What is Free Evolution?
Free evolution is the idea that the natural processes of organisms can lead them to evolve over time. This includes the emergence and development of new species.
This is evident in numerous examples, including stickleback fish varieties that can live in salt or fresh water, and walking stick insect varieties that have a preference for particular host plants. These mostly reversible traits permutations do not explain the fundamental changes in the basic body plan.
Evolution by Natural Selection
Scientists have been fascinated by the evolution of all living organisms that inhabit our planet for centuries. Charles Darwin's natural selectivity is the best-established explanation. This is because people who are more well-adapted have more success in reproduction and survival than those who are less well-adapted. Over time, a community of well adapted individuals grows and eventually creates a new species.
Natural selection is a cyclical process that involves the interaction of three factors that are inheritance, variation and reproduction. Mutation and sexual reproduction increase the genetic diversity of a species. Inheritance is the passing of a person's genetic traits to their offspring that includes recessive and dominant alleles. Reproduction is the process of generating viable, fertile offspring. This can be achieved through sexual or asexual methods.
Natural selection can only occur when all these elements are in balance. If, for instance, a dominant gene allele makes an organism reproduce and live longer than the recessive allele The dominant allele is more prevalent in a population. If the allele confers a negative advantage to survival or decreases the fertility of the population, it will disappear. This process is self-reinforcing meaning that an organism with an adaptive trait will live and reproduce more quickly than those with a maladaptive feature. The greater an organism's fitness, measured by its ability reproduce and survive, is the more offspring it can produce. Individuals with favorable characteristics, such as the long neck of Giraffes, or the bright white color patterns on male peacocks are more likely than others to reproduce and survive which eventually leads to them becoming the majority.
Natural selection only affects populations, not individuals. This is a major distinction from the Lamarckian theory of evolution that states that animals acquire traits due to usage or inaction. For instance, if a Giraffe's neck grows longer due to stretching to reach prey its offspring will inherit a larger neck. The difference in neck length between generations will continue until the giraffe's neck gets too long that it can not breed with other giraffes.
Evolution through Genetic Drift
In genetic drift, the alleles of a gene could be at different frequencies in a population due to random events. In the end, one will reach fixation (become so widespread that it cannot be removed by natural selection) and the other alleles drop to lower frequencies. This can lead to an allele that is dominant in extreme. Other alleles have been essentially eliminated and heterozygosity has diminished to a minimum. In a small number of people it could result in the complete elimination the recessive gene. This is known as the bottleneck effect. It is typical of the evolutionary process that occurs whenever an enormous number of individuals move to form a group.
A phenotypic bottleneck can also occur when the survivors of a disaster like an outbreak or mass hunt event are concentrated in the same area. The survivors will carry an dominant allele, and will share the same phenotype. This may be caused by a conflict, earthquake, or even a plague. The genetically distinct population, if it remains vulnerable to genetic drift.
Walsh, Lewens and Ariew define drift as a departure from the expected value due to differences in fitness. They provide a well-known example of twins that are genetically identical and have the exact same phenotype and yet one is struck by lightning and dies, whereas the other lives and reproduces.
This type of drift can play a significant part in the evolution of an organism. However, it is not the only way to develop. The main alternative is to use a process known as natural selection, in which phenotypic variation in a population is maintained by mutation and migration.
Stephens claims that there is a huge distinction between treating drift as a force or cause, and treating other causes such as migration and selection as forces and causes. He claims that a causal mechanism account of drift permits us to differentiate it from the other forces, and this distinction is crucial. He further argues that drift is both direction, i.e., it tends to reduce heterozygosity. It also has a size, which is determined by the size of the population.
Evolution by Lamarckism
When high school students study biology, they are often introduced to the work of Jean-Baptiste Lamarck (1744 - 1829). His theory of evolution, often referred to as “Lamarckism”, states that simple organisms evolve into more complex organisms taking on traits that are a product of an organism's use and disuse. Lamarckism can be illustrated by a giraffe extending its neck to reach higher branches in the trees. This causes the necks of giraffes that are longer to be passed onto their offspring who would grow taller.
Lamarck was a French zoologist and, in his opening lecture for his course on invertebrate Zoology at the Museum of Natural History in Paris on 17 May 1802, he introduced a groundbreaking concept that radically challenged previous thinking about organic transformation. According to him, living things had evolved from inanimate matter through the gradual progression of events. Lamarck was not the first to propose this but he was regarded as the first to give the subject a thorough and general explanation.
The dominant story is that Charles Darwin's theory of natural selection and Lamarckism were competing in the 19th Century. Darwinism eventually prevailed and led to the creation of what biologists refer to as the Modern Synthesis. The theory denies that acquired characteristics can be passed down through generations and instead argues that organisms evolve through the selective action of environment factors, including Natural Selection.
Although Lamarck believed in the concept of inheritance by acquired characters and his contemporaries also offered a few words about this idea however, it was not a central element in any of their evolutionary theorizing. This is due to the fact that it was never scientifically validated.
It's been over 200 year since Lamarck's birth and in the field of age genomics there is a growing evidence base that supports the heritability of acquired traits. This is referred to as "neo Lamarckism", or more generally epigenetic inheritance. This is a variant that is as valid as the popular neodarwinian model.
Evolution by the process of adaptation
One of the most popular misconceptions about evolution is that it is being driven by a struggle to survive. This notion is not true and overlooks other forces that drive evolution. The fight for survival can be more precisely described as a fight to survive in a specific environment, which can involve not only other organisms but also the physical environment.
Understanding how adaptation works is essential to understand evolution. It refers to a specific feature that allows an organism to live and reproduce within its environment. 무료에볼루션 could be a physical structure, such as feathers or fur. Or it can be a behavior trait, like moving towards shade during the heat, or escaping the cold at night.
The ability of an organism to draw energy from its environment and interact with other organisms, as well as their physical environments is essential to its survival. The organism must have the right genes to produce offspring, and it should be able to find enough food and other resources. The organism must also be able reproduce itself at a rate that is optimal for its particular niche.
These factors, together with gene flow and mutation can result in a change in the proportion of alleles (different varieties of a particular gene) in the population's gene pool. As time passes, this shift in allele frequency can result in the emergence of new traits and ultimately new species.
Many of the characteristics we appreciate in plants and animals are adaptations. For example the lungs or gills which extract oxygen from air, fur and feathers as insulation and long legs to get away from predators and camouflage for hiding. To understand the concept of adaptation it is crucial to distinguish between behavioral and physiological characteristics.
Physiological traits like large gills and thick fur are physical characteristics. Behavioral adaptations are not, such as the tendency of animals to seek companionship or move into the shade during hot temperatures. Additionally, it is important to understand that a lack of forethought does not make something an adaptation. A failure to consider the consequences of a decision even if it seems to be rational, could make it unadaptive.