It's The Good And Bad About Free Evolution
What is Free Evolution?
Free evolution is the idea that natural processes can cause organisms to develop over time. This includes the appearance and growth of new species.
Many examples have been given of this, including various varieties of fish called sticklebacks that can live in fresh or salt water and walking stick insect varieties that are attracted to specific host plants. These are mostly reversible traits, however, cannot explain fundamental changes in basic body plans.
Evolution through Natural Selection
Scientists have been fascinated by the evolution of all living creatures that live on our planet for ages. The best-established explanation is Darwin's natural selection, a process that occurs when individuals that are better adapted survive and reproduce more effectively than those who are less well-adapted. Over time, a community of well adapted individuals grows and eventually forms a whole new species.
Natural selection is a process that is cyclical and involves the interaction of 3 factors: variation, reproduction and inheritance. Variation is caused by mutation and sexual reproduction, both of which increase the genetic diversity within a species. Inheritance is the passing of a person's genetic characteristics to their offspring, which includes both dominant and recessive alleles. Reproduction is the process of generating viable, fertile offspring. This can be done through sexual or asexual methods.
All of these variables have to be in equilibrium to allow natural selection to take place. For 에볼루션 바카라 체험 when the dominant allele of the gene allows an organism to live and reproduce more often than the recessive allele the dominant allele will be more prominent in the population. However, if the allele confers an unfavorable survival advantage or reduces fertility, it will disappear from the population. The process is self-reinforcing, which means that an organism with a beneficial trait is more likely to survive and reproduce than an individual with an unadaptive trait. The higher the level of fitness an organism has, measured by its ability reproduce and survive, is the more offspring it can produce. People with good traits, like having a long neck in Giraffes, or the bright white color patterns on male peacocks are more likely than others to live and reproduce, which will eventually lead to them becoming the majority.
Natural selection is only a force for populations, not individuals. This is a significant distinction from the Lamarckian theory of evolution, which argues that animals acquire characteristics through use or neglect. If a giraffe stretches its neck to reach prey, and the neck becomes longer, then its children will inherit this characteristic. The difference in neck size between generations will increase until the giraffe is no longer able to breed with other giraffes.
Evolution by Genetic Drift
In the process of genetic drift, alleles within a gene can attain different frequencies in a population through random events. At some point, one will attain fixation (become so common that it can no longer be eliminated by natural selection) and other alleles fall to lower frequencies. This can result in an allele that is dominant at the extreme. The other alleles are eliminated, and heterozygosity is reduced to zero. In a small population it could lead to the total elimination of recessive allele. Such a scenario would be known as a bottleneck effect and it is typical of evolutionary process that takes place when a large number of people migrate to form a new group.
A phenotypic 'bottleneck' can also occur when survivors of a disaster such as an outbreak or mass hunt incident are concentrated in a small area. The surviving individuals will be largely homozygous for the dominant allele, which means that they will all share the same phenotype and will consequently share the same fitness characteristics. This can be caused by earthquakes, war or even a plague. The genetically distinct population, if it remains, could be susceptible to genetic drift.
Walsh Lewens, Walsh and Ariew define drift as a deviation from the expected value due to differences in fitness. They give a famous example of twins that are genetically identical and have identical phenotypes, but one is struck by lightning and dies, whereas the other lives and reproduces.
This kind of drift could play a crucial part in the evolution of an organism. However, it is not the only method to develop. Natural selection is the primary alternative, in which mutations and migration keep the phenotypic diversity in a population.
Stephens claims that there is a vast distinction between treating drift as an actual cause or force, and treating other causes like selection mutation and migration as forces and causes. He argues that a causal process account of drift permits us to differentiate it from these other forces, and this distinction is essential. He also argues that drift is a directional force: that is, it tends to eliminate heterozygosity. It also has a size, that is determined by the size of population.
Evolution by 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 is generally called "Lamarckism" and it asserts that simple organisms evolve into more complex organisms via the inheritance of characteristics that result from the organism's natural actions, use and disuse. Lamarckism is usually illustrated with the image of a giraffe stretching its neck further to reach leaves higher up in the trees. This causes the longer necks of giraffes to be passed on to their offspring who would then grow even taller.
Lamarck was a French zoologist and, in his lecture to begin his course on invertebrate zoology held at the Museum of Natural History in Paris on the 17th May 1802, he presented a groundbreaking concept that radically challenged previous thinking about organic transformation. According to Lamarck, living things evolved from inanimate matter by a series of 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 having given the subject its first general and comprehensive treatment.
The most popular story is that Lamarckism was an opponent to Charles Darwin's theory of evolutionary natural selection, and both theories battled it out in the 19th century. Darwinism ultimately prevailed and led to what biologists call the Modern Synthesis. This theory denies acquired characteristics can be passed down and instead argues that organisms evolve through the selective action of environment factors, including Natural Selection.
Lamarck and his contemporaries believed in the idea that acquired characters could be passed down to future generations. However, this notion was never a major part of 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 age genomics, there is an increasing evidence-based body of evidence to support the heritability-acquired characteristics. It is sometimes called "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 common misconceptions about evolution is that it is driven by a type of struggle to survive. In fact, this view is inaccurate and overlooks the other forces that are driving evolution. The fight for survival can be more accurately described as a struggle to survive in a certain environment. This may include not only other organisms as well as the physical environment.
Understanding adaptation is important to comprehend evolution. It refers to a specific feature that allows an organism to live and reproduce within its environment. It could be a physiological feature, such as fur or feathers, or a behavioral trait like moving into the shade in hot weather or stepping out at night to avoid the cold.
The survival of an organism depends on its ability to obtain energy from the surrounding environment and interact with other organisms and their physical environments. The organism must have the right genes to produce offspring, and it must be able to locate enough food and other resources. In addition, the organism should be able to reproduce itself at an optimal rate within its niche.
These factors, along with gene flow and mutation can result in an alteration in the percentage of alleles (different forms of a gene) in a population's gene pool. Over time, this change in allele frequency can lead to the emergence of new traits and ultimately new species.
A lot of the traits we admire about animals and plants are adaptations, for example, lung or gills for removing oxygen from the air, feathers or fur to protect themselves and long legs for running away from predators, and camouflage for hiding. To understand the concept of adaptation it is crucial to distinguish between behavioral and physiological characteristics.
Physical characteristics like the thick fur and gills are physical characteristics. Behavior adaptations aren't, such as the tendency of animals to seek out companionship or retreat into shade in hot temperatures. It is also important to remember that a insufficient planning does not make an adaptation. A failure to consider the implications of a choice even if it appears to be logical, can cause it to be unadaptive.