What is Free Evolution?
Free evolution is the idea that natural processes can cause organisms to evolve over time. This includes the appearance and development of new species.
This is evident in numerous examples of stickleback fish species that can live in saltwater or fresh water and walking stick insect types that have a preference for particular host plants. These reversible traits however, are not able to explain fundamental changes in basic body plans.
Evolution by Natural Selection
Scientists have been fascinated by the evolution of all the living organisms that inhabit our planet for centuries. The most well-known explanation is Darwin's natural selection, an evolutionary process that occurs when individuals that are better adapted survive and reproduce more effectively than those who are less well-adapted. Over time, a community of well-adapted individuals expands and eventually forms a whole new species.
Natural selection is an ongoing process that involves the interaction of three elements that are inheritance, variation and reproduction. Mutation and sexual reproduction increase genetic diversity in the species. Inheritance is the transfer of a person's genetic traits to the offspring of that person that includes dominant and recessive alleles. Reproduction is the production of fertile, viable offspring which includes both asexual and sexual methods.
All of these factors must be in balance for natural selection to occur. If, for example an allele of a dominant gene makes an organism reproduce and survive more than the recessive allele then the dominant allele is more common in a population. If the allele confers a negative survival advantage or lowers the fertility of the population, it will go away. The process is self reinforcing which means that an organism that has an adaptive trait will live and reproduce much more than one with a maladaptive characteristic. The more fit an organism is, measured by its ability reproduce and survive, is the greater number of offspring it produces. Individuals with favorable characteristics, such as a long neck in the giraffe, or bright white color patterns on male peacocks are more likely than others to reproduce and survive, which will eventually lead to them becoming the majority.
Natural selection only affects populations, not individuals. This is an important distinction from the Lamarckian theory of evolution, which argues that animals acquire characteristics through use or disuse. For instance, if a giraffe's neck gets longer through stretching to reach prey, its offspring will inherit a longer neck. The difference in neck size between generations will continue to grow until the giraffe is unable to breed with other giraffes.
Evolution by Genetic Drift
In the process of genetic drift, alleles of a gene could be at different frequencies in a group by chance events. In the end, only one will be fixed (become common enough that it can no more be eliminated through natural selection) and the other alleles diminish in frequency. This could lead to a dominant allele in the extreme. The other alleles are essentially eliminated and heterozygosity has diminished to zero. In a small population, this could result in the complete elimination the recessive gene. This is known as 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 can also occur when the survivors of a catastrophe such as an outbreak or mass hunting incident are concentrated in the same area. The survivors will share an dominant allele, and will have the same phenotype. This may be caused by war, earthquake, or even a plague. Whatever 에볼루션 바카라 무료체험 that is left might be susceptible to genetic drift.
Walsh Lewens, Walsh, and Ariew define drift as a departure from the expected values due to differences in fitness. They cite the famous example of twins that are genetically identical and share the same phenotype. However, 에볼루션 바카라 무료 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. However, it's not the only method to progress. Natural selection is the main alternative, where mutations and migrations maintain phenotypic diversity within a population.
Stephens argues that there is a significant distinction between treating drift as a force or a cause and considering other causes of evolution such as selection, mutation, and migration as forces or causes. Stephens claims that a causal process explanation of drift lets us differentiate it from other forces and this distinction is crucial. He argues further that drift has direction, i.e., it tends towards eliminating heterozygosity. It also has a size, that is determined by 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 is often known as "Lamarckism" and it asserts that simple organisms evolve into more complex organisms through the inheritance of traits that result from the natural activities of an organism use and misuse. Lamarckism is illustrated through the giraffe's neck being extended to reach higher leaves in the trees. This could cause giraffes' longer necks to be passed on to their offspring who would 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 the 17th May 1802, he introduced an original idea that fundamentally challenged the conventional wisdom about organic transformation. According Lamarck, living organisms evolved from inanimate material through a series of gradual steps. Lamarck was not the first to suggest this, but he was widely thought of as the first to provide the subject a thorough and general explanation.
The dominant story is that Charles Darwin's theory of natural selection and Lamarckism fought in the 19th century. Darwinism ultimately won and led to what biologists refer to as the Modern Synthesis. The theory argues the possibility that acquired traits can be inherited, and instead suggests that organisms evolve by the symbiosis of environmental factors, like natural selection.
Lamarck and his contemporaries supported the idea that acquired characters could be passed on to future generations. However, this concept was never a major part of any of their evolutionary theories. This is largely due to the fact that it was never validated scientifically.
It's been more than 200 years since Lamarck was born and, in the age of genomics, there is a large amount of evidence that supports the possibility of inheritance of acquired traits. This is often called "neo-Lamarckism" or, more often, epigenetic inheritance. This is a version that is just as valid as the popular Neodarwinian model.
Evolution by adaptation
One of the most popular misconceptions about evolution is that it is a result of a kind of struggle to survive. This notion is not true and overlooks other forces that drive evolution. The fight for survival can be more accurately described as a struggle to survive in a particular environment. This can include not only other organisms, but also the physical environment itself.
To understand how evolution works it is important to think about what adaptation is. Adaptation is any feature that allows a living organism to live in its environment and reproduce. It can be a physiological structure like feathers or fur or a behavior such as a tendency to move into the shade in the heat or leaving at night to avoid cold.
The capacity of an organism to draw energy from its environment and interact with other organisms, as well as their physical environment is essential to its survival. The organism must have the right genes to create offspring, and be able to find sufficient food and resources. The organism must also be able reproduce itself at a rate that is optimal for its particular niche.
These factors, together with mutation and gene flow can result in changes in the ratio of alleles (different forms of a gene) in a population's gene pool. As time passes, this shift in allele frequency can result in the development of new traits and eventually new species.
A lot of the traits we admire in animals and plants are adaptations, for example, the lungs or gills that extract oxygen from the air, feathers or fur to protect themselves long legs to run away from predators and camouflage for hiding. However, a proper understanding of adaptation requires paying attention to the distinction between behavioral and physiological traits.
Physical characteristics like large gills and thick fur are physical traits. The behavioral adaptations aren't, such as the tendency of animals to seek out companionship or to retreat into the shade in hot temperatures. In addition it is important to understand that a lack of forethought does not mean that something is an adaptation. In fact, a failure to think about the consequences of a decision can render it unadaptable despite the fact that it might appear logical or even necessary.