What is Free Evolution?
Free evolution is the notion that the natural processes of organisms can lead to their development over time. This includes the evolution of new species and the transformation of the appearance of existing species.
This is evident in numerous examples such as the stickleback fish species that can live in salt or fresh water, and walking stick insect varieties that have a preference for specific host plants. These reversible traits, however, cannot be the reason for fundamental changes in body plans.
Evolution by Natural Selection
The development of the myriad living organisms on Earth is a mystery that has intrigued scientists for centuries. Charles Darwin's natural selectivity is the most well-known explanation. This process occurs when people who are more well-adapted have more success in reproduction and survival than those who are less well-adapted. Over time, the population of well-adapted individuals grows and eventually forms a new species.
Natural selection is an ongoing process that involves the interaction of three factors that are inheritance, variation and reproduction. Variation is caused by mutation and sexual reproduction both of which increase the genetic diversity within an animal species. Inheritance refers to the transmission of a person's genetic traits, which include both dominant and recessive genes and their offspring. Reproduction is the process of producing fertile, viable offspring, which includes both asexual and sexual methods.
Natural selection can only occur when all of these factors are in balance. For example when the dominant allele of the gene allows an organism to live and reproduce more often than the recessive allele, the dominant allele will be more prevalent within the population. If the allele confers a negative survival advantage or lowers the fertility of the population, it will be eliminated. The process is self-reinforced, which means that an organism with a beneficial characteristic is more likely to survive and reproduce than an individual with a maladaptive characteristic. The higher the level of fitness an organism has which is measured by its ability to reproduce and survive, is the more offspring it produces. People with good traits, such as a longer neck in giraffes, or bright white colors in male peacocks are more likely survive and have offspring, so they will eventually make up the majority of the population in the future.
Natural selection only affects populations, not individual organisms. This is a crucial distinction from the Lamarckian theory of evolution, which states that animals acquire traits due to usage or inaction. If a giraffe extends its neck in order to catch prey, and the neck becomes larger, then its children will inherit this characteristic. The difference in neck size between generations will increase until the giraffe is no longer able to reproduce with other giraffes.
Evolution by Genetic Drift
In genetic drift, alleles of a gene could reach different frequencies within a population through random events. At some point, only one of them will be fixed (become common enough that it can no longer be eliminated through natural selection), and the other alleles decrease in frequency. This can lead to a dominant allele in extreme. Other alleles have been virtually eliminated and heterozygosity decreased to zero. In a small population, this could lead to the complete elimination of the recessive allele. This is known as the bottleneck effect and is typical of the evolutionary process that occurs whenever a large number individuals migrate to form a group.
A phenotypic bottleneck could occur when survivors of a catastrophe like an epidemic or a mass hunt, are confined into a small area. The survivors will be mostly homozygous for the dominant allele which means they will all have the same phenotype and will thus have the same fitness traits. This could be the result of a war, an earthquake, or even a plague. Regardless of the cause, the genetically distinct population that remains is susceptible to genetic drift.
Walsh Lewens and Ariew use a "purely outcome-oriented" definition of drift as any departure from expected values for different fitness levels. They give a famous example of twins that are genetically identical and have the exact same phenotype but one is struck by lightening and dies while the other lives and reproduces.
This kind of drift can play a crucial part in the evolution of an organism. It's not the only method for evolution. Natural selection is the main alternative, in which mutations and migrations maintain the phenotypic diversity of the population.
Stephens asserts that there is a significant difference between treating the phenomenon of drift as an actual cause or force, and considering other causes, such as migration and selection mutation as causes and forces. He claims that a causal mechanism account of drift allows us to distinguish it from the other forces, and this distinction is essential. He argues further that drift has both an orientation, i.e., it tends to eliminate heterozygosity. It also has a size, which is determined by population size.
Evolution by Lamarckism
Students of biology in high school are frequently exposed to Jean-Baptiste lamarck's (1744-1829) work. His theory of evolution is generally called "Lamarckism" and it states that simple organisms develop into more complex organisms via the inherited characteristics that result from the natural activities of an organism usage, use and disuse. Lamarckism can be demonstrated by a giraffe extending its neck to reach higher branches in the trees. This could cause giraffes to pass on their longer necks to their offspring, which then become taller.
Lamarck the French Zoologist, introduced an idea that was revolutionary in his 17 May 1802 opening lecture at the Museum of Natural History of Paris. He challenged traditional thinking about organic transformation. According Lamarck, living organisms evolved from inanimate material by a series of gradual steps. Lamarck was not the first to suggest that this could be the case, but he is widely seen as being the one who gave the subject its first broad and thorough treatment.
The popular narrative is that Lamarckism became a rival to Charles Darwin's theory of evolutionary natural selection and that the two theories fought each other in the 19th century. Darwinism eventually won and led to the development of what biologists today refer to as the Modern Synthesis. The theory argues the possibility that acquired traits can be inherited and instead argues that organisms evolve through the selective action of environmental factors, like natural selection.
Lamarck and his contemporaries supported the notion 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 partly because it was never scientifically tested.
However, it has been more than 200 years since Lamarck was born and, in the age of genomics there is a huge body of evidence supporting the heritability of acquired characteristics. This is also referred to as "neo Lamarckism", or more commonly epigenetic inheritance. It is a form of evolution that is as valid as the more popular neo-Darwinian model.
Evolution by adaptation
One of the most popular misconceptions about evolution is being driven by a struggle to survive. This notion is not true and overlooks other forces that drive evolution. The struggle for survival is more precisely described as a fight to survive in a specific environment, which could include not just other organisms but as well the physical environment.
Understanding 에볼루션 블랙잭 is important to comprehend evolution. The term "adaptation" refers to any specific feature that allows an organism to survive and reproduce in its environment. It can be a physiological structure such as feathers or fur or a behavioral characteristic, such as moving into the shade in hot weather or stepping out at night to avoid cold.
The ability of a living thing to extract energy from its environment and interact with other organisms, as well as their physical environment is essential to its survival. The organism must possess the right genes to generate offspring, and it should be able to access enough food and other resources. Furthermore, the organism needs to be capable of reproducing at an optimal rate within its environmental niche.
These elements, in conjunction with gene flow and mutation, lead to a change in the proportion of alleles (different varieties of a particular gene) in a population's gene pool. The change in frequency of alleles could lead to the development of new traits, and eventually, new species as time passes.
Many of the features we find appealing in animals and plants are adaptations. For instance the lungs or gills which draw oxygen from air, fur and feathers as insulation, long legs to run away from predators and camouflage to conceal. However, a complete understanding of adaptation requires attention to the distinction between the physiological and behavioral traits.
Physiological adaptations like the thick fur or gills are physical traits, whereas behavioral adaptations, such as the desire to find companions or to retreat to the shade during hot weather, are not. It is also important to note that lack of planning does not result in an adaptation. In fact, failing to think about the consequences of a decision can render it ineffective even though it might appear logical or even necessary.