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The Academy's Evolution Site Biological evolution is one of the most fundamental concepts in biology. The Academies have long been involved in helping those interested in science comprehend the theory of evolution and how it permeates all areas of scientific exploration. This site provides students, teachers and general readers with a variety of educational resources 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 of the interconnectedness of all life. It is used in many cultures and spiritual beliefs as a symbol of unity and love. It also has important practical uses, like providing a framework for understanding the history of species and how they react to changes in environmental conditions. Early attempts to represent the biological world were based on categorizing organisms based on their physical and metabolic characteristics. These methods, which are based on the sampling of different parts of organisms or short fragments of DNA, have significantly increased the diversity of a tree of Life2. These trees are largely composed by eukaryotes, and bacterial diversity is vastly underrepresented3,4. By avoiding the need for direct observation and experimentation genetic techniques have enabled us to depict the Tree of Life in a much more accurate way. In particular, molecular methods allow us to build trees by using sequenced markers such as the small subunit of ribosomal RNA gene. Despite the rapid growth of the Tree of Life through genome sequencing, a large amount of biodiversity is waiting to be discovered. This is particularly the case for microorganisms which are difficult to cultivate and are usually present in a single sample5. A recent study of all known genomes has produced a rough draft of the Tree of Life, including numerous bacteria and archaea that are not isolated and which are not well understood. This expanded Tree of Life is particularly useful for assessing the biodiversity of an area, assisting to determine whether specific habitats require 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 in conservation efforts. It can aid biologists in identifying the areas most likely to contain cryptic species with potentially important metabolic functions that may be vulnerable to anthropogenic change. Although funding to protect biodiversity are crucial, ultimately the best way to protect the world's biodiversity is for more people living in developing countries to be equipped with the knowledge to act locally to promote conservation from within. Phylogeny A phylogeny, also known as an evolutionary tree, reveals the connections between various groups of organisms. By using molecular information as well as morphological similarities and distinctions or ontogeny (the process of the development of an organism) scientists can create a phylogenetic tree that illustrates the evolution of taxonomic categories. Phylogeny is essential in understanding biodiversity, evolution and genetics. A basic phylogenetic tree (see Figure PageIndex 10 ) identifies the relationships between organisms that share similar traits that evolved from common ancestral. These shared traits may be analogous or homologous. Homologous traits are identical in their evolutionary roots and analogous traits appear like they do, but don't have the same origins. Scientists group similar traits into a grouping known as a the clade. For instance, all the species in a clade have the characteristic of having amniotic egg and evolved from a common ancestor who had eggs. A phylogenetic tree is constructed by connecting the clades to identify the species who are the closest to one another. Scientists utilize molecular DNA or RNA data to construct a phylogenetic graph that is more accurate and detailed. This information is more precise than morphological information and provides evidence of the evolutionary history of an individual or group. Researchers can utilize Molecular Data to estimate the age of evolution of organisms and identify the number of organisms that have the same ancestor. The phylogenetic relationships of organisms are influenced by many factors, including phenotypic flexibility, a kind of behavior that changes in response to specific environmental conditions. This can cause a characteristic to appear more similar to one species than to another and obscure the phylogenetic signals. However, 에볼루션 무료체험 can be solved through the use of methods such as cladistics that incorporate a combination of analogous and homologous features into the tree. Additionally, phylogenetics can help predict the length and speed of speciation. This information can aid conservation biologists in making choices about which species to save from extinction. In the end, it is the conservation of phylogenetic diversity which will create an ecosystem that is complete and balanced. Evolutionary Theory The fundamental concept of evolution is that organisms develop distinct characteristics over time due to their interactions with their environments. Many theories of evolution have been proposed by a variety of scientists such as the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who proposed that a living organism develop slowly in accordance with its requirements and needs, the Swedish botanist Carolus Linnaeus (1707-1778) who conceived the modern hierarchical taxonomy, as well as Jean-Baptiste Lamarck (1744-1829) who suggested that the use or non-use of traits causes changes that could be passed on to the offspring. In the 1930s and 1940s, theories from a variety of fields—including genetics, natural selection, and particulate inheritance — came together to form the modern synthesis of evolutionary theory, which defines how evolution is triggered by the variation of genes within a population and how these variants change in time due to natural selection. This model, which incorporates genetic drift, mutations as well as gene flow and sexual selection, can be mathematically described. Recent developments in the field of evolutionary developmental biology have shown that genetic variation can be introduced into a species via genetic drift, mutation, and reshuffling of genes during sexual reproduction, as well as through the movement of 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 that is defined as changes in the genome of the species over time, and also the change in phenotype over time (the expression of the genotype within the individual). Students can better understand phylogeny by incorporating evolutionary thinking in all areas of biology. A recent study by Grunspan and colleagues, for instance revealed that teaching students about the evidence supporting evolution helped students accept the concept of evolution in a college-level biology course. For more details on how to teach about evolution read The Evolutionary Power of Biology in all Areas of Biology or Thinking Evolutionarily A Framework for Integrating Evolution into Life Sciences Education. Evolution in Action Traditionally, scientists have studied evolution by studying fossils, comparing species, and observing 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 as a result of a changing world. The results are often visible. It wasn't until the 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 transferred from one generation to the next. In the past when one particular allele—the genetic sequence that defines color in a population of interbreeding species, it could rapidly become more common than the other alleles. As time passes, 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. It is easier to track evolutionary change when the species, like bacteria, has a high generation turnover. Since 1988, Richard Lenski, a biologist, has studied twelve populations of E.coli that are descended from a single strain. Samples from each population have been collected regularly and more than 500.000 generations of E.coli have been observed to have passed. Lenski's work has shown that mutations can alter the rate of change and the efficiency of a population's reproduction. It also proves that evolution takes time—a fact that some people find hard to accept. Microevolution can also be seen in the fact that mosquito genes for pesticide resistance are more prevalent in areas where insecticides have been used. Pesticides create an enticement that favors those who have resistant genotypes. The rapid pace at which evolution takes place has led to an increasing appreciation of its importance in a world shaped by human activity, including climate changes, pollution and the loss of habitats that hinder many species from adjusting. Understanding evolution can help us make better choices about the future of our planet, as well as the life of its inhabitants.