What is Free Evolution?
Free evolution is the concept that natural processes can cause organisms to evolve over time. This includes the creation of new species and the change in appearance of existing species.
This is evident in numerous examples such as the stickleback fish species that can be found in fresh or saltwater and walking stick insect species that are apprehensive about particular host plants. These typically reversible traits do not explain the fundamental changes in the body's basic plans.
Evolution by Natural Selection
Scientists have been fascinated by the development of all living creatures that live on our planet for ages. The most well-known explanation is Darwin's natural selection, a process that occurs when better-adapted individuals survive and reproduce more successfully than those less well adapted. As time passes, the number of well-adapted individuals becomes larger and eventually develops into a new species.
Natural selection is an ongoing process and involves the interaction of 3 factors that are: reproduction, variation and inheritance. Sexual reproduction and mutation increase genetic diversity in an animal species. Inheritance refers to the passing of a person's genetic characteristics to his or her offspring, which includes both dominant and recessive alleles. Reproduction is the production of fertile, viable offspring, which includes both sexual and asexual methods.
Natural selection can only occur when all the factors are in balance. For example, if the dominant allele of one gene allows an organism to live and reproduce more often than the recessive allele the dominant allele will become more prominent in the population. However, if the allele confers an unfavorable survival advantage or reduces fertility, it will be eliminated from the population. The process is self-reinforcing, meaning that an organism that has a beneficial trait can reproduce and survive longer than one 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. Individuals with favorable characteristics, like longer necks in giraffes and bright white patterns of color in male peacocks are more likely to be able to survive and create offspring, and thus will eventually make up the majority of the population over time.
Natural selection only acts on populations, not individual organisms. This is an important distinction from the Lamarckian theory of evolution, which states that animals acquire traits through use or neglect. If a giraffe stretches its neck in order to catch prey and its neck gets longer, then its children will inherit this characteristic. The difference in neck length between generations will continue until the giraffe's neck gets too long that it can no longer breed with other giraffes.
Evolution through Genetic Drift
Genetic drift occurs when the alleles of the same gene are randomly distributed within a population. In the end, only one will be fixed (become common enough to no longer be eliminated by natural selection), and the other alleles will drop in frequency. This could lead to a dominant allele at the extreme. The other alleles are virtually eliminated and heterozygosity decreased to a minimum. In a small population this could lead to the complete elimination of the recessive gene. This scenario is called the bottleneck effect and is typical of the evolutionary process that occurs when the number of individuals migrate to form a population.
A phenotypic bottleneck may occur when survivors of a disaster like an epidemic or mass hunting event, are concentrated into a small area. The remaining individuals will be mostly homozygous for the dominant allele meaning that they all have the same phenotype, and therefore have the same fitness traits. This may be caused by conflict, earthquake, or even a plague. The genetically distinct population, if it is left vulnerable to genetic drift.
Walsh, Lewens and Ariew define drift as a departure from the expected value due to differences in fitness. They provide a well-known instance of twins who are genetically identical and have identical phenotypes, and yet one is struck by lightning and dies, whereas the other lives and reproduces.
This kind of drift can play a very important role in the evolution of an organism. However, it's not the only method to progress. The most common alternative is a process called natural selection, where the phenotypic variation of the population is maintained through mutation and migration.
에볼루션바카라사이트 claims that there is a major distinction between treating drift as a force or as an underlying cause, and considering other causes of evolution like mutation, selection and migration as forces or causes. Stephens claims that a causal process account of drift allows us differentiate it from other forces and that this distinction is essential. 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 the 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 referred to as "Lamarckism" and it asserts that simple organisms evolve into more complex organisms through the inherited characteristics which result from the organism's natural actions usage, 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 give their longer necks to offspring, which then become taller.
Lamarck the French Zoologist from France, presented a revolutionary concept in his 17 May 1802 opening lecture at the Museum of Natural History of Paris. He challenged the conventional wisdom on organic transformation. In his view living things had evolved from inanimate matter through the gradual progression of events. Lamarck was not the only one to suggest that this might be the case but he is widely seen as being the one who gave the subject its first broad and thorough treatment.
The dominant story is that Charles Darwin's theory on natural selection and Lamarckism were rivals in the 19th Century. Darwinism ultimately prevailed which led to what biologists refer to as the Modern Synthesis. This theory denies that acquired characteristics can be inherited, and instead, it argues that organisms develop through the selective action of environmental factors, like natural selection.
Although Lamarck supported the notion of inheritance through acquired characters and his contemporaries also spoke of this idea but it was not a central element in any of their theories about evolution. This is largely due to the fact that it was never validated scientifically.
It's been more than 200 years since Lamarck was born and, in the age of genomics, there is a large body of evidence supporting the heritability of acquired characteristics. This is referred to as "neo Lamarckism", or more often epigenetic inheritance. This is a version that is just as valid as the popular Neodarwinian model.
Evolution through Adaptation
One of the most commonly-held misconceptions about evolution is being driven by a fight for survival. In fact, this view is inaccurate and overlooks the other forces that drive evolution. The fight for survival is better described as a struggle to survive in a specific environment. This can be a challenge for not just other living things as well as the physical environment.
Understanding how adaptation works is essential to understand evolution. Adaptation is any feature that allows a living thing to live in its environment and reproduce. It could be a physiological structure such as feathers or fur or a behavioral characteristic such as a tendency to move to the shade during the heat or leaving at night to avoid cold.
The survival of an organism depends on its ability to draw energy from the environment and to interact with other organisms and their physical environments. The organism must have the right genes to generate offspring, and it should be able to find enough food and other resources. The organism must also be able reproduce itself at the rate that is suitable for its niche.
These factors, together with mutation and gene flow can result in changes in the ratio of alleles (different forms of a gene) in the gene pool of a population. As time passes, this shift in allele frequencies can result in the development of new traits and ultimately new species.
Many of the characteristics we find appealing in animals and plants are adaptations. For instance lung or gills that extract oxygen from air feathers and fur as insulation and long legs to get away from predators, and camouflage to hide. However, a proper understanding of adaptation requires paying attention to the distinction between the physiological and behavioral characteristics.
Physiological adaptations like the thick fur or gills are physical traits, while behavioral adaptations, like the tendency to search for companions or to move into the shade in hot weather, aren't. It is important to keep in mind that insufficient planning does not cause an adaptation. In fact, failure to think about the consequences of a choice can render it ineffective despite the fact that it might appear logical or even necessary.