What is Free Evolution?
Free evolution is the idea that natural processes can cause organisms to evolve over time. This includes the appearance and development of new species.
Numerous examples have been offered of this, including different varieties of stickleback fish that can live in either fresh or salt water and walking stick insect varieties that are attracted to particular host plants. These mostly reversible traits permutations cannot explain fundamental changes to the body's basic plans.
Evolution through Natural Selection
The development of the myriad of living creatures on Earth is an enigma that has intrigued scientists for decades. Charles Darwin's natural selection is the most well-known explanation. This process occurs when individuals who are better-adapted are able to reproduce faster and longer 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 process that is cyclical and involves the interaction of three factors: variation, reproduction and inheritance. Variation is caused by mutation and sexual reproduction both of which increase the genetic diversity of the species. Inheritance is the passing of a person's genetic characteristics to the offspring of that person which includes both recessive and dominant alleles. Reproduction is the process of creating viable, fertile offspring. This can be done by both asexual or sexual methods.
All of these factors must be in balance for natural selection to occur. If, for instance, a dominant gene allele allows an organism to reproduce and survive more than the recessive gene, then the dominant allele becomes more prevalent in a group. However, if the gene confers an unfavorable survival advantage or reduces fertility, it will disappear from the population. The process is self-reinforcing meaning that an organism with an adaptive trait will live and reproduce much more than those with a maladaptive trait. The greater an organism's fitness as measured by its capacity to reproduce and survive, is the greater number of offspring it can produce. People with desirable traits, like having a longer neck in giraffes, or bright white color patterns in male peacocks are more likely survive and have offspring, and thus will eventually make up the majority of the population in the future.
Natural selection is only an aspect of populations and not on individuals. This is a significant distinction from the Lamarckian theory of evolution which states that animals acquire traits through use or neglect. For instance, if the giraffe's neck gets longer through reaching out to catch prey, its offspring will inherit a more long neck. The differences in neck length 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 from the same gene are randomly distributed within a population. At some point, one will attain fixation (become so widespread that it cannot be removed through natural selection) and other alleles fall to lower frequency. This can result in an allele that is dominant in extreme. The other alleles are essentially eliminated, and heterozygosity falls to zero. In a small group it could result in the complete elimination of recessive gene. This scenario is known as a bottleneck effect and it is typical of the kind of evolutionary process when a lot of individuals move to form a new population.
A phenotypic bottleneck can also happen when the survivors of a disaster, such as an epidemic or mass hunt, are confined in a limited area. The survivors will carry an dominant allele, and will have the same phenotype. This situation might be caused by a war, earthquake, or even a plague. Whatever the reason the genetically distinct group that remains could be prone to genetic drift.
Walsh Lewens and Ariew utilize Lewens, Walsh and Ariew employ a "purely outcome-oriented" definition of drift as any deviation from the expected values of variations in fitness. They give the famous example of twins who are both genetically identical and have exactly the same phenotype. However one is struck by lightning and dies, while the other continues to reproduce.
This type of drift is vital to the evolution of an entire species. This isn't the only method of evolution. 에볼루션게이밍 is the most common alternative, in which mutations and migration maintain phenotypic diversity within a population.
Stephens claims that there is a vast difference between treating the phenomenon of drift as an actual cause or force, and treating other causes like selection mutation and migration as causes and forces. He claims that a causal-process explanation of drift lets us distinguish it from other forces, and this distinction is crucial. He argues further that drift has direction, i.e., it tends to reduce heterozygosity. It also has a size that is determined by the size of the population.
Evolution through Lamarckism
When high school students take biology classes, they are frequently introduced to the work of Jean-Baptiste Lamarck (1744 - 1829). His theory of evolution is generally called "Lamarckism" and it states that simple organisms develop into more complex organisms via the inheritance of traits which result from an organism's natural activities usage, use and disuse. Lamarckism is usually illustrated with a picture of a giraffe extending its neck to reach the higher branches in the trees. This would cause giraffes to give their longer necks to their offspring, which then become taller.
Lamarck Lamarck, a French zoologist, presented an innovative idea in his 17 May 1802 opening lecture at the Museum of Natural History of Paris. He challenged conventional wisdom on organic transformation. According to Lamarck, living things evolved from inanimate material through a series gradual steps. Lamarck wasn't the first to suggest this however he was widely considered to be the first to give the subject a thorough and general overview.
The popular narrative is that Lamarckism was a rival to Charles Darwin's theory of evolution through natural selection, and both theories battled out in the 19th century. Darwinism eventually prevailed and led to what biologists call 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, including natural selection.
Lamarck and his contemporaries believed in the idea that acquired characters could be passed on to the next generation. However, this notion was never a central part of any of their evolutionary theories. 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 an increasing body of evidence that supports the heritability-acquired characteristics. This is also known as "neo Lamarckism", or more commonly epigenetic inheritance. This is a variant that is just as valid as the popular Neodarwinian model.
Evolution by Adaptation
One of the most commonly-held misconceptions about evolution is being driven by a struggle for survival. This notion is not true and ignores other forces driving evolution. The fight for survival can be better described as a struggle to survive in a certain environment. This can be a challenge for not just other living things as well as the physical surroundings themselves.
Understanding the concept of adaptation is crucial to comprehend evolution. Adaptation is any feature that allows living organisms to live in its environment and reproduce. It could be a physical structure, like fur or feathers. Or it can be a behavior trait that allows you to move towards shade during hot weather or escaping the cold at night.
The survival of an organism depends on its ability to extract energy from the surrounding environment and interact with other living organisms and their physical surroundings. The organism should possess the right genes to produce offspring, and be able to find sufficient food and resources. The organism should also be able to reproduce itself at an amount that is appropriate for its niche.
These factors, in conjunction with gene flow and mutations can result in changes in the proportion of different alleles in the population's gene pool. This shift in the frequency of alleles can lead to the emergence of new traits and eventually new species as time passes.
A lot of the traits we find appealing in plants and animals are adaptations. For instance lung or gills that draw oxygen from air feathers and fur as insulation and long legs to get away from predators, and camouflage to hide. However, a complete understanding of adaptation requires paying attention to the distinction between behavioral and physiological characteristics.
Physiological adaptations like thick fur or gills are physical characteristics, whereas behavioral adaptations, like the tendency to seek out companions or to retreat into the shade in hot weather, are not. Additionally, it is important to remember that lack of planning is not a reason to make something an adaptation. In fact, a failure to think about the consequences of a choice can render it unadaptable despite the fact that it appears to be reasonable or even essential.