What is Free Evolution?
Free evolution is the notion that the natural processes that organisms go through can lead to their development over time. This includes the appearance and growth of new species.
This has been proven by numerous examples such as the stickleback fish species that can live in saltwater or fresh water and walking stick insect types that prefer particular host plants. These typically reversible traits are not able to explain fundamental changes to basic body plans.
Evolution by Natural Selection
The evolution of the myriad living creatures on Earth is an enigma that has fascinated scientists for decades. Charles Darwin's natural selection is the best-established explanation. This process occurs when those who are better adapted are able to reproduce faster and longer than those who are less well-adapted. As time passes, a group of well adapted individuals grows and eventually forms a whole new species.
Natural selection is an ongoing process and involves the interaction of 3 factors including reproduction, variation and inheritance. Sexual reproduction and mutations increase the genetic diversity of an animal species. Inheritance refers to the passing of a person's genetic traits to their offspring that includes dominant and recessive alleles. Reproduction is the process of producing fertile, viable offspring. This can be accomplished by both asexual or sexual methods.
Natural selection can only occur when all of these factors are in harmony. For instance when an allele that is dominant at the gene causes an organism to survive and reproduce more frequently than the recessive one, the dominant allele will be more common within the population. However, if the gene confers an unfavorable survival advantage or reduces fertility, it will be eliminated from the population. The process is self-reinforcing, meaning that a species that has a beneficial trait will survive and reproduce more than an individual with an unadaptive characteristic. The higher the level of fitness an organism has which is measured by its ability to reproduce and survive, is the more offspring it produces. Individuals with favorable characteristics, like a longer neck in giraffes and bright white color patterns in male peacocks, are more likely to survive and produce offspring, which means they will make up the majority of the population over time.
Natural selection is only an element in the population and not on individuals. This is a major distinction from the Lamarckian theory of evolution, which states that animals acquire traits through the use or absence of use. If a giraffe stretches its neck to catch prey and the neck grows larger, then its offspring will inherit this characteristic. The differences in neck length between generations will persist until the giraffe's neck becomes too long that it can no longer breed with other giraffes.
Evolution through Genetic Drift
Genetic drift occurs when alleles from one gene are distributed randomly in a population. In the end, one will reach fixation (become so widespread that it can no longer be eliminated through natural selection), while other alleles will fall to lower frequency. This could lead to an allele that is dominant at the extreme. The other alleles are eliminated, and heterozygosity decreases to zero. In a small population this could lead to the complete elimination the recessive gene. This is known as the bottleneck effect and is typical of the evolution process that occurs when the number of individuals migrate to form a population.
A phenotypic bottleneck may occur when the survivors of a catastrophe such as an epidemic or a mass hunting event, are concentrated within a narrow area. The survivors will be mostly homozygous for the dominant allele which means that they will all have the same phenotype, and therefore have the same fitness traits. This could be caused by war, an earthquake or even a cholera outbreak. The genetically distinct population, if it remains, could be susceptible to genetic drift.
Full Content , Lewens, and Ariew utilize Lewens, Walsh, and Ariew use a "purely outcome-oriented" definition of drift as any departure from expected values for differences in fitness. They cite the famous example of twins who are genetically identical and have exactly the same phenotype, but 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. This isn't the only method for evolution. The most common alternative is to use a process known as natural selection, in which phenotypic variation in a population is maintained by mutation and migration.
Stephens argues there is a significant distinction between treating drift as an actual cause or force, and treating other causes such as migration and selection as causes and forces. Full Content argues that a causal process account of drift permits us to differentiate it from the other forces, and this distinction is vital. He also argues that drift has direction, i.e., it tends to reduce heterozygosity. It also has a size which is determined by population size.
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 is generally referred to as "Lamarckism" and it states that simple organisms develop into more complex organisms by the inherited characteristics that result from an organism's natural activities usage, use and disuse. Lamarckism is typically illustrated by a picture of a giraffe stretching its neck longer to reach leaves higher up in the trees. This would cause giraffes to pass on their longer necks to offspring, which then grow even 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 the 17th May 1802, he introduced a groundbreaking concept that radically challenged previous thinking about organic transformation. In his view living things evolved from inanimate matter through a series of gradual 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 treatment.
The prevailing story is that Lamarckism became an opponent to Charles Darwin's theory of evolution through natural selection and both theories battled each other in the 19th century. Darwinism eventually prevailed, leading to the development of what biologists today refer to as the Modern Synthesis. The theory argues that traits acquired through evolution can be inherited and instead argues that organisms evolve by the symbiosis of environmental factors, including natural selection.
Although Lamarck supported the notion of inheritance by acquired characters and his contemporaries offered a few words about this idea however, it was not a central element in any of their theories about evolution. This is due to the fact that it was never scientifically tested.
It's been more than 200 years since Lamarck was born and in the age of genomics, there is a large body of evidence supporting the heritability of acquired characteristics. This is often called "neo-Lamarckism" or more often epigenetic inheritance. It is a variant of evolution that is just as valid as the more well-known Neo-Darwinian model.
Evolution through the process of adaptation
One of the most widespread misconceptions about evolution is that it is driven by a type of struggle for survival. In reality, this notion misrepresents natural selection and ignores the other forces that are driving evolution. The struggle for existence is better described as a struggle to survive in a particular environment. This could be a challenge for not just other living things but also the physical environment itself.
Understanding adaptation is important to understand evolution. Adaptation refers to any particular characteristic that allows an organism to survive and reproduce within its environment. It can be a physiological structure, like feathers or fur, or a behavioral trait like moving to the shade during hot weather or stepping out at night to avoid the cold.
The survival of an organism depends on its ability to obtain 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 sufficient food and other resources. The organism must be able to reproduce at an amount that is appropriate for its specific niche.
에볼루션코리아 , in conjunction with mutations and gene flow can cause a shift in the proportion of different alleles within a population’s gene pool. The change in frequency of alleles can result in the emergence of new traits and eventually new species as time passes.
Many of the features we find appealing in animals and plants are adaptations. For instance lung or gills that extract oxygen from air, fur and feathers as insulation, long legs to run away from predators, and camouflage to hide. However, a complete understanding of adaptation requires a keen eye to the distinction between physiological and behavioral traits.
Physiological adaptations, like the thick fur or gills are physical traits, whereas behavioral adaptations, like the tendency to seek out companions or to retreat to the shade during hot weather, aren't. It is also important to note that the absence of planning doesn't cause an adaptation. Failure to consider the consequences of a decision even if it appears to be logical, can cause it to be unadaptive.