What is Free Evolution?
Free evolution is the notion that the natural processes of organisms can lead them to evolve over time. This includes the appearance and growth of new species.
A variety of examples have been provided of this, such as different kinds of stickleback fish that can live in either fresh or salt water and walking stick insect varieties that favor particular host plants. These mostly reversible trait permutations however, are not able to explain fundamental changes in body plans.
Evolution by Natural Selection
Scientists have been fascinated by the evolution of all the living creatures that inhabit our planet for ages. The most widely accepted explanation is Darwin's natural selection, a process that occurs when better-adapted individuals survive and reproduce more effectively than those who are less well adapted. Over time, the population of individuals who are well-adapted grows and eventually develops into an entirely new species.
Natural selection is a process that is cyclical and involves the interaction of three factors: variation, reproduction and inheritance. Variation is caused by mutation and sexual reproduction both of which enhance the genetic diversity within a species. Inheritance refers to the transmission of a person’s genetic traits, which include recessive and dominant genes to their offspring. Reproduction is the production of fertile, viable offspring, which includes both asexual and sexual methods.
All of these elements have to be in equilibrium to allow natural selection to take place. If, for instance, a dominant gene allele allows an organism to reproduce and live longer than the recessive gene, then the dominant allele is more prevalent in a population. However, if the gene confers a disadvantage in survival or decreases fertility, it will disappear from the population. The process is self-reinforcing, which means that an organism with a beneficial characteristic can reproduce and survive longer than one with a maladaptive characteristic. The greater an organism's fitness which is measured by its ability to reproduce and survive, is the more offspring it will produce. Individuals with favorable traits, like a longer neck in giraffes or bright white patterns of color in male peacocks, are more likely to be able to survive and create offspring, so they will become the majority of the population over time.
Natural selection is only an aspect of populations and not on individuals. This is an important distinction from the Lamarckian theory of evolution which argues that animals acquire traits through use or neglect. If a giraffe stretches its neck to reach prey and the neck grows larger, then its children will inherit this characteristic. The differences in neck size between generations will continue to grow until the giraffe is unable to reproduce with other giraffes.
Evolution through Genetic Drift
In the process of genetic drift, alleles of a gene could reach different frequencies in a group due to random events. At some point, one will attain fixation (become so widespread that it cannot be removed by natural selection) and other alleles fall to lower frequency. This can result in dominance in the extreme. The other alleles are essentially eliminated, and heterozygosity falls to zero. In a small group, this could lead to the total elimination of recessive allele. This is known as the bottleneck effect and is typical of the evolution process that occurs when a large number individuals migrate to form a population.
A phenotypic bottleneck may occur when the survivors of a disaster, such as an epidemic or a massive hunt, are confined within a narrow area. The remaining individuals will be mostly homozygous for the dominant allele, which means they will all share the same phenotype and thus have the same fitness traits. This could be caused by war, earthquakes or even a plague. Regardless of the cause, the genetically distinct population that remains is susceptible to genetic drift.
Walsh Lewens, Lewens, and Ariew use a "purely outcome-oriented" definition of drift as any deviation from the expected values of different fitness levels. They give a famous example of twins that are genetically identical, share identical phenotypes and yet one is struck by lightning and dies, while the other lives and reproduces.
This kind of drift could be vital to the evolution of an entire species. However, it's not the only method to progress. Natural selection is the main alternative, where mutations and migration keep phenotypic diversity within a population.
Stephens argues there is a significant difference between treating the phenomenon of drift as an agent or cause and treating other causes such as migration and selection as causes and forces. He argues that a causal process account of drift allows us to distinguish it from other forces, and that this distinction is vital. He also argues that drift has both a direction, i.e., it tends towards eliminating heterozygosity. It also has a size, that is determined by population size.
Evolution through Lamarckism
Biology students in high school are frequently introduced to Jean-Baptiste Lamarck's (1744-1829) work. His theory of evolution, often referred to as “Lamarckism” which means that simple organisms develop into more complex organisms taking on traits that result from the organism's use and misuse. Lamarckism can be illustrated by a giraffe extending its neck to reach higher levels of leaves in the trees. This could cause giraffes to give their longer necks to offspring, which then get taller.
Lamarck was a French zoologist and, in his inaugural lecture for his course on invertebrate zoology at the Museum of Natural History in Paris on the 17th May 1802, he introduced an original idea that fundamentally challenged the conventional wisdom about organic transformation. In his view, living things had evolved from inanimate matter through the gradual progression of events. Lamarck wasn't the only one to propose this but he was thought of as the first to give the subject a thorough and general overview.
The popular narrative is that Lamarckism became an opponent to Charles Darwin's theory of evolution through natural selection and that the two theories fought out in the 19th century. Darwinism eventually triumphed, leading to the development of what biologists today refer to as the Modern Synthesis. This theory denies that traits acquired through evolution can be inherited, and instead, it argues that organisms develop through the action of environmental factors, such as natural selection.
Although Lamarck supported the notion of inheritance by acquired characters and his contemporaries also offered a few words about this idea, it was never a major feature in any of their evolutionary theorizing. This is partly due to the fact that it was never validated scientifically.
It's been more than 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 often epigenetic inheritance. It is a form of evolution that is just as valid as the more popular Neo-Darwinian model.
Evolution through the process of adaptation
One of the most common misconceptions about evolution is being driven by a fight for survival. This view is inaccurate and ignores other forces driving evolution. The fight for survival is better described as a fight to survive in a certain environment. This may include not only other organisms, but also the physical environment itself.
To understand how evolution functions it is beneficial to think about what adaptation is. It refers to a specific characteristic that allows an organism to live and reproduce in its environment. It could be a physiological structure, like feathers or fur or a behavior such as a tendency to move into the shade in hot weather or coming out at night to avoid the cold.
The ability of a living thing to extract energy from its environment and interact with other organisms as well as their physical environment is essential to its survival. The organism must possess the right genes for producing offspring, and be able to 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 a shift in the proportion of different alleles within the gene pool of a population. Over time, this change in allele frequencies can result in the development of new traits and ultimately new species.
무료 에볼루션 of the characteristics we admire about animals and plants are adaptations, such as the lungs or gills that extract oxygen from the air, fur or feathers to provide insulation, long legs for running away from predators, and camouflage to hide. To understand adaptation it is crucial to distinguish between behavioral and physiological traits.
Physiological adaptations, like thick fur or gills, are physical traits, whereas behavioral adaptations, like the tendency to seek out friends or to move to shade in hot weather, are not. It is important to note that lack of planning does not cause an adaptation. A failure to consider the effects of a behavior even if it appears to be rational, could make it inflexible.