What is Free Evolution?
Free evolution is the concept that natural processes can cause organisms to develop over time. This includes the evolution of new species and the alteration of the appearance of existing species.
This is evident in numerous examples such as the stickleback fish species that can thrive in salt or fresh water, and walking stick insect varieties that are apprehensive about particular host plants. These are mostly reversible traits, however, cannot explain fundamental changes in body plans.
Evolution through Natural Selection
The evolution of the myriad living organisms on Earth is a mystery that has fascinated scientists for many centuries. The most well-known explanation is that of Charles Darwin's natural selection process, an evolutionary process that occurs when individuals that are better adapted survive and reproduce more successfully than those less well adapted. As time passes, a group of well adapted individuals grows and eventually forms a whole new species.
Natural selection is a cyclical process that involves the interaction of three elements: variation, inheritance and reproduction. Sexual reproduction and mutation increase genetic diversity in the species. Inheritance is the transfer of a person's genetic traits to their offspring, which includes both dominant and recessive alleles. Reproduction is the production of fertile, viable offspring, which includes both sexual and asexual methods.
All of these variables must be in balance to allow natural selection to take place. For instance, if the dominant allele of the gene allows an organism to live and reproduce more often than the recessive allele, the dominant allele will become more prominent in the 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 with a beneficial trait is more likely to survive and reproduce than one 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 greater number of offspring it produces. People with desirable traits, like a longer neck in giraffes, or bright white patterns of color 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 is a factor in populations and not on individuals. This is a crucial distinction from the Lamarckian evolution theory, which states that animals acquire traits through use or lack of use. If a giraffe extends its neck to reach prey and the neck grows larger, then its offspring will inherit this trait. The difference in neck length between generations will continue until the giraffe's neck gets too long that it can not breed with other giraffes.
Evolution through Genetic Drift
In the process of genetic drift, alleles within a gene can be at different frequencies in a population due to random events. At some point, one will reach fixation (become so common that it can no longer be removed through natural selection) and other alleles will fall to lower frequencies. This can lead to a dominant allele in extreme. The other alleles have been virtually eliminated and heterozygosity decreased to zero. In a small population this could lead to the complete elimination of recessive gene. This is known as the bottleneck effect and is typical of an evolutionary process that occurs whenever an enormous number of individuals move to form a population.
A phenotypic bottleneck can also occur when survivors of a disaster, such as an epidemic or a mass hunt, are confined within a narrow area. The survivors will be mostly homozygous for the dominant allele, which means that they will all have the same phenotype, and therefore have the same fitness traits. This could be caused by earthquakes, war or even a plague. Whatever the reason the genetically distinct group that is left might be susceptible to genetic drift.
Walsh, Lewens, and Ariew employ a "purely outcome-oriented" definition of drift as any deviation from the expected values of differences in fitness. They provide a well-known instance of twins who are genetically identical, share the exact same phenotype and yet one is struck by lightning and dies, while the other lives and reproduces.
This type of drift can play a very important part in the evolution of an organism. It's not the only method for evolution. Natural selection is the most common alternative, in which mutations and migration maintain the phenotypic diversity in a 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 as forces and causes. 에볼루션 바카라 체험 claims that a causal-process account of drift allows us differentiate it from other forces, and this differentiation is crucial. 에볼루션 바카라 체험 argues that drift is a directional force: that is it tends to eliminate heterozygosity. 에볼루션 룰렛 has a size, which is determined by the size of population.
Evolution through Lamarckism
When students in high school study biology, they are often introduced to the work of Jean-Baptiste Lamarck (1744 - 1829). His theory of evolution, often referred to as “Lamarckism”, states that simple organisms develop into more complex organisms adopting traits that are a product of an organism's use and disuse. Lamarckism is usually illustrated with the image of a giraffe extending its neck to reach leaves higher up in the trees. This could cause the longer necks of giraffes to be passed to their offspring, who would then grow even taller.
Lamarck Lamarck, a French zoologist, presented a revolutionary concept in his opening lecture at the Museum of Natural History of Paris. He challenged traditional thinking about organic transformation. According to Lamarck, living creatures evolved from inanimate matter by a series of gradual steps. Lamarck was not the only one to suggest that this could be the case but he is widely seen as having given the subject its first broad and thorough treatment.
The most popular story is that Lamarckism became an opponent to Charles Darwin's theory of evolutionary natural selection and that the two theories fought out in the 19th century. Darwinism ultimately prevailed which led to what biologists call the Modern Synthesis. This 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 supported the idea that acquired characters could be passed on to the next generation. However, this notion was never a central part of any of their evolutionary theories. This is partly because it was never scientifically tested.
It's been over 200 years since the birth of Lamarck and in the field of age genomics, there is an increasing body of evidence that supports the heritability acquired characteristics. This is also known as "neo Lamarckism", or more often epigenetic inheritance. It is a version of evolution that is as relevant as the more popular Neo-Darwinian theory.
Evolution by the process of adaptation
One of the most popular misconceptions about evolution is that it is driven by a type of struggle for survival. This view is a misrepresentation of natural selection and ignores the other forces that drive evolution. The struggle for survival is more accurately described as a struggle to survive within a specific environment, which can include not just other organisms, but also the physical environment itself.
Understanding how adaptation works is essential to comprehend evolution. The term "adaptation" refers to any characteristic that allows living organisms to survive in its environment and reproduce. It could be a physiological feature, like feathers or fur, or a behavioral trait like moving to the shade during the heat or leaving at night to avoid the cold.
The capacity of an organism to draw energy from its surroundings and interact with other organisms, as well as their physical environment is essential to its survival. The organism must possess the right genes for producing offspring and to be able to access sufficient food and resources. In addition, the organism should be capable of reproducing in a way that is optimally within its environment.
These factors, in conjunction with mutations and gene flow, can lead to a shift in the proportion of different alleles within a population’s gene pool. The change in frequency of alleles could lead to the development of novel traits and eventually, new species over time.
A lot of the traits we admire in animals and plants are adaptations, like lungs or gills to extract oxygen from the air, feathers or fur to provide insulation and long legs for running away from predators, and camouflage for hiding. However, a proper understanding of adaptation requires paying attention to the distinction between the physiological and behavioral characteristics.
Physiological traits like large gills and thick fur are physical characteristics. Behavior adaptations aren't like the tendency of animals to seek companionship or to retreat into the shade in hot temperatures. It is also important to keep in mind that the absence of planning doesn't make an adaptation. In fact, failing to think about the implications of a choice can render it unadaptive even though it might appear logical or even necessary.