What is Free Evolution?
Free evolution is the concept that the natural processes of organisms can cause them to develop over time. This includes the development of new species and the change in appearance of existing ones.
This has been proven by many examples, including stickleback fish varieties that can thrive in salt or fresh water, and walking stick insect species that prefer particular host plants. These are mostly reversible traits can't, however, explain fundamental changes in body plans.
Evolution by Natural Selection
Scientists have been fascinated by the evolution of all living organisms that inhabit our planet for ages. The most well-known explanation is that of Charles Darwin's natural selection, a process that occurs when individuals that are better adapted survive and reproduce more effectively than those less well adapted. As time passes, the number of well-adapted individuals grows and eventually forms a new species.
Natural selection is a cyclical process that involves the interaction of three elements including inheritance, variation, and reproduction. Variation is caused by mutations and sexual reproduction both of which enhance the genetic diversity of a species. Inheritance refers the transmission of genetic traits, including recessive and dominant genes, to their offspring. Reproduction is the generation of fertile, viable offspring, which includes both asexual and sexual methods.
Natural selection is only possible when all the factors are in equilibrium. For example, if the dominant allele of the gene can cause an organism to live and reproduce more often than the recessive allele the dominant allele will become more prominent in the population. However, if the allele confers an unfavorable survival advantage or decreases fertility, it will be eliminated from the population. This process is self-reinforcing which means that the organism with an adaptive characteristic will live and reproduce more quickly than one with a maladaptive characteristic. The more offspring an organism produces the better its fitness that is determined by its ability to reproduce itself and live. People with desirable characteristics, such as having a long neck in giraffes, or bright white patterns on male peacocks are more likely than others to live and reproduce and eventually lead to them becoming the majority.
Natural selection only acts on populations, not individual organisms. This is a significant distinction from the Lamarckian evolution theory that states that animals acquire traits either through usage or inaction. For instance, if the giraffe's neck gets longer through stretching to reach for prey its offspring will inherit a longer neck. The differences in neck size between generations will increase until the giraffe becomes unable to breed with other giraffes.
Evolution by Genetic Drift
Genetic drift occurs when the alleles of one gene are distributed randomly within a population. In the end, one will attain fixation (become so widespread that it can no longer be removed by natural selection) and other alleles fall to lower frequency. This could lead to dominance at the extreme. The other alleles are essentially eliminated, and heterozygosity decreases to zero. In a small population, this could result in the complete elimination of the recessive gene. This is known as a bottleneck effect and it is typical of evolutionary process when a large number of people migrate to form a new population.
A phenotypic bottleneck can also occur when the survivors of a catastrophe, such as an epidemic or a mass hunting event, are condensed within a narrow area. The survivors will carry an allele that is dominant and will have the same phenotype. This may be caused by a conflict, earthquake, or even a plague. Whatever the reason the genetically distinct population that is left might be prone to genetic drift.
Walsh Lewens, Walsh and Ariew define drift as a departure from the expected values due to differences in fitness. They provide a well-known example of twins that are genetically identical, have the exact same phenotype but one is struck by lightning and dies, while the other lives and reproduces.
This type of drift can play a significant role in the evolution of an organism. But, it's not the only method to develop. Natural selection is the main alternative, where mutations and migration keep the phenotypic diversity in the population.
Stephens argues that there is a major difference between treating the phenomenon of drift as a force or an underlying cause, and considering other causes of evolution such as selection, mutation and migration as forces or causes. He argues that a causal-process explanation of drift lets us differentiate it from other forces, and this distinction is essential. He also claims that drift has a direction, that is, it tends to eliminate heterozygosity. It also has a magnitude, which is determined by the size of the population.
Evolution by Lamarckism
Students of biology in high school are frequently introduced to Jean-Baptiste Lemarck's (1744-1829) work. His theory of evolution is often referred to as "Lamarckism" and it states that simple organisms grow into more complex organisms via the inheritance of traits that are a result of the organism's natural actions usage, use and disuse. Lamarckism can be demonstrated by a giraffe extending its neck to reach higher levels of leaves in the trees. This process would cause giraffes to give their longer necks to their offspring, which then grow even taller.
Lamarck the French zoologist, presented an idea that was revolutionary in his opening lecture at the Museum of Natural History of Paris. He challenged the conventional wisdom on organic transformation. In his view living things had evolved from inanimate matter via an escalating series of steps. Lamarck wasn't the only one to suggest this, but he was widely thought of as the first to offer the subject a thorough and general overview.
The most popular story is that Lamarckism became a rival to Charles Darwin's theory of evolutionary natural selection, and that the two theories fought out in the 19th century. Darwinism eventually prevailed, leading to the development of what biologists now call 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, such as natural selection.
Lamarck and his contemporaries endorsed the notion that acquired characters could be passed on to future generations. However, this notion was never a major part of any of their theories on evolution. This is partly due to the fact that it was never validated scientifically.
It's been more than 200 years since the birth of Lamarck, and in the age genomics there is a growing evidence-based body of evidence to support the heritability acquired characteristics. This is sometimes called "neo-Lamarckism" or more frequently epigenetic inheritance. It is a form of evolution that is as valid as the more well-known Neo-Darwinian theory.
Evolution through the process of adaptation
One of the most popular misconceptions about evolution is its being driven by a fight for survival. This view is inaccurate and ignores other forces driving evolution. The struggle for survival is more precisely described as a fight to survive within a particular environment, which may involve not only other organisms but also the physical environment itself.
To understand how evolution functions, it is helpful to understand what is adaptation. It refers to a specific feature that allows an organism to live and reproduce in its environment. It can be a physiological feature, such as feathers or fur, or a behavioral trait, such as moving into shade in the heat or leaving at night to avoid cold.
An organism's survival depends on its ability to obtain energy from the environment and to interact with other living organisms and their physical surroundings. 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 in a way that is optimally within its niche.
These elements, in conjunction with mutation and gene flow, lead to changes in the ratio of alleles (different types of a gene) in a population's gene pool. This shift in the frequency of alleles can result in the emergence of new traits and eventually, new species as time passes.
Many of the features we find appealing in plants and animals are adaptations. For instance, lungs or gills that draw oxygen from air, fur and feathers as insulation and long legs to get away from predators and camouflage to conceal. However, Info of adaptation requires a keen eye to the distinction between behavioral and physiological characteristics.
Physiological adaptations, such as thick fur or gills, are physical traits, whereas behavioral adaptations, like the tendency to seek out friends or to move to the shade during hot weather, aren't. It is also important to remember that a insufficient planning does not make an adaptation. In fact, a failure to think about the implications of a behavior can make it unadaptive even though it appears to be logical or even necessary.