What is Free Evolution?
Free evolution is the notion that natural processes can cause organisms to develop 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 species that prefer specific host plants. These typically reversible traits are not able to explain fundamental changes to the body's basic plans.
Evolution through Natural Selection
The evolution of the myriad living creatures on Earth is an enigma that has intrigued scientists for decades. The best-established explanation is Charles Darwin's natural selection, which is triggered when more well-adapted individuals live longer and reproduce more successfully than those less well-adapted. As time passes, a group of well-adapted individuals increases and eventually forms a whole new species.
Natural selection is a process that is cyclical and involves the interaction of 3 factors including reproduction, variation and inheritance. Sexual reproduction and mutations increase the genetic diversity of a species. Inheritance refers to the passing of a person's genetic traits to their offspring which includes both recessive and dominant alleles. Reproduction is the process of generating viable, fertile offspring. This can be accomplished via sexual or asexual methods.
Natural selection can only occur when all these elements are in balance. If, for instance, a dominant gene allele allows an organism to reproduce and last longer than the recessive allele, then the dominant allele becomes more prevalent in a group. However, if the gene confers an unfavorable survival advantage or decreases fertility, it will be eliminated from the population. This process is self-reinforcing, which means that an organism with an adaptive trait will survive and reproduce more quickly than one with a maladaptive characteristic. The more offspring an organism produces, the greater its fitness which is measured by its capacity to reproduce itself and live. People with good characteristics, like a longer neck in giraffes or bright white color patterns in male peacocks, are more likely to survive and produce offspring, which means they will make up the majority of the population over time.
Natural selection is only a force for populations, not individuals. This is a major distinction from the Lamarckian theory of evolution, which states that animals acquire characteristics through use or disuse. For instance, if a animal's neck is lengthened by reaching out to catch prey its offspring will inherit a larger neck. The difference in neck size between generations will increase until the giraffe becomes unable to breed with other giraffes.
Evolution through Genetic Drift
Genetic drift occurs when alleles of the same gene are randomly distributed within a population. In the end, one will reach fixation (become so widespread that it cannot be eliminated by natural selection) and other alleles fall to lower frequency. In the extreme this, it leads to one allele dominance. Other alleles have been virtually eliminated and heterozygosity been reduced to zero. In a small group it could result in the complete elimination of the recessive gene. This is known as 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 also occur when the survivors of a catastrophe like an outbreak or a mass hunting incident are concentrated in an area of a limited size. The survivors will share a dominant allele and thus will have the same phenotype. This could be caused by war, earthquakes, or even plagues. Whatever the reason the genetically distinct group that remains could be prone to genetic drift.
Walsh Lewens, Walsh, and Ariew define drift as a deviation from expected values due to differences in fitness. They cite the famous example of twins that are genetically identical and share the same phenotype. However, one is struck by lightning and dies, whereas the other continues to reproduce.
This kind of drift could be crucial in the evolution of a species. This isn't the only method for evolution. The most common alternative is to use a process known as natural selection, in which the phenotypic variation of a population is maintained by mutation and migration.
Stephens claims that there is a significant difference between treating drift as a force, or a cause and treating other causes of evolution such as mutation, selection and migration as forces or causes. He argues that a causal-process account of drift allows us separate it from other forces and this differentiation is crucial. He argues further that drift has both an orientation, i.e., it tends to reduce heterozygosity. It also has a size, which is determined by the size of the population.
Evolution through Lamarckism
Biology students in high school are frequently introduced to Jean-Baptiste Lamarck's (1744-1829) work. His theory of evolution is often known as "Lamarckism" and it states that simple organisms develop into more complex organisms through the inheritance of traits that result from the organism's natural actions, use and disuse. Lamarckism can be illustrated by the giraffe's neck being extended to reach higher levels of leaves in the trees. This could cause giraffes' longer necks to be passed to their offspring, who would then become taller.
Lamarck was a French Zoologist. In his inaugural lecture for 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 the conventional wisdom about organic transformation. In his opinion, living things had evolved from inanimate matter through a series of gradual steps. Lamarck was not the first to suggest that this could be the case, but the general consensus is that he was the one having given the subject his first comprehensive and comprehensive analysis.
에볼루션 코리아 is that Lamarckism was a rival to Charles Darwin's theory of evolution by natural selection, and both theories battled it out in the 19th century. Darwinism ultimately prevailed and led to what biologists call the Modern Synthesis. This theory denies the possibility that acquired traits can be inherited, and instead, it argues that organisms develop by the symbiosis of environmental factors, such as natural selection.
Lamarck and his contemporaries endorsed the idea that acquired characters could be passed on to future generations. However, this idea was never a central part of any of their theories on evolution. This is partly because it was never scientifically validated.
It's been more than 200 years since Lamarck was born and in the age genomics there is a vast amount of evidence to support the possibility of inheritance of acquired traits. This is often called "neo-Lamarckism" or, more frequently epigenetic inheritance. This is a model that is as valid as the popular neodarwinian model.
Evolution by Adaptation
One of the most widespread misconceptions about evolution is that it is a result of a kind of struggle for survival. This view is inaccurate and ignores other forces driving evolution. The fight for survival is better described as a struggle to survive in a certain environment. This can be a challenge for not just other living things but also the physical surroundings themselves.
To understand how evolution works, it is helpful to consider what adaptation is. Adaptation is any feature that allows living organisms to survive in its environment and reproduce. It could be a physiological structure, such as fur or feathers or a behavioral characteristic, such as moving into shade in hot weather or coming out at night to avoid the cold.
The survival of an organism is dependent on its ability to draw energy from the surrounding environment and interact with other living organisms and their physical surroundings. The organism must have the right genes to create offspring, and it must be able to access enough food and other resources. In addition, the organism should be capable of reproducing in a way that is optimally within its environment.
These factors, together with mutation and gene flow, lead to changes in the ratio of alleles (different varieties of a particular gene) in the population's gene pool. As time passes, this shift in allele frequencies could result in the emergence of new traits, and eventually new species.
Many of the features we find appealing in animals and plants are adaptations. For example, lungs or gills that extract oxygen from air feathers and fur for insulation, long legs to run away from predators, and camouflage to hide. To understand the concept of adaptation, it is important to distinguish between behavioral and physiological traits.
Physiological traits like the thick fur and gills are physical characteristics. The behavioral adaptations aren't like the tendency of animals to seek out companionship or to retreat into the shade in hot temperatures. Furthermore it is important to note that a lack of thought is not a reason to make something an adaptation. A failure to consider the implications of a choice even if it appears to be logical, can make it inflexible.