What is Free Evolution?
Free evolution is the notion that the natural processes that organisms go through can cause them to develop over time. This includes the evolution of new species and the transformation of the appearance of existing ones.
This has been proven by many examples of stickleback fish species that can thrive in salt or fresh water, and walking stick insect varieties that prefer particular host plants. These are mostly reversible traits however, are not able to be the reason for fundamental changes in body plans.
Evolution by Natural Selection
The development of the myriad living creatures on Earth is a mystery that has intrigued scientists for decades. Charles Darwin's natural selection theory is the most well-known explanation. This process occurs when those who are better adapted have more success in reproduction and survival than those who are less well-adapted. As time passes, a group of well adapted individuals grows and eventually forms a whole new species.
Natural selection is a process that is cyclical and involves the interaction of 3 factors that are: reproduction, variation and inheritance. Mutation and sexual reproduction increase genetic diversity in a species. Inheritance refers to the passing of a person's genetic characteristics to the offspring of that person that includes dominant and recessive alleles. Reproduction is the process of generating fertile, viable offspring. This can be done through sexual or asexual methods.
All of these factors have to be in equilibrium for natural selection to occur. For example when an allele that is dominant at one gene causes an organism to survive and reproduce more often than the recessive allele the dominant allele will become more prominent within the population. If the allele confers a negative survival advantage or reduces the fertility of the population, it will go away. This process is self-reinforcing, which means that an organism with an adaptive characteristic will live and reproduce more quickly than one with a maladaptive characteristic. The more offspring an organism can produce the more fit it is that is determined by its capacity to reproduce itself and survive. Individuals with favorable traits, like longer necks in giraffes, or bright white colors in male peacocks are more likely be able to survive and create offspring, which means they will become the majority of the population in the future.
Natural selection is only an aspect of populations and not on individuals. This is a major distinction from the Lamarckian evolution theory which holds that animals acquire traits through the use or absence of use. If a giraffe expands its neck to reach prey and its neck gets longer, then its children will inherit this characteristic. The differences in neck size between generations will increase until the giraffe is no longer able to reproduce with other giraffes.
Evolution through Genetic Drift
In genetic drift, the alleles within a gene can attain different frequencies in a group due to random events. At some point, one will attain fixation (become so widespread that it cannot be removed by natural selection), while the other alleles drop to lower frequency. This could lead to an allele that is dominant at the extreme. The other alleles are basically eliminated and heterozygosity has been reduced to zero. In a small population this could lead to the complete elimination of the recessive gene. This is known as the bottleneck effect and is typical of the evolutionary process that occurs when the number of individuals migrate to form a population.
A phenotypic bottleneck could happen when the survivors of a catastrophe like an epidemic or a massive hunting event, are concentrated within a narrow area. The remaining individuals are likely to be homozygous for the dominant allele which means that they will all have the same phenotype and thus share the same fitness characteristics. This can be caused by earthquakes, war or even a plague. Regardless of the cause, the genetically distinct population that remains could be susceptible to genetic drift.
Walsh Lewens and Ariew utilize Lewens, Walsh and Ariew employ a "purely outcome-oriented" definition of drift as any departure from the expected values for different fitness levels. They cite a famous example of twins that are genetically identical, have identical phenotypes, and yet one is struck by lightning and dies, while the other lives and reproduces.
This kind of drift can play a significant part in the evolution of an organism. It's not the only method of evolution. The most common alternative is to use a process known as natural selection, where the phenotypic diversity of a population is maintained by mutation and migration.
Stephens asserts that there is a significant distinction between treating drift as a force or as an underlying cause, and treating other causes of evolution like mutation, selection and migration as causes or causes. He claims that a causal-process model of drift allows us to differentiate it from other forces and that this differentiation is crucial. He also argues that drift is a directional force: that is, it tends to eliminate heterozygosity, and that it also has a specific magnitude that is determined by the size of the population.
Evolution by Lamarckism
Students of biology in high school are often exposed to Jean-Baptiste lamarck's (1744-1829) work. His theory of evolution is often known as "Lamarckism" and it states that simple organisms grow into more complex organisms by the inheritance of characteristics that are a result of the natural activities of an organism use and misuse. Lamarckism is typically illustrated with a picture of a giraffe extending its neck to reach the higher branches in the trees. This would cause giraffes to pass on their longer necks to offspring, who then get 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 the 17th of May in 1802, he presented an original idea that fundamentally challenged the previous understanding of organic transformation. According Lamarck, living organisms evolved from inanimate material 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 being the one who gave the subject its first broad and thorough treatment.
The dominant story is that Charles Darwin's theory on natural selection and Lamarckism were competing during the 19th century. Darwinism ultimately prevailed which led to what biologists call the Modern Synthesis. The theory denies that acquired characteristics can be passed down through generations and instead argues that organisms evolve through the selective influence of environmental factors, such as Natural Selection.
Lamarck and his contemporaries supported the idea that acquired characters could be passed down to the next generation. However, this idea was never a central part of any of their theories on evolution. This is due in part to the fact that it was never tested scientifically.
However, it has been more than 200 years since Lamarck was born and in the age of genomics there is a vast amount of evidence that supports the possibility of inheritance of acquired traits. This is sometimes called "neo-Lamarckism" or, more commonly epigenetic inheritance. It is a variant of evolution that is as relevant as the more popular Neo-Darwinian model.
Evolution through the process of adaptation
One of the most widespread misconceptions about evolution is that it is driven by a sort of struggle for survival. In reality, this notion is inaccurate and overlooks the other forces that are driving evolution. The fight for survival can be more accurately described as a struggle to survive within a particular environment, which may be a struggle that involves not only other organisms but also the physical environment itself.
To understand how evolution operates it is important to think about what adaptation is. Adaptation is any feature that allows a living organism to live in its environment and reproduce. It can be a physiological structure, such as feathers or fur or a behavioral characteristic like moving into shade in hot weather or stepping out at night to avoid the cold.
The ability of an organism to draw energy from its surroundings and interact with other organisms as well as their physical environment is essential to its survival. The organism needs to have the right genes to create offspring, and it should be able to locate sufficient food and other resources. The organism must also be able reproduce itself at the rate that is suitable for its particular niche.
evolutionkr , in conjunction with gene flow and mutations, can lead to an alteration in the ratio of different alleles within a population’s gene pool. This shift in the frequency of alleles can lead to the emergence of new traits and eventually, new species as time passes.
Many of the characteristics we admire about animals and plants are adaptations, for example, 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 comprehend adaptation it is crucial to discern between physiological and behavioral characteristics.
Physiological adaptations, such as the thick fur or gills are physical traits, whereas behavioral adaptations, like the tendency to search for companions or to move to shade in hot weather, are not. Additionally, it is important to understand that a lack of forethought does not make something an adaptation. Failure to consider the effects of a behavior even if it appears to be rational, may cause it to be unadaptive.