What is Free Evolution?
Free evolution is the idea that natural processes can cause organisms to develop over time. This includes the development of new species as well as the transformation of the appearance of existing ones.
Numerous examples have been offered 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 are attracted to particular host plants. These mostly reversible trait permutations can't, however, explain fundamental changes in body plans.
Evolution through Natural Selection
The evolution of the myriad living creatures on Earth is an enigma that has intrigued scientists for centuries. The most widely accepted explanation is that of Charles Darwin's natural selection process, an evolutionary process that occurs when better-adapted individuals survive and reproduce more successfully than those that are less well-adapted. Over time, the population of individuals who are well-adapted grows and eventually develops into a new species.
Natural selection is a process that is cyclical and involves the interaction of three factors that are: reproduction, variation and inheritance. Variation is caused by mutation and sexual reproduction both of which enhance the genetic diversity within a species. Inheritance refers the transmission of genetic traits, which include recessive and dominant genes to their offspring. Reproduction is the production of viable, fertile offspring, which includes both asexual and sexual methods.
All of these variables must be in harmony for natural selection to occur. For instance the case where the dominant allele of one gene can cause an organism to live and reproduce more frequently than the recessive allele the dominant allele will be more prominent in the population. But if the allele confers a disadvantage in survival or decreases fertility, it will disappear from the population. This process is self-reinforcing which means that an organism that has a beneficial trait can reproduce and survive longer than one with an inadaptive characteristic. The more offspring an organism can produce the more fit it is, which is measured by its capacity to reproduce itself and live. People with good traits, like having a long neck in the giraffe, or bright white patterns on male peacocks are more likely to others to live and reproduce, which will eventually lead to them becoming the majority.
Natural selection only affects populations, not on individuals. This is a major distinction from the Lamarckian evolution theory which holds that animals acquire traits either through use or lack of use. If a giraffe stretches its neck to reach prey, and the neck becomes longer, then its children will inherit this characteristic. The difference in neck length between generations will continue until the giraffe's neck becomes too long to not breed with other giraffes.
Evolution through Genetic Drift
Genetic drift occurs when the alleles of a gene are randomly distributed in a group. At some point, only one of them will be fixed (become widespread enough to not longer be eliminated by natural selection), and the other alleles will decrease in frequency. This can lead to an allele that is dominant in the extreme. The other alleles are basically eliminated and heterozygosity has been reduced to zero. In a small population this could result in the complete elimination of the recessive allele. This scenario is called a bottleneck effect, and it is typical of the kind of evolutionary process when a large number of individuals migrate to form a new population.
A phenotypic bottleneck may also occur when the survivors of a catastrophe like an outbreak or a mass hunting event are concentrated in the same area. The survivors will be largely homozygous for the dominant allele meaning that they all have the same phenotype and therefore share the same fitness characteristics. This could be the result of a conflict, earthquake or even a disease. The genetically distinct population, if it is left, could be susceptible to genetic drift.
Walsh, Lewens and Ariew define drift as a departure from expected values due to differences in fitness. They give the famous example of twins that are genetically identical and have exactly the same phenotype. However, one is struck by lightning and dies, whereas the other is able to reproduce.
This kind of drift could be crucial in the evolution of a species. It is not the only method for evolution. Natural selection is the main alternative, in which mutations and migration maintain phenotypic diversity within the population.
Stephens asserts that there is a big distinction between treating drift as a force, or a cause and considering other causes of evolution such as mutation, selection and migration as causes or causes. He argues that a causal-process account of drift allows us separate it from other forces and this distinction is essential. He also argues that drift is a directional force: that is it tends to reduce heterozygosity, and that it also has a magnitude, that is determined by the size of population.
Evolution through Lamarckism
Biology students in high school are often exposed to Jean-Baptiste lamarck's (1744-1829) work. His theory of evolution, also called "Lamarckism, states that simple organisms transform into more complex organisms through inheriting characteristics that result from the use and abuse of an organism. Lamarckism is usually illustrated with the image of a giraffe extending its neck longer to reach the higher branches in the trees. This could cause the necks of giraffes that are longer to be passed to their offspring, who would grow taller.
Lamarck was a French Zoologist. In his lecture to begin his course on invertebrate zoology at the Museum of Natural History in Paris on 17 May 1802, he introduced an innovative concept that completely challenged previous thinking about organic transformation. In his view living things had evolved from inanimate matter through an escalating series of steps. Lamarck wasn't the only one to make this claim but he was thought of as the first to give the subject a thorough and general overview.
The predominant story is that Charles Darwin's theory on natural selection and Lamarckism were competing during the 19th century. Darwinism ultimately won, leading to what biologists refer to as the Modern Synthesis. The theory denies that acquired characteristics can be passed down and instead argues that organisms evolve through the selective action of environment factors, such as Natural Selection.
While Lamarck supported the notion of inheritance through acquired characters, and his contemporaries also offered a few words about this idea, it was never an integral part of any of their evolutionary theorizing. This is largely due 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 genomics there is a huge body of evidence supporting the possibility of inheritance of acquired traits. This is often called "neo-Lamarckism" or more often, epigenetic inheritance. This is a model that is as reliable as the popular neodarwinian model.
Evolution by adaptation
One of the most widespread misconceptions about evolution is that it is driven by a type of struggle for survival. This view is inaccurate and overlooks other forces that drive evolution. The fight for survival can be more accurately described as a struggle to survive within a particular environment, which can be a struggle that involves not only other organisms, but as well the physical environment.
To understand how evolution operates it is beneficial to think about what adaptation is. My Source is any feature that allows living organisms to survive in its environment and reproduce. It could be a physiological feature, such as feathers or fur or a behavior like moving into the shade in hot weather or stepping out at night to avoid the cold.
The ability of an organism to extract energy from its environment and interact with other organisms and their physical environments is essential to its survival. The organism must possess the right genes to produce offspring, and must be able to access enough food and other resources. Furthermore, the organism needs to be capable of reproducing itself in a way that is optimally within its niche.
These elements, in conjunction with gene flow and mutation result in changes in the ratio of alleles (different forms of a gene) in the gene pool of a population. The change in frequency of alleles could lead to the development of new traits, and eventually new species over time.
Many of the features we appreciate in animals and plants are adaptations. For instance the lungs or gills which draw oxygen from air feathers and fur for insulation and long legs to get away from predators, and camouflage to hide. To understand the concept of adaptation, it is important to discern between physiological and behavioral characteristics.
Physiological adaptations like the thick fur or gills are physical traits, while behavioral adaptations, like the tendency to seek out friends or to move to shade in hot weather, are not. In addition, it is important to remember that a lack of forethought is not a reason to make something an adaptation. Inability to think about the implications of a choice, even if it appears to be rational, may cause it to be unadaptive.