energydrum0

The Academy's Evolution Site Biology is a key concept in biology. The Academies are committed to helping those interested in the sciences understand evolution theory and how it can be applied in all areas of scientific research. This site provides teachers, students and general readers with a range of learning resources about 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 symbolizes the interconnectedness of life. It is an emblem of love and unity across many cultures. It also has many practical applications, such as providing a framework to understand the history of species and how they react to changing environmental conditions. Early attempts to represent the biological world were built on categorizing organisms based on their metabolic and physical characteristics. These methods depend on the sampling of different parts of organisms, or DNA fragments have significantly increased the diversity of a Tree of Life2. The trees are mostly composed by eukaryotes, and bacterial diversity is vastly underrepresented3,4. Genetic techniques have greatly broadened our ability to visualize the Tree of Life by circumventing the requirement 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 significantly expanded by genome sequencing. However there is still a lot of diversity to be discovered. This is especially true of microorganisms that are difficult to cultivate and are often only represented in a single specimen5. A recent analysis of all genomes resulted in an unfinished draft of a Tree of Life. This includes a variety of archaea, bacteria, and other organisms that have not yet been identified or whose diversity has not been fully understood6. The expanded Tree of Life is particularly beneficial in assessing the biodiversity of an area, assisting to 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 crop yields. This information is also extremely beneficial for conservation efforts. It can help biologists identify areas most likely to be home to cryptic species, which may have vital metabolic functions and be vulnerable to changes caused by humans. While funding to protect biodiversity are important, the best method to preserve the world's biodiversity is to empower the people of developing nations with the necessary knowledge to act locally and support conservation. 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 course of development of an organism) scientists can create an phylogenetic tree that demonstrates the evolution of taxonomic groups. Phylogeny is essential in understanding the evolution of biodiversity, evolution and genetics. A basic phylogenetic Tree (see Figure PageIndex 10 ) determines the relationship between organisms that share similar traits that have evolved from common ancestral. These shared traits could be either analogous or homologous. Homologous traits are similar in their evolutionary paths. Analogous traits may look like they are but they don't have the same origins. Scientists arrange similar traits into a grouping called a the clade. For instance, all of the organisms that make up a clade share the characteristic of having amniotic eggs. They evolved from a common ancestor which had eggs. The clades then join to form a phylogenetic branch that can determine which organisms have the closest relationship. Scientists make use of molecular DNA or RNA data to construct a phylogenetic graph that is more precise and detailed. This information is more precise and gives evidence of the evolutionary history of an organism. 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 of organisms are influenced by many factors, including phenotypic plasticity an aspect of behavior that alters in response to specific environmental conditions. This can cause a trait to appear more similar to a species than another and obscure the phylogenetic signals. However, this problem can be solved through the use of techniques such as cladistics which combine similar and homologous traits into the tree. In addition, phylogenetics helps determine the duration and speed of speciation. This information can assist conservation biologists decide the species they should safeguard from the threat of extinction. In the end, it is the conservation of phylogenetic variety that will result in an ecosystem that is balanced and complete. try this behind evolution is that organisms acquire distinct characteristics over time due to their interactions with their environments. Many scientists have proposed theories of evolution, including the Islamic naturalist Nasir al-Din al-Tusi (1201-274), who believed that an organism could develop according to its own needs and needs, the Swedish taxonomist Carolus Linnaeus (1707-1778) who conceived the modern hierarchical system of taxonomy and Jean-Baptiste Lamarck (1844-1829), who suggested that the usage or non-use of traits can cause changes that are passed on to the 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 defines how evolution occurs through the variations of genes within a population, and how those variations change over time as a result of natural selection. This model, called genetic drift or mutation, gene flow, and sexual selection, is the foundation of current evolutionary biology, and is mathematically described. Recent advances in the field of evolutionary developmental biology have shown the ways in which variation can be introduced to a species by genetic drift, mutations, reshuffling genes during sexual reproduction, and even migration between populations. These processes, along with others such as directional selection and gene erosion (changes in frequency of genotypes over time) can result in evolution. Evolution is defined by changes in the genome over time and changes in phenotype (the expression of genotypes in an individual). Incorporating evolutionary thinking into all aspects of biology education could increase students' understanding of phylogeny and evolutionary. In a study by Grunspan et al. It was found that teaching students about the evidence for evolution boosted their understanding of evolution during an undergraduate biology course. For more information on how to teach about evolution, please look up The Evolutionary Potential in 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 studying fossils, comparing species and observing living organisms. Evolution isn't a flims event; it is a process that continues today. Bacteria transform and resist antibiotics, viruses re-invent themselves and elude new medications and animals alter their behavior to a changing planet. The changes that result are often visible. It wasn't until the late 1980s when biologists began to realize that natural selection was also at work. The main reason is that different traits confer a different rate of survival and reproduction, and they can be passed on from generation to generation. In the past, if one 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, this would mean that the number of moths with 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. The ability to observe evolutionary change 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 from each population are taken regularly 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 demonstrates that evolution takes time—a fact that many find difficult to accept. Another example of microevolution is how mosquito genes for resistance to pesticides appear more frequently in areas where insecticides are employed. This is because the use of pesticides causes a selective pressure that favors those with resistant genotypes. The rapid pace at which evolution takes place has led to an increasing recognition of its importance in a world that is shaped by human activity—including climate change, pollution and the loss of habitats that hinder the species from adapting. Understanding the evolution process will aid you in making better decisions regarding the future of the planet and its inhabitants.