What is Free Evolution?
Free evolution is the notion that natural processes can cause organisms to evolve over time. This includes the appearance and growth of new species.
This is evident in many examples such as the stickleback fish species that can live 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 basic body plans.
Evolution by Natural Selection
The development of the myriad living creatures on Earth is a mystery that has fascinated scientists for centuries. The most well-known explanation is Darwin's natural selection, which is triggered when more well-adapted individuals live longer and reproduce more successfully 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 elements: variation, inheritance and reproduction. Variation is caused by mutations and sexual reproduction both of which enhance the genetic diversity within the species. Inheritance refers the transmission of genetic traits, including recessive and dominant genes and their offspring. Reproduction is the process of generating fertile, viable offspring. This can be done through sexual or asexual methods.
All of these elements must be in harmony for natural selection to occur. For example the case where a dominant allele at a gene allows an organism to live and reproduce more often than the recessive allele, the dominant allele will be more prominent within the population. However, if the gene confers an unfavorable survival advantage or reduces fertility, it will be eliminated from the population. The process is self reinforcing which means that an organism that has an adaptive characteristic will live and reproduce far more effectively than one with a maladaptive characteristic. The greater an organism's fitness which is measured by its ability to reproduce and endure, is the higher number of offspring it produces. 에볼루션 무료체험 with good characteristics, such as having a long neck in giraffes, or bright white patterns on male peacocks are more likely than others to live and reproduce and eventually lead to them becoming the majority.
Natural selection only affects populations, not individuals. 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 expands its neck to reach prey, and the neck becomes longer, then its offspring will inherit this characteristic. The differences in neck size between generations will continue to grow until the giraffe is no longer able to breed with other giraffes.
Evolution by Genetic Drift
Genetic drift occurs when alleles from a gene are randomly distributed in a group. In the end, only one will be fixed (become common enough to no more be eliminated through natural selection), and the other alleles diminish in frequency. This can result in an allele that is dominant in the extreme. The other alleles are essentially eliminated, and heterozygosity decreases to zero. In a small population, this could lead to the total elimination of recessive allele. This is called a bottleneck effect, and it is typical of the kind of evolutionary process that takes place when a lot of individuals move to form a new population.
A phenotypic bottleneck may also occur when survivors of a disaster like an outbreak or a mass hunting event are confined to an area of a limited size. 에볼루션 바카라 사이트 remaining individuals are likely to be homozygous for the dominant allele, which means that they will all share the same phenotype and will consequently have the same fitness characteristics. This could be caused by earthquakes, war or even plagues. Regardless of the cause the genetically distinct group that remains is prone to genetic drift.
Walsh, Lewens and Ariew define drift as a departure from the expected values due to differences in fitness. They cite the famous example of twins who are both genetically identical and share the same phenotype, but one is struck by lightning and dies, but the other lives to reproduce.
This kind of drift can be vital to the evolution of an entire species. However, it's not the only way to progress. Natural selection is the most common alternative, where mutations and migrations maintain the phenotypic diversity of a population.
Stephens argues there is a vast distinction between treating drift as an agent or cause and treating other causes such as migration and selection as causes and forces. He argues that a causal-process explanation of drift lets us distinguish it from other forces and that this distinction is essential. He further argues that drift has both direction, i.e., it tends to eliminate heterozygosity. It also has a size which is determined by the size of the population.
Evolution by Lamarckism
Students of biology in high school are often exposed to Jean-Baptiste lamarck's (1744-1829) work. His theory of evolution is commonly known as "Lamarckism" and it states that simple organisms develop into more complex organisms through the inherited characteristics that are a result of the natural activities of an organism usage, use and disuse. Lamarckism can be demonstrated by a giraffe extending its neck to reach higher leaves in the trees. This process would cause giraffes to pass on their longer necks to their offspring, who would then grow even taller.
Lamarck the French Zoologist, introduced an innovative idea in his opening lecture at the Museum of Natural History of Paris. He challenged the conventional wisdom on organic transformation. In his view, living things had evolved from inanimate matter through a series of gradual steps. Lamarck wasn't the first to propose this, but he was widely regarded as the first to offer the subject a comprehensive and general treatment.
The popular narrative is that Lamarckism was an opponent to Charles Darwin's theory of evolution through natural selection and that the two theories fought it out in the 19th century. Darwinism eventually won and led to the development of what biologists today refer to as the Modern Synthesis. This theory denies acquired characteristics are passed down from generation to generation and instead argues that organisms evolve through the influence of environment factors, including Natural Selection.
While Lamarck supported the notion of inheritance through acquired characters and his contemporaries also spoke of this idea but it was not an integral part of any of their evolutionary theorizing. This is due in part to the fact that it was never tested scientifically.
But it is now more than 200 years since Lamarck was born and, in the age of genomics there is a vast amount of evidence that supports the heritability of acquired traits. This is also known as "neo Lamarckism", or more generally epigenetic inheritance. It is a version of evolution that is just as valid as the more popular Neo-Darwinian theory.
Evolution by the process of adaptation
One of the most common misconceptions about evolution is its being driven by a struggle to survive. In fact, this view is inaccurate and overlooks the other forces that determine the rate of evolution. The struggle for survival is more effectively described as a struggle to survive in a specific environment, which can be a struggle that involves not only other organisms but also the physical environment.
Understanding adaptation is important to comprehend evolution. Adaptation is any feature that allows a living organism to live in its environment and reproduce. It could be a physiological feature, such as fur or feathers, or a behavioral trait, such as moving into the shade in hot weather or coming out at night to avoid the cold.
The capacity of an organism to extract energy from its environment and interact with other organisms and their physical environment is essential to its survival. The organism needs to have the right genes to create offspring, and must be able to find sufficient food and other resources. The organism should also be able reproduce itself at a rate that is optimal for its specific niche.
These factors, together with mutations and gene flow, can lead to a shift in the proportion of different alleles in a population’s gene pool. This change in allele frequency could lead to the development of new traits and eventually, new species over time.
A lot of the traits we admire in animals and plants are adaptations. For example lung or gills that draw oxygen from air feathers and fur for insulation and long legs to get away from predators and camouflage to conceal. However, a complete understanding of adaptation requires attention to the distinction between the physiological and behavioral characteristics.
Physiological traits like large gills and thick fur are physical traits. The behavioral adaptations aren't, such as the tendency of animals to seek companionship or retreat into shade in hot temperatures. It is important to keep in mind that lack of planning does not cause an adaptation. In fact, failure to consider the consequences of a decision can render it ineffective even though it appears to be reasonable or even essential.