What is Free Evolution?
Free evolution is the idea that natural processes can cause organisms to develop over time. This includes the evolution of new species as well as the change in appearance of existing ones.
Many examples have been given of this, such as different kinds of stickleback fish that can live in either fresh or salt water and walking stick insect varieties that prefer particular host plants. These mostly reversible trait permutations, however, cannot explain fundamental changes in basic body plans.
Evolution through Natural Selection
The evolution of the myriad living creatures on Earth is an enigma that has intrigued scientists for centuries. Charles Darwin's natural selection is the most well-known explanation. This process occurs when individuals who are better-adapted survive and reproduce more than those who are 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 that is characterized by the interaction of three factors including inheritance, variation, and reproduction. Variation is caused by mutation and sexual reproduction both of which increase the genetic diversity of an animal species. Inheritance refers to the transmission of genetic characteristics, which includes recessive and dominant genes and their offspring. Reproduction is the generation of fertile, viable offspring which includes both asexual and sexual methods.
Natural selection can only occur when all of these factors are in harmony. If, for instance an allele of a dominant gene allows an organism to reproduce and live longer than the recessive gene allele then the dominant allele is more common in a population. If the allele confers a negative survival advantage or reduces the fertility of the population, it will disappear. The process is self reinforcing meaning that an organism with an adaptive characteristic will live and reproduce more quickly than those with a maladaptive trait. The more fit an organism is, measured by its ability reproduce and survive, is the greater number of offspring it can produce. Individuals with favorable traits, like having a long neck in giraffes, or bright white patterns on male peacocks are more likely than others to reproduce and survive, which will eventually lead to them becoming the majority.
Natural selection only acts on populations, not individual organisms. This is a significant distinction from the Lamarckian theory of evolution, which claims that animals acquire traits by use or inactivity. For example, if a Giraffe's neck grows longer due to stretching to reach for prey and its offspring will inherit a more long neck. The differences in neck length between generations will persist until the giraffe's neck becomes too long to not breed with other giraffes.
Evolution by Genetic Drift
In genetic drift, the alleles at a gene may be at different frequencies in a population by chance events. Eventually, one of them will attain fixation (become so widespread that it is unable to be removed through natural selection), while the other alleles drop to lower frequency. This can lead to a dominant allele in extreme. The other alleles are eliminated, and heterozygosity is reduced to zero. In a small group it could result in the complete elimination the recessive gene. This scenario is called the bottleneck effect and is typical of an evolutionary process that occurs whenever the number of individuals migrate to form a group.
A phenotypic bottleneck may occur when survivors of a catastrophe such as an epidemic or mass hunting event, are concentrated in a limited area. The survivors will share an allele that is dominant and will have the same phenotype. This could be caused by earthquakes, war or even a plague. Whatever the reason, the genetically distinct population that remains could be susceptible to genetic drift.
Walsh Lewens, Walsh and Ariew define drift as a departure from expected values due to differences in fitness. They cite a famous example of twins that are genetically identical and have identical phenotypes, but one is struck by lightning and dies, while the other lives and reproduces.
This type of drift can play a crucial part in the evolution of an organism. It is not the only method for evolution. The main alternative is a process called natural selection, in which the phenotypic variation of the population is maintained through mutation and migration.
에볼루션 블랙잭 argues that there is a significant difference between treating the phenomenon of drift as a force or as a cause and considering other causes of evolution, such as selection, mutation and migration as forces or causes. He claims that a causal mechanism account of drift permits us to differentiate it from these other forces, and this distinction is crucial. He also argues that drift is both direction, i.e., it tends towards eliminating heterozygosity. It also has a size, which is determined based on the size of the population.
Evolution through Lamarckism
In high school, students study biology they are often introduced to the work of Jean-Baptiste Lamarck (1744 - 1829). 에볼루션게이밍 of evolution is generally referred to as "Lamarckism" and it states that simple organisms develop into more complex organisms by the inheritance of characteristics which result from the natural activities of an organism, use and disuse. Lamarckism is illustrated through an giraffe's neck stretching to reach higher levels of leaves in the trees. This would cause the longer necks of giraffes to be passed onto their offspring who would then grow even 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 17 May 1802, he presented an innovative concept that completely challenged the previous understanding of organic transformation. According Lamarck, living organisms evolved from inanimate matter through a series gradual steps. Lamarck wasn't the first to suggest this but he was thought of as the first to offer the subject a comprehensive and general explanation.
The prevailing story is that Lamarckism grew into a rival to Charles Darwin's theory of evolutionary natural selection and both theories battled out in the 19th century. Darwinism eventually won and led to the development of what biologists now call the Modern Synthesis. This theory denies the possibility that acquired traits can be inherited, and instead argues that organisms evolve by the symbiosis of environmental factors, such as natural selection.
Lamarck and his contemporaries supported the idea that acquired characters could be passed down to the next generation. However, this notion was never a major part of any of their theories on evolution. This is partly because it was never scientifically tested.
However, it has been more than 200 years since Lamarck was born and in the age of genomics there is a vast amount of evidence that supports the possibility of inheritance of acquired traits. This is also referred to as "neo Lamarckism", or more often epigenetic inheritance. It is a version of evolution that is as relevant as the more popular Neo-Darwinian theory.
Evolution by the process of adaptation
One of the most common misconceptions about evolution is that it is driven by a sort of struggle to survive. In fact, this view is inaccurate and overlooks the other forces that drive evolution. The struggle for survival is more effectively described as a struggle to survive within a particular environment, which can involve not only other organisms but as well the physical environment.
Understanding the concept of adaptation is crucial to understand evolution. The term "adaptation" refers to any specific feature that allows an organism to live and reproduce in its environment. It can be a physiological structure, such as feathers or fur or a behavioral characteristic such as a tendency to move into shade in hot weather or stepping out at night to avoid cold.
The survival of an organism is dependent on its ability to draw energy from the environment and to interact with other organisms and their physical environments. The organism must possess the right genes to create offspring, and must be able to locate sufficient food and other resources. The organism must be able to reproduce at a rate that is optimal for its specific niche.
These factors, together with gene flow and mutation result in an alteration in the percentage of alleles (different forms of a gene) in the gene pool of a population. As time passes, this shift in allele frequencies can lead to the emergence of new traits and eventually new species.
Many of the features that we admire in animals and plants are adaptations, such as lungs or gills to extract oxygen from the air, feathers or fur to protect themselves long legs to run away from predators, and camouflage for hiding. To comprehend adaptation it is crucial to discern between physiological and behavioral characteristics.
Physiological traits like the thick fur and gills are physical traits. The behavioral adaptations aren't, such as the tendency of animals to seek out companionship or move into the shade in hot temperatures. It is also important to note that lack of planning does not make an adaptation. In fact, a failure to think about the consequences of a decision can render it ineffective, despite the fact that it might appear logical or even necessary.