A Guide To Free Evolution From Start To Finish
What is Free Evolution?
Free evolution is the idea that natural processes can cause organisms to evolve over time. This includes the appearance and growth of new species.
Many examples have been given of this, including different kinds of stickleback fish that can live in fresh or salt water and walking stick insect varieties that prefer specific host plants. These typically reversible traits cannot explain fundamental changes to basic body plans.
Evolution by Natural Selection
Scientists have been fascinated by the evolution of all the living creatures that inhabit our planet for centuries. Charles Darwin's natural selection theory is the most well-known explanation. This happens when individuals who are better-adapted survive and reproduce more than those who are less well-adapted. As time passes, the number of well-adapted individuals grows and eventually develops into a new species.
Natural selection is an ongoing process and involves the interaction of 3 factors: variation, reproduction and inheritance. Mutation and sexual reproduction increase the genetic diversity of an animal 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 process of producing fertile, viable offspring. This can be done through sexual or asexual methods.
All of these variables must be in balance for natural selection to occur. For example, if an allele that is dominant at the gene causes an organism to survive and reproduce more often than the recessive allele the dominant allele will become more prominent in the population. However, if the allele confers an unfavorable survival advantage or reduces fertility, it will disappear from the population. 에볼루션 사이트 is self-reinforcing which means that the organism with an adaptive characteristic will live and reproduce much more than one with a maladaptive characteristic. The more offspring that an organism has the more fit it is, which is measured by its ability to reproduce and survive. People with desirable traits, like having a long neck in the giraffe, or bright white color patterns on male peacocks, are more likely than others to reproduce and survive which eventually leads to them becoming the majority.
Natural selection is only an element in the population and not on individuals. This is a significant distinction from the Lamarckian theory of evolution that states that animals acquire traits due to usage or inaction. For instance, if the animal's neck is lengthened by reaching out to catch prey and its offspring will inherit a larger neck. The differences in neck length between generations will continue until the neck of the giraffe becomes too long that it can not breed with other giraffes.
Evolution by Genetic Drift
Genetic drift occurs when the alleles of one gene are distributed randomly within a population. At some point, only one of them will be fixed (become common enough that it can no longer be eliminated by natural selection) and the other alleles will diminish in frequency. This can lead to an allele that is dominant in extreme. The other alleles are eliminated, and heterozygosity falls to zero. In a small number of people, this could lead to the complete elimination of the recessive allele. This scenario is called the bottleneck effect. It is typical of the evolutionary process that occurs whenever the number of individuals migrate to form a group.
A phenotypic 'bottleneck' can also occur when the survivors of a catastrophe such as an outbreak or mass hunting event are concentrated in the same area. The survivors will have an dominant allele, and will have the same phenotype. This situation might be the result of a war, earthquake or even a disease. The genetically distinct population, if it is left vulnerable to genetic drift.
Walsh, Lewens and Ariew define drift as a departure from expected values due to differences in fitness. They give the famous example of twins that 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. This isn't the only method for evolution. Natural selection is the main alternative, where mutations and migrations maintain the phenotypic diversity in a population.
Stephens asserts that there is a major difference between treating drift as a force or a cause and considering other causes of evolution like selection, mutation and migration as forces or causes. He argues that a causal mechanism account of drift allows us to distinguish it from the other forces, and that this distinction is essential. He further argues that drift is both direction, i.e., it tends towards eliminating heterozygosity. It also has a size, that is determined by the size of the population.
Evolution through Lamarckism
When students in high school take biology classes, they are frequently introduced to the work of Jean-Baptiste Lamarck (1744 - 1829). His theory of evolution is generally known as "Lamarckism" and it asserts that simple organisms evolve into more complex organisms via the inheritance of traits that result from the natural activities of an organism use and misuse. Lamarckism is typically illustrated with a picture of a giraffe extending its neck longer to reach leaves higher up in the trees. This process would cause giraffes to pass on their longer necks to offspring, which then become taller.
Lamarck was a French zoologist and, in his opening lecture for his course on invertebrate zoology held at the Museum of Natural History in Paris on the 17th of May in 1802, he presented an innovative concept that completely challenged the previous understanding of organic transformation. In his opinion, living things had evolved from inanimate matter through the gradual progression of events. Lamarck was not the first to suggest this however he was widely considered to be the first to offer the subject a thorough and general overview.
The prevailing story is that Lamarckism became an opponent to Charles Darwin's theory of evolution by natural selection, and that the two theories fought each other in the 19th century. Darwinism ultimately won which led to what biologists refer to as the Modern Synthesis. The theory denies that acquired characteristics can be passed down through generations and instead, it claims that organisms evolve through the selective action of environment factors, including Natural Selection.
Although Lamarck endorsed the idea of inheritance by 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 theorizing. This is due to the fact that it was never tested scientifically.
However, it has been more than 200 years since Lamarck was born and, in the age of genomics there is a vast amount of evidence to support the heritability of acquired characteristics. This is also referred to as "neo Lamarckism", or more generally epigenetic inheritance. This is a version that is as reliable as the popular Neodarwinian model.
Evolution through adaptation
One of the most common misconceptions about evolution is that it is driven by a type of struggle for survival. In fact, this view misrepresents natural selection and ignores the other forces that drive evolution. The struggle for survival is more accurately described as a struggle to survive within a specific environment, which could be a struggle that involves not only other organisms, but also the physical environment itself.
To understand how evolution operates, it is helpful to understand what is adaptation. It is a feature that allows living organisms to live in its environment and reproduce. It could be a physiological feature, such as feathers or fur, or a behavioral trait like moving to the shade during the heat or leaving at night to avoid the cold.
An organism's survival depends on its ability to extract energy from the surrounding environment and interact with other organisms and their physical environments. The organism should possess the right genes for producing offspring and be able find sufficient food and resources. In addition, the organism should be capable of reproducing itself at a high rate within its environment.
These factors, together with mutation and gene flow, lead to an alteration in the percentage of alleles (different forms of a gene) in the population's gene pool. This shift in the frequency of alleles can result in the emergence of new traits, and eventually, new species in the course of time.
A lot of the traits we find appealing in animals and plants are adaptations. For instance, lungs or gills that extract oxygen from the air, fur and feathers as insulation and long legs to get away from predators and camouflage for hiding. However, a proper understanding of adaptation requires paying attention to the distinction between the physiological and behavioral characteristics.
Physiological adaptations like thick fur or gills, are physical traits, whereas behavioral adaptations, like the tendency to search for friends or to move into the shade in hot weather, are not. Additionally it is important to remember that a lack of thought does not make something an adaptation. A failure to consider the effects of a behavior even if it seems to be rational, could cause it to be unadaptive.