What is Free Evolution?
Free evolution is the concept that the natural processes that organisms go through can cause them to develop over time. This includes the emergence and development of new species.
Many examples have been given of this, such as different varieties of fish called sticklebacks that can be found in salt or fresh water, and walking stick insect varieties that favor specific host plants. These mostly reversible trait permutations can't, however, explain fundamental changes in body plans.
Evolution by Natural Selection
Scientists have been fascinated by the development of all living organisms that inhabit our planet for centuries. The most well-known explanation is that of Charles Darwin's natural selection, which is triggered when more well-adapted individuals live longer and reproduce more effectively than those less well adapted. Over time, a community of well-adapted individuals increases and eventually becomes a new species.
Natural selection is a process that is cyclical and involves the interaction of three factors including reproduction, variation and inheritance. Mutation and sexual reproduction increase genetic diversity in an animal species. Inheritance is the term used to describe the transmission of a person’s genetic traits, including both dominant and recessive genes to their offspring. Reproduction is the production of viable, fertile offspring, which includes both asexual and sexual methods.
Natural selection only occurs when all these elements are in harmony. For instance, if an allele that is dominant at one gene can cause an organism to live and reproduce more often than the recessive allele the dominant allele will become more common in the population. However, if the gene confers an unfavorable survival advantage or decreases fertility, it will be eliminated from the population. The process is self reinforcing meaning that an organism that has an adaptive trait will survive and reproduce much more than one with a maladaptive characteristic. The more offspring an organism produces the better its fitness, which is measured by its capacity to reproduce and survive. People with good characteristics, such as a long neck in the giraffe, or bright white patterns on male peacocks are more likely than others to survive and reproduce which eventually leads to them becoming the majority.
Natural selection only affects populations, not on individual organisms. This is a significant distinction from the Lamarckian theory of evolution that states that animals acquire traits through the use or absence of use. For instance, if the giraffe's neck gets longer through stretching to reach prey, its offspring will inherit a more long neck. The differences in neck size between generations will continue to grow until the giraffe becomes unable to breed with other giraffes.
Evolution through Genetic Drift
In genetic drift, the alleles within a gene can reach different frequencies within a population by chance events. In the end, one will attain fixation (become so widespread that it cannot be removed by natural selection) and the other alleles drop to lower frequencies. This can result in an allele that is dominant in the extreme. The other alleles are essentially eliminated, and heterozygosity is reduced to zero. In a small number of people, this could result in the complete elimination of recessive gene. Such a scenario would be known as a bottleneck effect and it is typical of the kind of evolutionary process that occurs when a lot of individuals migrate to form a new population.
A phenotypic bottleneck may happen when the survivors of a catastrophe like an epidemic or mass hunt, are confined into a small area. The survivors will be largely homozygous for the dominant allele, which means that they will all share the same phenotype and thus have the same fitness traits. This situation could be caused by war, earthquakes or even a plague. Whatever the reason the genetically distinct group that remains could be susceptible to genetic drift.
Walsh, Lewens, and Ariew utilize a "purely outcome-oriented" definition of drift as any departure from expected values for variations in fitness. They give a famous instance of twins who are genetically identical and have identical phenotypes, and yet one is struck by lightning and dies, whereas the other lives and reproduces.
This kind of drift could play a significant role in the evolution of an organism. But, it's not the only method to develop. The primary alternative is to use a process known as natural selection, in which the phenotypic diversity of a population is maintained by mutation and migration.
Stephens claims that there is a significant difference between treating the phenomenon of drift as a force or cause, and treating other causes such as migration and selection as causes and forces. He claims that a causal process explanation of drift allows us to distinguish it from the other forces, and this distinction is essential. He further argues that drift has a direction, that is it tends to eliminate heterozygosity. It also has a size, that is determined by the size of population.
Evolution by Lamarckism
When high school students study biology, they are often introduced to the work of Jean-Baptiste Lamarck (1744 - 1829). His theory of evolution, also referred to as "Lamarckism is based on the idea that simple organisms transform into more complex organisms by adopting traits that result from the organism's use and misuse. Lamarckism is illustrated through a giraffe extending its neck to reach higher branches in the trees. This causes giraffes' longer necks to be passed on to their offspring who would grow taller.
Lamarck was a French zoologist and, in his opening lecture for his course on invertebrate zoology held at the Museum of Natural History in Paris on 17 May 1802, he presented an original idea that fundamentally challenged the conventional wisdom about organic transformation. According to 에볼루션 , living things evolved from inanimate material through a series gradual steps. Lamarck wasn't the only one to make this claim but he was regarded as the first to provide the subject a comprehensive and general treatment.
The prevailing story is that Lamarckism became a rival to Charles Darwin's theory of evolution by natural selection, and that the two theories fought it out in the 19th century. Darwinism eventually won and led to the development of what biologists refer to as the Modern Synthesis. This theory denies acquired characteristics are passed down from generation to generation and instead argues that organisms evolve through the selective action of environment elements, like Natural Selection.
Lamarck and his contemporaries supported 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 due to the fact that it was never validated scientifically.
It's been over 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 also known as "neo Lamarckism", or more generally epigenetic inheritance. It is a version of evolution that is just as relevant as the more popular neo-Darwinian model.
Evolution through Adaptation
One of the most popular misconceptions about evolution is that it is driven by a sort of struggle for survival. In reality, this notion is a misrepresentation of natural selection and ignores the other forces that determine the rate of evolution. The fight for survival is better described as a fight to survive in a particular environment. This could include not just other organisms, but also the physical surroundings themselves.
To understand how evolution operates, it is helpful to consider what adaptation is. It is a feature that allows living organisms to live in its environment and reproduce. It can be a physiological structure, such as fur or feathers or a behavioral characteristic like moving into shade in hot weather or stepping out at night to avoid cold.
The ability of a living thing to extract energy from its surroundings and interact with other organisms, as well as their physical environment, is crucial to its survival. The organism should possess the right genes for producing offspring and to be able to access enough food and resources. Moreover, the organism must be able to reproduce itself in a way that is optimally within its environment.
These factors, in conjunction with mutations and gene flow can result in a shift in the proportion of different alleles in a population’s gene pool. The change in frequency of alleles could lead to the development of novel traits and eventually new species in the course of time.
A lot of the traits we appreciate in plants and animals are adaptations. For example lung or gills that draw oxygen from air feathers and fur for insulation, long legs to run away from predators and camouflage for hiding. To understand the concept of adaptation it is crucial to distinguish between behavioral and physiological characteristics.
Physical traits such as the thick fur and gills are physical traits. Behavioral adaptations are not, such as the tendency of animals to seek companionship or move into the shade during hot weather. In addition, it is important to understand that lack of planning does not mean that something is an adaptation. In fact, failing to think about the consequences of a behavior can make it unadaptable even though it may appear to be sensible or even necessary.