What is Free Evolution?
Free evolution is the concept that natural processes can cause organisms to develop over time. This includes the appearance and growth of new species.
Numerous examples have been offered of this, such as different varieties of stickleback fish that can live in fresh or salt water and walking stick insect varieties that are attracted to specific host plants. These mostly reversible traits permutations do not explain the fundamental changes in the basic body plan.
Evolution through Natural Selection
The evolution of the myriad living organisms on Earth is an enigma that has intrigued scientists for many centuries. The most widely accepted explanation is that of Charles Darwin's natural selection, a process that is triggered when more well-adapted individuals live longer and reproduce more successfully than those that are less well-adapted. As time passes, the number of well-adapted individuals becomes larger and eventually develops into a new species.
Natural selection is a process that is cyclical and involves the interaction of three factors including reproduction, variation and inheritance. Variation is caused by mutation and sexual reproduction both of which enhance the genetic diversity within the species. Inheritance refers to the passing of a person's genetic traits to his or her offspring which includes both dominant and recessive alleles. Reproduction is the process of producing fertile, viable offspring. This can be done by both asexual or sexual methods.
All of these elements must be in harmony for natural selection to occur. For example when a dominant allele at one gene can cause an organism to live and reproduce more often than the recessive allele the dominant allele will be more common in the population. If the allele confers a negative survival advantage or decreases the fertility of the population, it will disappear. This process is self-reinforcing which means that an organism with an adaptive trait will live and reproduce much more than those with a maladaptive trait. The more offspring an organism produces the more fit it is that is determined by its ability to reproduce itself and live. People with desirable traits, such as having a longer neck in giraffes, or bright white color patterns in male peacocks are more likely to survive and produce offspring, so they will eventually make up 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 holds that animals acquire traits due to use or lack of use. If a giraffe extends its neck in order to catch prey and the neck grows longer, then its children will inherit this characteristic. The differences in neck size between generations will increase until the giraffe is unable to reproduce with other giraffes.
Evolution by Genetic Drift
In the process of genetic drift, alleles at a gene may reach different frequencies within a population by chance events. In the end, only one will be fixed (become widespread enough to not longer be eliminated by natural selection), and the other alleles drop in frequency. This can lead to dominance in the extreme. The other alleles have been basically eliminated and heterozygosity has decreased to zero. In a small group it could result in the complete elimination of recessive gene. This is known as 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 occur when the survivors of a catastrophe such as an outbreak or mass hunt event are confined to an area of a limited size. The survivors will have an dominant allele, and will share the same phenotype. This may be the result of a conflict, earthquake or even a cholera outbreak. Whatever the reason the genetically distinct group that remains is prone to genetic drift.
Walsh, Lewens, and Ariew use Lewens, Walsh and Ariew employ a "purely outcome-oriented" definition of drift as any deviation from the expected values for differences in fitness. They give the famous example of twins who are genetically identical and have exactly the same phenotype. However, one is struck by lightning and dies, whereas the other is able to reproduce.
This kind of drift could play a very important role in the evolution of an organism. But, it's not the only way to evolve. Natural selection is the main alternative, where mutations and migration keep the phenotypic diversity of a population.
Stephens asserts that there is a major difference between treating the phenomenon of drift as a force, or a cause and considering other causes of evolution, such as selection, mutation and migration as causes or causes. He argues that a causal process account of drift permits us to differentiate it from these other forces, and this distinction is essential. He argues further that drift is both an orientation, i.e., it tends towards eliminating heterozygosity. It also has a size which is determined based on population size.
Evolution by Lamarckism
Students of biology in high school are often introduced to Jean-Baptiste Lamarck's (1744-1829) work. His theory of evolution, also called "Lamarckism is based on the idea that simple organisms develop into more complex organisms taking on traits that result from the use and abuse of an organism. Lamarckism is illustrated through an giraffe's neck stretching to reach higher leaves in the trees. This process would cause giraffes to give their longer necks to offspring, who then get taller.
Lamarck, a French zoologist, presented an idea that was revolutionary in his opening lecture at the Museum of Natural History of Paris. He challenged traditional thinking about organic transformation. According to Lamarck, living creatures evolved from inanimate matter through a series gradual steps. Lamarck wasn't the first to propose this however he was widely thought of as the first to offer the subject a thorough and general overview.
The dominant story is that Charles Darwin's theory of evolution by natural selection and Lamarckism fought in the 19th century. Darwinism eventually won and led to the development of what biologists today call the Modern Synthesis. The theory argues that acquired traits can be passed down and instead argues organisms evolve by the selective influence of environmental factors, such as Natural Selection.
Lamarck and his contemporaries endorsed the idea that acquired characters could be passed down to future generations. However, Evolution KR was never a key element of any of their theories about evolution. This is due in part to the fact that it was never tested scientifically.
It's been more than 200 years since Lamarck was born and in the age genomics there is a vast amount of evidence that supports the heritability of acquired characteristics. This is referred to as "neo Lamarckism", or more generally epigenetic inheritance. This is a variant that is as valid as the popular Neodarwinian model.
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. This notion is not true and ignores other forces driving evolution. The fight for survival can be better described as a fight to survive in a particular environment. This can include not only other organisms as well as the physical environment itself.
To understand how evolution works it is important to think about what adaptation is. The term "adaptation" refers to any specific feature that allows an organism to live and reproduce in its environment. It could be a physical structure, like fur or feathers. Or it can be a characteristic of behavior that allows you to move into the shade during the heat, or escaping the cold at night.
An organism's survival depends on its ability to draw energy from the environment and interact with other organisms and their physical environments. The organism should possess the right genes to create offspring and to be able to access sufficient food and resources. Furthermore, the organism needs to be able to reproduce itself at an optimal rate within its niche.
These elements, in conjunction with mutation and gene flow result in changes in the ratio of alleles (different forms of a gene) in the gene pool of a population. Over time, this change in allele frequencies can lead to the emergence of new traits, and eventually new species.
Many of the features we admire in animals and plants are adaptations. For instance the lungs or gills which extract oxygen from air feathers and fur for insulation long legs to run away from predators, and camouflage to hide. However, a thorough understanding of adaptation requires a keen eye to the distinction between the physiological and behavioral characteristics.
Physical traits such as thick fur and gills are physical characteristics. Behavior adaptations aren't, such as the tendency of animals to seek companionship or move into the shade during hot temperatures. It is also important to note that insufficient planning does not make an adaptation. In fact, failing to think about the consequences of a behavior can make it ineffective despite the fact that it might appear logical or even necessary.