What is Free Evolution?
Free evolution is the idea that natural processes can cause organisms to develop over time. This includes the creation of new species and transformation of the appearance of existing species.
Many examples have been given of this, such as different varieties of fish called sticklebacks that can live in either salt or fresh water, and walking stick insect varieties that favor specific host plants. These reversible traits, however, cannot be the reason for fundamental changes in body plans.
Evolution through Natural Selection
The evolution of the myriad living creatures on Earth is a mystery that has intrigued scientists for decades. Charles Darwin's natural selection is the most well-known explanation. This happens when individuals 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.
Natural selection is a cyclical process that involves the interaction of three factors that are inheritance, variation and reproduction. Sexual reproduction and mutation increase the genetic diversity of a species. Inheritance refers to the passing of a person's genetic traits to their offspring that includes recessive and dominant alleles. Reproduction is the process of producing fertile, viable offspring. This can be achieved by both asexual or sexual methods.
All of these factors have to be in equilibrium for natural selection to occur. For instance the case where a dominant allele at one gene allows an organism to live and reproduce more often than the recessive allele, the dominant allele will be more prevalent within the population. But if the allele confers an unfavorable survival advantage or decreases fertility, it will disappear from the population. The process is self-reinforcing, meaning that a species 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 capacity to reproduce itself and survive. People with desirable traits, such as having a longer neck in giraffes and bright white patterns of color in male peacocks, are more likely to survive and have offspring, so they will become the majority of the population over time.
Natural selection is a factor in populations and not on individuals. This is an important distinction from the Lamarckian theory of evolution, which states that animals acquire traits by use or inactivity. If a giraffe extends its neck to reach prey and its neck gets larger, then its offspring will inherit this characteristic. The differences in neck length between generations will continue until the giraffe's neck gets too long to not breed with other giraffes.
Evolution through Genetic Drift
Genetic drift occurs when the alleles of the same gene are randomly distributed within a population. Eventually, only one will be fixed (become common enough to no longer be eliminated through natural selection) and the other alleles drop in frequency. This can lead to dominance in extreme. The other alleles are eliminated, and heterozygosity decreases to zero. In a small population this could lead to the complete elimination of the recessive gene. Such a scenario would be called a bottleneck effect, and it is typical of the kind of evolutionary process when a large number of individuals move to form a new group.
A phenotypic bottleneck may happen when the survivors of a disaster, such as an epidemic or a massive hunting event, are condensed into a small area. The survivors will be largely homozygous for the dominant allele which means that they will all have the same phenotype, and therefore have the same fitness characteristics. This may be caused by war, an earthquake or even a cholera outbreak. Whatever the reason, the genetically distinct population that is left might be prone to genetic drift.
Walsh Lewens, Walsh, and Ariew define drift as a departure from the expected value due to differences in fitness. They cite the famous example of twins that are genetically identical and share the same phenotype, but one is struck by lightning and dies, but the other lives to reproduce.
This kind of drift could be vital to the evolution of a species. This isn't the only method of evolution. Natural selection is the main alternative, where mutations and migration maintain phenotypic diversity within a population.
Stephens argues there is a huge difference between treating drift like a force or cause, and treating other causes like migration and selection mutation as causes and forces. He argues that a causal mechanism account of drift permits us to differentiate it from the other forces, and that this distinction is essential. He further argues that drift is a directional force: that is, it tends to eliminate heterozygosity. He also claims that it also has a magnitude, that is determined by the size of the population.
Evolution through Lamarckism
In high school, students study biology, they are often introduced to the work of Jean-Baptiste Lamarck (1744 - 1829). His theory of evolution is often known as "Lamarckism" and it states that simple organisms develop into more complex organisms via the inheritance of traits that result from the natural activities of an organism use and misuse. 에볼루션 무료 바카라 is illustrated through a giraffe extending its neck to reach higher branches in the trees. This would cause giraffes' longer necks to be passed to their offspring, who would then grow even taller.
Lamarck, a French Zoologist from France, presented a revolutionary concept in his opening lecture at the Museum of Natural History of Paris. He challenged the conventional wisdom on organic transformation. According to Lamarck, living things evolved from inanimate materials by a series of gradual steps. Lamarck was not the first to suggest that this could be the case, but he is widely seen as being the one who gave the subject its first general and comprehensive analysis.
The predominant story is that Charles Darwin's theory on natural selection and Lamarckism were rivals during the 19th century. Darwinism ultimately won, leading to what biologists call 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.
Lamarck and his contemporaries believed in the idea that acquired characters could be passed down to future generations. However, this concept was never a central part of any of their theories on evolution. This is due in part to the fact that it was never validated scientifically.
But it is now more than 200 years since Lamarck was born and in the age of genomics there is a huge body of evidence supporting the heritability of acquired characteristics. This is also referred to as "neo Lamarckism", or more often epigenetic inheritance. This is a variant that is just as valid as the popular neodarwinian model.
Evolution through the process of adaptation
One of the most common misconceptions about evolution is that it is driven by a sort of struggle to survive. This is a false assumption and ignores other forces driving evolution. The struggle for survival is more effectively described as a struggle to survive within a specific environment, which could involve not only other organisms, but as well the physical environment.
Understanding how adaptation works is essential to comprehend evolution. Adaptation is any feature that allows a living organism to live in its environment and reproduce. It could be a physical feature, like feathers or fur. Or it can be a characteristic of behavior such as moving towards shade during the heat, or moving out to avoid the cold at night.
The survival of an organism is dependent on its ability to draw energy from the environment and to interact with other living organisms and their physical surroundings. The organism needs to have the right genes to produce offspring, and must be able to find sufficient food and other resources. Moreover, the organism must be able to reproduce itself in a way that is optimally within its environment.
These factors, in conjunction with gene flow and mutations can result in an alteration in the ratio of different alleles within a population’s gene pool. Over time, this change in allele frequencies can result in the development of new traits and ultimately new species.
A lot of the traits we appreciate in plants and animals are adaptations. For example 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 thorough understanding of adaptation requires paying attention to the distinction between the physiological and behavioral traits.
Physical characteristics like thick fur and gills are physical characteristics. The behavioral adaptations aren't an exception, for instance, the tendency of animals to seek companionship or move into the shade in hot temperatures. It is also important to remember that a the absence of planning doesn't result in an adaptation. Failure to consider the effects of a behavior, even if it appears to be logical, can make it inflexible.