What is Free Evolution?
Free evolution is the concept that the natural processes that organisms go through can lead them to evolve over time. This includes the appearance and growth of new species.
Many examples have been given of this, including various varieties of stickleback fish that can live in fresh or salt water and walking stick insect varieties that prefer specific host plants. These mostly reversible traits permutations cannot explain fundamental changes to basic body plans.
Evolution through Natural Selection
Scientists have been fascinated by the evolution of all living creatures that inhabit our planet for centuries. Charles Darwin's natural selection theory is the best-established explanation. This process occurs when those who are better adapted survive and reproduce more than those who are less well-adapted. As time passes, the number of well-adapted individuals becomes larger and eventually forms a new species.
Natural selection is a cyclical process that is characterized by the interaction of three elements including inheritance, variation, and reproduction. Sexual reproduction and mutation increase genetic diversity in the species. Inheritance refers to the transmission of genetic characteristics, which includes recessive and dominant genes and their offspring. Reproduction is the process of generating fertile, viable offspring. This can be done by both asexual or sexual methods.
Natural selection can only occur when all these elements are in balance. If, for instance an allele of a dominant gene causes an organism reproduce and last longer than the recessive allele then the dominant allele becomes more prevalent in a group. However, if the allele 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 trait is more likely to survive and reproduce than an individual with a maladaptive trait. The more offspring that an organism has the more fit it is, which is measured by its capacity to reproduce and survive. People with good traits, like the long neck of the giraffe, or bright white patterns on male peacocks are more likely than others to live and reproduce which eventually leads to them becoming the majority.
Natural selection is only a force for populations, not individual organisms. This is a crucial distinction from the Lamarckian theory of evolution which holds that animals acquire traits due to the use or absence of use. For instance, if a giraffe's neck gets longer through reaching out to catch prey its offspring will inherit a longer neck. The differences in neck length between generations will persist until the giraffe's neck gets too long to not breed with other giraffes.
바카라 에볼루션 by Genetic Drift
In genetic drift, alleles at a gene may be at different frequencies in a group due to random events. At some point, one will reach fixation (become so common that it is unable to be eliminated through natural selection) and other alleles will fall to lower frequency. In the extreme it can lead to dominance of a single allele. The other alleles are virtually eliminated and heterozygosity diminished to zero. In a small population it could result in the complete elimination of recessive gene. This scenario is called the bottleneck effect. It is typical of the evolution process that occurs when the number of individuals migrate to form a group.
A phenotypic bottleneck can also happen when the survivors of a catastrophe like an epidemic or mass hunt, are confined within a narrow area. The surviving individuals will be mostly homozygous for the dominant allele which means they will all have the same phenotype and will therefore have the same fitness traits. This could be caused by war, earthquakes, or even plagues. The genetically distinct population, if it is left susceptible to genetic drift.
Walsh Lewens, Walsh and Ariew define drift as a deviation from expected values due to differences in fitness. They give a famous example of twins that are genetically identical and have identical phenotypes and yet one is struck by lightning and dies, whereas the other lives and reproduces.
This type of drift can play a significant part in the evolution of an organism. This isn't the only method of evolution. The most common alternative is a process known as natural selection, in which the phenotypic diversity of an individual is maintained through mutation and migration.
Stephens argues that there is a significant distinction between treating drift as a force or as an underlying cause, and treating other causes of evolution such as mutation, selection and migration as forces or causes. Stephens claims that a causal process account of drift allows us to distinguish it from these other forces, and that this distinction is essential. 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 the size of the population.
Evolution by Lamarckism
Biology students in high school are frequently introduced to Jean-Baptiste Lemarck's (1744-1829) work. His theory of evolution is generally known as "Lamarckism" and it states that simple organisms grow into more complex organisms through the inheritance of traits which result from the organism's natural actions, use and disuse. Lamarckism is illustrated through a giraffe extending its neck to reach higher leaves in the trees. This could cause giraffes to give their longer necks to their 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 a groundbreaking concept that radically challenged previous thinking about organic transformation. According to Lamarck, living creatures evolved from inanimate material through a series of gradual steps. Lamarck was not the first to suggest this but he was thought of as the first to provide the subject a comprehensive and general explanation.
The predominant story is that Charles Darwin's theory of natural selection and Lamarckism fought during the 19th century. Darwinism ultimately won and led to what biologists refer to as the Modern Synthesis. This theory denies acquired characteristics are passed down from generation to generation and instead argues organisms evolve by the selective influence of environmental factors, including Natural Selection.
Although Lamarck endorsed the idea of inheritance by acquired characters and his contemporaries also paid lip-service to this notion however, it was not a major feature in any of their evolutionary theories. This is due in part to the fact that it was never tested scientifically.
However, it has been more than 200 years since Lamarck was born and in the age genomics there is a vast body of evidence supporting the heritability of acquired characteristics. This is also known as "neo Lamarckism", or more generally epigenetic inheritance. It is a version of evolution that is as valid as the more well-known Neo-Darwinian theory.
Evolution by the process of adaptation
One of the most common misconceptions about evolution is that it is driven by a type of struggle for survival. This view is inaccurate and overlooks other forces that drive evolution. The struggle for survival is more accurately described as a struggle to survive in a specific environment, which could involve not only other organisms, but also the physical environment.
To understand how evolution operates it is beneficial to understand what is adaptation. The term "adaptation" refers to any specific characteristic that allows an organism to survive and reproduce within its environment. It could be a physical structure, such as feathers or fur. Or it can be a trait of behavior, like moving towards shade during hot weather or moving out to avoid the cold at night.
The capacity of an organism 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 to create offspring, and it must be able to find enough food and other resources. The organism must also be able to reproduce itself at an amount that is appropriate for its particular niche.
These factors, in conjunction with gene flow and mutations can result in a shift in the proportion of different alleles within the gene pool of a population. The change in frequency of alleles can lead to the emergence of new traits, and eventually, new species over time.
Many of the features that we admire in animals and plants are adaptations, such as the lungs or gills that extract oxygen from the air, fur or feathers for insulation long legs to run away from predators and camouflage for hiding. However, a complete understanding of adaptation requires attention to the distinction between physiological and behavioral characteristics.
Physiological adaptations like thick fur or gills are physical characteristics, whereas behavioral adaptations, like the tendency to seek out friends or to move into the shade in hot weather, are not. It is important to remember that a the absence of planning doesn't cause an adaptation. In fact, a failure to think about the consequences of a decision can render it unadaptable despite the fact that it might appear reasonable or even essential.