What is Free Evolution?
Free evolution is the notion that the natural processes of living organisms can lead to their development over time. This includes the evolution of new species and the change in appearance of existing species.
This has been demonstrated by many examples of stickleback fish species that can live in fresh or saltwater and walking stick insect species that prefer particular host plants. These reversible traits are not able to explain fundamental changes to the body's basic plans.
Evolution through Natural Selection
The evolution of the myriad living creatures on Earth is a mystery that has fascinated scientists for decades. The most well-known explanation is that of Charles Darwin's natural selection, which occurs when better-adapted individuals survive and reproduce more effectively than those who are less well adapted. Over time, a population 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 that are: reproduction, variation and inheritance. Variation is caused by mutations and sexual reproduction both of which increase the genetic diversity within the species. Inheritance is the passing of a person's genetic traits to his or her offspring which includes both recessive and dominant alleles. Reproduction is the process of generating viable, fertile offspring. This can be achieved through sexual or asexual methods.
original site of these factors must be in harmony to allow natural selection to take place. If, for instance an allele of a dominant gene allows an organism to reproduce and last longer than the recessive gene allele The dominant allele is more prevalent in a population. If the allele confers a negative advantage to survival or lowers the fertility of the population, it will be eliminated. This process is self-reinforcing meaning that a species that has a beneficial trait will survive and reproduce more than an individual with a maladaptive characteristic. The more fit an organism is as measured by its capacity to reproduce and survive, is the greater number of offspring it will produce. People with desirable traits, like having a longer neck in giraffes, or bright white colors in male peacocks are more likely to be able to survive and create offspring, and thus will become the majority of the population over time.
Natural selection only affects populations, not on individual organisms. This is an important distinction from the Lamarckian theory of evolution which claims that animals acquire traits through use or disuse. If a giraffe stretches its neck in order to catch prey, and the neck becomes larger, then its offspring will inherit this characteristic. The length difference between generations will persist until the neck of the giraffe becomes too long to not breed with other giraffes.
Evolution through Genetic Drift
In the process of genetic drift, alleles within a gene can attain different frequencies in a group through random events. Eventually, one of them will attain fixation (become so common that it cannot be removed through natural selection) and the other alleles drop to lower frequencies. This can lead to dominance at the extreme. The other alleles are eliminated, and heterozygosity decreases to zero. In a small group, this could result in the complete elimination of recessive gene. This scenario is called the bottleneck effect and is typical of the evolution process that occurs when an enormous number of individuals move to form a population.
A phenotypic bottleneck may also occur when the survivors of a disaster like an outbreak or mass hunt event are confined to the same area. The remaining individuals will be largely homozygous for the dominant allele which means that they will all share the same phenotype and therefore have the same fitness characteristics. This situation could be caused by war, earthquakes, or even plagues. The genetically distinct population, if it is left vulnerable to genetic drift.
Walsh Lewens, Walsh, and Ariew define drift as a deviation from expected values due to differences in fitness. They cite the famous example of twins that are genetically identical and share the same phenotype, but one is struck by lightning and dies, but the other continues to reproduce.
This type of drift can play a very important part in the evolution of an organism. However, it is not the only way to develop. The primary alternative is to use a process known as natural selection, in which phenotypic variation in a population is maintained by mutation and migration.
Stephens claims that there is a big difference between treating the phenomenon of drift as a force, or a cause and treating 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 to distinguish it from other forces, and that this distinction is crucial. He argues further that drift has both an orientation, i.e., it tends towards eliminating heterozygosity. It also has a size which is determined based on the size of the population.
Evolution by Lamarckism
Students of biology in high school are frequently exposed to Jean-Baptiste lamarck's (1744-1829) work. His theory of evolution is generally referred to as "Lamarckism" and it states that simple organisms develop into more complex organisms via the inherited characteristics which result from an organism's natural activities usage, use and disuse. Lamarckism can be demonstrated by an giraffe's neck stretching to reach higher branches in the trees. This would result in giraffes passing on their longer necks to their offspring, who would then become taller.
Lamarck was a French zoologist and, in his lecture to begin his course on invertebrate zoology at the Museum of Natural History in Paris on the 17th May 1802, he introduced an original idea that fundamentally challenged the conventional wisdom about organic transformation. According to Lamarck, living things evolved from inanimate materials through a series gradual steps. Lamarck was not the only one to suggest that this could be the case, but the general consensus is that he was the one giving the subject its first general and comprehensive treatment.
The most popular story is that Charles Darwin's theory of natural selection and Lamarckism fought in the 19th century. Darwinism eventually triumphed and led to the creation of what biologists refer to as the Modern Synthesis. The Modern Synthesis theory denies that acquired characteristics can be acquired through inheritance and instead argues that organisms evolve through the selective action of environmental factors, like natural selection.
Although Lamarck endorsed the idea of inheritance by acquired characters and his contemporaries paid lip-service to this notion, it was never a central element in any of their evolutionary theories. This is largely due to the fact that it was never validated scientifically.
But it is now more than 200 years since Lamarck was born and in the age of genomics there is a huge body of evidence supporting the heritability of acquired characteristics. This is referred to as "neo Lamarckism", or more often epigenetic inheritance. This is a model that is as reliable as the popular neodarwinian model.
Evolution through Adaptation
One of the most popular misconceptions about evolution is that it is driven by a type of struggle for survival. In fact, this view is inaccurate and overlooks the other forces that determine the rate of evolution. The struggle for existence is better described as a struggle to survive in a certain environment. This may be a challenge for not just other living things, but also the physical environment.
Understanding adaptation is important to comprehend evolution. Adaptation refers to any particular characteristic that allows an organism to live and reproduce in its environment. It can be a physiological feature, like feathers or fur, or a behavioral trait, such as moving into the shade in hot weather or coming out at night to avoid cold.
An organism's survival depends on its ability to draw energy from the environment and interact with other living organisms and their physical surroundings. The organism must 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 at a high rate within its environmental niche.
These factors, together with mutations and gene flow, can lead to changes in the proportion 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 features that we admire in animals and plants are adaptations, for example, the lungs or gills that extract oxygen from the air, feathers or fur to protect themselves, long legs for running away from predators and camouflage for hiding. However, a proper understanding of adaptation requires attention to the distinction between behavioral and physiological traits.
Physical traits such as large gills and thick fur are physical traits. Behavior adaptations aren't an exception, for instance, the tendency of animals to seek companionship or to retreat into the shade in hot weather. In addition, it is important to note that lack of planning does not mean that something is an adaptation. Inability to think about the effects of a behavior, even if it appears to be logical, can make it unadaptive.