Free Evolution's History Of Free Evolution In 10 Milestones
What is Free Evolution?
Free evolution is the idea that natural processes can cause organisms to evolve over time. This includes the development of new species as well as the alteration of the 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 particular host plants. These mostly reversible trait permutations, however, cannot explain fundamental changes in body plans.
Evolution by Natural Selection
Scientists have been fascinated by the development of all the living creatures that live on our planet for centuries. The most widely accepted explanation is Darwin's natural selection process, which occurs when individuals that are better adapted survive and reproduce more effectively than those who are less well-adapted. As time passes, a group of well-adapted individuals expands and eventually forms a whole new species.
Natural selection is an ongoing process and involves the interaction of 3 factors including reproduction, variation and inheritance. Variation is caused by mutation and sexual reproduction both of which increase the genetic diversity within the species. Inheritance refers to the transmission of a person's genetic characteristics, which includes both dominant and recessive genes, to their offspring. Reproduction is the process of creating fertile, viable offspring. This can be done by both asexual or sexual methods.
Natural selection is only possible when all of these factors are in balance. For example when an allele that is dominant at a gene causes an organism to survive and reproduce more often than the recessive allele, the dominant allele will become more prominent within the population. However, if the allele confers a disadvantage in survival or reduces fertility, it will be eliminated from the population. The process is self-reinforced, meaning that a species with a beneficial trait can reproduce and survive longer than an individual with an unadaptive characteristic. The more offspring that an organism has the more fit it is which is measured by its ability to reproduce itself and survive. People with desirable characteristics, such as a long neck in giraffes, or bright white color patterns on male peacocks, are more likely than others to survive and reproduce which eventually leads to them becoming the majority.
Natural selection only acts on populations, not on individuals. This is a crucial distinction from the Lamarckian evolution theory that states that animals acquire traits due to usage or inaction. For instance, if the Giraffe's neck grows longer due to stretching to reach for prey, its offspring will inherit a larger neck. The differences in neck length between generations will continue until the giraffe's neck gets so long that it can not breed with other giraffes.
Evolution by Genetic Drift
In genetic drift, the alleles within a gene can attain different frequencies in a group due to random events. Eventually, one of them will reach fixation (become so widespread that it can no longer be removed through natural selection) and other alleles fall to lower frequency. This can lead to an allele that is dominant in the extreme. Other alleles have been virtually eliminated and heterozygosity decreased to zero. In a small number of people it could lead to the total elimination of the recessive allele. This is known as the bottleneck effect and is typical of an evolution process that occurs when a large number individuals migrate to form a population.
A phenotypic bottleneck can also occur when the survivors of a catastrophe, such as an epidemic or a massive hunting event, are condensed in a limited area. The survivors will be mostly homozygous for the dominant allele meaning that they all share the same phenotype, and therefore have the same fitness traits. This situation might be caused by war, an earthquake, or even a plague. The genetically distinct population, if it is left vulnerable to genetic drift.
Walsh Lewens, Lewens, and Ariew utilize a "purely outcome-oriented" definition of drift as any deviation from the expected values for differences in fitness. They give the famous example of twins who are genetically identical and share the same phenotype, but one is struck by lightning and dies, whereas the other continues to reproduce.
This type of drift is very important in the evolution of the species. It's not the only method for evolution. Natural selection is the primary alternative, in which mutations and migration maintain the phenotypic diversity of the population.
Stephens asserts that there is a big difference between treating the phenomenon of drift as a force or as a cause and considering other causes of evolution such as selection, mutation and migration as causes or causes. Stephens claims that a causal process model of drift allows us to separate it from other forces, and this distinction is essential. 에볼루션 룰렛 argues that drift has a direction, that is it tends to reduce heterozygosity. He also claims that it also has a size, which is determined by population size.
Evolution by Lamarckism
When students in high school study biology they are often introduced to the work of Jean-Baptiste Lamarck (1744 - 1829). His theory of evolution, commonly called "Lamarckism, states that simple organisms develop into more complex organisms through inheriting characteristics that are a product of the organism's use and misuse. Lamarckism is illustrated through a giraffe extending its neck to reach higher leaves in the trees. This could cause giraffes to pass on their longer necks to their offspring, who then become taller.
Lamarck the French Zoologist, introduced an idea that was revolutionary in his 17 May 1802 opening lecture at the Museum of Natural History of Paris. He challenged traditional thinking about organic transformation. According to Lamarck, living things evolved from inanimate material through a series gradual steps. Lamarck was not the only one to suggest that this might be the case but he is widely seen as giving the subject its first general and thorough treatment.
The predominant story is that Charles Darwin's theory of evolution by natural selection and Lamarckism were rivals in the 19th century. Darwinism eventually triumphed and led to the creation of what biologists now call the Modern Synthesis. This theory denies that acquired characteristics can be inherited and instead argues that organisms evolve through the action of environmental factors, including natural selection.
Although Lamarck believed in the concept of inheritance by acquired characters and his contemporaries paid lip-service to this notion but it was not an integral part of any of their evolutionary theorizing. This is due in part to the fact that it was never validated scientifically.
It's been more than 200 year since Lamarck's birth and in the field of genomics there is a growing body of evidence that supports the heritability acquired characteristics. This is also referred to as "neo Lamarckism", or more commonly epigenetic inheritance. This is a version that is just as valid as the popular Neodarwinian model.
Evolution by Adaptation
One of the most popular misconceptions about evolution is that it is driven by a type of struggle for survival. 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 may include not just other organisms as well as the physical environment itself.
Understanding how adaptation works is essential to understand evolution. It is a feature that allows a living organism to survive in its environment and reproduce. It can be a physiological structure, such as fur or feathers or a behavior such as a tendency to move into the shade in the heat or leaving at night to avoid cold.
The ability of an organism to draw energy from its environment and interact with other organisms, as well as their physical environments, is crucial to its survival. 에볼루션 룰렛 must possess the right genes to create offspring, and it must be able to access enough food and other resources. The organism should be able to reproduce itself at the rate that is suitable for its particular niche.
These elements, in conjunction with gene flow and mutation can result in changes in the ratio of alleles (different varieties of a particular gene) in a population's gene pool. As time passes, this shift in allele frequencies could result in the development of new traits and eventually new species.
Many of the features we find appealing in animals and plants are adaptations. For example lung or gills that extract oxygen from the air feathers and fur as insulation, long legs to run away from predators, and camouflage to hide. However, a complete understanding of adaptation requires a keen eye to the distinction between the physiological and behavioral characteristics.
Physiological adaptations like thick fur or gills, are physical traits, while behavioral adaptations, like the tendency to seek out companions or to move into the shade in hot weather, are not. In addition, it is important to understand that a lack of forethought does not make something an adaptation. In fact, a failure to think about the implications of a choice can render it ineffective, despite the fact that it appears to be reasonable or even essential.