The Academy's Evolution Site<br /><br />Biological evolution is a central concept in biology. The Academies have been active for a long time in helping those interested in science comprehend the theory of evolution and how it permeates all areas of scientific research.<br /><br />This site offers a variety of tools for students, teachers as well as general readers about evolution. It includes key video clip from NOVA and WGBH produced science programs on DVD.<br /><br />Tree of Life<br /><br />The Tree of Life is an ancient symbol of the interconnectedness of life. It is seen in a variety of spiritual traditions and cultures as symbolizing unity and love. It has numerous practical applications in addition to providing a framework for understanding the history of species and how they react to changing environmental conditions.<br /><br />The first attempts at depicting the world of biology focused on categorizing organisms into distinct categories which were distinguished by their physical and metabolic characteristics1. These methods, which rely on sampling of different parts of living organisms or short DNA fragments, significantly expanded the diversity that could be included in a tree of life2. However, these trees are largely composed of eukaryotes; bacterial diversity is not represented in a large way3,4.<br /><br />By avoiding the necessity for direct experimentation and observation genetic techniques have allowed us to represent the Tree of Life in a more precise way. Particularly, molecular techniques allow us to construct trees using sequenced markers, such as the small subunit ribosomal RNA gene.<br /><br />Despite the dramatic expansion of the Tree of Life through genome sequencing, a large amount of biodiversity awaits discovery. This is especially true of microorganisms, which can be difficult to cultivate and are often only found in a single specimen5. A recent analysis of all genomes resulted in a rough draft of a Tree of Life. This includes a large number of archaea, bacteria and other organisms that haven't yet been isolated or whose diversity has not been fully understood6.<br /><br />The expanded Tree of Life can be used to evaluate the biodiversity of a specific area and determine if certain habitats require special protection. This information can be utilized in a variety of ways, including finding new drugs, fighting diseases and enhancing crops. The information is also incredibly beneficial for conservation efforts. It can help biologists identify the areas that are most likely to contain cryptic species with potentially significant metabolic functions that could be at risk of anthropogenic changes. While conservation funds are important, the most effective method to protect the biodiversity of the world is to equip the people of developing nations with the information they require to act locally and promote conservation.<br /><br />Phylogeny<br /><br />A phylogeny (also known as an evolutionary tree) depicts the relationships between organisms. Utilizing molecular data, morphological similarities and differences or ontogeny (the process of the development of an organism) scientists can construct an phylogenetic tree that demonstrates the evolution of taxonomic groups. The phylogeny of a tree plays an important role in understanding biodiversity, genetics and evolution.<br /><br />A basic phylogenetic tree (see Figure PageIndex 10 Determines the relationship between organisms with similar characteristics and have evolved from a common ancestor. These shared traits may be homologous, or analogous. <a href="https://dahlgaard-ringgaard-2.hubstack.net/10-inspirational-graphics-about-evolution-gaming-1735079845">에볼루션바카라</a> share their evolutionary roots, while analogous traits look like they do, but don't have the same ancestors. Scientists group similar traits into a grouping referred to as a the clade. Every organism in a group share a trait, such as amniotic egg production. They all derived from an ancestor that had these eggs. The clades then join to form a phylogenetic branch that can identify organisms that have the closest connection to each other.<br /><br />Scientists make use of DNA or RNA molecular data to create a phylogenetic chart that is more accurate and detailed. This information is more precise and gives evidence of the evolutionary history of an organism. The use of molecular data lets researchers identify the number of organisms that have a common ancestor and to estimate their evolutionary age.<br /><br />The phylogenetic relationship can be affected by a variety of factors, including the phenomenon of phenotypicplasticity. This is a kind of behavior that changes due to unique environmental conditions. This can cause a particular trait to appear more similar in one species than another, clouding the phylogenetic signal. This problem can be mitigated by using cladistics, which incorporates an amalgamation of analogous and homologous features in the tree.<br /><br />Additionally, phylogenetics can help predict the time and pace of speciation. This information can assist conservation biologists in deciding which species to save from the threat of extinction. In the end, it's the preservation of phylogenetic diversity which will create an ecosystem that is complete and balanced.<br /><br />Evolutionary Theory<br /><br />The central theme of evolution is that organisms develop various characteristics over time based on their interactions with their surroundings. Many theories of evolution have been proposed by a wide 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 needs as well as 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 causes changes that could be passed on to the offspring.<br /><br />In the 1930s and 1940s, theories from various fields, including natural selection, genetics &amp; particulate inheritance, came together to form a modern synthesis of evolution theory. This defines how evolution occurs by the variation in genes within the population, and how these variants alter over time due to natural selection. This model, which encompasses genetic drift, mutations, gene flow and sexual selection, can be mathematically described.<br /><br />Recent discoveries in the field of evolutionary developmental biology have revealed that variation can be introduced into a species via mutation, genetic drift, and reshuffling genes during sexual reproduction, as well as through migration between populations. These processes, along with others, such as the directional selection process and the erosion of genes (changes to the frequency of genotypes over time) can lead to evolution. Evolution is defined by changes in the genome over time, as well as changes in phenotype (the expression of genotypes within individuals).<br /><br />Students can better understand phylogeny by incorporating evolutionary thinking into all aspects of biology. A recent study by Grunspan and colleagues, for example demonstrated that teaching about the evidence that supports evolution increased students' acceptance of evolution in a college biology course. For more information on how to teach about evolution, look up The Evolutionary Potential of all Areas of Biology and Thinking Evolutionarily: A Framework for Infusing the Concept of Evolution into Life Sciences Education.<br /><br />Evolution in Action<br /><br />Scientists have traditionally looked at evolution through the past, studying fossils, and comparing species. They also study living organisms. Evolution is not a distant moment; it is an ongoing process. Viruses reinvent themselves to avoid new medications and bacteria mutate to resist antibiotics. Animals adapt their behavior as a result of a changing world. The changes that result are often easy to see.<br /><br />However, it wasn't until late-1980s that biologists realized that natural selection can be seen in action, as well. The key to this is that different traits confer a different rate of survival as well as reproduction, and may be passed on from one generation to another.<br /><br />In the past, if one allele - the genetic sequence that determines colour appeared in a population of organisms that interbred, it could be more prevalent than any other allele. Over time, that would mean that 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.<br /><br />Observing evolutionary change in action is easier when a species has a fast generation turnover such as bacteria. Since 1988, Richard Lenski, a biologist, has tracked twelve populations of E.coli that descend from a single strain. Samples of each population have been taken regularly and more than 50,000 generations of E.coli have passed.<br /><br /><br /><br />Lenski's research has demonstrated that mutations can alter the rate of change and the efficiency of a population's reproduction. It also shows evolution takes time, something that is hard for some to accept.<br /><br />Microevolution can be observed in the fact that mosquito genes that confer resistance to pesticides are more prevalent in areas where insecticides have been used. This is because the use of pesticides creates a pressure that favors those with resistant genotypes.<br /><br />The rapid pace of evolution taking place has led to a growing awareness of its significance in a world that is shaped by human activity--including climate changes, pollution and the loss of habitats that prevent many species from adjusting. Understanding the evolution process can assist you in making better choices regarding the future of the planet and its inhabitants.<br /><br />