What is Free Evolution?
Free evolution is the notion that natural processes can cause organisms to evolve over time. This includes the creation of new species and the change in appearance of existing species.
This is evident in numerous examples, including stickleback fish varieties that can live in fresh or saltwater and walking stick insect varieties that prefer particular host plants. These reversible traits, however, cannot explain fundamental changes in body plans.
Evolution through Natural Selection
The evolution of the myriad living creatures on Earth is a mystery that has intrigued scientists for centuries. The most widely accepted explanation is Charles Darwin's natural selection, which occurs when individuals that are better adapted survive and reproduce more successfully than those who are less well-adapted. As time passes, the number of individuals who are well-adapted grows and eventually forms a new species.
Natural selection is a process that is cyclical and involves the interaction of 3 factors including reproduction, variation and inheritance. Variation is caused by mutations and sexual reproduction both of which enhance the genetic diversity within a species. Inheritance is the passing of a person's genetic traits to the offspring of that person that includes recessive and dominant alleles. Reproduction is the production of fertile, viable offspring which includes both asexual and sexual methods.
Natural selection is only possible when all of these factors are in harmony. If, for example an allele of a dominant gene makes an organism reproduce and survive more than the recessive allele then the dominant allele becomes more prevalent in a group. If the allele confers a negative advantage to survival or decreases the fertility of the population, it will disappear. The process is self reinforcing meaning that an organism that has an adaptive characteristic will live and reproduce more quickly than those with a maladaptive trait. The more offspring an organism produces, the greater its fitness which is measured by its ability to reproduce and survive. People with desirable traits, like having a long neck in the giraffe, or bright white patterns on male peacocks are more likely to others to survive and reproduce and eventually lead to them becoming the majority.
Natural selection is only an element in the population and not on individuals. This is a significant distinction from the Lamarckian evolution theory that states that animals acquire traits due to use or lack of use. For example, if a giraffe's neck gets longer through stretching to reach prey, its offspring will inherit a more long neck. The differences in neck size between generations will continue to increase until the giraffe is no longer able to reproduce with other giraffes.
Evolution through Genetic Drift
Genetic drift occurs when the alleles of a gene are randomly distributed in a population. At some point, one will attain fixation (become so widespread that it can no longer be removed through natural selection) and the other alleles drop to lower frequencies. In extreme cases this, it leads to dominance of a single allele. The other alleles are essentially eliminated, and heterozygosity falls to zero. In a small population, this could lead to the total elimination of recessive alleles. This is known as the bottleneck effect. It is typical of the evolution process that occurs when the number of individuals migrate to form a population.
A phenotypic 'bottleneck' can also occur when the survivors of a catastrophe such as an outbreak or mass hunting incident are concentrated in a small area. The survivors will carry an dominant allele, and will have the same phenotype. This may be the result of a conflict, earthquake, or even a plague. The genetically distinct population, if it is left vulnerable to genetic drift.
Walsh, Lewens and Ariew define drift as a deviation from expected values due to differences in fitness. They give a famous example of twins that are genetically identical and have identical phenotypes and yet one is struck by lightning and dies, while the other lives and reproduces.
This type of drift is very important in the evolution of the species. However, it is not the only way to develop. Natural selection is the main alternative, in which mutations and migration maintain phenotypic diversity within the population.
Stephens argues there is a significant difference between treating the phenomenon of drift as an actual cause or force, and treating other causes such as migration and selection as causes and forces. He argues that a causal mechanism account of drift permits us to differentiate it from the other forces, and this distinction is crucial. He also argues that drift has a direction: that is it tends to reduce heterozygosity, and that it also has a magnitude, which 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 referred to as "Lamarckism" and it asserts that simple organisms evolve into more complex organisms by the inheritance of traits which result from the organism's natural actions use and misuse. Lamarckism is typically illustrated with the image of a giraffe extending its neck longer to reach the higher branches in the trees. This could cause giraffes' longer necks to be passed on to their offspring who would then become taller.
Lamarck was a French Zoologist. In his lecture to begin his course on invertebrate zoology at the Museum of Natural History in Paris on 17 May 1802, he introduced an original idea that fundamentally challenged the conventional wisdom about organic transformation. According to Lamarck, living creatures evolved from inanimate matter through a series gradual steps. Lamarck wasn't the only one to suggest this, but he was widely considered to be the first to offer the subject a comprehensive and general treatment.
The prevailing story is that Lamarckism was an opponent to Charles Darwin's theory of evolution through natural selection, and that the two theories fought each other in the 19th century. Darwinism eventually triumphed and led to the creation of what biologists today call the Modern Synthesis. This theory denies that acquired characteristics can be inherited and instead suggests that organisms evolve through the selective action of environmental factors, like natural selection.
Lamarck and his contemporaries believed in the notion that acquired characters could be passed down to the next generation. However, this notion was never a central part of any of their evolutionary theories. This is largely due to the fact that it was never validated scientifically.
But it is now more than 200 years since Lamarck was born and in the age of genomics there is a vast body of evidence supporting the possibility of inheritance of acquired traits. This is sometimes called "neo-Lamarckism" or, more frequently, epigenetic inheritance. It is a form of evolution that is as valid as the more well-known Neo-Darwinian model.
Evolution by the process of adaptation
One of the most widespread misconceptions about evolution is that it is driven by a type of struggle for survival. This is a false assumption and overlooks other forces that drive evolution. The struggle for survival is more precisely described as a fight to survive in a specific environment, which may involve not only other organisms but also the physical environment itself.
To understand how evolution operates it is important to think about what adaptation is. It is a feature that allows a living thing to survive in its environment and reproduce. It could be a physical structure, such as feathers or fur. It could also be a characteristic of behavior such as moving into the shade during hot weather or coming out to avoid the cold at night.
The survival of an organism depends on its ability to draw energy from the surrounding environment and interact with other living organisms and their physical surroundings. The organism must have the right genes to create offspring, and it must be able to find enough food and other resources. Moreover, the organism must be capable of reproducing at an optimal rate within its niche.
These elements, along with gene flow and mutations can cause an alteration in the ratio of different alleles within a population’s gene pool. This change in allele frequency can result in the emergence of new traits and eventually new species over time.
Many of the features that we admire about animals and plants are adaptations, like lungs or gills to extract oxygen from the air, fur or feathers to provide insulation, long legs for running away from predators and camouflage for hiding. However, a thorough understanding of adaptation requires paying attention to the distinction between behavioral and physiological characteristics.
Physiological adaptations like the thick fur or gills are physical traits, whereas behavioral adaptations, like the tendency to search for companions or to move to the shade during hot weather, aren't. In addition it is important to remember that lack of planning is not a reason to make something an adaptation. 에볼루션 바카라사이트 to think about the effects of a behavior even if it seems to be logical, can make it unadaptive.