What is Free Evolution?
Free evolution is the notion that the natural processes of organisms can lead to their development over time. This includes the evolution of new species and the alteration of the appearance of existing ones.
Many examples have been given of this, such as different kinds of stickleback fish that can live in salt or fresh water, as well as walking stick insect varieties that are attracted to specific host plants. These reversible traits cannot explain fundamental changes to the body's basic plans.
Evolution by Natural Selection
The development of the myriad of living organisms on Earth is a mystery that has fascinated scientists for centuries. The most widely accepted explanation is Charles Darwin's natural selection, a process that occurs when better-adapted individuals survive and reproduce more successfully than those that are less well adapted. Over time, a community of well-adapted individuals expands and eventually creates a new species.
Natural selection is a process that is cyclical and involves the interaction of three factors including reproduction, variation and inheritance. Sexual reproduction and mutations increase genetic diversity in a species. Inheritance refers the transmission of a person's genetic traits, including both dominant and recessive genes to their offspring. Reproduction is the process of producing fertile, viable offspring. This can be accomplished through sexual or asexual methods.
All of these factors have to be in equilibrium to allow natural selection to take place. For instance the case where a dominant allele at the gene allows an organism to live and reproduce more frequently than the recessive one, the dominant allele will become more prevalent in the population. If the allele confers a negative advantage to survival or reduces the fertility of the population, it will be eliminated. The process is self-reinforcing, meaning that a species with a beneficial characteristic will survive and reproduce more than an individual with a maladaptive characteristic. The more offspring an organism produces the better its fitness that is determined by its capacity to reproduce and survive. Individuals with favorable characteristics, like having a longer neck in giraffes and bright white color patterns in male peacocks are more likely to be able to survive and create offspring, which means they will eventually make up the majority of the population in the future.
Natural selection only affects populations, not on individual organisms. This is a major distinction from the Lamarckian evolution theory which holds that animals acquire traits due to the use or absence of use. For instance, if a Giraffe's neck grows longer due to stretching to reach prey, its offspring will inherit a more long neck. The length difference between generations will persist until the giraffe's neck becomes too long that it can no longer breed with other giraffes.
Evolution by Genetic Drift
In genetic drift, the alleles of a gene could be at different frequencies in a population due to random events. Eventually, one of them will attain fixation (become so common that it can no longer be eliminated by natural selection), while the other alleles drop to lower frequencies. This could lead to an allele that is dominant in the extreme. The other alleles are essentially eliminated and heterozygosity has decreased to a minimum. In a small population, this could result in the complete elimination of the recessive gene. This scenario is 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 in a limited area. The remaining individuals will be largely homozygous for the dominant allele meaning that they all have the same phenotype and will consequently have the same fitness characteristics. This could be caused by war, an earthquake, or even a plague. The genetically distinct population, if it is left susceptible to genetic drift.
Walsh, Lewens, and Ariew employ Lewens, Walsh, and Ariew use a "purely outcome-oriented" definition of drift as any deviation from the expected values for different fitness levels. They cite a famous example of twins that are genetically identical, have the exact same phenotype and yet one is struck by lightening and dies while the other lives and reproduces.
This kind of drift can play a crucial part in the evolution of an organism. This isn't the only method of evolution. Natural selection is the most common alternative, where mutations and migrations maintain the phenotypic diversity of a population.
Stephens argues that there is a major distinction between treating 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 account of drift allows us distinguish it from other forces, and this differentiation is crucial. He also claims that drift is a directional force: that is it tends to eliminate heterozygosity. It also has a magnitude, that is determined by population size.
Evolution by Lamarckism
When students in high school take biology classes, they are frequently introduced to the work of Jean-Baptiste Lamarck (1744 - 1829). His theory of evolution is often called "Lamarckism" and it asserts that simple organisms evolve into more complex organisms by the inherited characteristics that result from the organism's natural actions use and misuse. Lamarckism can be demonstrated by an giraffe's neck stretching to reach higher branches in the trees. This causes the necks of giraffes that are longer to be passed on to their offspring who would then become taller.
Lamarck was a French zoologist and, in his inaugural lecture for his course on invertebrate zoology held at the Museum of Natural History in Paris on 17 May 1802, he introduced a groundbreaking concept that radically challenged the previous understanding of organic transformation. According Lamarck, living organisms evolved from inanimate materials through a series gradual steps. Lamarck was not the first to propose this, but he was widely considered to be the first to offer the subject a thorough and general overview.
The dominant story is that Charles Darwin's theory of evolution by natural selection and Lamarckism fought in the 19th Century. Darwinism eventually triumphed, leading to the development of what biologists call the Modern Synthesis. This theory denies the possibility that acquired traits can be acquired through inheritance and instead argues that organisms evolve through the selective action of environmental factors, including natural selection.
Lamarck and his contemporaries endorsed the notion that acquired characters could be passed down to the next generation. However, this idea was never a key element of any of their theories about evolution. This is largely due to the fact that it was never tested scientifically.
It's been more than 200 years since the birth of Lamarck and in the field of age genomics there is a growing evidence base that supports the heritability acquired characteristics. This is often referred to as "neo-Lamarckism" or more commonly epigenetic inheritance. This is a version that is just as valid as the popular Neodarwinian model.
Evolution by the process of adaptation
One of the most popular misconceptions about evolution is its being driven by a struggle to survive. This is a false assumption and ignores other forces driving evolution. The struggle for survival is more effectively described as a struggle to survive within a particular environment, which could involve not only other organisms but as well the physical environment.
Understanding the concept of adaptation is crucial to comprehend evolution. It refers to a specific feature that allows an organism to survive and reproduce within its environment. It could be a physical feature, like feathers or fur. Or it can be a trait of behavior that allows you to move to the shade during hot weather or coming out to avoid the cold at night.
The ability of an organism to draw energy from its environment and interact with other organisms and their physical environments, is crucial to its survival. The organism must possess the right genes to produce offspring and to be able to access sufficient food and resources. Moreover, the organism must be capable of reproducing in a way that is optimally within its environmental niche.
Recommended Website , together with mutation and gene flow, lead to an alteration in the percentage of alleles (different varieties of a particular gene) in the population's gene pool. The change in frequency of alleles can result in the emergence of new traits and eventually new species in the course of time.
Many of the features we find appealing in plants and animals are adaptations. For example the lungs or gills which extract oxygen from air feathers and fur for insulation long legs to run away from predators, and camouflage to hide. To comprehend adaptation, it is important to discern between physiological and behavioral traits.
Physiological adaptations like thick fur or gills, are physical traits, whereas behavioral adaptations, like the desire to find friends or to move into the shade in hot weather, are not. It is also important to remember that a the absence of planning doesn't make an adaptation. Inability to think about the implications of a choice even if it seems to be rational, could make it inflexible.