What is Free Evolution?
Free evolution is the notion that natural processes can lead to the development of organisms over time. This includes the appearance 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, and walking stick insect varieties that prefer specific host plants. These reversible traits cannot explain fundamental changes to the body's basic plans.
Evolution by Natural Selection
The evolution of the myriad living organisms on Earth is a mystery that has fascinated scientists for centuries. The most well-known explanation is Charles Darwin's natural selection, a process that occurs when better-adapted individuals survive and reproduce more successfully than those less well adapted. As time passes, a group of well-adapted individuals expands and eventually becomes a new species.
Natural selection is an ongoing process and involves the interaction of 3 factors that are: reproduction, variation and inheritance. Sexual reproduction and mutations increase the genetic diversity of the species. Inheritance refers the transmission of genetic characteristics, which includes recessive and dominant genes, to their offspring. Reproduction is the generation of viable, fertile offspring, which includes both asexual and sexual methods.
All of these elements have to be in equilibrium for natural selection to occur. If, for example an allele of a dominant gene causes an organism reproduce and last longer than the recessive gene then the dominant allele will become more prevalent in a group. However, if the gene confers a disadvantage in survival or reduces fertility, it will disappear from the population. This process is self-reinforcing meaning that an organism with a beneficial characteristic can reproduce and survive longer than one with a maladaptive characteristic. The more offspring an organism produces the more fit it is which is measured by its ability to reproduce itself and live. People with desirable traits, such as having a longer neck in giraffes or bright white color patterns in male peacocks are more likely to survive and have offspring, and thus will eventually make up the majority of the population in the future.
Natural selection only affects populations, not on individuals. This is a significant distinction from the Lamarckian theory of evolution, which states that animals acquire traits through use or disuse. For instance, if a Giraffe's neck grows longer due to stretching to reach prey and its offspring will inherit a longer neck. The differences in neck length between generations will persist until the neck of the giraffe becomes too long to not breed with other giraffes.
Evolution through Genetic Drift
Genetic drift occurs when alleles from the same gene are randomly distributed in a population. In the end, only one will be fixed (become widespread enough to not longer be eliminated through natural selection) and the other alleles will drop in frequency. In the extreme this, it leads to one allele dominance. The other alleles are essentially eliminated, and heterozygosity decreases to zero. In a small number of people, this could result in the complete elimination of the recessive gene. 에볼루션 바카라 무료체험 is known as the bottleneck effect. It is typical of an evolutionary process that occurs whenever a large number individuals migrate to form a population.
A phenotypic bottleneck could occur when survivors of a catastrophe such as an epidemic or a massive hunting event, are condensed within a narrow area. The survivors will be mostly homozygous for the dominant allele which means they will all share the same phenotype and will consequently have the same fitness traits. This can be caused by earthquakes, war or even a plague. Whatever the reason the genetically distinct population that remains is susceptible to genetic drift.
Walsh Lewens, Walsh, and Ariew define drift as a departure from expected values due to differences in fitness. They cite the famous example of twins who are both genetically identical and share the same phenotype. However one is struck by lightning and dies, whereas the other lives to reproduce.
This type of drift can play a crucial role in the evolution of an organism. It is not the only method for evolution. The most common alternative is to use a process known as natural selection, in which the phenotypic variation of a population is maintained by mutation and migration.
Stephens asserts that there is a major distinction between treating drift as a force, or a cause and considering other causes of evolution such as mutation, selection and migration as forces or causes. He claims that a causal process explanation of drift permits us to differentiate it from other forces, and this distinction is essential. He also argues that drift has both an orientation, i.e., it tends to reduce heterozygosity. It also has a size, which is determined based on population size.
Evolution through Lamarckism
Students of biology in high school are frequently introduced to Jean-Baptiste Lamarck's (1744-1829) work. His theory of evolution is generally known as "Lamarckism" and it states that simple organisms develop into more complex organisms through the inherited characteristics that result from the organism's natural actions, use and disuse. Lamarckism is illustrated through an giraffe's neck stretching to reach higher levels of leaves in the trees. This process would cause giraffes to pass on their longer necks to offspring, which then get taller.
Lamarck Lamarck, a French Zoologist, introduced an innovative idea in his 17 May 1802 opening lecture at the Museum of Natural History of Paris. He challenged conventional wisdom on organic transformation. In his opinion living things evolved from inanimate matter via an escalating series of 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 having given the subject its first general and thorough treatment.
The most popular story is that Lamarckism was a rival to Charles Darwin's theory of evolutionary natural selection and that the two theories fought out in the 19th century. Darwinism ultimately won and led to what biologists call the Modern Synthesis. The theory argues the possibility that acquired traits can be acquired through inheritance and instead argues that organisms evolve through the selective action of environmental factors, such as natural selection.
Although Lamarck endorsed the idea of inheritance by acquired characters, and his contemporaries also spoke of this idea however, it was not a central element in any of their evolutionary theories. This is partly because it was never tested scientifically.
It has been more than 200 year since Lamarck's birth and in the field of genomics, there is an increasing evidence base that supports the heritability of acquired traits. This is referred to as "neo Lamarckism", or more often epigenetic inheritance. This is a variant that is as reliable as the popular Neodarwinian model.
Evolution through Adaptation
One of the most widespread misconceptions about evolution is that it is driven by a sort of struggle for survival. In reality, this notion is a misrepresentation of 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 may include not just other organisms, but also the physical environment itself.
Understanding how adaptation works is essential to comprehend evolution. Adaptation is any feature that allows a living organism to survive in its environment and reproduce. It can be a physical structure like feathers or fur. It could also be a characteristic of behavior, like moving into the shade during hot weather or coming out to avoid the cold at night.
The survival of an organism is dependent on its ability to draw energy from the surrounding environment and interact with other living organisms and their physical surroundings. The organism must possess the right genes to produce offspring, and must be able to access enough food and other resources. The organism must be able to reproduce itself at the rate that is suitable for its particular niche.
These factors, along with mutation and gene flow, lead to a change in the proportion of alleles (different types of a gene) in the gene pool of a population. Over time, this change in allele frequency can result in the emergence of new traits, and eventually new species.
Many of the features that we admire about animals and plants are adaptations, for example, lungs or gills to extract oxygen from the air, feathers or fur for insulation long legs to run away from predators, and camouflage to hide. To comprehend adaptation it is essential to discern between physiological and behavioral characteristics.
Physical traits such as the thick fur and gills are physical traits. The behavioral adaptations aren't like the tendency of animals to seek companionship or move into the shade during hot temperatures. In addition it is important to understand that a lack of thought does not make something an adaptation. Inability to think about the effects of a behavior even if it appears to be logical, can make it inflexible.