What is Free Evolution?
Free evolution is the notion that the natural processes of living organisms can lead to their development over time. This includes the emergence and development of new species.
Many examples have been given of this, such as different varieties of fish called sticklebacks that can live in either salt or fresh water, and walking stick insect varieties that favor particular host plants. These mostly reversible traits permutations cannot explain fundamental changes to the body's basic plans.
Evolution by Natural Selection
Scientists have been fascinated by the development of all the living creatures that inhabit our planet for many centuries. The best-established explanation is that of Charles Darwin's natural selection, an evolutionary process that occurs when better-adapted individuals survive and reproduce more effectively than those that are less well adapted. As time passes, the number of well-adapted individuals grows and eventually forms an entirely new species.
Natural selection is an ongoing process that involves the interaction of three elements including inheritance, variation, and reproduction. Variation is caused by mutations and sexual reproduction both of which enhance the genetic diversity of a species. Inheritance refers the transmission of a person's genetic traits, which include both dominant and recessive genes, to their offspring. Reproduction is the generation of viable, fertile offspring, which includes both sexual and asexual methods.
All of these factors have to be in equilibrium to allow natural selection to take place. For instance when a dominant allele at the gene causes an organism to survive and reproduce more frequently than the recessive one, the dominant allele will be more prevalent in the population. If the allele confers a negative survival advantage or reduces the fertility of the population, it will go away. The process is self reinforcing, which means that an organism with an adaptive trait will survive and reproduce much more than one with a maladaptive characteristic. The more fit an organism is which is measured by its ability to reproduce and endure, is the higher number of offspring it can produce. Individuals with favorable characteristics, such as the long neck of Giraffes, or the bright white patterns on male peacocks are more likely than others to survive and reproduce, which will eventually lead to them becoming the majority.
Natural selection is an aspect of populations and not on individuals. This is a major distinction from the Lamarckian evolution theory, which states that animals acquire traits due to use or lack of use. If a giraffe extends its neck in order to catch prey and the neck grows larger, then its offspring will inherit this trait. The differences in neck size between generations will increase until the giraffe is no longer able to reproduce with other giraffes.
Evolution through Genetic Drift
In genetic drift, alleles at a gene may reach different frequencies in a population 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 will decrease in frequency. In extreme cases, this leads to dominance of a single allele. The other alleles are basically eliminated and heterozygosity has decreased to zero. In a small population it could lead to the complete elimination of the recessive allele. This scenario is called a bottleneck effect, and it is typical of the kind of evolutionary process that occurs when a lot of individuals migrate to form a new population.
A phenotypic bottleneck can also happen when the survivors of a catastrophe like an epidemic or a mass hunting event, are condensed in a limited area. The survivors will carry an dominant allele, and will share the same phenotype. This may be the result of a war, an earthquake or even a cholera outbreak. Regardless of the cause the genetically distinct population that remains could be prone to genetic drift.
Walsh Lewens, Lewens, and Ariew utilize Lewens, Walsh and Ariew employ a "purely outcome-oriented" definition of drift as any deviation from expected values for variations in fitness. They give a famous instance of twins who are genetically identical, share identical phenotypes but one is struck by lightening and dies while the other lives and reproduces.
This kind of drift could play a very important part in the evolution of an organism. But, it's not the only method to evolve. 에볼루션바카라 is to use a process known as natural selection, where the phenotypic diversity of an individual is maintained through mutation and migration.
Stephens asserts that there is a huge distinction between treating drift as an actual cause or force, and treating other causes like migration and selection mutation as forces and causes. Stephens claims that a causal process model of drift allows us to distinguish it from other forces and that this distinction is essential. He further argues that drift is a directional force: that is, it tends to eliminate heterozygosity, and that it also has a magnitude, that is determined by the size of population.
Evolution by 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 is commonly known as "Lamarckism" and it states that simple organisms develop into more complex organisms via the inheritance of traits which result from the organism's natural actions, use and disuse. Lamarckism can be illustrated by an giraffe's neck stretching to reach higher levels of leaves in the trees. This would result in giraffes passing on their longer necks to offspring, who then become taller.
Lamarck was a French zoologist and, in his opening lecture for his course on invertebrate zoology held at the Museum of Natural History in Paris on the 17th of May in 1802, he presented an original idea that fundamentally challenged previous thinking about organic transformation. According to him, living things had evolved from inanimate matter through the gradual progression of events. Lamarck wasn't the only one to propose this, but he was widely regarded as the first to provide the subject a thorough and general explanation.
The prevailing story is that Lamarckism became an opponent to Charles Darwin's theory of evolutionary natural selection, and that the two theories battled each other in the 19th century. Darwinism ultimately prevailed which led to what biologists refer to as the Modern Synthesis. The Modern Synthesis theory denies the possibility that acquired traits can be inherited and instead suggests that organisms evolve through the selective action of environmental factors, such as natural selection.
Lamarck and his contemporaries believed in the idea that acquired characters could be passed on to future generations. However, this idea was never a key element of any of their theories about evolution. This is due to the fact that it was never tested scientifically.
It has been more than 200 year since Lamarck's birth, and in the age genomics, there is an increasing body of evidence that supports the heritability-acquired characteristics. This is sometimes called "neo-Lamarckism" or, more often, epigenetic inheritance. It is a version of evolution that is just as relevant as the more popular Neo-Darwinian model.
Evolution by adaptation
One of the most popular misconceptions about evolution is being driven by a fight for survival. This notion is not true and overlooks other forces that drive evolution. The fight for survival is more accurately described as a struggle to survive in a certain environment. This can include not only other organisms as well as the physical surroundings themselves.
To understand how evolution works it is important to understand what is adaptation. The term "adaptation" refers to any characteristic that allows living organisms to survive in its environment and reproduce. It could be a physiological structure like feathers or fur or a behavior like moving into the shade in hot weather or coming out at night to avoid cold.
The survival of an organism depends on its ability to obtain energy from the environment and to interact with other living organisms and their physical surroundings. The organism must have the right genes to produce offspring, and it should be able to find sufficient food and other resources. Furthermore, the organism needs to be able to reproduce itself at an optimal rate within its environment.
These factors, together with gene flow and mutations, can lead to an alteration in the ratio of different alleles within the gene pool of a population. This shift in the frequency of alleles can lead to the emergence of new traits, and eventually new species in the course of time.
Many of the features we appreciate in animals and plants are adaptations. For example, lungs or gills that extract oxygen from the air, fur and feathers as insulation, long legs to run away from predators and camouflage to conceal. To understand adaptation it is crucial to discern between physiological and behavioral traits.
Physiological adaptations like thick fur or gills, are physical traits, whereas behavioral adaptations, such as the tendency to seek out companions or to move to shade in hot weather, are not. Furthermore it is important to remember that a lack of thought does not make something an adaptation. Inability to think about the implications of a choice even if it appears to be rational, could make it inflexible.