What is Free Evolution?
Free evolution is the idea that the natural processes of organisms can lead to their development over time. This includes the appearance and growth of new species.
This is evident in numerous examples, including stickleback fish varieties that can thrive in saltwater or fresh water and walking stick insect types that are apprehensive about specific host plants. These mostly reversible trait permutations however, are not able to explain fundamental changes in body plans.
Evolution through Natural Selection
The evolution of the myriad living organisms on Earth is an enigma that has intrigued scientists for decades. The best-established explanation is Charles Darwin's natural selection, an evolutionary process that occurs when individuals that are better adapted survive and reproduce more successfully than those less well-adapted. Over time, the population of well-adapted individuals grows and eventually creates a new species.
Natural selection is a cyclical process that is characterized by the interaction of three elements including inheritance, variation, and reproduction. Variation is caused by mutation and sexual reproduction, both of which increase the genetic diversity of a species. Inheritance is the passing of a person's genetic characteristics to his or her offspring which includes both dominant and recessive alleles. Reproduction is the generation of viable, fertile offspring, which includes both asexual and sexual methods.
All of these elements must be in balance for natural selection to occur. For example the case where the dominant allele of a gene allows an organism to live and reproduce more frequently than the recessive allele the dominant allele will become more common within the population. But if the allele confers a disadvantage in survival or decreases fertility, it will be eliminated from the population. The process is self-reinforced, meaning that an organism with a beneficial trait can reproduce and survive longer than one with a maladaptive trait. The greater an organism's fitness, measured by its ability reproduce and survive, is the more offspring it can produce. People with desirable traits, such as a longer neck in giraffes or bright white patterns of color in male peacocks are more likely be able to survive and create offspring, which means they will become the majority of the population in the future.
Natural selection is only a factor in populations and not on individuals. This is a major distinction from the Lamarckian evolution theory that states that animals acquire traits due to usage or inaction. For instance, if the Giraffe's neck grows longer due to stretching to reach for prey, its offspring will inherit a larger neck. The difference in neck size between generations will continue to grow until the giraffe becomes unable to reproduce with other giraffes.
Evolution through Genetic Drift
In genetic drift, alleles of a gene could be at different frequencies within a population due to random events. In the end, only one will be fixed (become widespread enough to not longer be eliminated by natural selection) and the other alleles drop in frequency. This can result in a dominant allele in the extreme. The other alleles are essentially eliminated and heterozygosity has decreased to a minimum. In a small population, this could lead to the total elimination of recessive alleles. This scenario is called the bottleneck effect. It is typical of the evolution process that occurs when an enormous number of individuals move to form a group.
A phenotypic bottleneck may happen when the survivors of a disaster like an epidemic or a mass hunting event, are concentrated within a narrow area. The survivors are likely to be homozygous for the dominant allele, meaning that they all have the same phenotype and consequently have the same fitness characteristics. This can be caused by war, earthquakes or even plagues. Regardless of the cause, the genetically distinct population that remains could be prone to genetic drift.
Walsh, Lewens, and Ariew use Lewens, Walsh, and Ariew use a "purely outcome-oriented" definition of drift as any departure from the expected values for differences in fitness. They provide the famous case of twins who are both genetically identical and share the same phenotype. However, one is struck by lightning and dies, while the other lives to reproduce.
This type of drift can play a crucial part in the evolution of an organism. It's not the only method of evolution. Natural selection is the main alternative, where mutations and migration keep the phenotypic diversity of the population.
Stephens asserts that there is a big difference between treating the phenomenon of drift as a force, or an underlying cause, and considering other causes of evolution like selection, mutation and migration as causes or causes. He claims that a causal mechanism account of drift permits us to differentiate it from other forces, and that this distinction is crucial. He further argues that drift has a direction, i.e., it tends to reduce heterozygosity. It also has a size, which is determined based on population size.
Evolution by Lamarckism
In high school, students study biology they are often introduced to the work of Jean-Baptiste Lamarck (1744 - 1829). His theory of evolution, commonly referred to as “Lamarckism” which means that simple organisms evolve into more complex organisms through inheriting characteristics that are a product of the use and abuse of an organism. Lamarckism is typically illustrated by a picture of a giraffe that extends its neck further to reach the higher branches in the trees. This process would cause giraffes to pass on their longer necks to their offspring, which then grow even taller.
Lamarck, a French Zoologist, introduced a revolutionary concept in his 17 May 1802 opening lecture at the Museum of Natural History of Paris. He challenged traditional thinking about organic transformation. According to Lamarck, living things evolved from inanimate matter through a series gradual steps. Lamarck was not the only one to suggest that this might be the case but his reputation is widely regarded as being the one who gave the subject its first general and comprehensive analysis.
The dominant story is that Charles Darwin's theory of evolution by natural selection and Lamarckism were competing in the 19th Century. Darwinism eventually won and led to the creation of what biologists now 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, including natural selection.
Lamarck and his contemporaries endorsed the notion that acquired characters could be passed down to the next generation. However, this concept was never a major part of 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 genomics there is a growing evidence base that supports the heritability acquired characteristics. This is sometimes referred to as "neo-Lamarckism" or, more commonly epigenetic inheritance. It is a variant of evolution that is as valid as the more popular neo-Darwinian model.
Evolution by adaptation
One of the most common misconceptions about evolution is that it is driven by a sort of struggle for survival. This notion is not true and ignores other forces driving evolution. The fight for survival can be more effectively described as a struggle to survive in a specific environment, which can include not just other organisms but also the physical environment.
To understand how evolution operates it is beneficial to understand what is adaptation. The term "adaptation" refers to any specific characteristic that allows an organism to live and reproduce within its environment. It could be a physical structure like fur or feathers. It could also be a characteristic of behavior such as moving to the shade during the heat, 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 interact with other living organisms and their physical surroundings. 에볼루션 슬롯 must possess 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 a high rate within its niche.
These factors, together with mutations and gene flow can cause a shift in the proportion of different alleles in the gene pool of a population. Over time, this change in allele frequencies could result in the emergence of new traits and ultimately new species.
A lot of the traits we admire in animals and plants are adaptations, like 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. To comprehend adaptation it is essential to discern between physiological and behavioral traits.
Physiological traits like thick fur and gills are physical characteristics. The behavioral adaptations aren't like the tendency of animals to seek out companionship or retreat into shade during hot temperatures. Additionally it is important to understand that lack of planning does not make something an adaptation. A failure to consider the implications of a choice even if it seems to be rational, may make it inflexible.