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The Academy's Evolution Site The concept of biological evolution is among the most important concepts in biology. The Academies are committed to helping those who are interested in the sciences understand evolution theory and how it can be applied in all areas of scientific research. This site offers a variety of tools for students, teachers, and general readers on evolution. It includes key video clips from NOVA and the WGBH-produced science programs on DVD. Tree of Life The Tree of Life is an ancient symbol that symbolizes the interconnectedness of life. It is used in many cultures and spiritual beliefs as symbolizing unity and love. It can be used in many practical ways as well, such as providing a framework to understand the evolution of species and how they respond to changing environmental conditions. Early approaches to depicting the world of biology focused on separating species into distinct categories that were identified by their physical and metabolic characteristics1. These methods, based on the sampling of various parts of living organisms or on small DNA fragments, greatly increased the variety of organisms that could be represented in the tree of life2. These trees are largely composed by eukaryotes, and bacterial diversity is vastly underrepresented3,4. By avoiding the necessity for direct observation and experimentation, genetic techniques have allowed us to depict the Tree of Life in a more precise manner. We can construct trees by using molecular methods such as the small subunit ribosomal gene. Despite the massive expansion of the Tree of Life through genome sequencing, a large amount of biodiversity is waiting to be discovered. This is especially true for microorganisms that are difficult to cultivate, and are typically found in a single specimen5. A recent analysis of all genomes that are known has produced a rough draft of the Tree of Life, including a large number of archaea and bacteria that are not 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. The information is useful in a variety of ways, including finding new drugs, fighting diseases and enhancing crops. This information is also extremely beneficial for conservation efforts. It helps biologists discover areas most likely to be home to cryptic species, which could have vital metabolic functions and are susceptible to changes caused by humans. While funds to protect biodiversity are essential, the best method to protect the biodiversity of the world is to equip more people in developing countries with the necessary knowledge to act locally and promote conservation. Phylogeny A phylogeny (also known as an evolutionary tree) shows the relationships between different organisms. Using molecular data as well as morphological similarities and distinctions or ontogeny (the course of development of an organism) scientists can create a phylogenetic tree which illustrates the evolutionary relationships between taxonomic categories. The concept of phylogeny is fundamental to understanding the evolution of biodiversity, evolution and genetics. A basic phylogenetic tree (see Figure PageIndex 10 Identifies the relationships between organisms that have similar characteristics and have evolved from an ancestor that shared traits. These shared traits can be homologous, or analogous. Homologous traits are identical in their evolutionary origins while analogous traits appear like they do, but don't have the identical origins. Scientists organize similar traits into a grouping referred to as a Clade. All members of a clade have a common characteristic, like amniotic egg production. They all came from an ancestor who had these eggs. A phylogenetic tree is then built by connecting the clades to identify the organisms that are most closely related to each other. To create a more thorough and accurate phylogenetic tree scientists make use of molecular data from DNA or RNA to establish the relationships among organisms. This information is more precise than morphological data and provides evidence of the evolutionary history of an organism or group. Researchers can utilize Molecular Data to estimate the age of evolution of organisms and determine the number of organisms that have an ancestor common to all. The phylogenetic relationship can be affected by a number of factors that include phenotypicplasticity. This is a type of behavior that alters in response to specific environmental conditions. This can cause a trait to appear more like a species other species, which can obscure the phylogenetic signal. 에볼루션코리아 can be mitigated by using cladistics, which is a a combination of homologous and analogous traits in the tree. Additionally, phylogenetics can help predict the length and speed of speciation. This information can assist conservation biologists make decisions about the species they should safeguard from the threat of extinction. Ultimately, it is the preservation of phylogenetic diversity that will create an ecosystem that is complete and balanced. Evolutionary Theory The main idea behind evolution is that organisms change over time due to their interactions with their environment. Many scientists have come up with theories of evolution, such as the Islamic naturalist Nasir al-Din al-Tusi (1201-274) who believed that an organism could evolve according to its individual needs and needs, the Swedish taxonomist Carolus Linnaeus (1707-1778) who conceived the modern taxonomy system that is hierarchical and Jean-Baptiste Lamarck (1844-1829), who suggested that the use or absence of traits can cause changes that can be passed on to future generations. In the 1930s & 1940s, theories from various areas, including genetics, natural selection and particulate inheritance, merged to form a modern theorizing of evolution. This explains how evolution occurs by the variations in genes within a population and how these variants change with time due to natural selection. This model, called genetic drift mutation, gene flow, and sexual selection, is a cornerstone of modern evolutionary biology and can be mathematically explained. Recent developments in evolutionary developmental biology have demonstrated how variations can be introduced to a species by genetic drift, mutations, reshuffling genes during sexual reproduction and the movement between populations. These processes, as well as others like directional selection and genetic erosion (changes in the frequency of the genotype over time), can lead to evolution which is defined by changes in the genome of the species over time, and the change in phenotype as time passes (the expression of the genotype within the individual). Incorporating evolutionary thinking into all areas of biology education can improve students' understanding of phylogeny and evolution. In a recent study conducted by Grunspan and co. It was found that teaching students about the evidence for evolution boosted their understanding of evolution in an undergraduate biology course. For more information on how to teach about evolution, please read The Evolutionary Potential of all Areas of Biology and Thinking Evolutionarily A Framework for Infusing the Concept of Evolution into Life Sciences Education. Evolution in Action Scientists have traditionally studied evolution by looking in the past—analyzing fossils and comparing species. They also observe living organisms. Evolution isn't a flims moment; it is an ongoing process. Viruses reinvent themselves to avoid new drugs and bacteria evolve to resist antibiotics. Animals adapt their behavior as a result of a changing environment. The changes that occur are often apparent. It wasn't until the late 1980s when biologists began to realize that natural selection was also at work. The key is that various traits confer different rates of survival and reproduction (differential fitness) and are passed down from one generation to the next. In the past, if a certain allele – the genetic sequence that determines colour – appeared in a population of organisms that interbred, it might become more common than other allele. In time, 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 rapid 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 frequently and more than 50,000 generations of E.coli have been observed to have passed. Lenski's research has shown that a mutation can profoundly alter the efficiency with which a population reproduces—and so the rate at which it alters. It also shows that evolution is slow-moving, a fact that some people find hard to accept. Another example of microevolution is that mosquito genes that confer resistance to pesticides appear more frequently in areas where insecticides are used. This is due to the fact that the use of pesticides creates a selective pressure that favors individuals with resistant genotypes. The rapidity of evolution has led to an increasing recognition of its importance especially in a planet which is largely shaped by human activities. This includes pollution, climate change, and habitat loss that prevents many species from adapting. Understanding the evolution process will help us make better decisions about the future of our planet, and the lives of its inhabitants.