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The Academy's Evolution Site Biology is a key concept in biology. The Academies have been active for a long time in helping people who are 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 educational resources on evolution. It contains important video clips from NOVA and WGBH-produced science programs on DVD. Tree of Life The Tree of Life, an ancient symbol, represents the interconnectedness of all life. It is used in many cultures and spiritual beliefs as a symbol of unity and love. It has many practical applications as well, such as providing a framework to understand the evolution of species and how they respond to changes in environmental conditions. Early approaches to depicting the world of biology focused on the classification of species into distinct categories that were distinguished by physical and metabolic characteristics1. These methods, which rely on the sampling of different parts of organisms or DNA fragments have significantly increased the diversity of a Tree of Life2. The trees are mostly composed of eukaryotes, while bacterial diversity is vastly underrepresented3,4. In avoiding the necessity of direct observation and experimentation, genetic techniques have enabled us to represent the Tree of Life in a more precise manner. In particular, molecular methods enable us to create trees using sequenced markers, such as the small subunit ribosomal RNA gene. Despite the dramatic expansion of the Tree of Life through genome sequencing, a large amount of biodiversity awaits discovery. This is especially true of microorganisms, which can be difficult to cultivate and are typically only present in a single sample5. Recent analysis of all genomes has produced a rough draft of a Tree of Life. 에볼루션사이트 includes a variety of archaea, bacteria, and other organisms that haven't yet been isolated, or their diversity is not fully understood6. This expanded Tree of Life can be used to assess the biodiversity of a specific region and determine if certain habitats need special protection. The information is useful in many ways, including identifying new drugs, combating diseases and enhancing crops. This information is also extremely beneficial for conservation efforts. It helps biologists determine those areas that are most likely contain cryptic species with potentially important metabolic functions that may be at risk from anthropogenic change. While funds to protect biodiversity are crucial however, the most effective method to preserve the world's biodiversity is for more people living 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, shows the connections between groups of organisms. By using molecular information similarities and differences in morphology, or ontogeny (the course of development of an organism), scientists can build a phylogenetic tree that illustrates the evolution of taxonomic categories. Phylogeny is crucial in understanding the evolution of biodiversity, evolution and genetics. A basic phylogenetic tree (see Figure PageIndex 10 Finds the connections between organisms that have similar traits and evolved from a common ancestor. These shared traits are either homologous or analogous. Homologous characteristics are identical in their evolutionary journey. Analogous traits could appear similar, but they do not have the same ancestry. Scientists arrange similar traits into a grouping called a Clade. For instance, all of the organisms in a clade have the characteristic of having amniotic eggs and evolved from a common ancestor who had these eggs. A phylogenetic tree is then constructed by connecting clades to identify the species which are the closest to each other. For a more precise and accurate phylogenetic tree scientists make use of molecular data from DNA or RNA to determine the relationships among organisms. This data is more precise than morphological information and provides evidence of the evolutionary history of an organism or group. Researchers can use Molecular Data to calculate the evolutionary age of organisms and determine the number of organisms that share an ancestor common to all. The phylogenetic relationships of a species can be affected by a number of factors such as phenotypicplasticity. This is a type behavior that changes in response to particular environmental conditions. This can cause a particular trait to appear more similar to one species than another, clouding the phylogenetic signal. However, this issue can be solved through the use of techniques such as cladistics that incorporate a combination of similar and homologous traits into the tree. Additionally, phylogenetics can help predict the duration and rate of speciation. This information can assist conservation biologists in making decisions about which species to safeguard from extinction. In the end, it is the preservation of phylogenetic diversity that will result in 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. Several theories of evolutionary change have been proposed by a variety of scientists such as the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who envisioned an organism developing slowly in accordance with its requirements, the Swedish botanist Carolus Linnaeus (1707-1778) who designed the modern hierarchical taxonomy, as well as Jean-Baptiste Lamarck (1744-1829) who suggested that the use or non-use of traits can cause changes that could be passed on to offspring. In the 1930s and 1940s, theories from a variety of fields — including genetics, natural selection, and particulate inheritance—came together to create the modern synthesis of evolutionary theory that explains how evolution occurs through the variations of genes within a population and how these variants change in time as a result of natural selection. This model, which is known as genetic drift, mutation, gene flow, and sexual selection, is the foundation of current evolutionary biology, and is mathematically described. Recent discoveries 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 in sexual reproduction, and also by migration between populations. These processes, along with other ones like directionally-selected selection and erosion of genes (changes to the frequency of genotypes over time) can lead to 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 gain a better understanding of the concept of phylogeny by using evolutionary thinking in all areas of biology. A recent study conducted by Grunspan and colleagues, for example, showed that teaching about the evidence for evolution increased students' acceptance of evolution in a college-level biology course. For more information on how to teach about evolution, read The Evolutionary Potential of 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—analyzing fossils, comparing species and studying living organisms. Evolution is not a past moment; it is an ongoing process. Viruses evolve to stay away from new antibiotics and bacteria transform to resist antibiotics. Animals alter their behavior because of a changing world. The changes that result are often easy to see. It wasn't until late 1980s that biologists realized that natural selection can be seen in action, as well. The key to this is that different traits confer an individual rate of survival and reproduction, and can be passed on from one generation to another. In the past, if one allele – the genetic sequence that determines colour was found in a group of organisms that interbred, it could be more prevalent than any other allele. In time, this could mean that the number of moths with black pigmentation in a population may 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 fast generation turnover like bacteria. Since 1988 biologist Richard Lenski has been tracking twelve populations of E. bacteria that descend from a single strain; samples of each are taken every day and more than 50,000 generations have now been observed. Lenski's research has demonstrated that mutations can alter the rate of change and the rate of a population's reproduction. It also demonstrates that evolution takes time, a fact that some people are unable to accept. Another example of microevolution is how mosquito genes that confer resistance to pesticides appear more frequently in areas where insecticides are employed. Pesticides create a selective pressure which favors those with resistant genotypes. The rapidity of evolution has led to an increasing recognition of its importance particularly in a world that is largely shaped by human activity. This includes climate change, pollution, and habitat loss that prevents many species from adapting. Understanding the evolution process will assist you in making better choices about the future of the planet and its inhabitants.