What is Free Evolution?
Free evolution is the notion that natural processes can lead to the development of organisms over time. This includes the appearance and growth of new species.
Numerous examples have been offered of this, including various varieties of fish called sticklebacks that can live in salt or fresh water, and walking stick insect varieties that prefer specific host plants. These mostly reversible traits permutations are not able to explain fundamental changes to the basic body plan.
Evolution by Natural Selection
The development of the myriad of living creatures on Earth is an enigma that has fascinated scientists for decades. Charles Darwin's natural selection theory is the best-established explanation. This happens when individuals who are better-adapted are able to reproduce faster and longer than those who are less well-adapted. Over time, the population of individuals who are well-adapted grows and eventually develops into a new species.
Natural selection is an ongoing process that is characterized by the interaction of three factors including inheritance, variation, and reproduction. Sexual reproduction and mutation increase genetic diversity in a species. Inheritance is the transfer of a person's genetic traits to the offspring of that person which includes both recessive and dominant alleles. Reproduction is the process of producing viable, fertile offspring, which includes both asexual and sexual methods.
All of these factors must be in harmony for natural selection to occur. If, for example an allele of a dominant gene allows an organism to reproduce and last longer than the recessive gene allele, then the dominant allele will become more prevalent in a group. If the allele confers a negative advantage to survival or reduces the fertility of the population, it will disappear. The process is self-reinforcing, meaning that a species with a beneficial trait will survive and reproduce more than one with an unadaptive trait. The more fit an organism is, measured by its ability reproduce and survive, is the greater number of offspring it will produce. People with desirable characteristics, such as having a long neck in the giraffe, or bright white color patterns on male peacocks are more likely to others to reproduce and survive and eventually lead to them becoming the majority.
Natural selection is a factor in populations and not on individuals. This is an important distinction from the Lamarckian theory of evolution, which states that animals acquire traits by use or inactivity. For instance, if a giraffe's neck gets longer through stretching to reach prey, its offspring will inherit a longer neck. The difference in neck size between generations will continue to increase until the giraffe is unable to reproduce with other giraffes.
Evolution through Genetic Drift
Genetic drift occurs when the alleles of one gene are distributed randomly within a population. In the end, only one will be fixed (become widespread enough to not longer be eliminated through natural selection), and the rest of the alleles will drop in frequency. This can lead to an allele that is dominant at the extreme. Other alleles have been essentially eliminated and heterozygosity has diminished to a minimum. In a small population, this could lead to the total elimination of the recessive allele. This is known as the bottleneck effect. It is typical of an evolutionary process that occurs whenever a large number individuals migrate to form a population.
A phenotypic bottleneck may also occur when the survivors of a disaster like an outbreak or mass hunting event are confined to a small area. The surviving individuals are likely to be homozygous for the dominant allele, which means that they will all have the same phenotype and consequently have the same fitness traits. 무료에볼루션 could be caused by earthquakes, war or even plagues. The genetically distinct population, if it is left vulnerable to genetic drift.
Walsh Lewens, Walsh, and Ariew define drift as a departure from the expected values due to differences in fitness. They give the famous example of twins who are both genetically identical and have exactly the same phenotype. However one is struck by lightning and dies, while the other is able to reproduce.
This kind of drift can be very important in the evolution of a species. This isn't the only method for evolution. The main alternative is a process called natural selection, where the phenotypic diversity of a population is maintained by mutation and migration.
Stephens claims that there is a significant difference between treating the phenomenon of drift as a force or cause, and treating other causes like selection mutation and migration as forces and causes. Stephens claims that a causal process model of drift allows us to separate it from other forces and this distinction is essential. He also argues that drift has a direction: that is it tends to reduce heterozygosity. It also has a specific magnitude that is determined by population size.
Evolution by Lamarckism
In high school, students take biology classes, they are frequently introduced to the work of Jean-Baptiste Lamarck (1744 - 1829). His theory of evolution is commonly called "Lamarckism" and it states that simple organisms grow into more complex organisms via the inheritance of characteristics which result from an organism's natural activities use and misuse. Lamarckism can be illustrated by an giraffe's neck stretching to reach higher leaves in the trees. This causes the necks of giraffes that are longer to be passed onto their offspring who would then grow even taller.
Lamarck was a French zoologist and, in his inaugural lecture for his course on invertebrate zoology held at the Museum of Natural History in Paris on the 17th of May in 1802, he introduced an original idea that fundamentally challenged the conventional wisdom about organic transformation. In his opinion living things evolved from inanimate matter via a series of gradual steps. Lamarck wasn't the first to propose this but he was considered to be the first to give the subject a comprehensive and general explanation.
The popular narrative is that Lamarckism grew into an opponent to Charles Darwin's theory of evolution by natural selection, and that the two theories battled each other in the 19th century. Darwinism eventually won and led to the creation of what biologists now call the Modern Synthesis. The Modern Synthesis theory denies that acquired characteristics can be inherited and instead, it argues that organisms develop by the symbiosis of environmental factors, like natural selection.
Lamarck and his contemporaries supported the idea that acquired characters could be passed down to future generations. However, this concept was never a central part of any of their theories on evolution. This is due in part to the fact that it was never tested scientifically.
But it is now more than 200 years since Lamarck was born and, in the age of genomics there is a vast amount of evidence to support the possibility of inheritance of acquired traits. This is referred to as "neo Lamarckism", or more commonly epigenetic inheritance. This is a model that is as valid as the popular Neodarwinian model.
Evolution by Adaptation
One of the most popular misconceptions about evolution is that it is being driven by a struggle to survive. In fact, this view misrepresents natural selection and ignores the other forces that are driving evolution. The fight for survival can be more effectively described as a struggle to survive in a specific environment, which can include not just other organisms but also the physical environment.
Understanding adaptation is important to understand evolution. Adaptation is any feature that allows living organisms to survive in its environment and reproduce. It can be a physical feature, like feathers or fur. It could also be a behavior trait, like moving to the shade during hot weather, or moving out to avoid the cold at night.
The survival of an organism is dependent on its ability to obtain energy from the environment and to interact with other living organisms and their physical surroundings. The organism must have the right genes to generate offspring, and it must be able to find enough food and other resources. The organism should also be able to reproduce itself at the rate that is suitable for its specific niche.
These elements, along with mutations and gene flow can result in a shift in the proportion of different alleles within the gene pool of a population. This shift in the frequency of alleles can result in the emergence of new traits, and eventually new species as time passes.
Many of the features we find appealing in animals and plants are adaptations. For instance the lungs or gills which extract oxygen from air, fur and feathers as insulation and long legs to get away from predators and camouflage for hiding. To understand adaptation it is crucial to discern between physiological and behavioral traits.
Physiological adaptations like the thick fur or gills are physical traits, whereas behavioral adaptations, like the tendency to seek out companions or to retreat to the shade during hot weather, aren't. Additionally it is important to understand that a lack of thought is not a reason to make something an adaptation. Failure to consider the implications of a choice even if it appears to be logical, can make it unadaptive.