What is Free Evolution?
Free evolution is the notion that the natural processes of organisms can cause them to develop over time. This includes the development of new species as well as the alteration of the appearance of existing ones.
A variety of examples have been provided of this, such as different varieties of fish called sticklebacks that can be found in fresh or salt water and walking stick insect varieties that prefer specific host plants. These are mostly reversible traits however, are not able to explain fundamental changes in basic body plans.
Evolution through Natural Selection
Scientists have been fascinated by the development of all the living creatures that inhabit our planet for centuries. The most well-known explanation is Charles Darwin's natural selection process, a process that occurs when individuals that are better adapted survive and reproduce more successfully than those that are less well adapted. Over time, a population of well adapted individuals grows and eventually becomes a new species.
Natural selection is an ongoing process that involves the interaction of three factors including inheritance, variation, and reproduction. Variation is caused by mutation and sexual reproduction both of which enhance the genetic diversity within the species. Inheritance is the term used to describe the transmission of genetic traits, including both dominant and recessive genes to their offspring. Reproduction is the process of producing fertile, viable offspring, which includes both asexual and sexual methods.
Natural selection can only occur when all these elements are in equilibrium. For example, if a dominant allele at a gene causes an organism to survive and reproduce more frequently than the recessive one, the dominant allele will be more prominent within the population. If the allele confers a negative advantage to survival or lowers the fertility of the population, it will be eliminated. This process is self-reinforcing meaning that an organism with a beneficial characteristic will survive and reproduce more than one with a maladaptive trait. The greater an organism's fitness which is measured by its ability to reproduce and endure, is the higher number of offspring it produces. People with desirable traits, such as longer necks in giraffes, or bright white color patterns in male peacocks, are more likely to survive and produce offspring, and thus will make up the majority of the population in the future.
Natural selection only affects populations, not on individual organisms. This is an important distinction from the Lamarckian theory of evolution, which states that animals acquire traits through use or neglect. For example, if a animal's neck is lengthened by stretching to reach prey and its offspring will inherit a more long neck. The differences in neck length between generations will continue until the neck of the giraffe becomes so long that it can not breed with other giraffes.
Evolution by Genetic Drift
Genetic drift occurs when the alleles of a gene are randomly distributed in a group. Eventually, only one will be fixed (become common enough that it can no longer be eliminated through natural selection), and the rest of the alleles will decrease in frequency. This can lead to a dominant allele in the extreme. Other alleles have been basically eliminated and heterozygosity has diminished to a minimum. In a small population, this could result in the complete elimination the recessive gene. This is known as the bottleneck effect and is typical of the evolutionary process that occurs when a large number individuals migrate to form a population.
A phenotypic bottleneck can also occur when survivors of a catastrophe such as an epidemic or a massive hunt, are confined within a narrow area. The survivors will carry an allele that is dominant and will have the same phenotype. This situation could be caused by earthquakes, war or even a plague. The genetically distinct population, if left susceptible to genetic drift.
Walsh, Lewens and Ariew define drift as a departure from the expected values due to differences in fitness. They give a famous example of twins that are genetically identical and have the exact same phenotype and yet one is struck by lightning and dies, while the other lives and reproduces.
This kind of drift could play a crucial part in the evolution of an organism. It's not the only method of evolution. The primary alternative is to use a process known as natural selection, where the phenotypic diversity of the population is maintained through mutation and migration.
Stephens argues that there is a big difference between treating drift as a force or an underlying cause, and treating other causes of evolution such as mutation, selection, and migration as forces or causes. 에볼루션 claims that a causal-process explanation of drift lets us separate it from other forces, and this distinction is essential. He further argues that drift has a direction, that is, it tends to eliminate heterozygosity, and that it also has a size, that is determined by population size.
Evolution by Lamarckism
Biology students in high school are frequently exposed to Jean-Baptiste lamarck's (1744-1829) work. His theory of evolution is commonly called "Lamarckism" and it states that simple organisms develop into more complex organisms through the inherited characteristics which result from an organism's natural activities usage, use and disuse. Lamarckism can be illustrated by an giraffe's neck stretching to reach higher leaves in the trees. This could cause the longer necks of giraffes to be passed on to their offspring who would then grow even taller.
Lamarck was a French Zoologist. In his inaugural lecture for his course on invertebrate zoology held at the Museum of Natural History in Paris on the 17th May 1802, he introduced an original idea that fundamentally challenged the previous understanding of organic transformation. According to Lamarck, living things evolved from inanimate matter by a series of gradual steps. Lamarck was not the only one 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 his first comprehensive and comprehensive treatment.
The most popular story is that Lamarckism became a rival to Charles Darwin's theory of evolutionary natural selection and both theories battled each other 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 that acquired traits can be passed down and instead, it claims that organisms evolve through the selective influence of environmental factors, such as Natural Selection.
Although Lamarck endorsed the idea of inheritance by acquired characters and his contemporaries also offered a few words about this idea but it was not a central element in any of their evolutionary theories. This is due to the fact that it was never tested scientifically.
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 characteristics. This is sometimes referred to as "neo-Lamarckism" or, more commonly, epigenetic inheritance. This is a variant that is as valid as the popular Neodarwinian model.
Evolution by adaptation
One of the most common misconceptions about evolution is its being driven by a struggle to survive. This view is inaccurate and overlooks the other forces that are driving evolution. The fight for survival can be more accurately described as a struggle to survive in a specific environment, which may involve not only other organisms but also the physical environment.
Understanding the concept of adaptation is crucial to comprehend evolution. The term "adaptation" refers to any specific characteristic that allows an organism to survive and reproduce within its environment. It can be a physiological structure, such as feathers or fur or a behavioral characteristic such as a tendency to move to the shade during the heat or leaving at night to avoid the cold.
The ability of an organism to draw energy from its surroundings and interact with other organisms and their physical environments is essential to its survival. The organism must possess the right genes to create offspring and be able find enough food and resources. The organism should also be able reproduce at the rate that is suitable for its niche.
These factors, together with gene flow and mutations can cause an alteration in the ratio of different alleles within 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.
Many of the features we appreciate in plants and animals are adaptations. For instance, lungs or gills that draw oxygen from air feathers and fur as insulation, long legs to run away from predators and camouflage for hiding. However, a thorough understanding of adaptation requires attention to the distinction between the physiological and behavioral characteristics.
Physiological adaptations, like thick fur or gills are physical traits, while behavioral adaptations, like the desire to find companions or to retreat 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 consider the consequences of a behavior can make it unadaptive, despite the fact that it appears to be reasonable or even essential.
