biology students in high school are frequently introduced to Jean-Baptiste Lamarck's (1744-1829) work. His theory of evolution, commonly referred to as “Lamarckism” is based on the idea that simple organisms transform into more complex organisms taking on traits that are a product of an organism's use and disuse. Lamarckism is usually illustrated with the image of a giraffe that extends its neck to reach the higher branches in the trees. This could cause the necks of giraffes that are longer to be passed onto their offspring who would then grow even taller.
Lamarck, a French Zoologist from France, presented a revolutionary concept in his opening lecture at the Museum of Natural History of Paris. He challenged the previous thinking on organic transformation. According to him, living things had evolved from inanimate matter via the gradual progression of events. Lamarck was not the only one 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 his first comprehensive and comprehensive analysis.
The predominant story is that Charles Darwin's theory on evolution by natural selection and Lamarckism were rivals during the 19th century. Darwinism eventually won and led to the development of what biologists call the Modern Synthesis. The theory argues that acquired traits can be passed down and instead argues organisms evolve by the selective action of environment factors, including Natural Selection.
While Lamarck believed in the concept of inheritance by acquired characters, and his contemporaries also paid lip-service to this notion but it was not a major feature in any of their evolutionary theorizing. 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 referred to as "neo-Lamarckism" or, more often, epigenetic inheritance. This is a model that is as reliable as the popular Neodarwinian model.
Evolution through Adaptation
One of the most widespread misconceptions about evolution is that it is driven by a type of struggle for survival. 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 in a specific environment, which may be a struggle that involves not only other organisms, but also the physical environment.
Understanding how adaptation works is essential to understand evolution. Adaptation refers to any particular feature that allows an organism to survive and reproduce in its environment. It could be a physical feature, like fur or feathers. It could also be a trait of behavior, like moving into the shade during the heat, or escaping the cold at night.
An organism's survival depends on its ability to draw energy from the environment and to interact with other living organisms and their physical surroundings. The organism must have the right genes to produce offspring and be able find enough food and resources. Moreover, the organism must be capable of reproducing at a high rate within its environmental niche.
These factors, in conjunction with mutations and gene flow, can lead to changes in the proportion of different alleles in a population’s gene pool. This change in allele frequency can result in the emergence of novel traits and eventually new species over time.
Many of the characteristics we find appealing in animals and plants are adaptations. For instance the lungs or gills which extract oxygen from air feathers and fur as insulation, long legs to run away from predators and camouflage for hiding. To understand adaptation it is crucial to discern between physiological and behavioral characteristics.
Physiological adaptations like thick fur or gills are physical traits, while behavioral adaptations, like the tendency to search for friends or to move into the shade in hot weather, aren't. Additionally it is important to note that a lack of forethought does not make something an adaptation. In fact, failure to consider the consequences of a behavior can make it ineffective despite the fact that it appears to be reasonable or even essential.