The Academy's Evolution Site
The concept of biological evolution is a fundamental concept in biology. The Academies are involved in helping those who are interested in science understand evolution theory and how it is permeated in all areas of scientific research.
This site provides students, teachers and general readers with a wide range of learning resources on evolution. It includes key video clip from NOVA and WGBH produced science programs on DVD.
Tree of Life
The Tree of Life, an ancient symbol, symbolizes the interconnectedness of all life. It is seen in a variety of spiritual traditions and cultures as a symbol of unity and love. It also has many practical uses, like providing a framework to understand the evolution of species and how they respond to changes in the environment.
The first attempts at depicting the biological world focused on categorizing organisms into distinct categories that were distinguished by physical and metabolic characteristics1. These methods rely on the sampling of different parts of organisms or DNA fragments have significantly increased the diversity of a tree of Life2. These trees are mostly populated by eukaryotes and the diversity of bacterial species is greatly underrepresented3,4.
By avoiding the need for direct experimentation and observation genetic techniques have made it possible to depict the Tree of Life in a more precise manner. Particularly, molecular methods allow us to build trees using sequenced markers, such as the small subunit of ribosomal RNA gene.
The Tree of Life has been greatly expanded thanks to genome sequencing. However there is still a lot of diversity to be discovered. This is especially the case for microorganisms which are difficult to cultivate, and which are usually only present in a single sample5. A recent analysis of all genomes that are known has created a rough draft of the Tree of Life, including many bacteria and archaea that have not been isolated and their diversity is not fully understood6.
The expanded Tree of Life can be used to evaluate the biodiversity of a particular area and determine if specific habitats require special protection. This information can be used in a variety of ways, such as identifying new drugs, combating diseases and improving the quality of crops. This information is also extremely useful for conservation efforts. It can aid biologists in identifying those areas that are most likely contain cryptic species with potentially important metabolic functions that may be at risk from anthropogenic change. Although funds to protect biodiversity are crucial however, the most effective method to protect the world's biodiversity is for more people in developing countries to be empowered with the knowledge to take action locally to encourage conservation from within.
에볼루션게이밍 (also called an evolutionary tree) illustrates the relationship between different organisms. Scientists can create an phylogenetic chart which shows the evolution of taxonomic groups using molecular data and morphological similarities or differences. The phylogeny of a tree plays an important role in understanding biodiversity, genetics and evolution.
A basic phylogenetic tree (see Figure PageIndex 10 Identifies the relationships between organisms with similar characteristics and have evolved from an ancestor with common traits. These shared traits can be either homologous or analogous. Homologous traits are the same in their evolutionary paths. Analogous traits might appear like they are but they don't share the same origins. Scientists arrange similar traits into a grouping known as a clade. For instance, all of the organisms that make up a clade share the trait of having amniotic egg and evolved from a common ancestor that had eggs. A phylogenetic tree is constructed by connecting the clades to identify the organisms which are the closest to each other.
Scientists utilize DNA or RNA molecular information to construct a phylogenetic graph that is more precise and precise. This information is more precise than the morphological data and gives evidence of the evolutionary history of an organism or group. The analysis of molecular data can help researchers determine the number of organisms that share a common ancestor and to estimate their evolutionary age.
에볼루션 바카라 of a species can be affected by a variety of factors that include phenotypicplasticity. This is a kind of behavior that changes due to unique environmental conditions. This can cause a trait to appear more similar to a species than to the other which can obscure the phylogenetic signal. This problem can be mitigated by using cladistics, which is a an amalgamation of homologous and analogous features in the tree.
In addition, phylogenetics helps determine the duration and rate of speciation. This information can aid conservation biologists in deciding which species to safeguard from extinction. In the end, it is the preservation of phylogenetic diversity that will result in an ecosystem that is balanced and complete.
Evolutionary Theory
The main idea behind evolution is that organisms change over time as a result of their interactions with their environment. Many theories of evolution have been proposed by a wide range of scientists including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who proposed that a living organism develop slowly in accordance with its requirements as well as the Swedish botanist Carolus Linnaeus (1707-1778) who conceived the modern hierarchical taxonomy Jean-Baptiste Lamarck (1744-1829) who suggested that use or disuse of traits cause changes that could be passed on to offspring.
In the 1930s and 1940s, theories from various fields, including genetics, natural selection, and particulate inheritance, were brought together to create a modern theorizing of evolution. This defines how evolution is triggered by the variation of genes in the population and how these variations alter over time due to natural selection. This model, which includes mutations, genetic drift as well as gene flow and sexual selection, can be mathematically described.
Recent developments in the field of evolutionary developmental biology have shown that genetic variation can be introduced into a species through genetic drift, mutation, and reshuffling of genes in sexual reproduction, and also through migration between populations. These processes, along with other ones like directional selection and genetic erosion (changes in the frequency of a genotype over time) can result in evolution, which is defined by changes in the genome of the species over time and also by changes in phenotype as time passes (the expression of that genotype in an individual).
Students can gain a better understanding of the concept of phylogeny through incorporating evolutionary thinking throughout all areas of biology. In a recent study conducted by Grunspan and co., it was shown that teaching students about the evidence for evolution boosted their acceptance of evolution during the course of a college biology. For more information on how to teach evolution, see The Evolutionary Power of Biology in all Areas of Biology or Thinking Evolutionarily: a Framework for Infusing Evolution into Life Sciences Education.
Evolution in Action
Scientists have studied evolution through looking back in the past--analyzing fossils and comparing species. They also study living organisms. Evolution is not a distant moment; it is a process that continues today. Viruses reinvent themselves to avoid new drugs and bacteria evolve to resist antibiotics. Animals adapt their behavior as a result of the changing environment. The changes that occur are often apparent.
However, it wasn't until late 1980s that biologists understood that natural selection can be observed in action as well. The key is the fact that different traits result in the ability to survive at different rates and reproduction, and can be passed on from one generation to another.
In the past, if one allele - the genetic sequence that determines color - was present in a population of organisms that interbred, it might become more common than any other allele. Over time, that would mean the number of black moths in the population could increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.
Monitoring evolutionary changes in action is easier when a species has a rapid turnover of its generation such as bacteria. Since 1988, Richard Lenski, a biologist, has studied twelve populations of E.coli that descend from one strain. Samples of each population were taken regularly, and more than 500.000 generations of E.coli have passed.
Lenski's work has demonstrated that a mutation can profoundly alter the efficiency with the rate at which a population reproduces, and consequently the rate at which it evolves. It also shows that evolution takes time--a fact that some people find hard to accept.
Another example of microevolution is the way mosquito genes that are resistant to pesticides are more prevalent in areas in which insecticides are utilized. This is because pesticides cause an exclusive pressure that favors individuals who have resistant genotypes.
The rapidity of evolution has led to a greater awareness of its significance especially in a planet that is largely shaped by human activity. This includes climate change, pollution, and habitat loss, which prevents many species from adapting. Understanding evolution can assist you in making better choices regarding the future of the planet and its inhabitants.