The Academy's Evolution Site
Biological evolution is one of the most central concepts in biology. The Academies have long been involved in helping people who are interested in science understand the concept of evolution and how it influences all areas of scientific exploration.
This site provides students, teachers and general readers with a variety of learning resources on evolution. It contains key video clips from NOVA and WGBH produced science programs on DVD.
Tree of Life
The Tree of Life is an ancient symbol of the interconnectedness of life. It is an emblem of love and unity in many cultures. 무료에볼루션 has many practical applications in addition to providing a framework to understand the history of species and how they react to changes in environmental conditions.
Early attempts to describe the world of biology were based on categorizing organisms based on their metabolic and physical characteristics. These methods, which rely on the sampling of various parts of living organisms or small fragments of their DNA, significantly increased the variety that could be included in the tree of life2. However the trees are mostly composed of eukaryotes; bacterial diversity remains vastly underrepresented3,4.
In avoiding the necessity of direct experimentation and observation genetic techniques have enabled us to represent the Tree of Life in a more precise manner. 에볼루션 슬롯게임 can be constructed using molecular methods such as the small subunit ribosomal gene.
Despite the dramatic expansion of the Tree of Life through genome sequencing, a large amount of biodiversity is waiting to be discovered. This is particularly true for microorganisms that are difficult to cultivate, and are usually found in one sample5. Recent analysis of all genomes has 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 fully understood6.
This expanded Tree of Life is particularly beneficial in assessing the biodiversity of an area, helping to determine if certain habitats require protection. This information can be used in a variety of ways, from identifying new treatments to fight disease to enhancing the quality of crops. This information is also extremely useful to conservation efforts. It can help biologists identify the areas that are most likely to contain cryptic species with potentially important metabolic functions that could be vulnerable to anthropogenic change. Although funds to protect biodiversity are crucial but the most effective 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 is also known as an evolutionary tree, illustrates the relationships between different groups of organisms. By using molecular information as well as morphological similarities and distinctions or ontogeny (the process of the development of an organism), scientists can build a phylogenetic tree which illustrates the evolution of taxonomic groups. The concept of phylogeny is fundamental to understanding biodiversity, evolution and genetics.
A basic phylogenetic Tree (see Figure PageIndex 10 Determines the relationship between organisms with similar characteristics and have evolved from an ancestor with common traits. These shared traits could be either analogous or homologous. Homologous traits are similar in their evolutionary origins while analogous traits appear like they do, but don't have the identical origins. Scientists combine similar traits into a grouping called a the clade. For example, all of the species in a clade share the trait of having amniotic eggs. They evolved from a common ancestor that had these eggs. A phylogenetic tree can be built by connecting the clades to identify the organisms who are the closest to one another.
Scientists utilize DNA or RNA molecular information to construct a phylogenetic graph that is more accurate and detailed. This information is more precise and provides evidence of the evolutionary history of an organism. Researchers can use Molecular Data to calculate the age of evolution of organisms and identify how many organisms have a common ancestor.
The phylogenetic relationships between species can be affected by a variety of 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 one species than other species, which can obscure the phylogenetic signal. This issue can be cured by using cladistics, which is a the combination of analogous and homologous features in the tree.
Additionally, phylogenetics can help determine the duration and speed at which speciation occurs. This information can assist conservation biologists make decisions about which species they should protect from extinction. It is ultimately the preservation of phylogenetic diversity which will lead to a complete and balanced ecosystem.
Evolutionary Theory
The central theme of evolution is that organisms acquire different features over time due to their interactions with their environments. Many scientists have come up with theories of evolution, such as the Islamic naturalist Nasir al-Din al-Tusi (1201-274), who believed that an organism could evolve according to its own requirements as well as the Swedish taxonomist Carolus Linnaeus (1707-1778) who conceived the modern hierarchical system of taxonomy, as well as Jean-Baptiste Lamarck (1844-1829), who suggested that the use or absence of traits can lead to changes that are passed on to the next generation.
In the 1930s and 1940s, concepts from various areas, including genetics, natural selection, and particulate inheritance, merged to form a contemporary theorizing of evolution. This describes how evolution occurs by the variation of genes in the population and how these variants change over time as a result of natural selection. This model, called genetic drift mutation, gene flow, and sexual selection, is a key element of modern evolutionary biology and is mathematically described.
Recent discoveries in the field of evolutionary developmental biology have revealed that genetic variation can be introduced into a species via mutation, genetic drift, and reshuffling genes during sexual reproduction, as well as by migration between populations. These processes, in conjunction with others, such as directionally-selected selection and erosion of genes (changes in frequency of genotypes over time) can result in evolution. Evolution is defined by changes in the genome over time as well as changes in the phenotype (the expression of genotypes in individuals).
Incorporating evolutionary thinking into all areas of biology education could increase student understanding of the concepts of phylogeny as well as evolution. In a recent study by Grunspan and colleagues. It was found that teaching students about the evidence for evolution increased their understanding of evolution in a college-level course in biology. To learn more about how to teach about evolution, 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
Traditionally scientists have studied evolution by looking back, studying fossils, comparing species and studying living organisms. But evolution isn't just something that occurred in the past, it's an ongoing process that is happening today. Viruses reinvent themselves to avoid new drugs and bacteria evolve to resist antibiotics. Animals adapt their behavior as a result of the changing environment. The changes that occur are often visible.
But it wasn't until the late 1980s that biologists realized that natural selection could be observed in action as well. The key to this is that different traits confer the ability to survive at different rates and reproduction, and can be passed down from one generation to the next.
In the past, if one allele - the genetic sequence that determines colour was present in a population of organisms that interbred, it might become more prevalent than any other allele. As time passes, this could mean that the number of moths that have 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.
Observing evolutionary change in action is easier when a particular species has a rapid generation turnover, as with 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 regularly, and over 50,000 generations have now passed.
무료 에볼루션 has shown that mutations can alter the rate of change and the efficiency of a population's reproduction. It also demonstrates that evolution takes time, a fact that some find difficult to accept.
Microevolution can also be seen in the fact that mosquito genes for pesticide resistance are more prevalent in populations where insecticides are used. This is because pesticides cause an exclusive pressure that favors those who have resistant genotypes.
The speed at which evolution takes place has led to an increasing appreciation of its importance in a world shaped by human activity, including climate changes, pollution and the loss of habitats that prevent many species from adapting. Understanding evolution can aid you in making better decisions about the future of the planet and its inhabitants.