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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 who are interested in the sciences comprehend the evolution theory and how it is permeated throughout all fields of scientific research. This site provides a range of resources for students, teachers and general readers of evolution. It includes key video clip from NOVA and WGBH produced science programs on DVD. Tree of Life The Tree of Life is an ancient symbol that represents the interconnectedness of life. It is an emblem of love and unity across many cultures. It also has important practical uses, like providing a framework to understand the history of species and how they respond to changing environmental conditions. The earliest attempts to depict the world of biology focused on categorizing organisms into distinct categories that were identified by their physical and metabolic characteristics1. These methods, based on the sampling of various parts of living organisms, or sequences of short fragments of their DNA greatly increased the variety of organisms that could be included in the tree of life2. These trees are mostly populated of eukaryotes, while the diversity of bacterial species is greatly underrepresented3,4. By avoiding the need for direct experimentation and observation, genetic techniques have allowed us to depict the Tree of Life in a much more accurate way. In particular, molecular methods allow us to construct trees by using sequenced markers such as the small subunit of ribosomal RNA gene. The Tree of Life has been dramatically expanded through genome sequencing. However, there is still much diversity to be discovered. This is especially true of microorganisms, which are difficult to cultivate and are usually only present in a single sample5. Recent analysis of all genomes produced a rough draft of the Tree of Life. This includes a variety of archaea, bacteria, and other organisms that have not yet been isolated, or whose diversity has not been thoroughly understood6. The expanded Tree of Life is particularly useful in assessing the diversity of an area, helping to determine whether specific habitats require protection. This information can be used in a variety of ways, from identifying the most effective medicines to combating disease to enhancing the quality of the quality of crops. This information is also beneficial to conservation efforts. It helps biologists determine the areas that are most likely to contain cryptic species with important metabolic functions that may be at risk of anthropogenic changes. While funding to protect news are essential, the best method to protect the world's biodiversity is to equip more people in developing nations with the necessary knowledge to act locally and support conservation. Phylogeny A phylogeny (also known as an evolutionary tree) shows the relationships between organisms. Using molecular data similarities and differences in morphology, or ontogeny (the process of the development of an organism) scientists can create a phylogenetic tree that illustrates the evolution of taxonomic categories. The concept of phylogeny is fundamental to understanding the evolution of biodiversity, evolution and genetics. A basic phylogenetic tree (see Figure PageIndex 10 Identifies the relationships between organisms that have similar characteristics and have evolved from an ancestor with common traits. These shared traits can be either homologous or analogous. Homologous traits share their underlying evolutionary path, while analogous traits look similar, but do not share the identical origins. Scientists put similar traits into a grouping called a Clade. All members of a clade have a common characteristic, for example, amniotic egg production. They all evolved from an ancestor with these eggs. A phylogenetic tree is constructed by connecting the clades to identify the organisms who are the closest to one another. Scientists use DNA or RNA molecular data to construct a phylogenetic graph that is more precise and precise. This information is more precise and gives evidence of the evolutionary history of an organism. Molecular data allows researchers to identify the number of species who share an ancestor common to them and estimate their evolutionary age. The phylogenetic relationships of organisms are influenced by many factors, including phenotypic plasticity a kind of behavior that alters in response to specific environmental conditions. This can cause a trait to appear more similar to a species than to another and obscure the phylogenetic signals. However, this issue can be solved through the use of techniques like cladistics, which incorporate a combination of analogous and homologous features into the tree. Additionally, phylogenetics aids determine the duration and rate at which speciation occurs. This information can help conservation biologists decide which species to protect from the threat of extinction. It is ultimately the preservation of phylogenetic diversity which will create an ecologically balanced and complete ecosystem. Evolutionary Theory The main idea behind evolution is that organisms alter over time because of their interactions with their environment. Many scientists have come up with 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 requirements as well as the Swedish taxonomist Carolus Linnaeus (1707-1778) who developed the modern hierarchical system of taxonomy, as well as Jean-Baptiste Lamarck (1844-1829), who believed that the usage or non-use of certain traits can result in changes that can be passed on to future generations. In the 1930s and 1940s, theories from various fields, including natural selection, genetics & particulate inheritance, merged to create a modern evolutionary theory. This explains how evolution is triggered by the variation of genes in the population and how these variants change with time due to natural selection. This model, known as genetic drift mutation, gene flow and sexual selection, is a cornerstone of the current evolutionary biology and can be mathematically described. Recent advances in evolutionary developmental biology have shown how variations can be introduced to a species by genetic drift, mutations and reshuffling of genes during sexual reproduction and the movement between populations. These processes, as well as other ones like directional selection and genetic erosion (changes in the frequency of an individual's genotype over time) can result in evolution, which is defined by change in the genome of the species over time and the change in phenotype over time (the expression of the genotype within the individual). Incorporating evolutionary thinking into all aspects of biology education can improve student understanding of the concepts of phylogeny as well as evolution. 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 biology course. To learn click through the following article how to teach about evolution, look up The Evolutionary Potential in All Areas of Biology and Thinking Evolutionarily: A Framework for Infusing the Concept of Evolution into Life Sciences Education. Evolution in Action Traditionally, scientists have studied evolution through looking back, studying fossils, comparing species and studying living organisms. Evolution is not a past event, but an ongoing process. Bacteria evolve and resist antibiotics, viruses reinvent themselves and are able to evade new medications and animals change their behavior to the changing environment. The changes that result are often evident. It wasn't until the 1980s when biologists began to realize that natural selection was in play. The key is that different traits have different rates of survival and reproduction (differential fitness) and are passed from one generation to the next. In the past, if a certain allele – the genetic sequence that determines colour – was present in a population of organisms that interbred, it might become more common than any other allele. Over time, that would mean the number of black moths within the 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 observe evolutionary change when a species, such as bacteria, has a high generation turnover. Since 1988, biologist Richard Lenski has been tracking twelve populations of E. coli that descended from a single strain; samples of each are taken every day and more than fifty thousand generations have passed. Lenski's research has revealed that a mutation can profoundly alter the speed at the rate at which a population reproduces, and consequently, the rate at which it alters. It also shows that evolution takes time, a fact that some people are unable to accept. Another example of microevolution is that mosquito genes that are resistant to pesticides show up more often in populations where insecticides are employed. This is due to pesticides causing an enticement that favors individuals who have resistant genotypes. The speed at which evolution takes place has led to a growing awareness of its significance in a world that is shaped by human activity, including climate change, pollution and the loss of habitats which prevent many species from adapting. Understanding evolution can assist you in making better choices about the future of the planet and its inhabitants.