15 Top Documentaries About Free Evolution
What is Free Evolution?
Free evolution is the notion that the natural processes that organisms go through can lead to their development over time. This includes the development of new species and the alteration of the appearance of existing species.
A variety of examples have been provided of this, including different kinds of stickleback fish that can live in salt or fresh water, as well as walking stick insect varieties that favor specific host plants. These are mostly reversible traits can't, however, explain fundamental changes in body plans.
Evolution through Natural Selection
Scientists have been fascinated by the evolution of all living creatures that live on our planet for many centuries. The most well-known explanation is Charles Darwin's natural selection process, an evolutionary process that occurs when individuals that are better adapted survive and reproduce more effectively than those that are less well adapted. Over time, a population of well adapted individuals grows and eventually forms a whole new species.
Natural selection is an ongoing process and involves the interaction of 3 factors that are: reproduction, variation and inheritance. Variation is caused by mutations and sexual reproduction both of which increase the genetic diversity within an animal species. Inheritance refers to the passing of a person's genetic traits to their offspring that includes recessive and dominant alleles. Reproduction is the process of creating viable, fertile offspring. This can be accomplished through sexual or asexual methods.
Natural selection only occurs when all these elements are in equilibrium. If, for instance, a dominant gene allele causes an organism reproduce and last longer than the recessive gene then the dominant allele is more common in a population. If the allele confers a negative advantage to survival or decreases the fertility of the population, it will go away. This process is self-reinforcing meaning that a species with a beneficial characteristic will survive and reproduce more than an individual with a maladaptive characteristic. The more fit an organism is, measured by its ability reproduce and survive, is the more offspring it can produce. Individuals with favorable characteristics, like a longer neck in giraffes, or bright white patterns of color in male peacocks are more likely be able to survive and create offspring, and thus will make up the majority of the population in the future.
Natural selection is an element in the population and not on individuals. This is a crucial distinction from the Lamarckian theory of evolution, which states that animals acquire traits either through usage or inaction. For example, if a Giraffe's neck grows longer due to stretching to reach prey its offspring will inherit a more long neck. The difference in neck length between generations will continue until the giraffe's neck gets too long that it can not breed with other giraffes.
Evolution through Genetic Drift
In genetic drift, alleles within a gene can reach different frequencies in a population by chance events. At some point, only one of them will be fixed (become common enough to no longer be eliminated through natural selection), and the rest of the alleles will diminish in frequency. This could lead to a dominant allele in the extreme. The other alleles are essentially eliminated, and heterozygosity decreases to zero. In a small group, this could result in the complete elimination of the recessive gene. This scenario is called a bottleneck effect, and it is typical of evolutionary process that occurs when a lot of people migrate to form a new population.
A phenotypic bottleneck may also occur when the survivors of a disaster like an outbreak or a mass hunting incident are concentrated in the same area. The survivors will share a dominant allele and thus will share the same phenotype. This may be caused by conflict, earthquake or even a disease. 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 instance of twins who are genetically identical, share the exact same phenotype and yet one is struck by lightning and dies, while the other lives and reproduces.
This type of drift can play a significant role in the evolution of an organism. It is not the only method of evolution. Natural selection is the main alternative, in which mutations and migration maintain phenotypic diversity within the population.
Stephens asserts that there is a big difference between treating the phenomenon of drift as a force or as a cause and treating other causes of evolution, such as mutation, selection, and migration as forces or causes. He claims that a causal-process model of drift allows us to differentiate it from other forces and that this distinction is crucial. He also claims that drift has a direction: that is, it tends to eliminate heterozygosity, and that it also has a magnitude, that is determined by the size of the population.
Evolution by Lamarckism
When students in high school study biology they are often introduced to the work of Jean-Baptiste Lamarck (1744 - 1829). His theory of evolution is often called "Lamarckism" and it states that simple organisms develop into more complex organisms by the inherited characteristics which result from an organism's natural activities use and misuse. Lamarckism is usually illustrated with a picture of a giraffe extending its neck to reach the higher branches in the trees. This causes the necks of giraffes that are longer to be passed to their offspring, who would then grow even taller.
Lamarck was a French Zoologist. In his inaugural lecture for his course on invertebrate Zoology at the Museum of Natural History in Paris on 17 May 1802, he presented an innovative concept that completely challenged previous thinking about organic transformation. According to him living things had evolved from inanimate matter through an escalating series of 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 being the one who gave the subject its first broad and comprehensive analysis.
The popular narrative is that Lamarckism was a rival to Charles Darwin's theory of evolution through natural selection, and both theories battled it out in the 19th century. Darwinism eventually won and led to the creation of what biologists today call the Modern Synthesis. The theory argues that acquired traits can be passed down through generations and instead argues that organisms evolve through the selective action of environment elements, like Natural Selection.
While Lamarck supported the notion of inheritance through acquired characters and his contemporaries paid lip-service to this notion but it was not a central element in any of their evolutionary theories. This is due in part to the fact that it was never validated scientifically.
It's been more than 200 years since Lamarck was born and, in the age of genomics there is a huge amount of evidence that supports the heritability of acquired characteristics. This is often called "neo-Lamarckism" or, more frequently epigenetic inheritance. This is a variant that is as reliable as the popular Neodarwinian model.
에볼루션 바카라 무료체험 through Adaptation
One of the most common misconceptions about evolution is that it is driven by a sort of struggle for survival. This view is inaccurate and overlooks other forces that drive evolution. The fight for survival can be better described as a struggle to survive in a certain environment. This can be a challenge for not just other living things as well as the physical environment.
To understand how evolution functions, it is helpful to consider what adaptation is. It refers to a specific characteristic that allows an organism to live and reproduce in its environment. It could be a physical structure, such as feathers or fur. Or it can be a trait of behavior that allows you to move towards shade during hot weather or coming out to avoid the cold at night.
The capacity of an organism to extract energy from its surroundings and interact with other organisms as well as their physical environment, is crucial to its survival. The organism must have the right genes for producing offspring, and be able to find enough food and resources. In addition, the organism should be able to reproduce itself in a way that is optimally within its environment.
These elements, along with mutations and gene flow can result in changes in the proportion of different alleles within the gene pool of a population. This change in allele frequency can result in the emergence of new traits, and eventually new species in the course of time.
Many of the features we find appealing in animals and plants are adaptations. For instance lung or gills that extract oxygen from the air feathers and fur for insulation, long legs to run away from predators, and camouflage to hide. To understand adaptation it is crucial to distinguish between behavioral and physiological traits.
Physiological adaptations, such as the thick fur or gills are physical characteristics, whereas behavioral adaptations, like the tendency to seek out friends or to move to shade in hot weather, aren't. In addition it is important to understand that a lack of forethought does not mean that something is an adaptation. A failure to consider the implications of a choice even if it seems to be rational, may make it unadaptive.