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The Academy's Evolution Site The concept of biological evolution is among the most central concepts in biology. The Academies are committed to helping those interested in science to comprehend the evolution theory and how it can be applied across all areas of scientific research. This site provides teachers, students and general readers with a wide range of learning resources on evolution. It contains key 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 a symbol of unity and love. It has many practical applications in addition to providing a framework to understand the history of species, and how they react to changing environmental conditions. The first attempts at depicting the biological world focused on the classification of species into distinct categories that had been distinguished by physical and metabolic characteristics1. These methods are based on the sampling of different parts of organisms or short DNA fragments, have significantly increased the diversity of a tree of Life2. The trees are mostly composed by eukaryotes and the diversity of bacterial species is greatly underrepresented3,4. In avoiding the necessity of direct experimentation and observation genetic techniques have made it possible to represent the Tree of Life in a more precise way. Particularly, molecular techniques enable us to create trees using sequenced markers, such as the small subunit ribosomal gene. Despite the rapid expansion of the Tree of Life through genome sequencing, much biodiversity still is waiting to be discovered. This is particularly true for microorganisms that are difficult to cultivate, and which are usually only present in a single sample5. A recent analysis of all genomes has produced an unfinished draft of the Tree of Life. This includes a variety of bacteria, archaea and other organisms that haven't yet been isolated or the diversity of which is not well understood6. This expanded Tree of Life can be used to determine the diversity of a particular area and determine if specific habitats need special protection. This information can be utilized in a variety of ways, from identifying the most effective treatments to fight disease to enhancing the quality of crops. This information is also valuable in conservation efforts. It helps biologists determine those areas that are most likely contain cryptic species with potentially significant metabolic functions that could be vulnerable to anthropogenic change. While funds to protect biodiversity are crucial, ultimately the best way 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. 무료에볼루션 (also called an evolutionary tree) illustrates the relationship between organisms. Scientists can create an phylogenetic chart which shows the evolution of taxonomic groups based on molecular data and morphological differences or similarities. Phylogeny plays a crucial role in understanding genetics, biodiversity and evolution. A basic phylogenetic tree (see Figure PageIndex 10 Determines the relationship between organisms with similar traits and evolved from an ancestor with common traits. These shared traits can be either analogous or homologous. Homologous traits share their evolutionary roots, while analogous traits look like they do, but don't have the identical origins. Scientists arrange similar traits into a grouping known as a the clade. Every organism in a group share a characteristic, like amniotic egg production. They all evolved from an ancestor who had these eggs. A phylogenetic tree is built by connecting the clades to identify the species which are the closest to one another. For a more precise and precise phylogenetic tree scientists use molecular data from DNA or RNA to determine the connections between organisms. This data is more precise than morphological information and provides evidence of the evolution history of an organism or group. Molecular data allows researchers to identify the number of species that share an ancestor common to them and estimate their evolutionary age. Phylogenetic relationships can be affected by a number of factors, including the phenotypic plasticity. This is a type behaviour that can change in response to specific environmental conditions. This can cause a trait to appear more similar to a species than to another, obscuring the phylogenetic signals. This problem can be addressed by using cladistics, which is a the combination of analogous and homologous features in the tree. In addition, phylogenetics helps determine the duration and rate of speciation. This information can help conservation biologists decide which species to protect from extinction. It is ultimately the preservation of phylogenetic diversity that will create an ecosystem that is complete and balanced. Evolutionary Theory The central theme of evolution is that organisms acquire various characteristics over time due to their interactions with their environment. Several theories of evolutionary change have been proposed by a wide variety of scientists including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who envisioned an organism developing slowly according to its requirements and needs, the Swedish botanist Carolus Linnaeus (1707-1778) who conceived the modern hierarchical taxonomy Jean-Baptiste Lamarck (1744-1829) who suggested that use or disuse of traits causes changes that could be passed on to the offspring. In the 1930s and 1940s, ideas from various fields, including natural selection, genetics, and particulate inheritance — came together to form the modern synthesis of evolutionary theory that explains how evolution occurs through the variations of genes within a population and how those variants change in time due to natural selection. This model, known as genetic drift or mutation, gene flow and sexual selection, is the foundation of the current evolutionary biology and can be mathematically described. Recent advances in the field of evolutionary developmental biology have shown how variations can be introduced to a species via mutations, genetic drift or reshuffling of genes in sexual reproduction, and even 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, which is defined by changes in the genome of the species over time and also by changes in phenotype as time passes (the expression of that genotype in an individual). Students can gain a better understanding of phylogeny by incorporating evolutionary thinking throughout all aspects of biology. In a recent study by Grunspan and colleagues. It was demonstrated that teaching students about the evidence for evolution increased their understanding of evolution during the course of a college biology. To find out more about how to teach about evolution, please see 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 in the present. Bacteria evolve and resist antibiotics, viruses reinvent themselves and escape new drugs and animals alter their behavior in response to the changing environment. The changes that result are often easy to see. It wasn't until late 1980s that biologists began to realize that natural selection was in play. The key to this is that different traits can confer an individual rate of survival and reproduction, and they can be passed on from one generation to the next. In the past, if one particular allele—the genetic sequence that controls coloration – was present in a population of interbreeding species, it could rapidly become more common than the other alleles. Over time, that would mean 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. It is easier to see evolution when a species, such as bacteria, has a high generation turnover. Since 1988, Richard Lenski, a biologist, has tracked twelve populations of E.coli that are descended from one strain. Samples of each population were taken frequently and more than 500.000 generations of E.coli have passed. Lenski's work has demonstrated that mutations can drastically alter the efficiency with which a population reproduces—and so, the rate at which it changes. It also shows evolution takes time, something that is difficult for some to accept. Another example of microevolution is how mosquito genes that confer resistance to pesticides appear more frequently in populations where insecticides are employed. This is because the use of pesticides causes a selective pressure that favors people 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 climate change, pollution, and habitat loss that hinders many species from adapting. Understanding evolution can help us make better decisions about the future of our planet, and the lives of its inhabitants.