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에볼루션코리아 Site The concept of biological evolution is a fundamental concept in biology. The Academies are committed to helping those who are interested in the sciences learn about the theory of evolution and how it is permeated in all areas of scientific research. This site offers a variety of tools for students, teachers and general readers of evolution. It has important video clips from NOVA and the WGBH-produced science programs on DVD. Tree of Life The Tree of Life, an ancient symbol, represents the interconnectedness of all life. It is a symbol of love and harmony in a variety of cultures. It also has important practical applications, such as providing a framework to understand the evolution of species and how they respond to changes in the environment. Early attempts to represent the biological world were built on categorizing organisms based on their physical and metabolic characteristics. These methods depend on the sampling of different parts of organisms or fragments of DNA, have significantly increased the diversity of a tree of Life2. The trees are mostly composed by eukaryotes and bacterial diversity is vastly underrepresented3,4. Genetic techniques have significantly expanded our ability to visualize the Tree of Life by circumventing the need for direct observation and experimentation. Trees can be constructed by using molecular methods like the small-subunit ribosomal 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 particularly relevant to microorganisms that are difficult to cultivate, and are typically found in one sample5. A recent analysis of all known genomes has created a rough draft of the Tree of Life, including a large number of archaea and bacteria that are not isolated and whose diversity is poorly understood6. This expanded Tree of Life can be used to determine the diversity of a specific region and determine if specific habitats need special protection. This information can be utilized in many ways, including finding new drugs, fighting diseases and improving the quality of crops. This information is also valuable for conservation efforts. It helps biologists determine the areas most likely to contain cryptic species with potentially significant metabolic functions that could be vulnerable to anthropogenic change. Although funds to protect biodiversity are essential, ultimately the best way to ensure the preservation of biodiversity around the world is for more people in developing countries to be empowered with the necessary knowledge to act locally in order to promote conservation from within. Phylogeny A phylogeny, also known as an evolutionary tree, reveals the relationships between various groups of organisms. Utilizing molecular data, morphological similarities and differences or ontogeny (the course of development of an organism), scientists can build a phylogenetic tree which illustrates the evolutionary relationships between taxonomic categories. Phylogeny is crucial in understanding biodiversity, evolution and genetics. A basic phylogenetic tree (see Figure PageIndex 10 Determines the relationship between organisms with similar characteristics and have evolved from an ancestor that shared traits. These shared traits can be either analogous or homologous. Homologous characteristics are identical in terms of their evolutionary path. Analogous traits may look like they are however they do not share the same origins. Scientists arrange similar traits into a grouping called a the clade. For instance, all the organisms in a clade share the characteristic of having amniotic egg and evolved from a common ancestor who had these eggs. A phylogenetic tree is constructed by connecting the clades to identify the organisms that are most closely related to one another. For a more precise and precise phylogenetic tree scientists use molecular data from DNA or RNA to identify the relationships among organisms. This data is more precise than the morphological data and gives evidence of the evolutionary background of an organism or group. The use of molecular data lets researchers identify the number of species that share an ancestor common to them and estimate their evolutionary age. The phylogenetic relationship can be affected by a variety of factors, including the phenotypic plasticity. This is a type of behaviour that can change in response to particular environmental conditions. This can cause a trait to appear more like a species other species, which can obscure the phylogenetic signal. However, this issue can be reduced by the use of techniques such as cladistics that incorporate a combination of similar and homologous traits into the tree. Furthermore, phylogenetics may help predict the duration and rate of speciation. This information can assist conservation biologists in making decisions about which species to protect from the threat of extinction. It is ultimately the preservation of phylogenetic diversity which will result in a complete and balanced ecosystem. Evolutionary Theory The central theme of evolution is that organisms acquire distinct characteristics over time as a result of their interactions with their environments. Many scientists have developed theories of evolution, including the Islamic naturalist Nasir al-Din al-Tusi (1201-274) who believed that an organism would evolve according to its own needs as well as the Swedish taxonomist Carolus Linnaeus (1707-1778) who conceived the modern hierarchical taxonomy and Jean-Baptiste Lamarck (1844-1829), who believed that the use or absence of traits can lead to changes that can be passed on to future generations. In the 1930s and 1940s, concepts from a variety of fields — including genetics, natural selection and particulate inheritance — came together to create the modern evolutionary theory synthesis, which defines how evolution is triggered by the variations of genes within a population, and how these variants change in time as a result of natural selection. This model, called genetic drift or mutation, gene flow, and sexual selection, is a key element of current evolutionary biology, and can be mathematically described. Recent discoveries in the field of evolutionary developmental biology have shown the ways in which variation can be introduced to a species via mutations, genetic drift and reshuffling of genes during sexual reproduction and the movement between populations. These processes, as well as others, such as directionally-selected selection and erosion of genes (changes in the frequency of genotypes over time) can lead to evolution. Evolution is defined as changes in the genome over time, as well as changes in the phenotype (the expression of genotypes in individuals). Incorporating evolutionary thinking into all areas of biology education can improve student understanding of the concepts of phylogeny and evolutionary. In a recent study conducted by Grunspan and colleagues. It was found that teaching students about the evidence for evolution increased their understanding of evolution in the course of a college biology. To find out more about how to teach about evolution, see The Evolutionary Potential in all Areas of Biology and Thinking Evolutionarily: A Framework for Infusing Evolution into Life Sciences Education. Evolution in Action Scientists have studied evolution by looking in the past, studying fossils, and comparing species. They also study living organisms. Evolution is not a distant event; it is a process that continues today. Viruses reinvent themselves to avoid new medications and bacteria mutate to resist antibiotics. Animals alter their behavior because of the changing environment. The resulting changes are often easy to see. It wasn't until late-1980s that biologists realized that natural selection could be observed in action as well. The key is that various traits confer different rates of survival and reproduction (differential fitness), and can be passed down from one generation to the next. In the past, if a certain allele – the genetic sequence that determines colour was present in a population of organisms that interbred, it could become more common than any other allele. In time, this could mean that the number of black moths within a particular population could rise. The same is true for many other characteristics—including morphology and behavior—that vary among populations of organisms. The ability to observe evolutionary change is easier when a species has a rapid generation turnover, as with bacteria. Since 1988 biologist Richard Lenski has been tracking twelve populations of E. bacteria that descend from a single strain. samples from each population are taken on a regular basis and over fifty thousand generations have passed. Lenski's research has shown that a mutation can profoundly alter the rate at which a population reproduces and, consequently the rate at which it evolves. It also proves that evolution takes time, a fact that some people find hard to accept. Another example of microevolution is the way mosquito genes for resistance to pesticides are more prevalent in populations in which insecticides are utilized. Pesticides create an exclusive pressure that favors individuals who have resistant genotypes. The rapidity of evolution has led to a greater appreciation of its importance particularly in a world which is largely shaped by human activities. This includes pollution, climate change, and habitat loss that hinders many species from adapting. Understanding the evolution process will aid you in making better decisions about the future of our planet and its inhabitants.