What is Free Evolution?
Free evolution is the concept that the natural processes of living organisms can cause them to develop over time. This includes the emergence and development of new species.
This has been demonstrated by many examples, including stickleback fish varieties that can be found in saltwater or fresh water and walking stick insect species that have a preference for particular host plants. These reversible traits can't, however, explain fundamental changes in body plans.
Evolution through Natural Selection
The development of the myriad of living creatures on Earth is an enigma that has fascinated scientists for many centuries. Charles Darwin's natural selection theory is the best-established explanation. This happens when individuals who are better-adapted have more success in reproduction and survival than those who are less well-adapted. Over time, a community of well adapted individuals grows and eventually creates a new species.
Natural selection is an ongoing process and involves the interaction of 3 factors including reproduction, variation and inheritance. Variation is caused by mutation and sexual reproduction both of which enhance the genetic diversity within a species. Inheritance refers to the transmission of genetic characteristics, which includes recessive and dominant genes and their offspring. Reproduction is the production of viable, fertile offspring, which includes both asexual and sexual methods.
All of these variables have to be in equilibrium for natural selection to occur. For example when a dominant allele at the gene causes an organism to survive and reproduce more often than the recessive allele the dominant allele will become more prevalent within 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 that has an adaptive trait will survive and reproduce more quickly than those with a maladaptive feature. The higher the level of fitness an organism has which is measured by its ability to reproduce and survive, is the more offspring it will produce. People with good traits, such as longer necks in giraffes and bright white patterns of color in male peacocks are more likely be able to survive and create offspring, and thus will eventually make up the majority of the population over time.
Natural selection only affects populations, not individuals. This is a significant distinction from the Lamarckian theory of evolution which states that animals acquire traits through use or disuse. If a giraffe extends its neck to catch prey and its neck gets longer, then the children will inherit this characteristic. The differences 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
In genetic drift, alleles within a gene can attain different frequencies within a population through random events. At some point, one will attain fixation (become so widespread that it can no longer be eliminated through natural selection) and the other alleles drop to lower frequency. This can result in an allele that is dominant at the extreme. The other alleles are eliminated, and heterozygosity is reduced to zero. In a small population, this could result in the complete elimination the recessive gene. This is known as the bottleneck effect and is typical of the evolutionary process that occurs whenever the number of individuals migrate to form a group.
A phenotypic bottleneck can also occur when survivors of a catastrophe, such as an epidemic or a massive hunting event, are concentrated in a limited area. The survivors will be largely homozygous for the dominant allele, meaning that they all have the same phenotype, and thus share the same fitness characteristics. This situation could be caused by earthquakes, war or even a plague. Regardless of the cause, the genetically distinct population that remains could be prone to genetic drift.
Walsh Lewens, Walsh, and Ariew define drift as a departure from the expected value due to differences in fitness. They cite the famous example of twins who are genetically identical and have exactly the same phenotype, but one is struck by lightning and dies, while the other lives to reproduce.
This kind of drift could be vital to the evolution of an entire species. But, it's not the only method to progress. The primary alternative is a process known as natural selection, where the phenotypic diversity of an individual is maintained through mutation and migration.
Stephens argues there is a huge difference between treating drift like an agent or cause and considering other causes, such as migration and selection as causes and forces. Stephens claims that a causal process explanation of drift lets us differentiate it from other forces, and this distinction is crucial. He argues further that drift has an orientation, i.e., it tends to eliminate 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). 에볼루션 블랙잭 of evolution is generally referred to as "Lamarckism" and it states that simple organisms develop into more complex organisms by the inheritance of characteristics that result from an organism's natural activities, use and disuse. Lamarckism can be demonstrated by the giraffe's neck being extended to reach higher branches in the trees. This would cause giraffes to pass on their longer necks to their offspring, who would then become taller.
Lamarck Lamarck, a French Zoologist, introduced an innovative idea in his 17 May 1802 opening lecture at the Museum of Natural History of Paris. He challenged the previous thinking on organic transformation. In his view living things evolved from inanimate matter through the gradual progression of events. Lamarck wasn't the only one to make this claim however he was widely thought of as the first to offer the subject a comprehensive and general treatment.
The dominant story is that Charles Darwin's theory of natural selection and Lamarckism fought in the 19th Century. Darwinism ultimately prevailed, leading to 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 suggests that organisms evolve by the symbiosis of environmental factors, like natural selection.
Although Lamarck endorsed the idea of inheritance through acquired characters and his contemporaries spoke of this idea, it was never an integral part of any of their theories about evolution. This is due to the fact that it was never tested scientifically.
It has been more than 200 year since Lamarck's birth, and in the age genomics there is a growing body of evidence that supports the heritability acquired characteristics. This is referred to as "neo Lamarckism", or more generally epigenetic inheritance. This is a model that is as valid as the popular Neodarwinian model.
Evolution through Adaptation
One of the most popular 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 are driving evolution. The struggle for survival is more precisely described as a fight to survive in a specific environment, which could include not just other organisms but as well the physical environment.
Understanding adaptation is important to understand evolution. It refers to a specific characteristic that allows an organism to live and reproduce within its environment. It can be a physiological structure such as feathers or fur, or a behavioral trait like moving into the shade in hot weather or coming out at night to avoid cold.
The capacity of an organism to draw energy from its surroundings and interact with other organisms and their physical environments, is crucial to its survival. The organism must have the right genes for producing offspring and be able find sufficient food and resources. Moreover, the organism must be capable of reproducing at an optimal rate within its environmental niche.
These factors, together with mutation and gene flow result in an alteration in the percentage of alleles (different varieties of a particular gene) in the population's gene pool. This shift in the frequency of alleles can lead to the emergence of new traits and eventually, new species in the course of time.
A lot of the traits we admire about animals and plants are adaptations, such as lung or gills for removing oxygen from the air, fur or feathers for insulation long legs to run away from predators and camouflage for hiding. To understand adaptation it is essential to differentiate between physiological and behavioral traits.
Physiological adaptations, such as the thick fur or gills are physical traits, whereas behavioral adaptations, like the tendency to seek out companions or to retreat to the shade during hot weather, aren't. Additionally it is important to remember that a lack of forethought does not make something an adaptation. In fact, failure to think about the implications of a choice can render it ineffective even though it appears to be logical or even necessary.