The Academy's Evolution Site
The concept of biological evolution is a fundamental concept in biology. The Academies are involved in helping those interested in the sciences learn about the theory of evolution and how it is incorporated throughout all fields of scientific research.
This site provides teachers, students and general readers with a wide range of learning resources about evolution. It includes important video clips from NOVA and the WGBH-produced science programs on DVD.
Tree of Life
The Tree of Life, an ancient symbol, represents the interconnectedness of all life. It is seen in a variety of religions and cultures as a symbol of unity and love. It also has important practical applications, such as providing a framework for understanding the history of species and how they react to changes in the environment.
The first attempts to depict the biological world were founded on categorizing organisms on their metabolic and physical characteristics. These methods, which relied on the sampling of different parts of living organisms or on sequences of short fragments of their DNA greatly increased the variety of organisms that could be represented 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 allowed us to represent the Tree of Life in a more precise way. Trees can be constructed using molecular techniques like the small-subunit ribosomal gene.
The Tree of Life has been greatly expanded thanks to genome sequencing. However there is a lot of diversity to be discovered. This is particularly relevant to microorganisms that are difficult to cultivate and are usually found in a single specimen5. A recent study of all known genomes has produced a rough draft of the Tree of Life, including numerous archaea and bacteria that have not been isolated and whose diversity is poorly understood6.
This expanded Tree of Life is particularly useful for assessing the biodiversity of an area, helping to determine if specific habitats require protection. This information can be used in a variety of ways, including finding new drugs, battling diseases and improving crops. The information is also incredibly beneficial to conservation efforts. It can help biologists identify the areas that are most likely to contain cryptic species with important metabolic functions that could be at risk from anthropogenic change. While funds to protect biodiversity are crucial, 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 to promote conservation from within.
Phylogeny
A phylogeny is also known as an evolutionary tree, shows the connections between various groups of organisms. Scientists can create a phylogenetic diagram that illustrates the evolutionary relationship of taxonomic groups based on molecular data and morphological similarities or differences. The role of phylogeny is crucial in understanding genetics, biodiversity and evolution.
A basic phylogenetic Tree (see Figure PageIndex 10 ) is a method of identifying the relationships between organisms with similar traits that have evolved from common ancestors. These shared traits are either homologous or analogous. Homologous traits 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 known as a the clade. For instance, all of the organisms in a clade share the trait of having amniotic egg and evolved from a common ancestor which had these eggs. A phylogenetic tree is then built by connecting the clades to identify the organisms that are most closely related to one another.
Scientists utilize DNA or RNA molecular data to construct a phylogenetic graph that is more accurate and precise. This information is more precise than morphological data and provides evidence of the evolutionary history of an individual or group. The analysis of molecular data can help researchers identify the number of species that have an ancestor common to them and estimate their evolutionary age.
The phylogenetic relationships of organisms can be influenced by several factors, including phenotypic flexibility, an aspect of behavior that changes in response to unique environmental conditions. This can make a trait appear more resembling to one species than to the other and obscure the phylogenetic signals. This problem can be mitigated by using cladistics, which incorporates a combination of analogous and homologous features in the tree.
Furthermore, phylogenetics may help predict the length and speed of speciation. This information can aid conservation biologists to make decisions about which species to protect from the threat of extinction. It is ultimately the preservation of phylogenetic diversity which will result in an ecosystem that is complete and balanced.
Evolutionary Theory
The main idea behind evolution is that organisms acquire various characteristics over time as a result of their interactions with their surroundings. Many scientists have proposed theories of evolution, such as the Islamic naturalist Nasir al-Din al-Tusi (1201-274), who believed that an organism could develop according to its own needs as well as the Swedish taxonomist Carolus Linnaeus (1707-1778) who developed the modern hierarchical taxonomy, as well as Jean-Baptiste Lamarck (1844-1829), who suggested that the use or non-use of traits can lead to changes that are passed on to the next generation.
In the 1930s and 1940s, ideas from different fields, including natural selection, genetics & particulate inheritance, were brought together to create a modern evolutionary theory. This explains how evolution happens through the variation of genes in the population and how these variations change with time due to natural selection. This model, which is known as genetic drift, mutation, gene flow, and sexual selection, is a cornerstone of the current evolutionary biology and is mathematically described.
Recent developments in the field of evolutionary developmental biology have revealed that variations can be introduced into a species through genetic drift, mutation, and reshuffling of genes during sexual reproduction, and also by 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 result in evolution. Evolution is defined as changes in the genome over time and changes in the phenotype (the expression of genotypes within individuals).
Full Content can gain a better understanding of the concept of phylogeny by using evolutionary thinking into all aspects of biology. In a study by Grunspan and co. It was found that teaching students about the evidence for evolution boosted their acceptance of evolution during a college-level course in biology. For more details on how to teach about evolution look up The Evolutionary Potency in All Areas of Biology or Thinking Evolutionarily: a Framework for Infusing Evolution into Life Sciences Education.
Evolution in Action
Scientists have looked at evolution through the past, studying fossils, and comparing species. They also study living organisms. However, evolution isn't something that occurred in the past. It's an ongoing process that is taking place today. The virus reinvents itself to avoid new drugs and bacteria evolve to resist antibiotics. Animals adapt their behavior in the wake of a changing environment. The results are usually evident.
It wasn't until late 1980s that biologists began to realize that natural selection was in action. The main reason is that different traits confer a different rate of survival as well as reproduction, and may be passed down from generation to generation.
In the past, when one particular allele - the genetic sequence that defines color in a group of interbreeding species, it could quickly become more common than the other alleles. In 에볼루션 , 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.
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. just click the following document that descended from a single strain; samples of each are taken regularly, and over 500.000 generations have been observed.
Lenski's work has demonstrated that a mutation can profoundly alter the rate at the rate at which a population reproduces, and consequently the rate at which it changes. It also shows that evolution takes time, a fact that some people are unable to accept.
Microevolution is also evident in the fact that mosquito genes that confer resistance to pesticides are more prevalent in populations where insecticides are used. This is due to pesticides causing a selective pressure which favors those with resistant genotypes.
The rapidity of evolution has led to an increasing recognition of its importance especially in a planet which is largely shaped by human activities. This includes pollution, climate change, and habitat loss, which prevents many species from adapting. Understanding the evolution process can aid you in making better decisions about the future of our planet and its inhabitants.