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The Academy's Evolution Site Biology is a key concept in biology. The Academies have long been involved in helping people who are interested in science understand the theory of evolution and how it affects all areas of scientific exploration. This site provides teachers, students and general readers with a wide range of learning resources on evolution. It contains the most important video clips 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 religions and cultures as symbolizing unity and love. It also has many practical applications, like providing a framework to understand the history of species and how they respond to changes in environmental conditions. Early attempts to represent the world of biology were founded on categorizing organisms on their physical and metabolic characteristics. These methods, which depend on the sampling of different parts of organisms or DNA fragments have significantly increased the diversity of a tree of Life2. These trees are largely composed by eukaryotes and the diversity of bacterial species is greatly underrepresented3,4. Genetic techniques have greatly expanded our ability to depict the Tree of Life by circumventing the requirement for direct observation and experimentation. Particularly, molecular methods enable us to create trees using sequenced markers like the small subunit ribosomal RNA gene. The Tree of Life has been dramatically expanded through genome sequencing. However, there is still much diversity to be discovered. This is particularly the case for microorganisms which are difficult to cultivate and are typically found in a single specimen5. Recent analysis of all genomes has produced a rough draft of a Tree of Life. This includes a large number of archaea, bacteria and other organisms that haven't yet been isolated or the diversity of which is not well understood6. The expanded Tree of Life is particularly useful for assessing the biodiversity of an area, helping to determine if certain habitats require protection. This information can be utilized 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 help biologists identify areas that are likely to have cryptic species, which may have important metabolic functions, and could be susceptible to the effects of human activity. While funds to protect biodiversity are important, the best method to protect the biodiversity of the world is to equip the people of developing nations with the necessary knowledge to act locally and support conservation. Phylogeny A phylogeny, also known as an evolutionary tree, reveals the relationships between groups of organisms. Scientists can build a phylogenetic diagram that illustrates the evolution of taxonomic groups based on molecular data and morphological differences or similarities. Phylogeny plays a crucial role in understanding biodiversity, genetics and evolution. A basic phylogenetic tree (see Figure PageIndex 10 ) identifies the relationships between organisms that share similar traits that have evolved from common ancestral. These shared traits can be either homologous or analogous. Homologous traits are similar in their underlying evolutionary path, while analogous traits look similar, but do not share the same ancestors. Scientists group similar traits together into a grouping known as a clade. All members of a clade share a characteristic, like amniotic egg production. They all came from an ancestor who had these eggs. The clades are then connected to form a phylogenetic branch to determine which organisms have the closest relationship to. For 에볼루션 사이트 detailed and accurate phylogenetic tree, scientists rely on molecular information from DNA or RNA to establish the connections between organisms. This information is more precise and provides evidence of the evolution of an organism. The analysis of molecular data can help researchers identify the number of species who share the same ancestor and estimate their evolutionary age. The phylogenetic relationships of organisms can be affected by a variety of factors including phenotypic plasticity, an aspect of behavior that changes in response to specific environmental conditions. This can cause a trait to appear more similar to a species than to another which can obscure the phylogenetic signal. This issue can be cured by using cladistics, which is a the combination of homologous and analogous traits in the tree. Additionally, phylogenetics can help predict the duration and rate of speciation. This information can aid conservation biologists in making choices about which species to safeguard from extinction. In the end, it is the conservation of phylogenetic diversity which will create an ecosystem that is complete and balanced. Evolutionary Theory The fundamental concept in evolution is that organisms alter over time because of their interactions with their environment. Many scientists have developed theories of evolution, including the Islamic naturalist Nasir al-Din al-Tusi (1201-274), who believed that a living thing would evolve according to its own requirements as well as the Swedish taxonomist Carolus Linnaeus (1707-1778) who developed the modern hierarchical system of taxonomy and Jean-Baptiste Lamarck (1844-1829), who suggested that the use or absence of certain traits can result in changes that are passed on to the In the 1930s and 1940s, theories from a variety of fields — including genetics, natural selection, and particulate inheritance – came together to form the current evolutionary theory, which defines how evolution is triggered by the variations of genes within a population, and how those variations change over time as a result of natural selection. This model, which includes mutations, genetic drift as well as gene flow and sexual selection, can be mathematically described mathematically. Recent developments in the field of evolutionary developmental biology have demonstrated that genetic variation can be introduced into a species via mutation, genetic drift and reshuffling of genes during sexual reproduction, as well as through migration between populations. These processes, along with others, such as directionally-selected selection and erosion of genes (changes in the frequency of genotypes over time) can result in evolution. Evolution is defined by changes in the genome over time, as well as changes in the phenotype (the expression of genotypes in individuals). Students can better understand the concept of phylogeny through incorporating evolutionary thinking throughout all aspects of biology. A recent study conducted by Grunspan and colleagues, for instance demonstrated that teaching about the evidence that supports evolution increased students' understanding of evolution in a college-level biology class. For more information on how to teach evolution look up The Evolutionary Potency in all Areas of Biology or Thinking Evolutionarily as a Framework for Infusing Evolution into Life Sciences Education. Evolution in Action Scientists have looked at evolution through the past, analyzing fossils and comparing species. They also observe living organisms. Evolution isn't a flims event, but an ongoing process. Viruses reinvent themselves to avoid new antibiotics and bacteria transform to resist antibiotics. Animals adapt their behavior because of the changing environment. The changes that occur are often evident. But it wasn't until the late 1980s that biologists realized that natural selection can be observed in action as well. The key is that different traits have different rates of survival and reproduction (differential fitness) and can be transferred from one generation to the next. In 에볼루션 사이트 , when one particular allele – the genetic sequence that controls coloration – was present in a group of interbreeding species, it could quickly become more prevalent than other alleles. As time passes, this could mean that the number of moths that have black pigmentation may increase. The same is true for many other characteristics—including morphology and behavior—that vary among populations of organisms. Observing evolutionary change in action is much easier when a species has a fast generation turnover like bacteria. Since 1988, Richard Lenski, a biologist, has studied twelve populations of E.coli that descend from a single strain. Samples of each population were taken regularly and more than 50,000 generations of E.coli have passed. Lenski's research has demonstrated that mutations can alter the rate of change and the efficiency of a population's reproduction. It also shows evolution takes time, which is hard for some to accept. Microevolution can also be seen in the fact that mosquito genes that confer resistance to pesticides are more prevalent in areas where insecticides are used. This is due to the fact that the use of pesticides creates a pressure that favors people with resistant genotypes. The rapidity of evolution has led to a greater awareness of its significance, especially in a world shaped largely by human activity. This includes the effects of climate change, pollution and habitat loss, which prevents many species from adapting. Understanding the evolution process can help us make smarter choices about the future of our planet and the life of its inhabitants.