What is Free Evolution?
Free evolution is the concept that the natural processes that organisms go through can lead them to evolve over time. This includes the appearance and development of new species.
This has been proven by numerous examples such as the stickleback fish species that can thrive in saltwater or fresh water and walking stick insect types that are apprehensive about specific host plants. These are mostly reversible traits, however, cannot explain fundamental changes in body plans.
Evolution by Natural Selection
The development of the myriad living creatures on Earth is a mystery that has intrigued scientists for centuries. The most widely accepted explanation is that of Charles Darwin's natural selection process, a process that occurs when better-adapted individuals survive and reproduce more successfully than those who are less well-adapted. Over time, the population of well-adapted individuals becomes larger and eventually develops into an entirely new species.
Natural selection is a cyclical process that is characterized by the interaction of three factors that are inheritance, variation and reproduction. Sexual reproduction and mutations increase the genetic diversity of the species. Inheritance refers the transmission of genetic traits, including both dominant and recessive genes and their offspring. Reproduction is the production of fertile, viable offspring which includes both sexual and asexual methods.
Natural selection is only possible when all the factors are in harmony. For example, if a dominant allele at one gene can cause an organism to live and reproduce more often than the recessive allele the dominant allele will become more prevalent within the population. But if the allele confers an unfavorable survival advantage or decreases fertility, it will be eliminated from the population. The process is self-reinforced, meaning that an organism with a beneficial trait will survive and reproduce more than an individual with an inadaptive characteristic. The higher the level of fitness an organism has as measured by its capacity to reproduce and endure, is the higher number of offspring it produces. People with desirable traits, such as longer necks in giraffes, or bright white patterns of color in male peacocks are more likely survive and have offspring, and thus will become the majority of the population over time.
Natural selection is only a force for populations, not individuals. This is a significant distinction from the Lamarckian theory of evolution that states that animals acquire traits due to the use or absence of use. If a giraffe stretches its neck to reach prey, and the neck becomes longer, then its children will inherit this characteristic. The difference in neck length between generations will persist until the neck of the giraffe becomes so long that it can not breed with other giraffes.
Evolution by Genetic Drift
Genetic drift occurs when alleles of the same gene are randomly distributed in a population. Eventually, only one will be fixed (become widespread enough to not longer be eliminated by natural selection), and the rest of the alleles will drop in frequency. This can lead to an allele that is dominant in the extreme. The other alleles are eliminated, and heterozygosity is reduced to zero. In a small number of people it could lead to the complete elimination of recessive alleles. This scenario is called the bottleneck effect. It is typical of an evolutionary process that occurs when an enormous number of individuals move to form a group.
A phenotypic 'bottleneck' can also occur when survivors of a disaster such as an outbreak or a mass hunting event are concentrated in the same area. The survivors will have an dominant allele, and will share the same phenotype. This situation could be caused by earthquakes, war or even a plague. 무료에볼루션 , if it remains, could be susceptible to genetic drift.
Walsh Lewens and Ariew employ Lewens, Walsh and Ariew employ a "purely outcome-oriented" definition of drift as any departure from the expected values for variations in fitness. They give a famous example of twins that are genetically identical and have identical phenotypes but one is struck by lightning and dies, whereas the other lives and reproduces.
This kind of drift can be crucial in the evolution of a species. It is not the only method of evolution. The primary alternative is to use a process known as natural selection, where the phenotypic diversity of the population is maintained through mutation and migration.
Stephens argues that there is a big difference between treating drift as a force, or a cause and considering other causes of evolution, such as mutation, selection, and migration as forces or causes. Stephens claims that a causal process account of drift allows us to distinguish it from the other forces, and that this distinction is vital. He further argues that drift has a direction, that is it tends to reduce heterozygosity. It also has a specific magnitude which is determined by the size of the population.
Evolution through Lamarckism
Biology students in high school are frequently introduced to Jean-Baptiste Lamarck's (1744-1829) work. His theory of evolution, commonly called "Lamarckism is based on the idea that simple organisms evolve into more complex organisms by adopting traits that are a product of the organism's use and misuse. Lamarckism is typically illustrated by an image of a giraffe that extends its neck to reach higher up in the trees. This would cause the necks of giraffes that are longer to be passed on to their offspring who would then become taller.
Lamarck, a French Zoologist, introduced an innovative idea in his 17 May 1802 opening lecture at the Museum of Natural History of Paris. He challenged previous thinking on organic transformation. According Lamarck, living organisms evolved from inanimate material by a series of gradual steps. Lamarck wasn't the only one to suggest this however he was widely thought of as the first to give the subject a thorough and general overview.
The most popular story is that Lamarckism was 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 ultimately prevailed which led to what biologists call the Modern Synthesis. The Modern Synthesis theory denies that traits acquired through evolution can be inherited and instead argues that organisms evolve through the selective action of environmental factors, like natural selection.
Although Lamarck believed in the concept of inheritance by 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 due in part to the fact that it was never tested scientifically.
It's been over 200 year since Lamarck's birth and in the field of age genomics there is a growing evidence base that supports the heritability of acquired traits. This is often referred to as "neo-Lamarckism" or, more commonly, epigenetic inheritance. This is a model that is as valid as the popular Neodarwinian model.
Evolution by adaptation
One of the most common misconceptions about evolution is being driven by a struggle to survive. 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 fight to survive in a specific environment. This could include not just other organisms as well as the physical surroundings themselves.
To understand how evolution works, it is helpful to understand what is adaptation. It is a feature that allows a living organism to survive in its environment and reproduce. It can be a physical structure, like fur or feathers. Or it can be a behavior trait that allows you to move to the shade during hot weather or coming out to avoid the cold at night.
An organism's survival depends on its ability to obtain energy from the environment and interact with other organisms and their physical environments. The organism must have the right genes to create offspring, and be able to find enough food and resources. The organism should be able to reproduce itself at a rate that is optimal for its particular niche.
These elements, along with mutations and gene flow, can lead to an alteration in the ratio of different alleles within the gene pool of a population. As time passes, this shift in allele frequencies can result in the emergence of new traits, and eventually new species.
Many of the characteristics we admire about animals and plants are adaptations, such as the lungs or gills that extract oxygen from the air, fur or feathers to provide insulation and long legs for running away from predators and camouflage to hide. To understand adaptation it is crucial to differentiate between physiological and behavioral traits.
Physical traits such as large gills and thick fur are physical traits. Behavior adaptations aren't, such as the tendency of animals to seek companionship or to retreat into the shade during hot temperatures. It is important to keep in mind that the absence of planning doesn't cause an adaptation. Failure to consider the consequences of a decision even if it seems to be rational, may make it inflexible.