What is Free Evolution?
Free evolution is the concept that natural processes can cause organisms to develop over time. This includes the appearance and growth of new species.
A variety of examples have been provided of this, such as different varieties of stickleback fish that can live in either fresh or salt water and walking stick insect varieties that favor specific host plants. These reversible traits, however, cannot explain fundamental changes in body plans.
Evolution through Natural Selection
Scientists have been fascinated by the development of all the living creatures that inhabit our planet for ages. Charles Darwin's natural selectivity is the best-established explanation. This process occurs when those who are better adapted survive and reproduce more than those who are less well-adapted. Over time, a community of well-adapted individuals expands and eventually forms a whole new species.
Natural selection is a process that is cyclical and involves the interaction of 3 factors that are: reproduction, variation and inheritance. Sexual reproduction and mutation increase the genetic diversity of the species. Inheritance refers the transmission of genetic traits, including both dominant and recessive genes and their offspring. Reproduction is the process of producing fertile, viable offspring. This can be done via sexual or asexual methods.
All of these factors must be in balance to allow natural selection to take place. For example when a dominant allele at one gene causes an organism to survive and reproduce more often than the recessive one, the dominant allele will become more prominent within the population. However, if the gene confers a disadvantage in survival or reduces fertility, it will be eliminated from the population. The process is self-reinforcing, meaning that an organism with a beneficial characteristic is more likely to survive and reproduce than one with an unadaptive trait. The greater an organism's fitness which is measured by its ability to reproduce and survive, is the greater number of offspring it will produce. People with good characteristics, like a longer neck in giraffes, or bright white color patterns in male peacocks are more likely to be able to survive and create offspring, so they will become the majority of the population in the future.
Natural selection only acts on populations, not individuals. This is an important distinction from the Lamarckian theory of evolution, which states 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 longer neck. 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 by Genetic Drift
Genetic drift occurs when alleles from the same gene are randomly distributed within a population. At 에볼루션 코리아 , only one of them will be fixed (become widespread enough to not longer be eliminated by natural selection), and the other alleles will decrease in frequency. This could lead to dominance at the extreme. The other alleles are essentially eliminated, and heterozygosity falls to zero. In a small group this could lead to the complete elimination of recessive gene. This is called a bottleneck effect, and it is typical of the kind of evolutionary process that occurs when a large amount of people migrate to form a new population.
A phenotypic bottleneck may occur when the survivors of a catastrophe like an epidemic or a mass hunt, are confined into a small area. The survivors will carry an dominant allele, and will have the same phenotype. This situation might be caused by war, earthquake, or even a plague. The genetically distinct population, if it is left vulnerable to genetic drift.
Walsh Lewens, Walsh 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 very important in the evolution of a species. However, it's not the only way to develop. The most common alternative is a process known as natural selection, where the phenotypic variation of an individual is maintained through mutation and migration.
Stephens asserts that there is a huge difference between treating the phenomenon of drift as an actual cause or force, and treating other causes such as migration and selection mutation as causes and forces. He argues that a causal process explanation of drift allows us to distinguish it from the other forces, and that this distinction is vital. He also argues that drift is a directional force: that is it tends to eliminate heterozygosity. He also claims that it also has a specific magnitude which is determined by the size of the population.
Evolution through Lamarckism
Biology students in high school are frequently exposed to Jean-Baptiste lamarck's (1744-1829) work. His theory of evolution is often known as "Lamarckism" and it states that simple organisms develop into more complex organisms through the inheritance of characteristics that are a result of the organism's natural actions, use and disuse. Lamarckism is typically illustrated with the image of a giraffe stretching its neck longer to reach the higher branches in the trees. This could cause giraffes to pass on their longer necks to their offspring, which then grow even taller.
Lamarck Lamarck, a French Zoologist, introduced a revolutionary concept 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 creatures evolved from inanimate material by a series of gradual steps. Lamarck was not the first to suggest that this could be the case but the general consensus is that he was the one being the one who gave the subject its first broad and comprehensive treatment.
The most popular story is that Charles Darwin's theory of evolution by natural selection and Lamarckism were competing in the 19th Century. Darwinism eventually prevailed and led to what biologists refer to as the Modern Synthesis. The Modern Synthesis theory denies the possibility that acquired traits can be inherited, and instead suggests that organisms evolve by the symbiosis of environmental factors, such as natural selection.
While Lamarck believed in the concept of inheritance through acquired characters and his contemporaries also offered a few words about this idea however, it was not an integral part of any of their evolutionary theories. This is partly due to the fact that it was never tested scientifically.
It's been more than 200 years since Lamarck was born and, in the age of genomics, there is a large amount of evidence that supports the heritability of acquired characteristics. This is sometimes called "neo-Lamarckism" or more frequently epigenetic inheritance. It is a version of evolution that is just as relevant as the more popular Neo-Darwinian theory.
Evolution by the process of adaptation
One of the most common misconceptions about evolution is that it is driven by a type of struggle to survive. In fact, this view is a misrepresentation of natural selection and ignores the other forces that drive evolution. The fight for survival is more accurately described as a struggle to survive in a particular environment. This could include not only other organisms as well as the physical environment.
Understanding how adaptation works is essential to comprehend evolution. It is a feature that allows living organisms to survive in its environment and reproduce. It can be a physical structure, such as feathers or fur. Or it can be a characteristic of behavior such as moving into the shade during the heat, or moving out to avoid the cold at night.
The capacity of a living thing to extract energy from its surroundings and interact with other organisms, as well as their physical environments, is crucial to its survival. The organism needs to have the right genes to produce offspring, and it should be able to access enough food and other resources. Furthermore, the organism needs to be capable of reproducing at an optimal rate within its environment.
These factors, along with gene flow and mutation, lead to an alteration in the percentage of alleles (different varieties of a particular gene) in a population's gene pool. This change in allele frequency can result in the emergence of new traits, and eventually new species over time.
Many of the features that we admire about animals and plants are adaptations, such as lung or gills for removing oxygen from the air, feathers or fur for insulation long legs to run away from predators, and camouflage to hide. To comprehend adaptation it is essential to distinguish between behavioral and physiological characteristics.
Physiological adaptations, such as the thick fur or gills are physical characteristics, whereas behavioral adaptations, such as the desire to find companions or to move into the shade in hot weather, aren't. Additionally it is important to note that a lack of forethought does not make something an adaptation. Failure to consider the consequences of a decision even if it appears to be rational, may make it inflexible.