What is Free Evolution?
Free evolution is the notion that the natural processes that organisms go through can cause them to develop over time. This includes the appearance and growth of new species.
This is evident in many examples such as the stickleback fish species that can thrive in salt or fresh water, and walking stick insect varieties that are apprehensive about particular host plants. These are mostly reversible traits however, are not able to explain fundamental changes in basic body plans.
Evolution through Natural Selection
Scientists have been fascinated by the evolution of all living creatures that inhabit our planet for centuries. Charles Darwin's natural selectivity is the best-established explanation. This process occurs when people who are more well-adapted survive and reproduce more than those who are less well-adapted. As time passes, the number of well-adapted individuals grows and eventually forms an entirely new species.
Natural selection is an ongoing process and involves the interaction of 3 factors that are: reproduction, variation and inheritance. Variation is caused by mutations and sexual reproduction both of which enhance the genetic diversity within the species. Inheritance refers to the passing of a person's genetic traits to his or her offspring which includes both dominant and recessive alleles. Reproduction is the process of producing fertile, viable offspring. This can be achieved through sexual or asexual methods.
Natural selection only occurs when all these elements are in harmony. If, for instance an allele of a dominant gene allows an organism to reproduce and survive more than the recessive allele then the dominant allele becomes more prevalent in a group. If the allele confers a negative advantage to survival or reduces the fertility of the population, it will go away. The process is self-reinforcing meaning that the organism with an adaptive trait will survive and reproduce far more effectively than those with a maladaptive trait. The more offspring that an organism has, the greater its fitness that is determined by its capacity to reproduce and survive. People with good characteristics, such as the long neck of Giraffes, or the bright white patterns on male peacocks, are more likely than others to live and reproduce, which will eventually lead to them becoming the majority.
Natural selection only acts on populations, not on individuals. This is a crucial distinction from the Lamarckian theory of evolution which holds that animals acquire traits through the use or absence of use. For instance, if the giraffe's neck gets longer through stretching to reach for prey, its offspring will inherit a more long neck. The difference in neck length between generations will persist until the giraffe's neck becomes too long that it can no longer breed with other giraffes.
Evolution through Genetic Drift
Genetic drift occurs when the alleles of a gene are randomly distributed in a population. Eventually, 에볼루션 바카라 무료체험 of them will attain fixation (become so widespread that it is unable to be removed through natural selection), while other alleles will fall to lower frequencies. In extreme cases, this leads to a single allele dominance. The other alleles are eliminated, and heterozygosity falls to zero. In a small group, this could lead to the complete elimination of the recessive allele. This is called a bottleneck effect, and it is typical of evolutionary process when a lot of people migrate to form a new population.
A phenotypic bottleneck can also happen when the survivors of a disaster, such as an epidemic or a mass hunt, are confined into a small area. The survivors will carry an allele that is dominant and will share the same phenotype. This situation could be caused by war, earthquakes or even a plague. Whatever the reason, the genetically distinct population that is left might be prone to genetic drift.
Walsh Lewens, Lewens, and Ariew utilize a "purely outcome-oriented" definition of drift as any departure from the expected values for differences in fitness. They give a famous instance of twins who are genetically identical, have the exact same phenotype but one is struck by lightning and dies, whereas the other lives and reproduces.
This kind of drift can play a significant role in the evolution of an organism. It's not the only method of evolution. The main alternative is a process known as natural selection, where phenotypic variation in an individual is maintained through mutation and migration.
Stephens claims that there is a significant difference between treating drift like an actual cause or force, and treating other causes such as migration and selection as causes and forces. Stephens claims that a causal process explanation of drift lets us separate it from other forces and that this differentiation is crucial. He also argues that drift has both direction, i.e., it tends to reduce heterozygosity. It also has a size that is determined by population size.
Evolution by Lamarckism
Biology students in high school are often exposed to Jean-Baptiste lamarck's (1744-1829) work. His theory of evolution, commonly called "Lamarckism, states that simple organisms transform into more complex organisms by taking on traits that result from an organism's use and disuse. Lamarckism is usually illustrated with the image of a giraffe extending its neck longer to reach the higher branches in the trees. This would cause giraffes to give their longer necks to offspring, who 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 conventional wisdom on organic transformation. According Lamarck, living organisms evolved from inanimate matter through a series of gradual steps. Lamarck was not the first to suggest this, but he was widely regarded as the first to offer the subject a thorough and general treatment.
The most popular story is that Charles Darwin's theory of evolution by natural selection and Lamarckism were competing during the 19th century. Darwinism ultimately won and led to what biologists refer to as the Modern Synthesis. The theory argues that acquired characteristics can be acquired through inheritance and instead, it argues that organisms develop by the symbiosis of environmental factors, like natural selection.
While Lamarck believed in the concept of inheritance through acquired characters and his contemporaries paid lip-service to this notion, it was never a major feature in any of their evolutionary theories. This is largely due to the fact that it was never tested scientifically.
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 to support the heritability of acquired characteristics. It is sometimes called "neo-Lamarckism" or, more commonly, epigenetic inheritance. It is a form of evolution that is just as relevant as the more popular Neo-Darwinian model.
Evolution by adaptation
One of the most common misconceptions about evolution is being driven by a struggle for survival. In fact, this view is inaccurate and overlooks the other forces that are driving evolution. The fight for survival can be better described as a struggle to survive in a certain environment. This can include not only other organisms as well as the physical surroundings themselves.
To understand how evolution works it is beneficial to understand what is adaptation. Adaptation is any feature that allows a living organism to survive in its environment and reproduce. It can be a physical structure, such as feathers or fur. Or it can be a trait of behavior such as moving towards shade during hot weather, or coming out to avoid the cold at night.
The survival of an organism is dependent on its ability to extract energy from the environment and to interact with other organisms and their physical environments. The organism must have the right genes to create offspring, and it must be able to locate sufficient food and other resources. In addition, the organism should be capable of reproducing itself at an optimal rate within its environmental niche.
These factors, together with gene flow and mutations can result in a shift in the proportion of different alleles within a population’s gene pool. The change in frequency of alleles could lead to the development of novel traits and eventually new species in the course of time.
Many of the features we appreciate in animals and plants are adaptations. For example, lungs or gills that extract oxygen from the air feathers and fur for insulation and long legs to get away from predators, and camouflage to hide. To understand adaptation it is crucial to discern between physiological and behavioral traits.
Physical characteristics like the thick fur and gills are physical traits. The behavioral adaptations aren't an exception, for instance, 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 thought is not a reason to make something an adaptation. In fact, failing to consider the consequences of a behavior can make it ineffective even though it may appear to be logical or even necessary.