What is Free Evolution?
Free evolution is the concept that natural processes can cause organisms to evolve over time. This includes the development of new species as well as the transformation of the appearance of existing species.
This has been proven by numerous examples such as the stickleback fish species that can thrive in fresh or saltwater and walking stick insect types that are apprehensive about particular host plants. These mostly reversible trait permutations however, are not able to explain fundamental changes in basic body plans.
Evolution by Natural Selection
Scientists have been fascinated by the evolution of all the living creatures that live on our planet for many centuries. The most widely accepted explanation is Charles Darwin's natural selection, which occurs when individuals that are better adapted survive and reproduce more successfully than those less well-adapted. As time passes, a group of well-adapted individuals expands and eventually forms a whole new species.
Natural selection is an ongoing process that is characterized by the interaction of three elements including inheritance, variation, and reproduction. Variation is caused by mutations and sexual reproduction both of which enhance the genetic diversity within the species. Inheritance refers the transmission of a person’s genetic characteristics, which includes both dominant and recessive genes, to their offspring. Reproduction is the generation of fertile, viable offspring which includes both asexual and sexual methods.
Natural selection is only possible when all these elements are in equilibrium. If, for instance, a dominant gene allele makes an organism reproduce and live longer than the recessive allele, then the dominant allele will become more prevalent in a population. If the allele confers a negative survival advantage or decreases the fertility of the population, it will be eliminated. The process is self-reinforcing, which means that an organism with a beneficial characteristic is more likely to survive and reproduce than one with an inadaptive characteristic. The more offspring an organism can produce the more fit it is which is measured by its ability to reproduce itself and live. People with good characteristics, such as having a long neck in the giraffe, or bright white color patterns on male peacocks are more likely to others to reproduce and survive which eventually leads to them becoming the majority.
Natural selection only affects populations, not individuals. This is a significant distinction from the Lamarckian evolution theory that states that animals acquire traits either through the use or absence of use. For instance, if the Giraffe's neck grows longer due to stretching to reach for prey, its offspring will inherit a larger neck. The difference 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 of a gene could attain different frequencies in a population due to random events. In the end, one will reach fixation (become so common that it is unable to be removed through natural selection) and the other alleles drop to lower frequency. In extreme cases it can lead to a single allele dominance. The other alleles are eliminated, and heterozygosity falls to zero. In a small number of people, this could result in the complete elimination the recessive gene. This is known as the bottleneck effect. It is typical of an evolutionary process that occurs when an enormous number of individuals move to form a population.
A phenotypic bottleneck can also happen when the survivors of a catastrophe like an epidemic or a massive hunt, are confined in a limited area. The survivors will share a dominant allele and thus will share the same phenotype. This could be caused by war, earthquakes or even plagues. Whatever the reason the genetically distinct population that remains could be susceptible to genetic drift.
Walsh, Lewens and Ariew define drift as a deviation from expected values due to differences in fitness. They give the famous example of twins who are both genetically identical and have exactly the same phenotype, but one is struck by lightning and dies, while the other lives to reproduce.
This type of drift can play a significant part in the evolution of an organism. However, it's not the only way to progress. Natural selection is the main alternative, in which mutations and migrations maintain the phenotypic diversity of a population.
Stephens asserts that there is a big distinction between treating drift as a force or a cause and treating other causes of evolution like selection, mutation and migration as causes or causes. Stephens claims that a causal process account of drift allows us separate it from other forces and this distinction is essential. He argues further that drift has both direction, i.e., it tends to reduce heterozygosity. It also has a size, which is determined by population size.
Evolution by Lamarckism
Biology students in high school are often exposed to Jean-Baptiste lamarck's (1744-1829) work. His theory of evolution, often referred to as “Lamarckism” which means that simple organisms transform into more complex organisms taking on traits that are a product of an organism's use and disuse. Lamarckism is usually illustrated with the image of a giraffe stretching its neck longer to reach leaves higher up in the trees. This would cause the necks of giraffes that are longer to be passed to their offspring, who would grow 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 a series of gradual steps. Lamarck was not the first to suggest that this could be the case but the general consensus is that he was the one giving the subject his first comprehensive and thorough treatment.
The most popular story is that Lamarckism was an opponent to Charles Darwin's theory of evolution through natural selection, and that the two theories battled out in the 19th century. simply click for source prevailed, leading to what biologists refer to as the Modern Synthesis. This theory denies the possibility that acquired traits can be inherited and instead suggests that organisms evolve through the action of environmental factors, including natural selection.
While Lamarck endorsed the idea of inheritance through acquired characters and his contemporaries offered a few words about this idea however, it was not an integral part of any of their evolutionary theorizing. This is partly because it was never scientifically tested.
It's been over 200 year since Lamarck's birth and in the field of age genomics, there is a growing evidence-based body of evidence to support the heritability acquired characteristics. This is also known as "neo Lamarckism", or more generally 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 being driven by a struggle to survive. This is a false assumption and ignores other forces driving evolution. The fight for survival is better described as a fight to survive in a certain environment. This may be a challenge for not just other living things as well as the physical environment.
To understand how evolution works, it is helpful to understand what is adaptation. Adaptation is any feature that allows a living organism to live in its environment and reproduce. It could be a physical structure, such as feathers or fur. Or it can be a behavior trait, like moving to the shade during hot weather or moving out to avoid the cold at night.
The ability of a living thing to extract energy from its surroundings and interact with other organisms as well as their physical environment is essential to its survival. The organism needs to have the right genes to generate offspring, and it must be able to access sufficient food and other resources. Moreover, the organism must be capable of reproducing in a way that is optimally within its environment.
These factors, together with gene flow and mutations, can lead to 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 as time passes.
A lot of the traits we appreciate in plants and animals are adaptations. For example, lungs or gills that draw oxygen from air feathers and fur as insulation and long legs to get away from predators and camouflage to conceal. However, a thorough understanding of adaptation requires a keen eye to the distinction between the physiological and behavioral traits.
Physical characteristics like thick fur and gills are physical traits. The behavioral adaptations aren't, such as the tendency of animals to seek out companionship or to retreat into the shade during hot temperatures. In addition it is important to note that a lack of forethought does not make something an adaptation. In fact, failing to think about the consequences of a choice can render it ineffective despite the fact that it may appear to be sensible or even necessary.