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The Academy's Evolution Site The concept of biological evolution is among the most fundamental concepts in biology. The Academies have been active for a long time in helping those interested in science understand the theory of evolution and how it affects every area of scientific inquiry. This site provides students, teachers and general readers with a range of learning resources about 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 religions and cultures as symbolizing unity and love. It can be used in many practical ways as well, such as providing a framework for understanding the evolution of species and how they respond to changes in environmental conditions. The earliest attempts to depict the world of biology focused on separating species into distinct categories that had been distinguished by their physical and metabolic characteristics1. These methods are based on the collection of various parts of organisms or fragments of DNA, have greatly increased the diversity of a tree of Life2. However these trees are mainly comprised of eukaryotes, and bacterial diversity is not represented in a large way3,4. Genetic techniques have greatly broadened our ability to depict the Tree of Life by circumventing the need for direct observation and experimentation. We can construct trees using molecular methods, such as the small-subunit ribosomal gene. Despite the massive expansion of the Tree of Life through genome sequencing, a lot of biodiversity awaits discovery. This is particularly true for microorganisms that are difficult to cultivate and are typically found in a single specimen5. A recent study 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 whose diversity is poorly understood6. This expanded Tree of Life is particularly useful in assessing the diversity of an area, which can help to determine whether specific habitats require protection. This information can be used in a range of ways, from identifying the most effective treatments to fight disease to improving the quality of crops. The information is also incredibly beneficial in conservation efforts. It helps biologists determine those areas that are most likely contain cryptic species with important metabolic functions that may be at risk of anthropogenic changes. While funding to protect biodiversity are important, the most effective way to conserve the biodiversity of the world is to equip more people in developing nations with the information they require 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 chart that shows the evolutionary relationship of taxonomic categories using molecular information and morphological differences or similarities. The phylogeny of a tree plays an important role in understanding the relationship between genetics, biodiversity 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 may be homologous, or analogous. Homologous traits share their underlying evolutionary path while analogous traits appear like they do, but don't have the identical origins. Scientists group similar traits into a grouping known as a Clade. Every organism in a group share a trait, such as amniotic egg production. They all came from an ancestor who had these eggs. The clades then join to form a phylogenetic branch to determine the organisms with the closest relationship. Scientists make use of DNA or RNA molecular data to create a phylogenetic chart that is more precise and detailed. This information is more precise and gives evidence of the evolution of an organism. Molecular data allows researchers to determine the number of species that have the same ancestor and estimate their evolutionary age. The phylogenetic relationships between species are influenced by many factors including phenotypic plasticity, a type of behavior that changes in response to specific environmental conditions. This can make a trait appear more similar to one species than to another, obscuring the phylogenetic signals. However, this problem can be cured by the use of techniques such as cladistics that incorporate a combination of similar and homologous traits into the tree. In addition, phylogenetics helps predict the duration and rate at which speciation takes place. This information will assist conservation biologists in making choices about which species to save from extinction. In the end, it's the preservation of phylogenetic diversity which will result in a complete and balanced ecosystem. Evolutionary Theory The central theme in evolution is that organisms change over time due to their interactions with their environment. Many scientists have proposed theories of evolution, including the Islamic naturalist Nasir al-Din al-Tusi (1201-274) who believed that an organism could develop according to its own requirements, the Swedish taxonomist Carolus Linnaeus (1707-1778) who conceived the modern hierarchical taxonomy, as well as Jean-Baptiste Lamarck (1844-1829), who believed that the use or non-use of traits can lead to changes that are passed on to the next generation. In the 1930s & 1940s, concepts from various fields, such as genetics, natural selection and particulate inheritance, were brought together to form a contemporary synthesis of evolution theory. This describes how evolution occurs by the variation of genes in the population, and how these variations alter over time due to natural selection. This model, called genetic drift, mutation, gene flow, and sexual selection, is a cornerstone of modern evolutionary biology and is mathematically described. Recent discoveries in the field of evolutionary developmental biology have demonstrated that variations can be introduced into a species by mutation, genetic drift and reshuffling of genes in sexual reproduction, and also through migration between populations. These processes, as well as others such as directional selection or genetic erosion (changes in the frequency of the genotype over time) can result in evolution that is defined as changes in the genome of the species over time and the change in phenotype as time passes (the expression of that genotype in the individual). Incorporating evolutionary thinking into all aspects of biology education can improve student understanding of the concepts of phylogeny and evolution. A recent study by Grunspan and colleagues, for example, showed that teaching about the evidence supporting evolution helped students accept the concept of evolution in a college-level biology course. To learn more about how to teach about evolution, read The Evolutionary Potential in All Areas of Biology and Thinking Evolutionarily A Framework for Infusing Evolution in Life Sciences Education. Evolution in Action Traditionally scientists have studied evolution by looking back, studying fossils, comparing species, and observing living organisms. But evolution isn't a thing that happened in the past; it's an ongoing process, happening today. Bacteria mutate and resist antibiotics, viruses re-invent themselves and elude new medications, and animals adapt their behavior to the changing environment. The resulting changes are often visible. It wasn't until the late 1980s when biologists began to realize that natural selection was also in play. The key is that various traits have different rates of survival and reproduction (differential fitness), and can be passed down from one generation to the next. In the past, if one allele – the genetic sequence that determines colour – was present in a population of organisms that interbred, it might become more prevalent than any other allele. As time passes, that could mean that the number of black moths in a population could increase. 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 much easier when a species has a rapid generation turnover such as bacteria. Since 1988 biologist Richard Lenski has been tracking twelve populations of E. coli that descended from a single strain; samples from each population are taken on a regular basis and more than 50,000 generations have now passed. Lenski's research has revealed that mutations can drastically alter the rate at which a population reproduces and, consequently the rate at which it alters. It also shows evolution takes time, a fact that is difficult for some to accept. Microevolution can be observed in the fact that mosquito genes for pesticide resistance are more prevalent in populations where insecticides are used. This is because pesticides cause an exclusive pressure that favors those with resistant genotypes. The speed of evolution taking place has led to an increasing appreciation of its importance in a world that is shaped by human activities, including climate change, pollution, and the loss of habitats that prevent many species from adapting. Understanding 바카라 에볼루션 can help you make better decisions about the future of our planet and its inhabitants.