What is Free Evolution?
Free evolution is the idea that the natural processes that organisms go through can lead to their development over time. This includes the emergence and development of new species.
This has been demonstrated by many examples, including stickleback fish varieties that can be found in salt or fresh water, and walking stick insect varieties that prefer specific host plants. These are mostly reversible traits however, are not able to be the reason for fundamental changes in body plans.
Evolution through Natural Selection
The development of the myriad of living organisms on Earth is a mystery that has fascinated scientists for many centuries. Charles Darwin's natural selection is the best-established explanation. This is because people who are more well-adapted are able to reproduce faster and longer than those who are less well-adapted. Over time, a population of well-adapted individuals expands and eventually forms a whole new species.
Natural selection is an ongoing process that involves the interaction of three factors: variation, inheritance and reproduction. Sexual reproduction and mutation increase the genetic diversity of an animal species. Inheritance refers to the transmission of a person’s genetic traits, including recessive and dominant genes, to their offspring. Reproduction is the generation of fertile, viable offspring which includes both sexual and asexual methods.
All of these factors must be in harmony to allow natural selection to take place. If, for example an allele of a dominant gene allows an organism to reproduce and live longer than the recessive allele then the dominant allele is more prevalent in a population. If the allele confers a negative survival advantage or decreases the fertility of the population, it will disappear. The process is self-reinforced, which means that an organism with a beneficial trait is more likely to survive and reproduce than one with a maladaptive characteristic. The more offspring an organism produces the better its fitness, which is measured by its ability to reproduce and survive. People with good characteristics, like having a longer neck in giraffes and bright white patterns of color 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 only acts on populations, not individuals. This is a significant distinction from the Lamarckian evolution theory that states that animals acquire traits through use or lack of use. For example, if a giraffe's neck gets longer through stretching to reach prey and its offspring will inherit a longer neck. The differences in neck length between generations will persist until the giraffe's neck becomes too long to no longer breed with other giraffes.
Evolution by Genetic Drift
In genetic drift, alleles at a gene may attain different frequencies in a group due to random events. At some point, one will attain fixation (become so widespread that it can no longer be eliminated by natural selection) and other alleles will fall to lower frequencies. In the extreme this, it leads to a single allele dominance. The other alleles are essentially eliminated, and heterozygosity falls to zero. In a small group this could lead to the complete elimination the recessive gene. 바카라 에볼루션 is called a bottleneck effect, and it is typical of the kind of evolutionary process when a large number of people migrate to form a new group.
A phenotypic bottleneck may occur when survivors of a disaster like an epidemic or a massive hunting event, are condensed in a limited area. The survivors will be largely homozygous for the dominant allele, meaning that they all share the same phenotype, and consequently share the same fitness characteristics. This may be caused by war, earthquake or even a disease. Whatever the reason, the genetically distinct population that remains could be susceptible to genetic drift.
Walsh Lewens, Walsh and Ariew define drift as a deviation from the expected value due to 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, whereas the other lives to reproduce.
This kind of drift could be crucial in the evolution of a species. It's not the only method for evolution. The primary alternative is to use a process known as natural selection, in which the phenotypic variation of the population is maintained through mutation and migration.
Stephens asserts that there is a major distinction between treating drift as a force or an underlying cause, and considering other causes of evolution like selection, mutation and migration as causes or causes. He claims that a causal process explanation of drift permits us to differentiate it from other forces, and this distinction is crucial. He argues further that drift is both a direction, i.e., it tends to eliminate heterozygosity. It also has a size which 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, commonly referred to as “Lamarckism” is based on the idea that simple organisms develop into more complex organisms inheriting characteristics that result from an organism's use and disuse. Lamarckism is usually illustrated with the image of a giraffe stretching its neck longer to reach the higher branches in the trees. This would cause giraffes to give their longer necks to their offspring, who then grow even 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 the 17th May 1802, he presented an innovative concept that completely challenged the previous understanding of organic transformation. According to him, living things had evolved from inanimate matter via the gradual progression of events. Lamarck wasn't the only one to propose this but he was thought of as the first to give the subject a comprehensive and general overview.
The most popular story is that Lamarckism was an opponent to Charles Darwin's theory of evolutionary natural selection and both theories battled each other in the 19th century. Darwinism eventually triumphed and led to the development of what biologists refer to as the Modern Synthesis. This theory denies acquired characteristics are passed down from generation to generation and instead, it claims that organisms evolve through the selective influence of environmental factors, including Natural Selection.
While Lamarck supported the notion of inheritance through acquired characters and his contemporaries also paid lip-service to this notion 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 year since Lamarck's birth and in the field of age genomics, there is an increasing evidence base that supports the heritability of acquired traits. It is sometimes referred to as "neo-Lamarckism" or, more commonly, epigenetic inheritance. This is a version that is as reliable as the popular neodarwinian model.
Evolution through Adaptation
One of the most popular misconceptions about evolution is that it is driven by a type of struggle to survive. This view is inaccurate and overlooks the other forces that drive evolution. The struggle for survival is more precisely described as a fight to survive within a specific environment, which could involve not only other organisms, but as well the physical environment.
To understand how evolution operates, it is helpful to think about what adaptation is. The term "adaptation" refers to any characteristic that allows living organisms to survive in its environment and reproduce. It can be a physiological feature, such as feathers or fur or a behavioral characteristic, such as moving to the shade during hot weather or coming 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 organisms and their physical environments. The organism needs to have the right genes to generate offspring, and it should be able to locate sufficient food and other resources. In addition, the organism should be capable of reproducing in a way that is optimally within its niche.
These factors, together with gene flow and mutation, lead to changes in the ratio of alleles (different types of a gene) in the population's gene pool. As time passes, this shift in allele frequencies can result in the emergence of new traits, and eventually new species.
Many of the features that we admire in animals and plants are adaptations, for example, lung or gills for removing oxygen from the air, fur or feathers for insulation and long legs for running away from predators and camouflage for hiding. However, a proper understanding of adaptation requires attention to the distinction between the physiological and behavioral traits.
Physiological adaptations, like thick fur or gills are physical traits, while behavioral adaptations, like the desire to find friends or to move to shade in hot weather, aren't. In addition, it is important to note that lack of planning is not a reason to make something an adaptation. In fact, failing to think about the consequences of a decision can render it unadaptable even though it appears to be reasonable or even essential.