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The Academy's Evolution Site Biological evolution is a central concept 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 influences all areas of scientific exploration. This site provides a wide range of tools for students, teachers and general readers of 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, represents the interconnectedness of all life. It is an emblem of love and unity in many cultures. It also has important practical uses, like providing a framework to understand the evolution of species and how they react to changes in the environment. Early attempts to represent the biological world were founded on categorizing organisms 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 greatly increased the diversity of a tree of Life2. However click the next web page are mainly comprised of eukaryotes, and bacterial diversity remains 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 much more accurate way. Particularly, molecular methods enable us to create trees by using sequenced markers, such as the small subunit of ribosomal RNA gene. The Tree of Life has been significantly expanded by genome sequencing. However there is a lot of diversity to be discovered. This is particularly true of microorganisms, which are difficult to cultivate and are usually only represented in a single sample5. A recent study of all genomes known to date has produced a rough draft of the Tree of Life, including a large number of bacteria and archaea that are not isolated and which are not well understood. This expanded Tree of Life can be used to evaluate the biodiversity of a specific region and determine if specific habitats require special protection. This information can be used in a variety of ways, from identifying new remedies to fight diseases to improving the quality of crops. The information is also incredibly valuable to conservation efforts. It helps biologists discover areas that are likely to have cryptic species, which could have vital metabolic functions and are susceptible to the effects of human activity. While funds to protect biodiversity are essential, 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 in order to promote conservation from within. Phylogeny A phylogeny (also called an evolutionary tree) illustrates the relationship between species. Scientists can build a phylogenetic chart that shows the evolutionary relationship of taxonomic groups using 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 Finds the connections between organisms with similar traits and evolved from an ancestor with common traits. These shared traits can be either analogous or homologous. Homologous traits are similar in their evolutionary paths. Analogous traits could appear similar, but they do not have the same origins. Scientists organize similar traits into a grouping called a clade. All members of a clade have a common characteristic, like amniotic egg production. They all evolved from an ancestor with these eggs. A phylogenetic tree is built by connecting the clades to identify the organisms who are the closest to one another. Scientists make use of molecular DNA or RNA data to build a phylogenetic chart that is more accurate and detailed. This information is more precise than morphological data and provides evidence of the evolution history of an individual or group. The analysis of molecular data can help researchers identify the number of organisms who share an ancestor common to them and estimate their evolutionary age. The phylogenetic relationships between species can be influenced by several factors, including phenotypic flexibility, a type of behavior that alters in response to specific environmental conditions. This can make a trait appear more resembling to one species than to the other, obscuring the phylogenetic signals. However, this issue can be reduced by the use of methods such as cladistics which incorporate a combination of homologous and analogous features into the tree. Additionally, phylogenetics can aid in predicting the length and speed of speciation. This information can assist conservation biologists in making decisions about which species to safeguard from extinction. In the end, it's the preservation of phylogenetic diversity that will result in an ecosystem that is complete and balanced. Evolutionary Theory The fundamental concept 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 a living thing would evolve according to its individual needs, the Swedish taxonomist Carolus Linnaeus (1707-1778) who conceived the modern taxonomy system that is hierarchical 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 In the 1930s and 1940s, theories from various fields, including genetics, natural selection and particulate inheritance, came together to form a contemporary theorizing of evolution. This explains how evolution happens through the variation in genes within the population and how these variants change over time as a result of natural selection. This model, which incorporates mutations, genetic drift, gene flow and sexual selection is mathematically described mathematically. Recent advances in evolutionary developmental biology have demonstrated how variation can be introduced to a species via genetic drift, mutations or reshuffling of genes in sexual reproduction and migration between populations. These processes, along with other ones like directional selection and genetic erosion (changes in the frequency of the genotype over time) can lead to evolution which is defined by changes in the genome of the species over time and also the change in phenotype over time (the expression of that genotype in an individual). Incorporating evolutionary thinking into all areas of biology education can increase students' understanding of phylogeny and evolutionary. A recent study conducted by Grunspan and colleagues, for example revealed that teaching students about the evidence for evolution helped students accept the concept of evolution in a college-level biology class. To find out more about how to teach about evolution, please see The Evolutionary Potential of all Areas of Biology and Thinking Evolutionarily: A Framework for Infusing the Concept of Evolution into Life Sciences Education. Evolution in Action Scientists have studied evolution through looking back in the past—analyzing fossils and comparing species. They also study living organisms. Evolution isn't a flims event; it is an ongoing process that continues to be observed today. Viruses reinvent themselves to avoid new medications and bacteria mutate to resist antibiotics. Animals alter their behavior as a result of a changing environment. The results are usually evident. It wasn't until the 1980s when biologists began to 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 transferred from one generation to the next. In the past, if a certain allele – the genetic sequence that determines color – appeared in a population of organisms that interbred, it could be more common than any other allele. Over time, that would mean the number of black moths within a particular population could rise. The same is true for many other characteristics—including morphology and behavior—that vary among populations of organisms. Observing evolutionary change in action is easier when a species has a rapid generation turnover such as bacteria. Since 1988 the biologist Richard Lenski has been tracking twelve populations of E. Coli that descended from a single strain. samples of each population are taken every day and more than 500.000 generations have been observed. Lenski's research has demonstrated that mutations can alter the rate of change and the rate at which a population reproduces. It also shows that evolution is slow-moving, a fact that some find difficult to accept. Microevolution can also be seen in the fact that mosquito genes for resistance to pesticides are more prevalent in areas where insecticides have been used. This is due to pesticides causing 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 which is largely shaped by human activities. This includes pollution, climate change, and habitat loss that hinders many species from adapting. Understanding the evolution process can aid you in making better decisions about the future of our planet and its inhabitants.