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 many examples such as the stickleback fish species that can thrive in fresh or saltwater and walking stick insect species that prefer particular host plants. These typically reversible traits do not explain the fundamental changes in the basic body plan.
Evolution by Natural Selection
The evolution of the myriad living organisms on Earth is an enigma that has intrigued scientists for many centuries. Charles Darwin's natural selection theory is the most well-known explanation. This happens when people who are more well-adapted have more success in reproduction and survival than those who are less well-adapted. Over time, the population of well-adapted individuals grows and eventually forms a new species.
Natural selection is an ongoing process and involves the interaction of three factors: variation, reproduction and inheritance. Sexual reproduction and mutations increase the genetic diversity of the species. Inheritance refers to the transmission of genetic traits, including recessive and dominant genes and their offspring. Reproduction is the process of creating viable, fertile offspring. This can be done by both asexual or sexual methods.
Natural selection is only possible when all these elements are in equilibrium. If, for instance an allele of a dominant gene allows an organism to reproduce and survive more than the recessive allele The dominant allele will become more prevalent in a population. However, if the gene confers an unfavorable survival advantage or reduces fertility, it will disappear from the population. The process is self-reinforcing, which means that an organism that has a beneficial trait can reproduce and survive longer than one with an unadaptive trait. The greater an organism's fitness which is measured by its ability to reproduce and endure, is the higher number of offspring it will produce. Individuals with favorable traits, like a long neck in giraffes, or bright white patterns on male peacocks are more likely to others to live and reproduce which eventually leads to them becoming the majority.
Natural selection is only a factor in populations and not on individuals. This is an important distinction from the Lamarckian theory of evolution which claims that animals acquire characteristics by use or inactivity. If a giraffe expands its neck to reach prey and the neck grows longer, then its offspring will inherit this characteristic. The differences in neck size between generations will continue to increase until the giraffe is no longer able to breed with other giraffes.
Evolution through Genetic Drift
In the process of genetic drift, alleles within a gene can attain different frequencies in a population through random events. At some point, one will reach fixation (become so widespread that it cannot be removed through natural selection) and other alleles will fall to lower frequencies. This can lead to an allele that is dominant in the extreme. The other alleles are essentially eliminated, and heterozygosity falls to zero. In a small group this could lead to the complete elimination of the recessive gene. This is known as the bottleneck effect. Suggested Resource site is typical of the evolutionary process that occurs whenever a large number individuals migrate to form a group.
A phenotypic bottleneck could occur when survivors of a disaster like an epidemic or a massive hunt, are confined in a limited area. The remaining individuals will be largely homozygous for the dominant allele which means they will all have the same phenotype and will thus have the same fitness characteristics. This situation might be caused by a conflict, earthquake, or even a plague. Regardless of the cause the genetically distinct group that remains could be susceptible to genetic drift.
Walsh, Lewens, and Ariew employ a "purely outcome-oriented" definition of drift as any departure from the expected values for different fitness levels. They cite a famous example of twins that are genetically identical, have identical phenotypes, but one is struck by lightning and dies, while the other lives and reproduces.
This kind of drift can play a crucial role in the evolution of an organism. It is not the only method of evolution. The most common alternative is a process called natural selection, in which the phenotypic diversity of the population is maintained through mutation and migration.
Stephens claims that there is a vast difference between treating the phenomenon of drift as an actual cause or force, and considering other causes, such as migration and selection as causes and forces. He argues that a causal mechanism account of drift allows us to distinguish it from the other forces, and that this distinction is vital. He argues further that drift is both a direction, i.e., it tends to eliminate heterozygosity. It also has a size, that is determined by the size of the population.
Evolution through Lamarckism
Students of biology in high school are often exposed to Jean-Baptiste lamarck's (1744-1829) work. His theory of evolution, also referred to as “Lamarckism” which means that simple organisms evolve into more complex organisms taking on traits that result from the organism's use and misuse. Lamarckism is typically illustrated with a picture of a giraffe extending its neck longer to reach higher up in the trees. This could cause giraffes to give their longer necks to their offspring, which then become taller.
Lamarck was a French zoologist and, in his opening lecture for his course on invertebrate zoology at the Museum of Natural History in Paris on 17 May 1802, he presented a groundbreaking concept that radically challenged previous thinking about organic transformation. According to him living things evolved from inanimate matter via an escalating series of steps. Lamarck wasn't the first to propose this however he was widely regarded as the first to provide the subject a thorough and general treatment.
The predominant story is that Charles Darwin's theory on evolution by natural selection and Lamarckism were rivals during the 19th century. Darwinism eventually prevailed, leading to the development of what biologists now refer to as the Modern Synthesis. This theory denies that traits acquired through evolution can be acquired through inheritance and instead suggests that organisms evolve by the symbiosis of environmental factors, including natural selection.
While Lamarck supported the notion of inheritance through acquired characters and his contemporaries also offered a few words about this idea, it was never an integral part of any of their evolutionary theories. This is largely due to the fact that it was never tested scientifically.
It's been 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 frequently, epigenetic inheritance. This is a model that is as reliable as the popular neodarwinian model.
Evolution by Adaptation
One of the most common misconceptions about evolution is its being driven by a fight for survival. In fact, this view misrepresents natural selection and ignores the other forces that determine the rate of evolution. The struggle for survival is more effectively described as a struggle to survive within a specific environment, which may be a struggle that involves not only other organisms but as well the physical environment.
Understanding adaptation is important to comprehend evolution. Adaptation is any feature that allows living organisms to survive in its environment and reproduce. It could be a physical feature, like feathers or fur. It could also be a trait of behavior, like moving to the shade during the heat, or escaping the cold at night.
An organism's survival depends on its ability to obtain energy from the environment and to interact with other living organisms and their physical surroundings. The organism must possess the right genes to produce offspring and be able find enough food and resources. Moreover, the organism must be able to reproduce itself at a high rate within its environment.
These factors, together with gene flow and mutations, can lead to a shift in the proportion of different alleles in a population’s gene pool. This shift in the frequency of alleles could lead to the development of new traits and eventually, new species over time.
A lot of the traits we appreciate in plants and animals are adaptations. For example lung or gills that extract oxygen from air feathers and fur as insulation and long legs to get away from predators and camouflage for hiding. To understand adaptation, it is important to distinguish between behavioral and physiological traits.
Physical characteristics like thick fur and gills are physical traits. Behavior adaptations aren't, such as the tendency of animals to seek out companionship or to retreat into the shade during hot temperatures. Furthermore, it is important to remember that a lack of thought does not mean that something is an adaptation. In fact, failure to think about the implications of a decision can render it ineffective despite the fact that it may appear to be reasonable or even essential.