What is Free Evolution?
Free evolution is the idea that the natural processes of organisms can cause them to develop over time. This includes the emergence and development of new species.
Numerous examples have been offered of this, including various varieties of fish called sticklebacks that can be found in fresh or salt 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 development of the myriad living creatures on Earth is a mystery that has fascinated scientists for centuries. The most well-known explanation is that of Charles Darwin's natural selection, which occurs when individuals that are better adapted survive and reproduce more effectively than those that are less well adapted. Over time, the population of well-adapted individuals becomes larger and eventually creates a new species.
Natural selection is a cyclical process that is characterized by the interaction of three elements that are inheritance, variation and reproduction. Mutation and sexual reproduction increase genetic diversity in a species. Inheritance is the transfer of a person's genetic characteristics to their offspring which includes both dominant and recessive alleles. Reproduction is the process of generating fertile, viable offspring. This can be accomplished by both asexual or sexual methods.
All of these elements must be in balance to allow natural selection to take place. If, for This Internet page makes an organism reproduce and survive more than the recessive allele then the dominant allele is more prevalent in a group. If the allele confers a negative advantage to survival or decreases the fertility of the population, it will go away. This process is self-reinforcing meaning that an organism with a beneficial trait can reproduce and survive longer than one with an unadaptive trait. The more offspring an organism can produce the better its fitness that is determined by its ability to reproduce and survive. People with good traits, like having a longer neck in giraffes or bright white colors in male peacocks, are more likely to survive and have offspring, so they will eventually make up the majority of the population in the future.
Natural selection is an aspect of populations and not on individuals. This is an important distinction from the Lamarckian theory of evolution which claims that animals acquire characteristics through use or neglect. For instance, if a giraffe's neck gets longer through stretching to reach prey its offspring will inherit a longer neck. The differences in neck length between generations will continue until the giraffe's neck gets so long that it can not breed with other giraffes.
Evolution by Genetic Drift
In the process of genetic drift, alleles at a gene may reach different frequencies within a population due to random events. At some point, one will attain fixation (become so common that it is unable to be eliminated through natural selection) and the other alleles drop to lower frequencies. In the extreme it can lead to a single allele dominance. The other alleles are essentially eliminated, and heterozygosity is reduced to zero. In a small population this could result in the total elimination of the recessive allele. This scenario is called the bottleneck effect. It is typical of an evolutionary process that occurs whenever the number of individuals migrate to form a population.
A phenotypic bottleneck may occur when survivors of a catastrophe like an epidemic or a mass hunting event, are condensed into a small area. The surviving individuals are likely to be homozygous for the dominant allele, which means they will all have the same phenotype, and consequently share the same fitness characteristics. This situation might be caused by a conflict, earthquake or even a cholera outbreak. Whatever the reason the genetically distinct population that remains could be susceptible to genetic drift.
Walsh, Lewens, and Ariew employ Lewens, Walsh, and Ariew use a "purely outcome-oriented" definition of drift as any deviation from the expected values for differences in fitness. They give a famous instance of twins who are genetically identical, share identical phenotypes but one is struck by lightning and dies, whereas the other lives and reproduces.
This kind of drift could play a very important role in the evolution of an organism. But, it's not the only way to progress. The primary alternative is a process called natural selection, in which the phenotypic diversity of a population is maintained by mutation and migration.
Stephens claims that there is a significant difference between treating the phenomenon of drift as a force or a cause and treating other causes of evolution such as mutation, selection and migration as forces or causes. Stephens claims that a causal process account of drift permits us to differentiate it from the other forces, and this distinction is vital. He also argues that drift is both direction, i.e., it tends to reduce heterozygosity. It also has a size, that is determined by population size.
Evolution by Lamarckism
Students of biology in high school are frequently introduced to Jean-Baptiste Lamarck's (1744-1829) work. His theory of evolution is generally known as "Lamarckism" and it asserts that simple organisms evolve into more complex organisms by the inheritance of characteristics that result from the organism's natural actions usage, use and disuse. Lamarckism is typically illustrated with a picture of a giraffe extending its neck further to reach higher up in the trees. This would cause the necks of giraffes that are longer to be passed onto their offspring who would then become taller.
Lamarck, a French zoologist, presented an innovative idea in his 17 May 1802 opening lecture at the Museum of Natural History of Paris. He challenged traditional thinking about organic transformation. In his view living things evolved from inanimate matter through a series of gradual steps. Lamarck wasn't the only one to suggest this but he was considered to be the first to provide the subject a comprehensive and general explanation.
The most popular story is that Lamarckism grew into a rival to Charles Darwin's theory of evolutionary natural selection, and that the two theories fought out in the 19th century. Darwinism eventually prevailed and led to the creation of what biologists today refer to as the Modern Synthesis. The theory argues the possibility that acquired traits can be inherited, and instead, it argues that organisms develop through the selective action of environmental factors, like natural selection.
Lamarck and his contemporaries believed in the idea that acquired characters could be passed on to the next generation. However, this concept was never a major part of any of their theories on evolution. This is due to the fact that it was never scientifically validated.
But it is now more than 200 years since Lamarck was born and in the age of genomics there is a vast body of evidence supporting the heritability of acquired traits. This is sometimes called "neo-Lamarckism" or more frequently epigenetic inheritance. This is a variant that is just as valid as the popular Neodarwinian model.
Evolution by the process of adaptation
One of the most popular misconceptions about evolution is that it is being driven by a struggle for survival. In reality, this notion 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 within a particular environment, which may be a struggle that involves not only other organisms, but also the physical environment.
To understand how evolution works it is important to think about what adaptation is. Adaptation is any feature that allows living organisms to live in its environment and reproduce. It can be a physiological structure, such as feathers or fur or a behavior such as a tendency to move to the shade during the heat or leaving at night to avoid cold.
The capacity of an organism to draw energy from its surroundings and interact with other organisms as well as their physical environment is essential to its survival. The organism must possess the right genes to generate offspring, and it must be able to locate sufficient food and other resources. The organism must be able to reproduce itself at an amount that is appropriate for its specific niche.
These factors, together with mutations and gene flow can result in a shift in the proportion of different alleles in a population’s gene pool. As time passes, this shift in allele frequencies can result in the development of new traits, and eventually new species.
Many of the features that we admire about animals and plants are adaptations, for example, lungs or gills to extract oxygen from the air, fur or feathers for insulation long legs to run away from predators and camouflage to hide. However, a thorough understanding of adaptation requires a keen eye to the distinction between physiological and behavioral traits.
Physiological traits like large gills and thick fur are physical traits. The behavioral adaptations aren't, such as the tendency of animals to seek companionship or retreat into shade in hot temperatures. It is also important to keep in mind that insufficient planning does not cause an adaptation. In fact, a failure to think about the consequences of a behavior can make it ineffective even though it might appear sensible or even necessary.