What is Free Evolution?
Free evolution is the notion that the natural processes that organisms go through can cause them to develop over time. This includes the emergence and development of new species.
Numerous examples have been offered of this, including various varieties of fish called sticklebacks that can be found in salt or fresh water, and walking stick insect varieties that are attracted to specific host plants. These mostly reversible trait permutations however, are not able to explain fundamental changes in body plans.
Evolution by Natural Selection
The development of the myriad living organisms on Earth is an enigma that has fascinated scientists for decades. The most well-known explanation is Darwin's natural selection, an evolutionary process that is triggered when more well-adapted individuals live longer and reproduce more effectively than those less well-adapted. Over time, the population of individuals who are well-adapted grows and eventually creates an entirely new species.
Natural selection is a cyclical process that involves the interaction of three factors: variation, inheritance and reproduction. Sexual reproduction and mutations increase the genetic diversity of a species. Inheritance is the transfer of a person's genetic traits to his or her offspring which includes both dominant and recessive alleles. Reproduction is the production of fertile, viable offspring, which includes both sexual and asexual methods.
Natural selection can only occur when all of these factors are in equilibrium. If, for example an allele of a dominant gene makes an organism reproduce and last longer than the recessive gene allele The dominant allele is more prevalent in a group. But if the allele confers a disadvantage in survival or reduces fertility, it will be eliminated from the population. The process is self-reinforced, which means that an organism with a beneficial trait is more likely to survive and reproduce than an individual with a maladaptive characteristic. The more offspring that an organism has, the greater its fitness which is measured by its capacity to reproduce itself and survive. People with good characteristics, like a longer neck in giraffes and bright white patterns of color in male peacocks, are more likely to survive and produce offspring, which means they will become the majority of the population over time.
Natural selection only affects populations, not individuals. This is a major distinction from the Lamarckian evolution theory that states that animals acquire traits due to usage or inaction. If a giraffe stretches its neck to reach prey and its neck gets longer, then the offspring will inherit this characteristic. The differences in neck length between generations will persist until the giraffe's neck gets too long to not breed with other giraffes.
Evolution by Genetic Drift
Genetic drift occurs when the alleles of one gene are distributed randomly in a population. Eventually, one of them will attain fixation (become so widespread that it cannot be eliminated through natural selection) and other alleles will fall to lower frequencies. In the extreme, this leads to a single allele dominance. The other alleles have been virtually eliminated and heterozygosity been reduced to zero. In a small group it could lead to the total elimination of recessive allele. This is called a bottleneck effect, and it is typical of evolutionary process that occurs when a large number of individuals move to form a new population.
A phenotypic bottleneck may occur when survivors of a disaster like an epidemic or a massive hunting event, are condensed in a limited area. The survivors will have an dominant allele, and will have the same phenotype. This can be caused by war, earthquakes or even a plague. The genetically distinct population, if it is left, could be susceptible to genetic drift.
Walsh Lewens, Walsh and Ariew define drift as a departure from the expected values due to differences in fitness. They provide the famous case of twins that are genetically identical and share the same phenotype. However, one is struck by lightning and dies, while the other is able to reproduce.
This kind of drift could be very important in the evolution of the species. It's not the only method of evolution. The primary alternative is to use a process known as natural selection, in which the phenotypic diversity of the population is maintained through mutation and migration.
Stephens asserts that there is a huge distinction between treating drift as an agent or cause and treating other causes like migration and selection mutation as forces and causes. He claims that a causal process explanation of drift permits us to differentiate it from these other forces, and this distinction is crucial. He further argues that drift has both a direction, i.e., it tends to eliminate heterozygosity. It also has a size which is determined by the size of the population.
Evolution through Lamarckism
Biology students in high school are frequently introduced to Jean-Baptiste Lamarck's (1744-1829) work. His theory of evolution, often called "Lamarckism which means that simple organisms develop into more complex organisms through inheriting characteristics that are a product of an organism's use and disuse. Lamarckism can be demonstrated by an giraffe's neck stretching to reach higher levels of leaves in the trees. This causes giraffes' longer necks to be passed onto their offspring who would then grow even taller.
Lamarck the French Zoologist, introduced an innovative idea in his 17 May 1802 opening lecture at the Museum of Natural History of Paris. He challenged the conventional wisdom on organic transformation. According to Lamarck, living creatures evolved from inanimate material through a series of gradual steps. Lamarck was not the first to propose this, but he was widely considered to be the first to provide the subject a comprehensive and general treatment.
The popular narrative is that Lamarckism became a rival to Charles Darwin's theory of evolutionary natural selection, and both theories battled it out in the 19th century. Darwinism eventually triumphed and led to the development of what biologists today refer to as the Modern Synthesis. This theory denies acquired characteristics can be passed down through generations and instead argues that organisms evolve through the selective action of environment factors, such as Natural Selection.
에볼루션 바카라 무료 Evolution KR and his contemporaries supported the idea that acquired characters could be passed down to future generations. However, this notion 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 year since Lamarck's birth, and in the age genomics, there is an increasing body of evidence that supports the heritability-acquired characteristics. It is sometimes referred to as "neo-Lamarckism" or more often epigenetic inheritance. It is a variant of evolution that is just as relevant as the more popular Neo-Darwinian theory.
Evolution through adaptation
One of the most popular misconceptions about evolution is that it is being driven by a fight for survival. In reality, this notion is a misrepresentation of natural selection and ignores the other forces that determine the rate of evolution. The struggle for survival is more accurately described as a struggle to survive within a specific environment, which may be a struggle that involves not only other organisms but also the physical environment itself.
Understanding the concept of adaptation is crucial to understand evolution. The term "adaptation" refers to any characteristic that allows a living organism to live in its environment and reproduce. It could be a physical structure, like feathers or fur. Or it can be a characteristic of behavior, like moving into the shade during the heat, or moving out to avoid the cold at night.
The capacity of an organism to draw energy from its surroundings and interact with other organisms and their physical environment, is crucial to its survival. The organism needs to have the right genes to generate offspring, and it must be able to locate enough food and other resources. Furthermore, the organism needs to be capable of reproducing itself at a high rate within its environmental niche.
These factors, together with gene flow and mutations can result in changes in the proportion of different alleles within the gene pool of a population. Over time, this change in allele frequencies could result in the development of new traits and ultimately new species.
Many of the features that we admire in animals and plants are adaptations, for example, lung or gills for removing oxygen from the air, feathers or fur to protect themselves long legs to run away from predators and camouflage to hide. To understand adaptation it is essential to differentiate between physiological and behavioral traits.
Physical characteristics like the thick fur and gills are physical traits. Behavior adaptations aren't like the tendency of animals to seek companionship or to retreat into the shade in hot temperatures. It is also important to remember that a the absence of planning doesn't make an adaptation. In fact, failing to think about the implications of a choice can render it unadaptable even though it appears to be sensible or even necessary.