What is 에볼루션 룰렛 ?
Free evolution is the idea that the natural processes of organisms can lead to their development over time. This includes the emergence and development of new species.
A variety of examples have been provided of this, including various varieties of fish called sticklebacks that can be found in salt or fresh water, as well as walking stick insect varieties that favor particular host plants. These are mostly reversible traits however, are not able to be the reason for fundamental changes in body plans.
Evolution by Natural Selection
Scientists have been fascinated by the development of all living creatures that inhabit our planet for centuries. Charles Darwin's natural selectivity is the most well-known explanation. This process occurs when individuals who are better-adapted have more success in reproduction and survival than those who are less well-adapted. Over time, a community of well-adapted individuals increases and eventually becomes a new species.
Natural selection is a cyclical process that involves the interaction of three factors that are inheritance, variation and reproduction. Sexual reproduction and mutation increase the genetic diversity of the species. Inheritance is the transfer of a person's genetic traits to his or her offspring which includes both recessive and dominant alleles. Reproduction is the process of generating viable, fertile offspring. This can be accomplished through sexual or asexual methods.
Natural selection is only possible when all of these factors are in balance. If, for example an allele of a dominant gene allows an organism to reproduce and live longer than the recessive gene then the dominant allele will become more prevalent in a population. However, if the allele confers an unfavorable survival advantage or reduces fertility, it will disappear from the population. The process is self-reinforcing, meaning that a species that has a beneficial trait will survive and reproduce more than one with an unadaptive 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 longer neck in giraffes or bright white patterns of color in male peacocks, are more likely to be able to survive and create offspring, and thus will become the majority of the population over time.
Natural selection is only an aspect of populations and not on individuals. This is a major distinction from the Lamarckian theory of evolution, which argues that animals acquire traits by use or inactivity. If a giraffe extends its neck to reach prey and its neck gets longer, then its offspring will inherit this trait. The differences in neck size between generations will continue to grow until the giraffe is unable to reproduce with other giraffes.
Evolution through Genetic Drift
In genetic drift, the alleles within a gene can attain different frequencies in a group by chance events. At some point, only one of them will be fixed (become widespread enough to not more be eliminated through natural selection), and the other alleles diminish in frequency. This could lead to dominance at the extreme. The other alleles are eliminated, and heterozygosity falls to zero. In a small population it could lead to the complete elimination of recessive allele. This scenario is called the bottleneck effect. It is typical of an evolutionary process that occurs whenever an enormous number of individuals move to form a group.
A phenotypic bottleneck may occur when the survivors of a catastrophe such as an epidemic or a mass hunting event, are condensed in a limited area. The survivors will have a dominant allele and thus will have the same phenotype. This situation could be caused by war, earthquakes or even plagues. The genetically distinct population, if left, could be susceptible to genetic drift.
Walsh Lewens, Walsh, and Ariew define drift as a departure from the expected value due to differences in fitness. They provide a well-known instance of twins who are genetically identical, share identical phenotypes, and yet one is struck by lightening and dies while the other lives and reproduces.
This kind of drift can play a significant role in the evolution of an organism. However, it's not the only method to evolve. The primary alternative is a process known as natural selection, in which phenotypic variation in an individual is maintained through mutation and migration.
Stephens argues there is a huge difference between treating the phenomenon of drift as an actual cause or force, and considering other causes, such as selection mutation and migration as forces and causes. He argues that a causal process account of drift permits us to differentiate it from other forces, and this distinction is crucial. He further argues that drift has a direction: that is it tends to eliminate heterozygosity. It also has a magnitude, that is determined by population size.
Evolution through Lamarckism
Biology students in high school are often introduced to Jean-Baptiste Lemarck's (1744-1829) work. His theory of evolution is generally called "Lamarckism" and it asserts that simple organisms evolve into more complex organisms through the inheritance of traits that are a result of an organism's natural activities use and misuse. Lamarckism is usually illustrated with an image of a giraffe extending its neck longer to reach the higher branches in the trees. This could cause giraffes to pass on their longer necks to their offspring, who then grow even 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 17 May 1802, he introduced an innovative concept that completely challenged the conventional wisdom about organic transformation. According to Lamarck, living things evolved from inanimate materials 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 prevailing story is that Lamarckism became an opponent to Charles Darwin's theory of evolution by natural selection, and that the two theories battled each other in the 19th century. Darwinism eventually prevailed, leading to what biologists refer to as the Modern Synthesis. The theory argues that acquired traits are passed down from generation to generation and instead argues that organisms evolve through the influence of environment elements, like Natural Selection.
Lamarck and his contemporaries supported the idea that acquired characters could be passed down to future generations. However, this idea was never a key element of any of their evolutionary theories. This is due in part to the fact that it was never validated scientifically.
However, it has been more than 200 years since Lamarck was born and in the age genomics there is a vast amount of evidence to support the heritability of acquired characteristics. It is sometimes called "neo-Lamarckism" or more often epigenetic inheritance. This is a model that is as reliable as the popular Neodarwinian model.
Evolution through the process of adaptation
One of the most popular misconceptions about evolution is being driven by a fight for survival. This view misrepresents natural selection and ignores the other forces that determine the rate of evolution. The fight for survival is more accurately described as a struggle to survive in a specific environment. This can include not just other organisms as well as the physical environment itself.
To understand how evolution works it is important to understand what is adaptation. Adaptation is any feature that allows a living thing to live in its environment and reproduce. It can be a physiological feature, such as feathers or fur or a behavior such as a tendency to move into the shade in hot weather or coming out at night to avoid the cold.
The ability of an organism to draw energy from its surroundings and interact with other organisms and their physical environments, is crucial to its survival. The organism must have the right genes to create offspring, and be able to find sufficient food and resources. The organism should also be able reproduce at a rate that is optimal for its particular niche.
These elements, along with gene flow and mutations can result in a shift in the proportion of different alleles in the gene pool of a population. This shift in the frequency of alleles could lead to the development of novel traits and eventually new species in the course of time.
Many of the characteristics we admire about animals and plants are adaptations, like lung or gills for removing oxygen from the air, feathers or fur for insulation, long legs for running away from predators and camouflage for hiding. To comprehend adaptation, it is important to differentiate between physiological and behavioral characteristics.
Physical traits such as thick fur and gills are physical traits. Behavioral adaptations are not, such as the tendency of animals to seek out companionship or retreat into shade in hot weather. In addition, it is important to understand that a lack of forethought is not a reason to make something an adaptation. Failure to consider the consequences of a decision even if it appears to be logical, can cause it to be unadaptive.