What is Free Evolution?
Free evolution is the concept that natural processes can cause organisms to develop over time. This includes the appearance and development of new species.
This has been proven by many examples of stickleback fish species that can thrive in salt or fresh water, and walking stick insect species that have a preference for specific host plants. These typically reversible traits are not able to explain fundamental changes to the body's basic plans.
Evolution by Natural Selection
The development of the myriad living organisms on Earth is a mystery that has intrigued scientists for centuries. The most well-known 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 that are less well-adapted. As time passes, the number of individuals who are well-adapted grows and eventually forms a new species.
Natural selection is a cyclical process that involves the interaction of three factors: variation, inheritance and reproduction. Variation is caused by mutations and sexual reproduction both of which enhance the genetic diversity of the species. Inheritance is the transfer of a person's genetic characteristics to his or her offspring that includes recessive and dominant alleles. Reproduction is the process of generating fertile, viable offspring. This can be done through sexual or asexual methods.
All of these elements must be in balance for natural selection to occur. For instance, if an allele that is dominant at the gene can cause an organism to live and reproduce more often than the recessive one, the dominant allele will be more prevalent within the population. However, if the allele confers a disadvantage in survival or reduces fertility, it will disappear from the population. The process is self-reinforcing which means that the organism with an adaptive characteristic will live and reproduce more quickly than one with a maladaptive characteristic. The more offspring that an organism has, the greater its fitness which is measured by its ability to reproduce itself and live. People with good characteristics, like longer necks in giraffes and bright white colors in male peacocks, are more likely to survive and have offspring, so they will become the majority of the population in the future.
Natural selection only acts on populations, not on individual organisms. This is a major distinction from the Lamarckian theory of evolution which claims that animals acquire characteristics through use or disuse. For example, if a animal's neck is lengthened by stretching to reach for prey its offspring will inherit a larger neck. The difference in neck size between generations will continue to grow until the giraffe is no longer able to breed with other giraffes.
Evolution through Genetic Drift
Genetic drift occurs when alleles of a gene are randomly distributed in a group. At some point, one will attain fixation (become so widespread that it can no longer be eliminated by natural selection), while the other alleles drop to lower frequencies. In extreme cases this, it leads to one allele dominance. Other alleles have been essentially eliminated and heterozygosity has decreased to zero. In a small group this could result in the complete elimination of recessive alleles. This is known as the bottleneck effect. It is typical of an evolution process that occurs when the number of individuals migrate to form a population.
A phenotypic bottleneck can also occur when survivors of a disaster like an outbreak or mass hunting incident are concentrated in the same area. The survivors will share an dominant allele, and will have the same phenotype. This may be caused by war, an earthquake, or even a plague. Regardless of the cause, the genetically distinct population that is left might be prone to genetic drift.
Walsh Lewens, Walsh, and Ariew define drift as a deviation from the expected value due to differences in fitness. They cite the famous example of twins who are both genetically identical and have exactly the same phenotype. However one is struck by lightning and dies, while the other continues to reproduce.
This type of drift is very important in the evolution of the species. This isn't the only method of evolution. Natural selection is the primary alternative, in which mutations and migration maintain the phenotypic diversity in the population.
Stephens argues there is a huge distinction between treating drift as an agent or cause and treating other causes such as migration and selection as causes and forces. He claims that a causal mechanism account of drift allows us to distinguish it from other forces, and this distinction is crucial. He argues further that drift is both direction, i.e., it tends towards eliminating 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 frequently introduced to Jean-Baptiste Lamarck's (1744-1829) work. His theory of evolution, also called "Lamarckism which means that simple organisms evolve into more complex organisms by inheriting characteristics that result from an organism's use and disuse. 바카라 에볼루션 is illustrated through the giraffe's neck being extended to reach higher branches in the trees. This would result in giraffes passing on their longer necks to offspring, which then become taller.
Lamarck was a French zoologist and, in his lecture to begin his course on invertebrate Zoology at the Museum of Natural History in Paris on the 17th May 1802, he presented an innovative concept that completely challenged the previous understanding of organic transformation. According to him living things evolved from inanimate matter through the gradual progression of events. Lamarck was not the first to propose this however he was widely regarded as the first to offer the subject a thorough and general explanation.
The most popular story is that Charles Darwin's theory of evolution by natural selection and Lamarckism were competing in the 19th century. Darwinism eventually prevailed and led to the creation of what biologists now refer to as the Modern Synthesis. The theory argues that acquired traits are passed down from generation to generation and instead argues organisms evolve by the influence of environment factors, including Natural Selection.
Although Lamarck endorsed the idea of inheritance through acquired characters, and his contemporaries also paid lip-service to this notion however, it was not a central element in any of their evolutionary theorizing. This is largely due to the fact that it was never validated scientifically.
It has been more than 200 years since the birth of Lamarck and in the field of genomics there is a growing evidence base that supports the heritability of acquired traits. This is referred to as "neo Lamarckism", or more commonly epigenetic inheritance. This is a model that is as valid as the popular neodarwinian model.
Evolution by adaptation
One of the most commonly-held misconceptions about evolution is that it is being driven by a struggle for survival. In fact, this view misrepresents natural selection and ignores the other forces that determine the rate of evolution. The fight for survival can be more precisely described as a fight to survive within a particular environment, which may be a struggle that involves not only other organisms, but also the physical environment itself.
Understanding adaptation is important to comprehend evolution. It is a feature that allows a living thing to live in its environment and reproduce. It can be a physiological structure, such as fur or feathers or a behavioral characteristic like moving into the shade in hot weather or coming out at night to avoid cold.
The survival of an organism is dependent on its ability to obtain energy from the surrounding environment and interact with other organisms and their physical environments. The organism must have the right genes to produce offspring, and it should be able to find sufficient food and other resources. Furthermore, the organism needs to be capable of reproducing itself in a way that is optimally within its environmental niche.
These factors, together with gene flow and mutations, can lead to changes in the proportion of different alleles in the population's gene pool. As time passes, this shift in allele frequency can result in the emergence of new traits and ultimately new species.
A lot of the traits we admire about animals and plants are adaptations, for example, lungs or gills to extract oxygen from the air, feathers or fur for insulation, long legs for running away from predators and camouflage for hiding. However, a complete understanding of adaptation requires a keen eye to the distinction between the physiological and behavioral characteristics.
Physiological adaptations, such as thick fur or gills, are physical traits, while behavioral adaptations, like the tendency to seek out friends or to move into the shade in hot weather, are not. In addition, it is important to note that lack of planning does not mean that something is an adaptation. In fact, failure to think about the consequences of a decision can render it unadaptable even though it might appear sensible or even necessary.