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The Academy's Evolution Site The concept of biological evolution is among the most important concepts in biology. The Academies have been for a long time involved in helping those interested in science comprehend the theory of evolution and how it affects all areas of scientific exploration. This site provides a range of tools for students, teachers, and general readers on evolution. It contains key video clips from NOVA and the 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 spiritual traditions and cultures as a symbol of unity and love. It also has practical uses, like providing a framework for understanding the history 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 were distinguished by their physical and metabolic characteristics1. 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 mostly populated of eukaryotes, while bacterial diversity is vastly underrepresented3,4. Genetic techniques have greatly broadened our ability to represent the Tree of Life by circumventing the requirement for direct observation and experimentation. In particular, molecular methods allow us to build trees by using sequenced markers, such as the small subunit ribosomal RNA gene. Despite the dramatic growth of the Tree of Life through genome sequencing, a large amount of biodiversity awaits discovery. This is especially true for microorganisms that are difficult to cultivate and are typically present in a single sample5. A recent study of all genomes known to date has created a rough draft of the Tree of Life, including many archaea and bacteria that are not isolated and their diversity is not fully understood6. This expanded Tree of Life can be used to assess the biodiversity of a particular area and determine if certain habitats need special protection. The information can be used in a range of ways, from identifying new medicines to combating disease to enhancing the quality of crop yields. The information is also incredibly beneficial for conservation efforts. It helps biologists discover areas that are likely to have species that are cryptic, which could perform important metabolic functions, and could be susceptible to changes caused by humans. Although funding to safeguard biodiversity are vital, ultimately the best way to preserve the world's biodiversity is for more people in developing countries to be empowered with the knowledge to act locally in order to promote conservation from within. Phylogeny A phylogeny, also called an evolutionary tree, reveals the relationships between groups of organisms. Scientists can create a phylogenetic diagram that illustrates the evolutionary relationships between taxonomic categories using molecular information and morphological similarities or differences. The role of phylogeny is crucial in understanding the relationship between genetics, biodiversity and evolution. A basic phylogenetic tree (see Figure PageIndex 10 Finds the connections between organisms that have similar traits and evolved from an ancestor that shared traits. These shared traits could be analogous or homologous. Homologous characteristics are identical in their evolutionary path. Analogous traits might appear similar, but they do not have the same ancestry. Scientists combine similar traits into a grouping referred to as a the clade. All members of a clade share a trait, such as amniotic egg production. They all evolved from an ancestor with these eggs. The clades are then linked to form a phylogenetic branch that can determine which organisms have the closest connection to each other. To create a more thorough and accurate phylogenetic tree scientists use molecular data from DNA or RNA to determine the connections between organisms. This information is more precise than the morphological data and gives evidence of the evolutionary background of an organism or group. The use of molecular data lets researchers determine the number of organisms that have a common ancestor and to estimate their evolutionary age. The phylogenetic relationships between species can be influenced by several factors, including phenotypic flexibility, a type of behavior that changes in response to specific environmental conditions. This can cause a trait to appear more like a species another, obscuring the phylogenetic signal. This problem can be mitigated by using cladistics, which is a the combination of analogous and homologous features in 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 disappearance. 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 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 proposed that a living organism develop 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 the use or misuse of traits can cause changes that could be passed on to the offspring. In the 1930s and 1940s, ideas from a variety of fields—including natural selection, genetics, and particulate inheritance—came together to form the modern synthesis of evolutionary theory that explains how evolution is triggered by the variation 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 can be mathematically described. Recent advances in the field of evolutionary developmental biology have demonstrated the ways in which variation can be introduced to a species by mutations, genetic drift or reshuffling of genes in sexual reproduction and the movement between populations. These processes, along with other ones like directional selection and genetic erosion (changes in the frequency of a genotype over time), can lead to evolution, which is defined by change 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 the concept of phylogeny by using evolutionary thinking into all areas of biology. 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 the course of a college biology. To find out more about how to teach about evolution, please read The Evolutionary Potential of All Areas of Biology and Thinking Evolutionarily: A Framework for Infusing Evolution into 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 event; it is an ongoing process. Bacteria evolve and resist antibiotics, viruses re-invent themselves and are able to evade new medications and animals change their behavior to a changing planet. The changes that result are often easy to see. It wasn't until the 1980s that biologists began realize that natural selection was at work. The key is that various traits confer different rates of survival and reproduction (differential fitness) and can be passed down from one generation to the next. In the past, if an allele – the genetic sequence that determines colour – was present in a population of organisms that interbred, it might become more common than other allele. Over time, this would mean that the number of moths that have black pigmentation in a population could 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 rapid 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 population are taken regularly and more than 500.000 generations have passed. Lenski's work has demonstrated that a mutation can profoundly alter the speed at which a population reproduces and, consequently the rate at which it evolves. It also shows evolution takes time, which is difficult for some to accept. click through the next webpage of microevolution is how mosquito genes that are resistant to pesticides appear more frequently in areas where insecticides are employed. That's because the use of pesticides causes a selective pressure that favors individuals who have resistant genotypes. The rapidity of evolution has led to a growing recognition of its importance, especially in a world that is largely shaped by human activity. This includes pollution, climate change, and habitat loss that hinders many species from adapting. Understanding evolution will aid you in making better decisions about the future of the planet and its inhabitants.