What is Free Evolution?
Free evolution is the notion that natural processes can cause organisms to develop over time. This includes the emergence and development of new species.
Many examples have been given of this, including different varieties of stickleback fish that can live in salt or fresh water, as well as walking stick insect varieties that favor specific host plants. These reversible traits cannot explain fundamental changes to basic body plans.
Evolution through Natural Selection
Scientists have been fascinated by the development of all living creatures that inhabit our planet for centuries. The most well-known explanation is that of Charles Darwin's natural selection, an evolutionary process that occurs when individuals that are better adapted survive and reproduce more effectively than those less well adapted. Over time, a population of well adapted individuals grows and eventually becomes a new species.
Natural selection is a cyclical process that is characterized by the interaction of three elements that are inheritance, variation and reproduction. Variation is caused by mutations and sexual reproduction, both of which increase the genetic diversity of a species. Inheritance refers the transmission of genetic characteristics, which includes both dominant and recessive genes to their offspring. Reproduction is the process of creating fertile, viable offspring. This can be done through sexual or asexual methods.
All of these factors have to be in equilibrium for natural selection to occur. For instance, if an allele that is dominant at one gene can cause an organism to live and reproduce more often than the recessive allele the dominant allele will become more prevalent in the population. If the allele confers a negative advantage to survival or decreases the fertility of the population, it will disappear. This process is self-reinforcing meaning that a species with a beneficial trait is more likely to survive and reproduce than an individual with an inadaptive trait. The more offspring that an organism has, the greater its fitness which is measured by its capacity to reproduce itself and live. People with good traits, like a long neck in giraffes, or bright white patterns on male peacocks are more likely than others to live and reproduce which eventually leads to them becoming the majority.
Natural selection is only a force for populations, not on individuals. This is a crucial distinction from the Lamarckian evolution theory which holds that animals acquire traits through the use or absence of use. If a giraffe extends its neck to catch prey and its neck gets larger, then its offspring will inherit this trait. The difference in neck length between generations will persist until the giraffe's neck gets too long to not breed with other giraffes.
Evolution through Genetic Drift
Genetic drift occurs when alleles of a gene are randomly distributed within a population. Eventually, one of them will reach fixation (become so widespread that it is unable to be eliminated by natural selection), while other alleles will fall to lower frequencies. This can result in dominance at the extreme. The other alleles are essentially eliminated, and heterozygosity falls to zero. In a small group it could lead to the total elimination of recessive alleles. This scenario is called the bottleneck effect and is typical of the evolutionary process that occurs when an enormous number of individuals move to form a group.
A phenotypic bottleneck could occur when the survivors of a disaster like an epidemic or a massive hunt, are confined into a small area. The remaining individuals will be mostly homozygous for the dominant allele which means they will all have the same phenotype, and thus have the same fitness characteristics. This could be caused by earthquakes, war or even plagues. Whatever the reason the genetically distinct population that is left might be prone to genetic drift.
Walsh Lewens, Lewens, and Ariew utilize Lewens, Walsh, and Ariew use a "purely outcome-oriented" definition of drift as any departure from expected values for variations in fitness. They cite a famous example of twins that are genetically identical, share the exact same phenotype 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 an entire species. This isn't the only method of evolution. The main alternative is a process known as natural selection, in which the phenotypic variation of an individual is maintained through mutation and migration.
Stephens asserts that there is a vast distinction between treating drift as a force or cause, and considering other causes, such as migration and selection mutation as forces and causes. He claims that a causal-process explanation of drift lets us separate it from other forces, and this differentiation is crucial. He also argues that drift is both direction, i.e., it tends to eliminate heterozygosity. 에볼루션게이밍 has a size that is determined by the size of the population.
Evolution through Lamarckism
Biology students in high school are often exposed to Jean-Baptiste lamarck's (1744-1829) work. His theory of evolution, commonly referred to as “Lamarckism” is based on the idea that simple organisms develop into more complex organisms by inheriting characteristics that result from an organism's use and disuse. Lamarckism is illustrated through a giraffe extending its neck to reach higher leaves in the trees. This could cause giraffes to pass on their longer necks to their offspring, which then grow even taller.
Lamarck Lamarck, a French zoologist, presented an idea that was revolutionary in his 17 May 1802 opening lecture at the Museum of Natural History of Paris. He challenged conventional wisdom on organic transformation. In his view living things had evolved from inanimate matter through a series of gradual steps. Lamarck was not the only one to suggest that this might be the case but the general consensus is that he was the one giving the subject its first general and comprehensive treatment.
The popular narrative is that Lamarckism was an opponent to Charles Darwin's theory of evolution through natural selection, and that the two theories fought it out in the 19th century. Darwinism ultimately prevailed, leading to what biologists refer to as the Modern Synthesis. The Modern Synthesis theory denies that acquired characteristics can be inherited, and instead suggests that organisms evolve through the selective action of environmental factors, including natural selection.
While Lamarck supported the notion of inheritance by acquired characters, and his contemporaries also offered a few words about this idea, it was never a major feature in any of their theories about evolution. This is due to the fact that it was never tested scientifically.
However, it has been more than 200 years since Lamarck was born and in the age genomics, there is a large amount of evidence to support the heritability of acquired traits. This is referred to as "neo Lamarckism", or more commonly epigenetic inheritance. It is a variant of evolution that is just as relevant as the more popular neo-Darwinian model.
Evolution through Adaptation
One of the most popular 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 better described as a fight to survive in a particular environment. This may include not only other organisms but also the physical environment itself.
To understand how evolution functions, it is helpful to understand what is adaptation. Adaptation is any feature that allows living organisms to survive in its environment and reproduce. It can be a physiological feature, such as feathers or fur or a behavioral characteristic like moving into the shade in hot weather or coming out at night to avoid the cold.
The ability of an organism to extract energy from its surroundings and interact with other organisms and their physical environment, is crucial to its survival. The organism should possess the right genes to produce offspring and be able find sufficient food and resources. The organism should also be able to reproduce at a rate that is optimal for its niche.
These factors, along with gene flow and mutation, lead to an alteration in the percentage of alleles (different types of a gene) in the gene pool of a population. This shift in the frequency of alleles can lead to the emergence of new traits, and eventually, new species as time passes.
Many of the characteristics we admire about animals and plants are adaptations, such as the lungs or gills that extract oxygen from the air, feathers or fur for insulation, long legs for running away from predators, and camouflage to hide. However, a thorough understanding of adaptation requires attention to the distinction between the physiological and behavioral traits.
Physiological adaptations like thick fur or gills, are physical traits, while behavioral adaptations, such as the tendency to seek out friends or to move to shade in hot weather, aren't. It is also important to remember that a lack of planning does not make an adaptation. A failure to consider the effects of a behavior even if it seems to be rational, could cause it to be unadaptive.