What is Free Evolution?
Free evolution is the idea that natural processes can lead to the development of organisms over time. This includes the creation of new species and the transformation of the appearance of existing species.
This has been demonstrated by many examples, including stickleback fish varieties that can live in fresh or saltwater and walking stick insect species that are apprehensive about particular host plants. These typically reversible traits cannot explain fundamental changes to the body's basic plans.
Evolution through Natural Selection
Scientists have been fascinated by the development of all living creatures that inhabit our planet for ages. Charles Darwin's natural selection theory is the best-established explanation. This process occurs when individuals who are better-adapted have more success in reproduction and survival than those who are less well-adapted. Over time, the population of well-adapted individuals grows and eventually develops into an entirely 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 increase the genetic diversity of the species. Inheritance refers to the transmission of a person's genetic traits, including recessive and dominant genes to their offspring. Reproduction is the process of creating viable, fertile offspring. This can be achieved via sexual or asexual methods.
Natural selection can only occur when all the factors are in equilibrium. For instance the case where the dominant allele of one gene allows an organism to live and reproduce more frequently than the recessive allele the dominant allele will be more prevalent within the 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 a beneficial characteristic is more likely to survive and reproduce than an individual with an unadaptive characteristic. The more offspring an organism produces the more fit it is which is measured by its ability to reproduce itself and survive. People with good traits, like a longer neck in giraffes and bright white patterns of color in male peacocks, are more likely to survive and produce offspring, so they will eventually make up the majority of the population over time.
Natural selection is only an element in the population and not on individuals. This is an important distinction from the Lamarckian theory of evolution, which states that animals acquire traits by use or inactivity. If a giraffe extends its neck in order to catch prey and the neck grows larger, then its offspring will inherit this characteristic. The length difference between generations will persist until the giraffe's neck becomes too long that it can not breed with other giraffes.
Evolution by Genetic Drift
Genetic drift occurs when alleles of one gene are distributed randomly 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 will decrease in frequency. In extreme cases it can lead to a single allele dominance. The other alleles have been basically eliminated and heterozygosity has been reduced to zero. In a small population it could result in the complete elimination the recessive gene. Such a scenario would be known as a bottleneck effect and it is typical of the kind of evolutionary process when a lot of people migrate to form a new group.
A phenotypic 'bottleneck' can also occur when survivors of a disaster like an outbreak or mass hunting incident are concentrated in an area of a limited size. The survivors will have an allele that is dominant and will share the same phenotype. This situation might be the result of a war, earthquake or even a disease. The genetically distinct population, if it is left, could be susceptible to genetic drift.
Walsh, Lewens and Ariew define drift as a deviation from expected values due to differences in fitness. They cite the famous example of twins who are genetically identical and share the same phenotype. However, one is struck by lightning and dies, but the other is able to reproduce.
This type of drift is crucial in the evolution of a species. But, it's not the only method to progress. Natural selection is the primary alternative, where mutations and migration maintain phenotypic diversity within the population.
Stephens claims that there is a significant distinction between treating drift as a force or a cause and considering other causes of evolution, such as selection, mutation, and migration as forces or causes. 에볼루션게이밍 claims that a causal process explanation of drift allows us to distinguish it from these other forces, and that this distinction is essential. He also argues that drift is both an orientation, i.e., it tends towards eliminating heterozygosity. It also has a size, that is determined by population size.
Evolution by Lamarckism
In high school, students take biology classes, they are frequently introduced to the work of Jean-Baptiste Lamarck (1744 - 1829). His theory of evolution, commonly referred to as "Lamarckism which means that simple organisms develop into more complex organisms through adopting traits that are a product of the organism's use and misuse. Lamarckism can be demonstrated by a giraffe extending its neck to reach higher levels of leaves in the trees. This causes giraffes' longer necks to be passed onto their offspring who would grow taller.
Lamarck was a French zoologist and, in his inaugural lecture for his course on invertebrate Zoology at the Museum of Natural History in Paris on the 17th May 1802, he presented a groundbreaking concept that radically challenged the conventional wisdom about organic transformation. According Lamarck, living organisms evolved from inanimate matter through a series of gradual steps. Lamarck was not the first to suggest this but he was regarded as the first to provide the subject a comprehensive and general overview.
The predominant story is that Charles Darwin's theory on natural selection and Lamarckism fought during the 19th century. Darwinism ultimately prevailed, leading to what biologists refer to as the Modern Synthesis. This theory denies acquired characteristics can be passed down and instead argues organisms evolve by the selective action of environment 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 notion was never a central part of any of their theories about evolution. This is largely due 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 body of evidence supporting the heritability of acquired characteristics. This is referred to as "neo Lamarckism", or more often epigenetic inheritance. It is a variant of evolution that is just as valid as the more popular Neo-Darwinian theory.
Evolution through the process of adaptation
One of the most popular misconceptions about evolution is that it is driven by a sort of struggle for survival. In reality, this notion misrepresents natural selection and ignores the other forces that are driving evolution. The fight for survival can be better described as a fight to survive in a specific environment. This could include not only other organisms but also the physical environment itself.
Understanding adaptation is important to comprehend evolution. Adaptation refers to any particular characteristic that allows an organism to survive and reproduce in its environment. It could be a physical feature, such as feathers or fur. It could also be a characteristic of behavior, like moving into the shade during the heat, or moving out to avoid the cold at night.
The ability of an organism to extract energy from its environment and interact with other organisms as well as their physical environment is essential to its survival. The organism must possess the right genes to generate offspring, and must be able to find enough food and other resources. Moreover, the organism must be capable of reproducing at an optimal rate within its environmental niche.
These elements, in conjunction with mutation and gene flow result in an alteration in the percentage of alleles (different types of a gene) in the population's gene pool. As time passes, this shift in allele frequencies could result in the emergence of new traits, and eventually new species.
A lot of the traits we admire about animals and plants are adaptations, such as lung or gills for removing oxygen from the air, fur or feathers for insulation long legs to run away from predators and camouflage for hiding. To comprehend adaptation it is crucial to discern between physiological and behavioral characteristics.
Physical characteristics like the thick fur and gills are physical traits. Behavior adaptations aren't, such as the tendency of animals to seek companionship or move into the shade in hot weather. Furthermore, it is important to note that a lack of thought does not make something an adaptation. A failure to consider the consequences of a decision even if it seems to be rational, may cause it to be unadaptive.