What is Free Evolution?
Free evolution is the notion that natural processes can cause organisms to develop over time. This includes the emergence and development of new species.
This has been proven by numerous examples such as the stickleback fish species that can thrive in saltwater or fresh water and walking stick insect varieties that are apprehensive about particular host plants. These mostly reversible traits permutations cannot explain fundamental changes to the body's basic plans.
Evolution by Natural Selection
Scientists have been fascinated by the evolution of all living organisms that inhabit our planet for centuries. The best-established explanation is Charles Darwin's natural selection process, an evolutionary process that occurs when individuals that are better adapted survive and reproduce more effectively than those who are less well adapted. As time passes, the number of individuals who are well-adapted grows and eventually develops into a new species.
Natural selection is a process that is cyclical and involves the interaction of three factors including reproduction, variation and inheritance. Variation is caused by mutations and sexual reproduction, both of which 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 recessive and dominant alleles. Reproduction is the process of producing fertile, viable offspring which includes both sexual and asexual methods.
Natural selection can only occur when all these elements are in balance. If, for instance an allele of a dominant gene allows an organism to reproduce and survive more than the recessive gene allele then the dominant allele becomes more common in a population. However, if the gene confers an unfavorable survival advantage or decreases fertility, it will disappear from the population. The process is self-reinforcing meaning that the organism with an adaptive trait will survive and reproduce more quickly than those with a maladaptive feature. The greater an organism's fitness which is measured by its ability to reproduce and survive, is the more offspring it can produce. People with good traits, such as longer necks in giraffes and bright white color patterns in male peacocks, are more likely to be able to survive and create offspring, so they will eventually make up the majority of the population in the future.
Natural selection is an element in the population and not on individuals. This is a major distinction from the Lamarckian evolution theory which holds that animals acquire traits either through usage or inaction. For example, if a Giraffe's neck grows longer due to stretching to reach for prey and its offspring will inherit a larger neck. The difference in neck length between generations will continue until the neck of the giraffe becomes too long to not breed with other giraffes.
Evolution by Genetic Drift
Genetic drift occurs when alleles from one gene are distributed randomly in a group. At some point, only one of them will be fixed (become common enough to no more be eliminated through natural selection) and the other alleles decrease in frequency. This can lead to an allele that is dominant in the extreme. The other alleles have been essentially eliminated and heterozygosity has decreased to zero. In a small group 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 also occur when the survivors of a catastrophe like an outbreak or a mass hunting event are confined to an area of a limited size. The surviving individuals will be mostly homozygous for the dominant allele which means they will all share the same phenotype and consequently share the same fitness characteristics. This situation might be caused by a conflict, earthquake or even a disease. Regardless of the cause the genetically distinct group that remains is prone to genetic drift.
Walsh Lewens, Walsh, and Ariew define drift as a departure from the expected value 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 lightening and dies while the other lives and reproduces.
This type of drift can play a crucial role in the evolution of an organism. But, it's not the only way to progress. The primary alternative is to use a process known as natural selection, where phenotypic variation in an individual is maintained through mutation and migration.
Stephens claims that there is a major distinction between treating drift as a force or an underlying cause, and treating other causes of evolution like selection, mutation, and migration as forces or causes. He argues that a causal process explanation of drift allows us to distinguish it from other forces, and that this distinction is essential. He also claims that drift has a direction, that is it tends to eliminate heterozygosity. click hyperlink claims that it also has a size, that is determined by the size of the population.
Evolution by 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 commonly referred to as "Lamarckism" and it states that simple organisms grow into more complex organisms by the inherited characteristics which result from an organism's natural activities use and misuse. Lamarckism is usually illustrated with an image of a giraffe that extends its neck further to reach higher up in the trees. This process would cause giraffes to pass on their longer necks to offspring, who then grow even taller.
Lamarck was a French Zoologist. In his inaugural lecture for his course on invertebrate zoology at the Museum of Natural History in Paris on the 17th of May in 1802, he presented a groundbreaking concept that radically challenged previous thinking about organic transformation. In his view 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 widely regarded as the first to give the subject a comprehensive and general treatment.
The predominant story is that Charles Darwin's theory of evolution by natural selection and Lamarckism were rivals during the 19th century. Darwinism eventually triumphed and led to the creation of what biologists today refer to as the Modern Synthesis. The theory argues that acquired traits are passed down from generation to generation and instead, it claims that organisms evolve through the selective influence of environmental elements, like Natural Selection.
Although Lamarck supported the notion of inheritance through acquired characters and his contemporaries also spoke of this idea but it was not an integral part of any of their evolutionary theorizing. This is partly 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 amount of evidence that supports the heritability of acquired characteristics. This is also known as "neo Lamarckism", or more often epigenetic inheritance. This is a model 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 its being driven by a fight for survival. This is a false assumption and overlooks other forces that drive evolution. The fight for survival can be more accurately described as a struggle to survive within a specific environment, which may involve not only other organisms but as well the physical environment.
Understanding the concept of adaptation is crucial to comprehend evolution. The term "adaptation" refers to any characteristic that allows a living thing to survive in its environment and reproduce. It could be a physical feature, such as feathers or fur. It could also be a characteristic of behavior such as moving towards shade during hot weather or moving out to avoid the cold at night.
The ability of a living thing to extract energy from its environment and interact with other organisms, as well as their physical environment, is crucial to its survival. The organism must possess the right genes to generate offspring, and it must be able to find sufficient food and other resources. Furthermore, the organism needs to be able to reproduce itself at a high rate within its environment.
These factors, in conjunction with gene flow and mutations can cause a shift in the proportion of different alleles within a population’s gene pool. The change in frequency of alleles can lead to the emergence of new traits, and eventually new species as time passes.
Many of the characteristics we admire about animals and plants are adaptations, like lungs or gills to extract oxygen from the air, feathers or fur for insulation and long legs for running away from predators and camouflage to hide. However, a proper understanding of adaptation requires a keen eye to the distinction between behavioral and physiological characteristics.
Physical characteristics like the thick fur and gills are physical characteristics. The behavioral adaptations aren't, such as the tendency of animals to seek out companionship or to retreat into the shade in hot weather. It is important to keep in mind that the absence of planning doesn't cause an adaptation. Inability to think about the effects of a behavior even if it appears to be rational, could make it unadaptive.