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 and the transformation of the appearance of existing ones.
Many examples have been given of this, including various varieties of stickleback fish that can live in fresh or salt water and walking stick insect varieties that are attracted to specific host plants. These mostly reversible traits permutations are not able to explain fundamental changes to basic body plans.
Evolution by Natural Selection
The development of the myriad living organisms on Earth is an enigma that has intrigued scientists for decades. The best-established explanation is that of Charles Darwin's natural selection process, a process that is triggered when more well-adapted individuals live longer and reproduce more successfully than those less well adapted. As time passes, the number of individuals who are well-adapted grows and eventually develops into a new species.
Natural selection is a process that is cyclical and involves the interaction of 3 factors including reproduction, variation and inheritance. Sexual reproduction and mutations increase the genetic diversity of a species. Inheritance is the transfer of a person's genetic traits to their offspring which includes both recessive and dominant alleles. Reproduction is the process of generating viable, fertile offspring. This can be achieved through sexual or asexual methods.
All of these elements have to be in equilibrium for natural selection to occur. For instance the case where an allele that is dominant at the gene allows an organism to live and reproduce more often than the recessive allele, the dominant allele will be more prevalent in the population. If the allele confers a negative survival advantage or decreases the fertility of the population, it will go away. This process is self-reinforcing meaning that an organism with a beneficial characteristic will survive and reproduce more than one with an inadaptive trait. The more offspring an organism produces the better its fitness that is determined by its ability to reproduce itself and live. People with good traits, like the long neck of giraffes, or bright white color patterns on male peacocks are more likely to others to live and reproduce and eventually lead to them becoming the majority.
Natural selection is an element in the population and not on individuals. This is an important distinction from the Lamarckian theory of evolution which argues that animals acquire characteristics through use or neglect. If a giraffe expands its neck to catch prey and its neck gets larger, then its offspring will inherit this trait. The length difference between generations will continue until the neck of the giraffe becomes too long to not breed with other giraffes.
Evolution by Genetic Drift
In genetic drift, the alleles at a gene may be at different frequencies within a population through random events. Eventually, one of them will reach fixation (become so widespread that it cannot be eliminated by natural selection), while the other alleles drop to lower frequency. In the extreme it can lead to one allele dominance. Other alleles have been basically eliminated and heterozygosity has diminished to zero. In a small number of people this could lead to the complete elimination of the recessive gene. This is known as a bottleneck effect and it is typical of evolutionary process that occurs when a large number of individuals migrate to form a new population.
A phenotypic bottleneck can also occur when the survivors of a disaster such as an outbreak or mass hunt event are confined to a small area. The survivors will share an dominant allele, and will share the same phenotype. This may be caused by a war, earthquake, or even a plague. The genetically distinct population, if left, could be susceptible to genetic drift.
Walsh Lewens, Lewens, and Ariew employ Lewens, Walsh and Ariew employ a "purely outcome-oriented" definition of drift as any departure from the expected values of different fitness levels. They provide the famous case of twins who are both genetically identical and have exactly the same phenotype. However 에볼루션 무료 바카라 is struck by lightning and dies, but the other lives to reproduce.
This type of drift can play a very important role in the evolution of an organism. It's not the only method of evolution. The primary alternative is a process called natural selection, in which the phenotypic variation of 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 considering other causes, such as selection mutation and migration as causes and forces. He argues that a causal-process explanation of drift lets us distinguish it from other forces, and this distinction is essential. He also claims that drift is a directional force: that is it tends to reduce heterozygosity. It also has a specific magnitude that 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, also called "Lamarckism which means that simple organisms evolve into more complex organisms adopting traits that are a product of the organism's use and misuse. 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 offspring, which then become taller.
Lamarck was a French Zoologist. In his opening lecture for his course on invertebrate zoology at the Museum of Natural History in Paris on the 17th of May in 1802, he introduced an innovative concept that completely challenged the previous understanding of organic transformation. In his view living things had evolved from inanimate matter through an escalating series of steps. Lamarck was not the first to suggest that this could be the case, but his reputation is widely regarded as having given the subject its first broad and thorough treatment.
The most popular story is that Lamarckism grew into a rival to Charles Darwin's theory of evolution by natural selection, and that the two theories fought each other in the 19th century. Darwinism eventually won and led to the creation of what biologists today refer to as the Modern Synthesis. The theory argues that traits acquired through evolution can be inherited and instead suggests that organisms evolve through the action of environmental factors, like natural selection.
Although Lamarck believed in the concept of inheritance through acquired characters, and his contemporaries also spoke of this idea but it was not an integral part of any of their theories about evolution. This is due to the fact that it was never tested 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 often called "neo-Lamarckism" or, more frequently, epigenetic inheritance. It is a version of evolution that is just as valid as the more well-known Neo-Darwinian theory.
Evolution by the process of adaptation
One of the most widespread misconceptions about evolution is that it is driven by a type of struggle to survive. In reality, this notion is inaccurate and overlooks the other forces that determine the rate of evolution. The fight for survival can be more accurately described as a struggle to survive in a certain environment. This can include not only other organisms, but also the physical environment itself.
To understand how evolution works, it is helpful to consider what adaptation is. The term "adaptation" refers to any characteristic that allows a living thing to survive in its environment and reproduce. It can be a physiological feature, such as feathers or fur, or a behavioral trait such as a tendency to move into the shade in hot weather or stepping out at night to avoid the cold.
The survival of an organism depends on its ability to extract energy from the environment and interact with other organisms and their physical environments. The organism must have the right genes for producing offspring, and be able to find enough food and resources. The organism must be able to reproduce at an amount that is appropriate for its specific niche.
These factors, along with mutation and gene flow result in a change in the proportion of alleles (different varieties of a particular gene) in the gene pool of a population. As time passes, this shift in allele frequencies could result in the development of new traits and eventually new species.
Many of the features that we admire about animals and plants are adaptations, like the lungs or gills that extract oxygen from the air, fur or feathers for insulation long legs to run away from predators and camouflage for hiding. To understand adaptation it is crucial to differentiate between physiological and behavioral characteristics.
Physiological adaptations, like thick fur or gills, are physical characteristics, whereas behavioral adaptations, such as the tendency to seek out companions or to retreat to shade in hot weather, aren't. Additionally, it is important to note that lack of planning does not mean that something is an adaptation. A failure to consider the consequences of a decision even if it seems to be rational, may make it unadaptive.