What is Free Evolution?
Free evolution is the idea that natural processes can lead to the development of organisms over time. This includes the emergence and development of new species.
This has been demonstrated by numerous examples such as the stickleback fish species that can be found in fresh or saltwater and walking stick insect varieties that have a preference for specific host plants. These reversible traits however, are not able to explain fundamental changes in basic body plans.
Evolution by Natural Selection
The development of the myriad of living organisms on Earth is an enigma that has fascinated scientists for centuries. The most well-known explanation is that of Charles Darwin's natural selection process, a process that is triggered when more well-adapted individuals live longer and reproduce more successfully than those 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 an ongoing process and involves the interaction of 3 factors that are: reproduction, variation and inheritance. Variation is caused by mutation and sexual reproduction, both of which increase the genetic diversity of the species. Inheritance refers the transmission of genetic traits, including recessive and dominant genes and their offspring. Reproduction is the process of generating viable, fertile offspring. This can be accomplished through sexual or asexual methods.
Natural selection only occurs when all of these factors are in harmony. For example the case where an allele that is dominant at one gene causes an organism to survive and reproduce more often than the recessive allele, the dominant allele will become more prevalent in the population. If the allele confers a negative advantage to survival or lowers the fertility of the population, it will disappear. The process is self-reinforcing, which means that an organism that has a beneficial trait is more likely to survive and reproduce than an individual with an inadaptive characteristic. The higher the level of fitness an organism has as measured by its capacity to reproduce and endure, is the higher number of offspring it can produce. Individuals with favorable characteristics, such as having a long neck in the giraffe, or bright white color patterns on male peacocks, are more likely than others to survive and reproduce which eventually leads to them becoming the majority.
Natural selection is only an element in the population and not on individuals. This is an important distinction from the Lamarckian theory of evolution which states that animals acquire characteristics by use or inactivity. If a giraffe stretches its neck to catch prey, and the neck becomes longer, then its offspring will inherit this characteristic. The difference in neck size between generations will continue to increase until the giraffe becomes unable to breed with other giraffes.
Evolution by Genetic Drift
Genetic drift occurs when alleles of the same gene are randomly distributed in a group. At some point, one will attain fixation (become so common that it cannot be eliminated through natural selection), while the other alleles drop to lower frequency. This could lead to dominance in the extreme. The other alleles are virtually eliminated and heterozygosity diminished to zero. In a small group it could lead to the total elimination of recessive alleles. This scenario is called the bottleneck effect and is typical of an evolutionary process that occurs when a large number individuals migrate to form a group.
A phenotypic bottleneck can also occur when the survivors of a catastrophe like an epidemic or a mass hunting event, are condensed within a narrow area. The remaining individuals will be mostly homozygous for the dominant allele, meaning that they all share the same phenotype and will consequently share the same fitness characteristics. This situation could be caused by war, earthquakes or even a plague. The genetically distinct population, if it is left susceptible to genetic drift.
Walsh Lewens and Ariew utilize Lewens, Walsh and Ariew employ a "purely outcome-oriented" definition of drift as any deviation from the expected values for different fitness levels. They provide the famous case of twins who are both genetically identical and share the same phenotype. However one is struck by lightning and dies, but the other is able to reproduce.
This kind of drift can play a very important role in the evolution of an organism. It is not the only method of evolution. Natural selection is the main alternative, where mutations and migration keep the phenotypic diversity of a population.
무료 에볼루션 asserts that there is a huge distinction between treating drift as an agent or cause and considering other causes, such as selection mutation and migration as causes and forces. He argues that a causal-process model of drift allows us to differentiate it from other forces, and this distinction is crucial. He also argues that drift is a directional force: that is, it tends to eliminate heterozygosity. He also claims that it also has a specific magnitude that is determined by the size of population.
Evolution through Lamarckism
Biology students in high school are often introduced to Jean-Baptiste Lemarck's (1744-1829) work. His theory of evolution, commonly referred to as “Lamarckism”, states that simple organisms develop into more complex organisms by inheriting characteristics that are a product of the organism's use and misuse. Lamarckism can be illustrated by the giraffe's neck being extended to reach higher leaves in the trees. This could cause the longer necks of giraffes to be passed onto their offspring who would grow taller.
Lamarck was a French Zoologist. In his opening lecture for his course on invertebrate zoology held at the Museum of Natural History in Paris on 17 May 1802, he introduced an original idea that fundamentally challenged previous thinking about organic transformation. In his opinion living things evolved from inanimate matter through a series of gradual steps. Lamarck wasn't the only one to make this claim, but he was widely thought of as the first to give the subject a comprehensive and general explanation.
The prevailing story is that Lamarckism grew into an opponent to Charles Darwin's theory of evolutionary natural selection, and that the two theories battled out in the 19th century. Darwinism eventually won and led to the creation of what biologists refer to as the Modern Synthesis. The Modern Synthesis theory denies the possibility that acquired traits can be acquired through inheritance and instead argues that organisms evolve through the action of environmental factors, including natural selection.
While Lamarck supported the notion of inheritance by acquired characters and his contemporaries spoke of this idea but it was not a major feature in any of their theories about evolution. This is partly because it was never scientifically tested.
It's been more than 200 years since Lamarck was born and, in the age of genomics, there is a large amount of evidence to support the heritability of acquired traits. This is also referred to as "neo Lamarckism", or more generally epigenetic inheritance. This is a version that is just as valid as the popular neodarwinian model.
Evolution through Adaptation
One of the most common misconceptions about evolution is that it is driven by a type of struggle for survival. This view is a misrepresentation of natural selection and ignores the other forces that are driving evolution. The fight for survival can be more accurately described as a struggle to survive in a specific environment. This may include not just other organisms as well as the physical environment.
Understanding the concept of adaptation is crucial to comprehend evolution. Adaptation refers to any particular characteristic that allows an organism to live and reproduce within its environment. It could be a physiological feature, like feathers or fur or a behavioral characteristic, such as moving into the shade in hot weather or stepping out at night to avoid cold.
The ability of an organism 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 have the right genes to produce offspring, and be able to find enough food and 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 cause an alteration in the ratio of different alleles within the population's gene pool. Over time, this change in allele frequencies could lead to the emergence of new traits and ultimately new species.
A lot of the traits we find appealing in plants and animals are adaptations. For instance the lungs or gills which extract oxygen from the air feathers and fur as insulation and long legs to get away from predators and camouflage to conceal. To comprehend adaptation it is crucial to distinguish between behavioral and physiological characteristics.
Physical traits such as the thick fur and gills are physical traits. Behavior adaptations aren't an exception, for instance, the tendency of animals to seek out companionship or retreat into shade during hot weather. It is also important to keep in mind that the absence of planning doesn't make an adaptation. In fact, failure to think about the consequences of a behavior can make it unadaptable despite the fact that it may appear to be reasonable or even essential.