What is Free Evolution?
Free evolution is the idea that the natural processes of organisms can lead to their development over time. This includes the development of new species and the change in appearance of existing ones.
Numerous examples have been offered of this, including various varieties of fish called sticklebacks that can be found in salt or fresh water, as well as walking stick insect varieties that favor specific host plants. These reversible traits are not able to explain fundamental changes to basic body plans.
Evolution by Natural Selection
Scientists have been fascinated by the evolution of all the living creatures that live on our planet for ages. The best-established explanation is Charles Darwin's natural selection, a process that is triggered when more well-adapted individuals live longer and reproduce more successfully than those less well adapted. As time passes, the number of well-adapted individuals becomes larger and eventually develops into a new species.
Natural selection is an ongoing process that is characterized by the interaction of three factors: variation, inheritance and reproduction. Variation is caused by mutations and sexual reproduction both of which increase the genetic diversity of the species. Inheritance is the transfer of a person's genetic characteristics to his or her offspring which includes both recessive and dominant alleles. Reproduction is the generation of viable, fertile offspring, which includes both asexual and sexual methods.
All of these variables must be in balance to allow natural selection to take place. If, for example, a dominant gene allele causes an organism reproduce and last longer than the recessive gene allele The dominant allele becomes more common in a population. But if the allele confers a disadvantage in survival or decreases fertility, it will be eliminated from the population. This process is self-reinforcing, which means that the organism with an adaptive characteristic will live and reproduce more quickly than those with a maladaptive trait. The greater an organism's fitness, measured by its ability reproduce and survive, is the more offspring it can produce. People with desirable traits, like having a longer neck in giraffes or bright white colors in male peacocks, are more likely to be able to survive and create offspring, which means they will become the majority of the population over time.
Natural selection is a factor in populations and not on individuals. This is a significant distinction from the Lamarckian theory of evolution, which claims that animals acquire characteristics through use or neglect. For example, if a animal's neck is lengthened by stretching to reach for prey its offspring will inherit a more long neck. The differences in neck size between generations will increase until the giraffe is no longer able to breed with other giraffes.
Evolution by Genetic Drift
In genetic drift, alleles within a gene can attain different frequencies in a group through random events. At some point, one will attain fixation (become so common that it cannot be eliminated through natural selection), while other alleles fall to lower frequencies. In the extreme it can lead to one allele dominance. The other alleles have been basically eliminated and heterozygosity has been reduced to zero. In a small number of people it could lead to the complete elimination of recessive allele. This scenario is called the bottleneck effect and is typical of an evolutionary process that occurs when the number of individuals migrate to form a population.
A phenotypic bottleneck may happen when the survivors of a disaster like an epidemic or a mass hunting event, are concentrated into a small area. The survivors will carry a dominant allele and thus will have the same phenotype. This situation could be caused by earthquakes, war, or even plagues. Whatever 에볼루션 게이밍 that is left might be prone to genetic drift.
Walsh, Lewens and Ariew define drift as a deviation from the expected values due to differences in fitness. They cite a famous instance of twins who are genetically identical and have identical phenotypes, but one is struck by lightning and dies, whereas the other lives and reproduces.
This type of drift can play a crucial part in the evolution of an organism. It's not the only method for evolution. Natural selection is the main alternative, where mutations and migrations maintain the phenotypic diversity of a population.
Stephens claims that there is a vast difference between treating drift like an actual cause or force, and treating other causes like migration and selection as forces and causes. He argues that a causal-process account of drift allows us separate it from other forces and this distinction is crucial. He argues further that drift is both an orientation, i.e., it tends to reduce heterozygosity. It also has a size, that is determined by population size.
Evolution through Lamarckism
When high school students study biology they are often introduced to the work of Jean-Baptiste Lamarck (1744 - 1829). His theory of evolution, commonly referred to as "Lamarckism is based on the idea that simple organisms develop into more complex organisms adopting traits that result from the use and abuse of an organism. Lamarckism is usually illustrated with an image of a giraffe that extends its neck longer to reach the higher branches in the trees. This process would cause giraffes to give their longer necks to their offspring, who would then grow even taller.
Lamarck Lamarck, a French Zoologist from France, presented a revolutionary concept in his opening lecture at the Museum of Natural History of Paris. He challenged the previous thinking on organic transformation. According to him living things had evolved from inanimate matter through an escalating series of steps. Lamarck was not the only one to suggest that this might be the case but his reputation is widely regarded as being the one who gave the subject its first general and comprehensive analysis.
The most popular story is that Lamarckism grew into an opponent to Charles Darwin's theory of evolutionary natural selection, and that the two theories battled each other in the 19th century. Darwinism eventually prevailed and led to what biologists call the Modern Synthesis. The theory denies that acquired characteristics can be passed down through generations and instead argues that organisms evolve through the selective influence of environmental factors, such as Natural Selection.
Lamarck and his contemporaries supported the idea that acquired characters could be passed down to the next generation. However, this concept was never a central part of any of their evolutionary theories. This is partly 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 genomics, there is a large amount of evidence that supports the possibility of inheritance of acquired traits. It is sometimes referred to as "neo-Lamarckism" or, more often epigenetic inheritance. This is a model that is as reliable as the popular Neodarwinian model.
Evolution by the process of adaptation
One of the most common misconceptions about evolution is that it is driven by a type of struggle for survival. This notion is not true and ignores other forces driving evolution. The fight for survival can be better described as a fight to survive in a certain environment. This may include not only other organisms as well as the physical surroundings themselves.
To understand how evolution operates, it is helpful to think about what adaptation is. It is a feature that allows living organisms to survive in its environment and reproduce. It can be a physiological feature, like feathers or fur or a behavioral characteristic such as a tendency to move into the shade in the heat or leaving at night to avoid the cold.
The ability of an organism to draw energy from its surroundings and interact with other organisms as well as their physical environments is essential to its survival. The organism must have the right genes for producing offspring and to be able to access sufficient food and 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 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 result in the emergence of novel traits and eventually, new species over time.
A lot of the traits we appreciate in plants and animals are adaptations. For example lung or gills that draw oxygen from air feathers and fur for insulation long legs to run away from predators and camouflage to conceal. However, a thorough understanding of adaptation requires paying attention to the distinction between physiological and behavioral traits.
Physiological traits like large gills and thick fur are physical characteristics. The behavioral adaptations aren't an exception, for instance, the tendency of animals to seek companionship or move into the shade in hot weather. It is important to note that the absence of planning doesn't result in an adaptation. A failure to consider the consequences of a decision even if it appears to be rational, may make it unadaptive.