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 creation of new species as well as the alteration of the appearance of existing species.
This has been proven by numerous examples such as the stickleback fish species that can thrive in salt or fresh water, and walking stick insect varieties that prefer specific host plants. These are mostly reversible traits however, are not able to be the reason for fundamental changes in body plans.
Evolution through Natural Selection
The development of the myriad of living creatures on Earth is an enigma that has intrigued scientists for centuries. The most widely accepted explanation is Charles Darwin's natural selection, an evolutionary process that occurs when better-adapted individuals survive and reproduce more effectively than those less well-adapted. Over time, the population of well-adapted individuals grows and eventually develops into a new species.
Natural selection is a process that is cyclical and involves the interaction of three factors: variation, reproduction and inheritance. Variation is caused by mutation and sexual reproduction, both of which increase the genetic diversity of the species. Inheritance is the passing of a person's genetic traits to his or her offspring, which includes both dominant and recessive alleles. Reproduction is the process of producing viable, fertile offspring. This can be done by both asexual or sexual methods.
Natural selection only occurs when all the factors are in equilibrium. If, for example, a dominant gene allele causes an organism reproduce and last longer than the recessive gene The dominant allele will become more prevalent in a population. If the allele confers a negative survival advantage or decreases the fertility of the population, it will be eliminated. This process is self-reinforcing which means that an organism with a beneficial trait is more likely to survive and reproduce than an individual with a maladaptive trait. The higher the level of fitness an organism has which is measured by its ability to reproduce and endure, is the higher number of offspring it will produce. Individuals with favorable characteristics, like having a longer neck in giraffes, or bright white color patterns in male peacocks are more likely to survive and have offspring, and thus will become the majority of the population in the future.
Natural selection is only a force for populations, not on individuals. This is a significant distinction from the Lamarckian theory of evolution which holds that animals acquire traits either through usage or inaction. For example, if a giraffe's neck gets longer through stretching to reach for prey and its offspring will inherit a longer neck. The length difference between generations will continue until the neck of the giraffe becomes so long that it can not breed with other giraffes.
Evolution through Genetic Drift
Genetic drift occurs when alleles from a gene are randomly distributed in a group. In the end, one will reach fixation (become so common that it can no longer be eliminated through natural selection) and the other alleles drop to lower frequency. This can lead to an allele that is dominant in the extreme. The other alleles are eliminated, and heterozygosity falls to zero. In a small number of people this could lead to the complete elimination of the recessive gene. Such a scenario would be called a bottleneck effect, and it is typical of the kind of evolutionary process that occurs when a large amount of individuals migrate to form a new population.
A phenotypic bottleneck may also occur when the survivors of a disaster like an outbreak or mass hunting event are concentrated in a small area. The survivors will carry an allele that is dominant and will share the same phenotype. This may be caused by a war, an earthquake or even a disease. Regardless of the cause the genetically distinct population that remains is susceptible to genetic drift.
Walsh, Lewens and Ariew define drift as a deviation from the expected value due to differences in fitness. They cite a famous example of twins that are genetically identical, have the exact same phenotype and yet one is struck by lightning and dies, while the other lives and reproduces.
This kind of drift could be very important in the evolution of an entire species. But, it's not the only method to develop. The most common alternative is a process called natural selection, in which phenotypic variation in a population is maintained by mutation and migration.
Stephens asserts that there is a major difference between treating the phenomenon of drift as a force, or an underlying cause, and treating other causes of evolution such as selection, mutation and migration as causes or causes. He argues that a causal mechanism account of drift allows us to distinguish it from these other forces, and that this distinction is vital. He also argues that drift has both direction, i.e., it tends towards eliminating heterozygosity. It also has a size, that is determined by population size.
Evolution by Lamarckism
Biology students in high school are frequently exposed to Jean-Baptiste lamarck's (1744-1829) work. His theory of evolution is commonly referred to as "Lamarckism" and it asserts that simple organisms evolve into more complex organisms through the inherited characteristics which result from the organism's natural actions use and misuse. Lamarckism can be illustrated by the giraffe's neck being extended to reach higher leaves in the trees. This would cause the longer necks of giraffes to be passed to their offspring, who would grow taller.
Lamarck Lamarck, a French Zoologist from France, presented an idea that was revolutionary in his opening lecture at the Museum of Natural History of Paris. He challenged traditional thinking about organic transformation. In his view, living things had evolved from inanimate matter via a series of gradual steps. Lamarck wasn't the first to suggest this but he was considered to be the first to offer the subject a comprehensive and general explanation.
The dominant story is that Charles Darwin's theory of natural selection and Lamarckism were rivals in the 19th century. Darwinism eventually won and led to the creation of what biologists refer to as the Modern Synthesis. The Modern Synthesis theory denies the possibility that acquired traits can be inherited, and instead suggests that organisms evolve through the selective action of environmental factors, like natural selection.
While Lamarck endorsed the idea of inheritance through acquired characters and his contemporaries also spoke of this idea, it was never a major feature in any of their theories about evolution. This is due in part to the fact that it was never validated scientifically.
It's been over 200 year since Lamarck's birth and in the field of genomics, there is an increasing evidence-based body of evidence to support the heritability acquired characteristics. This is sometimes referred to as "neo-Lamarckism" or, more commonly, epigenetic inheritance. It is a version of evolution that is as relevant as the more popular neo-Darwinian model.
Evolution through Adaptation
One of the most popular misconceptions about evolution is that it is driven by a type of struggle for survival. This is a false assumption and ignores other forces driving evolution. The struggle for survival is more accurately described as a struggle to survive in a specific environment, which may include not just other organisms, but as well the physical environment.
Understanding the concept of adaptation is crucial to understand evolution. The term "adaptation" refers to any characteristic that allows living organisms to survive in its environment and reproduce. It could be a physiological feature, like feathers or fur or a behavior like moving into shade in hot weather or coming out at night to avoid cold.
The survival of an organism depends on its ability to draw energy from the environment and to interact with other living organisms and their physical surroundings. The organism needs to have the right genes to produce offspring, and it must be able to access enough food and other resources. The organism should also be able to reproduce itself at a rate that is optimal for its specific niche.
These factors, along with gene flow and mutation result in a change in the proportion of alleles (different forms of a gene) in a population's gene pool. This shift in the frequency of alleles can lead to the emergence of new traits, and eventually, new species over time.
A lot of the traits we admire in animals and plants are adaptations. For discover here , lungs or gills that draw oxygen from air, fur and feathers as insulation, long legs to run away from predators, and camouflage to hide. To understand the concept of adaptation, it is important to distinguish between behavioral and physiological traits.
Physiological traits like the thick fur and gills are physical traits. Behavior adaptations aren't like the tendency of animals to seek companionship or move into the shade in hot weather. It is also important to remember that a the absence of planning doesn't make an adaptation. A failure to consider the consequences of a decision even if it appears to be rational, may make it unadaptive.