What is Free Evolution?
Free evolution is the concept that natural processes can lead to the development of organisms over time. This includes the appearance and development of new species.
Numerous examples have been offered of this, such as different varieties of fish called sticklebacks that can live in fresh or salt water and walking stick insect varieties that are attracted to specific 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 the living organisms that inhabit our planet for centuries. The best-established explanation is Darwin's natural selection process, a process that occurs when individuals that are better adapted survive and reproduce more effectively than those less well-adapted. Over time, a population of well adapted individuals grows and eventually becomes a new species.
Natural selection is an ongoing process and involves the interaction of 3 factors including reproduction, variation and inheritance. Variation is caused by mutations and sexual reproduction both of which increase the genetic diversity within an animal species. 에볼루션 is the transfer of a person's genetic traits to the offspring of that person which includes both dominant and recessive alleles. Reproduction is the process of producing fertile, viable offspring which includes both asexual and sexual methods.
Natural selection can only occur when all the factors are in balance. If, for instance an allele of a dominant gene allows an organism to reproduce and live longer than the recessive gene allele The dominant allele is more prevalent in a population. However, if the gene confers an unfavorable survival advantage or reduces fertility, it will be eliminated from the population. The process is self-reinforcing, which means that an organism with an adaptive characteristic will live and reproduce more quickly than one with a maladaptive characteristic. The higher the level of fitness an organism has which is measured by its ability to reproduce and endure, is the higher number of offspring it will produce. Individuals with favorable traits, such as longer necks in giraffes or bright white patterns of color in male peacocks are more likely survive and produce offspring, which means they will make up the majority of the population over time.
Natural selection is only a force for populations, not on individuals. This is a significant distinction from the Lamarckian theory of evolution that states that animals acquire traits either through the use or absence of use. If a giraffe stretches its neck to reach prey and the neck grows larger, then its offspring will inherit this trait. The length difference between generations will continue until the giraffe's neck gets too long to not breed with other giraffes.
Evolution by Genetic Drift
In genetic drift, the alleles of a gene could be at different frequencies in a group through random events. At some point, only one of them will be fixed (become common enough to no longer be eliminated through natural selection) and the other alleles will decrease in frequency. In extreme cases this, it leads to one allele dominance. The other alleles are eliminated, and heterozygosity decreases to zero. In a small population this could result in the total elimination of the recessive allele. This scenario is called the bottleneck effect and is typical of the evolution process that occurs when the number of individuals migrate to form a group.
A phenotypic bottleneck can also occur when survivors of a catastrophe like an epidemic or a mass hunt, are confined within a narrow area. The survivors will be mostly homozygous for the dominant allele, meaning that they all share the same phenotype and thus have the same fitness characteristics. This could be caused by earthquakes, war or even a plague. The genetically distinct population, if it is left, could be susceptible to genetic drift.
Walsh Lewens, Lewens, and Ariew utilize Lewens, Walsh, and Ariew use a "purely outcome-oriented" definition of drift as any deviation from the expected values of differences in fitness. They provide a well-known example of twins that are genetically identical, have the exact same phenotype and yet one is struck by lightning and dies, whereas the other lives and reproduces.
This type of drift is very important in the evolution of a species. This isn't the only method of evolution. The main alternative is a process called natural selection, where phenotypic variation in the population is maintained through mutation and migration.
Stephens asserts that there is a significant difference between treating the phenomenon of drift as an agent or cause and treating other causes such as migration and selection as forces and causes. Stephens claims that a causal process explanation of drift allows us to distinguish it from other forces, and that this distinction is vital. He argues further that drift has direction, i.e., it tends to eliminate heterozygosity. 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 is generally called "Lamarckism" and it asserts that simple organisms evolve into more complex organisms by the inherited characteristics that are a result of an organism's natural activities, use and disuse. Lamarckism is illustrated through an giraffe's neck stretching to reach higher branches in the trees. This would cause the longer necks of giraffes to be passed to their offspring, who would then grow even taller.
Lamarck Lamarck, a French zoologist, presented a revolutionary concept in his 17 May 1802 opening lecture at the Museum of Natural History of Paris. He challenged the previous thinking on organic transformation. According Lamarck, living organisms evolved from inanimate material by a series of gradual steps. Lamarck was not the only one to suggest that this might be the case, but the general consensus is that he was the one being the one who gave the subject his first comprehensive and thorough 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 each other in the 19th century. Darwinism eventually prevailed and led to the creation of what biologists today call the Modern Synthesis. This theory denies that acquired characteristics can be inherited, and instead suggests that organisms evolve through the selective action of environmental factors, like natural selection.
While Lamarck believed in the concept of inheritance by acquired characters, and his contemporaries also spoke of this idea but it was not a major feature in any of their theories about evolution. This is largely due to the fact that it was never validated scientifically.
It has been more than 200 years since the birth of Lamarck and in the field of age genomics, there is an increasing evidence-based body of evidence to support the heritability-acquired characteristics. This is also referred to as "neo Lamarckism", or more often epigenetic inheritance. It is a form of evolution that is just as relevant as the more popular Neo-Darwinian model.
Evolution through Adaptation
One of the most common misconceptions about evolution is that it is driven by a type of struggle to survive. In fact, this view misrepresents natural selection and ignores the other forces that drive evolution. The struggle for existence is better described as a fight to survive in a certain environment. This may include not only other organisms, but also the physical environment.
Understanding adaptation is important to understand evolution. Adaptation is any feature that allows living organisms to survive in its environment and reproduce. It could be a physiological structure, like feathers or fur or a behavior such as a tendency to move to the shade during the heat or leaving at night to avoid the cold.
The capacity of an organism to extract energy from its surroundings and interact with other organisms as well as their physical environment is essential to its survival. The organism must possess the right genes to generate offspring, and it should be able to find enough food and other resources. The organism must also be able to reproduce at a rate that is optimal for its particular niche.
These elements, along with mutations and gene flow can result in an alteration in the ratio of different alleles within the population's gene pool. Over time, this change in allele frequencies can result in the emergence of new traits, and eventually new species.
A lot of the traits we admire in animals and plants are adaptations, such as the lungs or gills that 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 adaptation it is essential to differentiate between physiological and behavioral characteristics.
Physical characteristics like the thick fur and gills are physical characteristics. Behavior adaptations aren't, such as the tendency of animals to seek out companionship or retreat into shade during hot temperatures. In addition it is important to note that a lack of forethought is not a reason to make something an adaptation. A failure to consider the implications of a choice, even if it appears to be rational, may cause it to be unadaptive.