What is Free Evolution?
Free evolution is the idea that natural processes can cause organisms to develop over time. This includes the emergence and development of new species.
This has been demonstrated by numerous examples, including stickleback fish varieties that can be found in fresh or saltwater and walking stick insect species that prefer specific host plants. These reversible traits however, are not able to explain fundamental changes in body plans.
Evolution by Natural Selection
The evolution of the myriad living creatures on Earth is a mystery that has fascinated scientists for decades. The most widely accepted explanation is Charles Darwin's natural selection, which is triggered when more well-adapted individuals live longer and reproduce more successfully than those who are less well adapted. As time passes, a group of well-adapted individuals increases and eventually becomes a new species.
Natural selection is a process that is cyclical and involves the interaction of 3 factors: variation, reproduction and inheritance. Variation is caused by mutation and sexual reproduction both of which enhance the genetic diversity of a species. Inheritance refers the transmission of a person’s genetic traits, including both dominant and recessive genes and their offspring. Reproduction is the generation of fertile, viable offspring which includes both sexual and asexual methods.
Natural selection can only occur when all of these factors are in balance. If, for example an allele of a dominant gene makes an organism reproduce and live longer than the recessive allele The dominant allele will become more prevalent in a group. If the allele confers a negative advantage to survival or reduces the fertility of the population, it will be eliminated. The process is self reinforcing which means that an organism with an adaptive trait will survive and reproduce much more than those with a maladaptive feature. The higher the level of fitness an organism has, measured by its ability reproduce and survive, is the greater number of offspring it can produce. People with good characteristics, such as the long neck of Giraffes, or the bright white color patterns on male peacocks, are more likely than others to reproduce and survive, which will eventually lead to them becoming the majority.
Natural selection only acts on populations, not on individuals. This is a major distinction from the Lamarckian theory of evolution which states that animals acquire traits through use or disuse. If a giraffe expands its neck to reach prey, and the neck becomes larger, then its offspring will inherit this trait. The difference in neck size between generations will continue to increase until the giraffe is no longer able to reproduce with other giraffes.
Evolution through Genetic Drift
Genetic drift occurs when alleles of the same gene are randomly distributed within a population. Eventually, one of them will reach fixation (become so common that it can no longer be eliminated by natural selection), while other alleles will fall to lower frequency. In extreme cases this, it leads to a single allele dominance. The other alleles are essentially eliminated, and heterozygosity decreases to zero. In a small group, this could result in the complete elimination of the recessive gene. This is called a bottleneck effect, and it is typical of evolutionary process that takes place when a lot of individuals migrate to form a new population.
A phenotypic bottleneck may occur when survivors of a disaster such as an epidemic or a massive hunt, are confined in a limited area. The surviving individuals will be mostly homozygous for the dominant allele which means that they will all have the same phenotype, and thus have the same fitness traits. This may be caused by conflict, earthquake, or even a plague. The genetically distinct population, if it remains susceptible to genetic drift.
Walsh Lewens and Ariew employ Lewens, Walsh and Ariew employ a "purely outcome-oriented" definition of drift as any deviation from expected values for variations in fitness. They give the famous example of twins who are genetically identical and share the same phenotype. However, one is struck by lightning and dies, whereas the other lives to reproduce.
This kind of drift could play a crucial part in the evolution of an organism. It is not the only method of evolution. The main alternative is a process called natural selection, where the phenotypic diversity of a population is maintained by mutation and migration.
Stephens asserts that there is a big distinction between treating 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 mechanism account of drift permits us to differentiate it from these other forces, and this distinction is crucial. He further argues that drift has a direction, that is, it tends to eliminate heterozygosity, and that it also has a magnitude, that is determined by population size.
Evolution through Lamarckism
When high school students study biology they are often introduced to the work of Jean-Baptiste Lamarck (1744 - 1829). His theory of evolution, often called "Lamarckism, states that simple organisms transform into more complex organisms through taking on traits that are a product of an organism's use and disuse. Lamarckism is illustrated through a giraffe extending its neck to reach higher levels of leaves in the trees. This process would cause giraffes to give their longer necks to their offspring, who would then get taller.
Lamarck the French Zoologist from France, presented a revolutionary concept in his opening lecture at the Museum of Natural History of Paris. He challenged traditional thinking about organic transformation. In his view living things evolved from inanimate matter via the gradual progression of events. Lamarck was not the first to suggest this however he was widely regarded as the first to provide the subject a comprehensive and general treatment.
The dominant story is that Charles Darwin's theory of natural selection and Lamarckism fought in the 19th Century. Darwinism eventually prevailed and led to what biologists call the Modern Synthesis. The theory argues that acquired characteristics can be acquired through inheritance and instead suggests that organisms evolve by the symbiosis of environmental factors, such as natural selection.
While Lamarck endorsed the idea of inheritance by acquired characters and his contemporaries also paid lip-service to this notion, it was never a central element in any of their theories about evolution. This is due to the fact that it was never scientifically tested.
But it is now more than 200 years since Lamarck was born and, in the age of genomics, there is a large amount of evidence that supports the heritability of acquired characteristics. This is also known as "neo Lamarckism", or more commonly epigenetic inheritance. It is a variant of evolution that is as valid as the more popular Neo-Darwinian theory.
Evolution through Adaptation
One of the most popular misconceptions about evolution is that it is driven by a type of struggle to survive. This notion is not true and overlooks other forces that drive evolution. The fight for survival can be more precisely described as a fight to survive within a specific environment, which could be a struggle that involves not only other organisms but as well the physical environment.
To understand how evolution works it is important to understand what is adaptation. Adaptation is any feature that allows living organisms to live in its environment and reproduce. It can be a physical structure such as feathers or fur. Or it can be a behavior trait, like moving into the shade during hot weather, or escaping the cold at night.
The ability of a living thing to extract energy from its surroundings and interact with other organisms as well as their physical environment, is crucial to its survival. The organism must have the right genes for producing offspring and be able find sufficient food and resources. The organism should also be able to reproduce at an amount that is appropriate for its specific niche.
These factors, along with gene flow and mutation can result in changes in the ratio of alleles (different varieties of a particular gene) in the population's gene pool. Over time, this change in allele frequency can result in the emergence of new traits and ultimately new species.
A lot of the traits we admire in animals and plants are adaptations, for example, the lungs or gills that extract oxygen from the air, fur or feathers to protect themselves, long legs for running away from predators, and camouflage for hiding. To understand the concept of adaptation it is crucial to distinguish between behavioral and physiological traits.
에볼루션 바카라 체험 , such as the thick fur or gills are physical traits, whereas behavioral adaptations, such as the tendency to search for companions or to retreat into the shade in hot weather, aren't. Additionally, it is important to remember that a lack of thought is not a reason to make something an adaptation. In fact, failing to think about the consequences of a behavior can make it unadaptable, despite the fact that it may appear to be reasonable or even essential.