What is Free Evolution?
Free evolution is the concept that the natural processes of living organisms can lead them to evolve over time. This includes the evolution of new species and alteration of the appearance of existing ones.
Numerous examples have been offered of this, including various kinds of stickleback fish that can live in either salt or fresh water, and walking stick insect varieties that are attracted to particular host plants. These typically reversible traits are not able to explain fundamental changes to basic body plans.
Evolution by Natural Selection
The development of the myriad living creatures on Earth is an enigma that has fascinated scientists for centuries. Charles Darwin's natural selection is the best-established explanation. This is because those who are better adapted are able to reproduce faster and longer than those who are less well-adapted. Over time, the population of well-adapted individuals grows and eventually creates a new species.
에볼루션코리아 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 a species. Inheritance is the transfer of a person's genetic characteristics to the offspring of that person which includes both dominant and recessive alleles. Reproduction is the production of fertile, viable offspring which includes both asexual and sexual methods.
All of these factors must be in harmony to allow natural selection to take place. For instance the case where an allele that is dominant at a gene allows an organism to live and reproduce more often than the recessive one, the dominant allele will be more prominent in the population. If the allele confers a negative advantage to survival or lowers the fertility of the population, it will go away. The process is self-reinforcing meaning that an organism that has an adaptive characteristic will live and reproduce much more than one with a maladaptive characteristic. The greater an organism's fitness as measured by its capacity to reproduce and survive, is the greater number of offspring it will produce. People with desirable traits, like longer necks in giraffes and bright white color patterns in male peacocks are more likely be able to survive and create offspring, and thus will eventually make up the majority of the population over time.
Natural selection is an aspect of populations and not on individuals. This is a major distinction from the Lamarckian theory of evolution which claims that animals acquire traits by use or inactivity. For instance, if the animal's neck is lengthened by reaching out to catch prey, its offspring will inherit a more long neck. The difference in neck size between generations will continue to grow until the giraffe is no longer able to breed with other giraffes.
Evolution by Genetic Drift
Genetic drift occurs when alleles from the same gene are randomly distributed in a population. In the end, one will attain fixation (become so widespread that it can no longer be removed by natural selection) and other alleles fall to lower frequency. In extreme cases this, it leads to a single allele dominance. Other alleles have been essentially eliminated and heterozygosity has diminished to zero. In a small number of people, this could result in the complete elimination the recessive gene. This is known as the bottleneck effect. It is typical of an evolutionary process that occurs when an enormous number of individuals move to form a population.
A phenotypic bottleneck can also occur when survivors of a disaster like an outbreak or a mass hunting event are concentrated in the same area. The survivors will share an allele that is dominant and will share the same phenotype. This situation might be caused by a war, earthquake, or even a plague. The genetically distinct population, if left, could be susceptible to genetic drift.
Walsh Lewens, Walsh and Ariew define drift as a deviation from the expected values due to differences in fitness. They cite the famous example of twins who are genetically identical and have exactly the same phenotype. However one is struck by lightning and dies, while the other is able to reproduce.
This kind of drift can be vital to the evolution of the 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 asserts that there is a huge difference between treating drift like a force or cause, and treating other causes such as selection mutation and migration as causes and forces. Stephens claims that a causal process explanation of drift lets us separate it from other forces and this distinction is essential. He also argues that drift has an orientation, i.e., it tends towards eliminating heterozygosity. It also has a size which is determined based on the size of the population.
Evolution through Lamarckism
Students of biology in high school are frequently introduced to Jean-Baptiste Lamarck's (1744-1829) work. His theory of evolution is generally known as "Lamarckism" and it states that simple organisms develop into more complex organisms through the inheritance of characteristics that result from the organism's natural actions use and misuse. Lamarckism can be demonstrated by an giraffe's neck stretching 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. In his opening lecture for his course on invertebrate Zoology at the Museum of Natural History in Paris on 17 May 1802, he presented an original idea that fundamentally challenged previous thinking about organic transformation. According to Lamarck, living things evolved from inanimate material by a series of gradual steps. Lamarck wasn't the first to propose this, but he was widely thought of as the first to provide the subject a comprehensive and general treatment.
The most popular story is that Charles Darwin's theory on natural selection and Lamarckism were rivals in the 19th Century. Darwinism eventually prevailed and led to the development of what biologists now refer to as the Modern Synthesis. The theory argues the possibility that acquired traits can be inherited, and instead suggests that organisms evolve through the selective action of environmental factors, like natural selection.
Lamarck and his contemporaries endorsed the idea that acquired characters could be passed down to future generations. However, this notion was never a major part of any of their evolutionary theories. This is partly because it was never scientifically validated.
But it is now 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 traits. This is referred to as "neo Lamarckism", or more generally epigenetic inheritance. It is a form of evolution that is as relevant as the more popular Neo-Darwinian theory.
에볼루션 by Adaptation
One of the most popular misconceptions about evolution is that it is driven by a type of struggle for survival. In reality, this notion is inaccurate and overlooks the other forces that are driving evolution. The fight for survival can be better described as a fight to survive in a particular environment. This may include not only other organisms but also the physical surroundings themselves.
To understand how evolution works, it is helpful to consider what adaptation is. It refers to a specific feature that allows an organism to live and reproduce in its environment. It can be a physiological feature, such as feathers or fur or a behavior like moving into shade in hot weather or stepping out at night to avoid the cold.
The survival of an organism is dependent on its ability to obtain energy from the environment and to 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 locate sufficient food and other resources. In addition, the organism should be capable of reproducing itself at an optimal rate within its environmental niche.
These factors, together with mutation and gene flow can result in changes in the ratio of alleles (different forms of a gene) in a population's gene pool. As time passes, this shift in allele frequencies can result in the development of new traits and ultimately new species.
A lot of the traits we admire about animals and plants are adaptations, like lungs or gills to extract oxygen from the air, feathers or fur to provide insulation, long legs for running away from predators, and camouflage for hiding. However, a thorough understanding of adaptation requires a keen eye to the distinction between the physiological and behavioral traits.
Physiological adaptations, like thick fur or gills are physical characteristics, whereas behavioral adaptations, like the tendency to seek out friends or to move to shade in hot weather, are not. Additionally, it is important to note that lack of planning does not make something an adaptation. In fact, failure to think about the implications of a behavior can make it ineffective, despite the fact that it may appear to be logical or even necessary.