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The Academy's Evolution Site The concept of biological evolution is among the most fundamental concepts in biology. The Academies have long been involved in helping those interested in science comprehend the concept of evolution and how it affects all areas of scientific exploration. This site offers a variety of sources for teachers, students and general readers of evolution. It includes key video clips from NOVA and WGBH's science programs on DVD. Tree of Life The Tree of Life is an ancient symbol that represents the interconnectedness of all life. It is used in many religions and cultures as an emblem of unity and love. It has many practical applications in addition to providing a framework for understanding the history of species and how they respond to changing environmental conditions. Early attempts to describe the biological world were founded on categorizing organisms on their physical and metabolic characteristics. These methods, based on sampling of different parts of living organisms, or sequences of short fragments of their DNA, significantly expanded the diversity that could be represented in a tree of life2. These trees are mostly populated of eukaryotes, while bacterial diversity is vastly underrepresented3,4. Genetic techniques have significantly expanded our ability to depict the Tree of Life by circumventing the need for direct observation and experimentation. Particularly, molecular techniques allow us to construct trees using sequenced markers, such as the small subunit of ribosomal RNA gene. The Tree of Life has been greatly expanded thanks to genome sequencing. However there is still a lot of biodiversity to be discovered. This is particularly relevant to microorganisms that are difficult to cultivate and are typically found in one sample5. A recent analysis of all genomes has produced an initial draft of a Tree of Life. This includes a variety of archaea, bacteria, and other organisms that haven't yet been identified or their diversity is not thoroughly understood6. This expanded Tree of Life is particularly useful for assessing the biodiversity of an area, which can help to determine if certain habitats require 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. The information is also valuable for conservation efforts. It helps biologists discover areas that are most likely to be home to species that are cryptic, which could perform important metabolic functions and are susceptible to changes caused by humans. While funds to safeguard biodiversity are vital, ultimately the best way to ensure the preservation of biodiversity around the world 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. Phylogeny A phylogeny (also called an evolutionary tree) depicts the relationships between different organisms. By using molecular information, morphological similarities and differences, or ontogeny (the process of the development of an organism) scientists can construct a phylogenetic tree that illustrates the evolutionary relationships between taxonomic categories. Phylogeny is crucial in understanding the evolution of biodiversity, evolution and genetics. A basic phylogenetic Tree (see Figure PageIndex 10 ) identifies the relationships between organisms with similar traits that evolved from common ancestral. These shared traits could be homologous, or analogous. Homologous traits share their underlying evolutionary path and analogous traits appear similar but do not have the identical origins. Scientists put similar traits into a grouping called a clade. All organisms in a group have a common characteristic, like amniotic egg production. They all came from an ancestor with these eggs. A phylogenetic tree can be built by connecting the clades to identify the species which are the closest to each other. Scientists use molecular DNA or RNA data to build a phylogenetic chart which is more precise and precise. This information is more precise than morphological information and provides evidence of the evolutionary history of an organism or group. Researchers can use Molecular Data to estimate the evolutionary age of living organisms and discover how many organisms have a common ancestor. The phylogenetic relationships of a species can be affected by a number of factors such as phenotypicplasticity. This is a type behavior that changes due to specific environmental conditions. This can make a trait appear more resembling to one species than to another which can obscure the phylogenetic signal. However, this problem can be solved through the use of techniques such as cladistics that incorporate a combination of homologous and analogous features into the tree. Additionally, phylogenetics can help determine the duration and speed of speciation. This information can assist conservation biologists decide which species to protect from extinction. In the end, it's the preservation of phylogenetic diversity that 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 theories of evolution have been developed by a wide range of scientists, including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who believed that an organism would evolve slowly according to its needs as well as the Swedish botanist Carolus Linnaeus (1707-1778) who designed the modern hierarchical taxonomy, as well as Jean-Baptiste Lamarck (1744-1829) who suggested that use or disuse of traits can cause changes that can be passed onto offspring. In the 1930s and 1940s, concepts from a variety of fields—including natural selection, genetics, and particulate inheritance — came together to create the modern synthesis of evolutionary theory which explains how evolution is triggered by the variations of genes within a population, and how these variants change over time as a result of natural selection. This model, which encompasses mutations, genetic drift, gene flow and sexual selection, can be mathematically described mathematically. Recent advances in the field of evolutionary developmental biology have demonstrated how variations can be introduced to a species through mutations, genetic drift or reshuffling of genes in sexual reproduction and migration between populations. These processes, as well as other ones like the directional selection process and the erosion of genes (changes in frequency of genotypes over time) can result in evolution. Evolution is defined as changes in the genome over time as well as changes in phenotype (the expression of genotypes in an individual). Students can better understand the concept of phylogeny by using evolutionary thinking into all areas of biology. In a study by Grunspan and colleagues. It was demonstrated that teaching students about the evidence for evolution boosted their acceptance of evolution during the course of a college biology. For more information on how to teach about evolution, see The Evolutionary Potential in all Areas of Biology or Thinking Evolutionarily: a Framework for Infusing Evolution into Life Sciences Education. Evolution in Action Traditionally, scientists have studied evolution through studying fossils, comparing species and observing living organisms. Evolution isn't a flims moment; it is an ongoing process. Bacteria evolve and resist antibiotics, viruses reinvent themselves and are able to evade new medications, and animals adapt their behavior to the changing environment. The results are usually easy to see. It wasn't until late-1980s that biologists realized that natural selection can be observed in action as well. The key is that various characteristics result in different rates of survival and reproduction (differential fitness) and are passed from one generation to the next. In the past, when one particular allele – the genetic sequence that defines color in a group of interbreeding organisms, it could quickly become more common than other alleles. In Get Source , this could mean that the number of black moths in 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 much easier when a species has a rapid generation turnover like bacteria. 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 taken frequently 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 demonstrates that evolution is slow-moving, a fact that many find hard to accept. Another example of microevolution is the way mosquito genes that are resistant to pesticides are more prevalent in areas in which insecticides are utilized. This is because the use of pesticides creates a pressure that favors individuals who have resistant genotypes. The speed of evolution taking place has led to a growing 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 decisions about the future of our planet, and the lives of its inhabitants.