What is Free Evolution?
Free evolution is the concept that natural processes can cause organisms to develop over time. This includes the appearance and growth of new species.
A variety of examples have been provided of this, including various varieties of stickleback fish that can live in fresh or salt water and walking stick insect varieties that prefer specific host plants. These reversible traits however, are not able to explain fundamental changes in basic body plans.
Evolution by Natural Selection
Scientists have been fascinated by the development of all living creatures that live on our planet for centuries. Charles Darwin's natural selection is the most well-known explanation. This process occurs when individuals who are better-adapted survive and reproduce more than those who are less well-adapted. Over time, a population of well adapted individuals grows and eventually becomes a new species.
Natural selection is an ongoing process and involves the interaction of three factors including reproduction, variation and inheritance. Variation is caused by mutation and sexual reproduction, both of which increase the genetic diversity of the species. Inheritance is the term used to describe the transmission of genetic traits, including both dominant and recessive genes and their offspring. Reproduction is the production of viable, fertile offspring, which includes both asexual and sexual methods.
Natural selection can only occur when all the factors are in harmony. If, for example an allele of a dominant gene causes an organism reproduce and last longer than the recessive gene allele, then the dominant allele will become more common in a population. If the allele confers a negative advantage to survival or lowers the fertility of the population, it will go away. This process is self-reinforcing meaning that a species that has a beneficial trait can reproduce and survive longer than one with an unadaptive trait. The more offspring an organism can produce, the greater its fitness, which is measured by its ability to reproduce and survive. People with desirable characteristics, like a longer neck in giraffes or bright white color patterns in male peacocks are more likely to survive and have offspring, which means they will eventually make up the majority of the population over time.
Natural selection is only an aspect of populations and not on individuals. This is a significant distinction from the Lamarckian theory of evolution which argues that animals acquire traits through use or neglect. For instance, if the giraffe's neck gets longer through stretching to reach prey, its offspring will inherit a larger neck. The difference 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 at a gene may be at different frequencies in a population due to random events. In the end, only one will be fixed (become common enough to no longer be eliminated through natural selection) and the rest of the alleles will drop in frequency. This could lead to an allele that is dominant in extreme. The other alleles are essentially eliminated, and heterozygosity is reduced to zero. In a small number of people it could lead to the total elimination of recessive alleles. 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 group.
A phenotypic bottleneck may also occur when survivors of a disaster like an outbreak or a mass hunting event are concentrated in an area of a limited size. The survivors will be mostly homozygous for the dominant allele which means that they will all share the same phenotype and therefore have the same fitness characteristics. This may be caused by a war, an earthquake or even a disease. The genetically distinct population, if left susceptible to genetic drift.
Walsh Lewens, Lewens, and Ariew utilize Lewens, Walsh and Ariew employ a "purely outcome-oriented" definition of drift as any deviation from the expected values of differences in fitness. They cite the famous example of twins who are genetically identical and have exactly the same phenotype. However, one is struck by lightning and dies, but the other continues to reproduce.
This type of drift can play a significant part in the evolution of an organism. This isn't the only method of evolution. Natural selection is the primary alternative, where mutations and migration maintain the phenotypic diversity of the population.
Stephens argues that there is a big difference between treating drift as a force or a cause and treating other causes of evolution, such as selection, mutation and migration as causes or causes. He argues that a causal-process account of drift allows us distinguish it from other forces and this differentiation is crucial. He further argues that drift is a directional force: that is it tends to reduce heterozygosity, and that it also has a specific magnitude which is determined by the size of the population.
Evolution through Lamarckism
When high school students take biology classes, they are frequently introduced to the work of Jean-Baptiste Lamarck (1744 - 1829). His theory of evolution, commonly referred to as “Lamarckism” which means that simple organisms transform into more complex organisms taking on traits that are a product of the use and abuse of an organism. Lamarckism is usually illustrated with a picture of a giraffe stretching its neck to reach the higher branches in the trees. This would cause giraffes to give their longer necks to their offspring, which then grow even 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 the 17th May 1802, he presented a groundbreaking concept that radically challenged the previous understanding of organic transformation. In his opinion living things had evolved from inanimate matter via the gradual progression of events. Lamarck wasn't the only one to propose this however he was widely considered to be the first to provide the subject a comprehensive and general treatment.
The most popular story is that Lamarckism was a rival to Charles Darwin's theory of evolution through natural selection and that the two theories fought each other in the 19th century. Darwinism ultimately prevailed, leading to what biologists refer to as the Modern Synthesis. The theory argues that acquired traits can be passed down through generations and instead argues organisms evolve by the selective influence of environmental elements, like Natural Selection.
While Lamarck believed in the concept of inheritance by acquired characters, and his contemporaries also paid lip-service to this notion but it was not a central element in any of their evolutionary theorizing. This is due in part to the fact that it was never validated scientifically.
It's been over 200 years since the birth of Lamarck, and in the age genomics, there is an increasing body of evidence that supports the heritability acquired characteristics. This is sometimes called "neo-Lamarckism" or, more frequently epigenetic inheritance. It is a form of evolution that is just as valid as the more well-known Neo-Darwinian model.
Evolution through the process of adaptation
One of the most common misconceptions about evolution is that it is driven by a sort of struggle for survival. This is a false assumption and overlooks other forces that drive evolution. The fight for survival can be more precisely described as a fight to survive within a particular environment, which could include not just other organisms, but as well the physical environment.
Understanding how adaptation works is essential to comprehend evolution. The term "adaptation" refers to any specific characteristic that allows an organism to live and reproduce within its environment. It could be a physical structure, like feathers or fur. Or click through the up coming website page can be a trait of behavior, like moving towards shade during hot weather or coming out to avoid the cold at night.
An organism's survival depends on its ability to draw energy from the environment and interact with other organisms and their physical environments. The organism must have the right genes to generate offspring, and must be able to access sufficient food and other resources. The organism should also be able to reproduce at the rate that is suitable for its specific niche.
These elements, in conjunction with gene flow and mutation can result in changes in the ratio of alleles (different varieties of a particular gene) in the gene pool of a population. Over time, this change in allele frequencies could lead to the emergence of new traits and ultimately new species.
A lot of the traits we find appealing in animals and plants are adaptations. For example lung or gills that extract oxygen from air feathers and fur as insulation, long legs to run away from predators and camouflage for hiding. However, a proper understanding of adaptation requires attention to the distinction between behavioral and physiological traits.
Physiological adaptations like the thick fur or gills are physical characteristics, whereas behavioral adaptations, such as the tendency to seek out companions or to move to shade in hot weather, are not. It is also important to keep in mind that lack of planning does not result in an adaptation. In fact, failing to consider the consequences of a behavior can make it unadaptive even though it might appear reasonable or even essential.