The Academy's Evolution Site
Biology is a key concept in biology. The Academies have been active for a long time in helping people who are interested in science comprehend the theory of evolution and how it affects all areas of scientific research.
This site provides students, teachers and general readers with a wide range of learning resources on evolution. It contains key video clips from NOVA and the WGBH-produced science programs on DVD.
Tree of Life
The Tree of Life is an ancient symbol of the interconnectedness of life. It is a symbol of love and unity in many cultures. It can be used in many practical ways as well, such as providing a framework for understanding the evolution of species and how they react to changing environmental conditions.
The first attempts at depicting the world of biology focused on categorizing organisms into distinct categories which were identified by their physical and metabolic characteristics1. These methods rely on the collection of various parts of organisms, or DNA fragments, have significantly increased the diversity of a tree of Life2. However these trees are mainly made up of eukaryotes. Bacterial diversity is still largely unrepresented3,4.
By avoiding the necessity for direct experimentation and observation genetic techniques have made it possible to represent the Tree of Life in a more precise way. Trees can be constructed using molecular methods such as the small subunit ribosomal gene.
Despite the massive expansion of the Tree of Life through genome sequencing, a large amount of biodiversity awaits discovery. This is particularly true of microorganisms, which can be difficult to cultivate and are usually only present in a single specimen5. 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 have not yet been isolated or the diversity of which is not fully understood6.
에볼루션바카라 expanded Tree of Life can be used to determine the diversity of a specific area and determine if particular habitats need special protection. This information can be utilized in a range of ways, from identifying the most effective medicines to combating disease to improving crops. The information is also valuable for conservation efforts. It can aid biologists in identifying areas that are most likely to have cryptic species, which could perform important metabolic functions and be vulnerable to human-induced change. While funds to protect biodiversity are important, the most effective method to protect the world's biodiversity is to empower more people in developing countries with the information they require to take action locally and encourage conservation.
Phylogeny
A phylogeny is also known as an evolutionary tree, illustrates the connections between various groups of organisms. Scientists can build a phylogenetic diagram that illustrates the evolution of taxonomic groups based on molecular data and morphological differences or similarities. Phylogeny is crucial in understanding evolution, biodiversity and genetics.
A basic phylogenetic Tree (see Figure PageIndex 10 ) identifies the relationships between organisms with similar traits that evolved from common ancestors. These shared traits may be analogous, or homologous. Homologous traits are similar in their evolutionary origins, while analogous traits look similar, but do not share the same origins. Scientists arrange similar traits into a grouping called a the clade. For instance, all the organisms that make up a clade share the characteristic of having amniotic eggs. They evolved from a common ancestor who had eggs. A phylogenetic tree is then built by connecting the clades to identify the species which are the closest to one another.
Scientists utilize DNA or RNA molecular information to build a phylogenetic chart which is more precise and detailed. This information is more precise and provides evidence of the evolutionary history of an organism. Researchers can utilize Molecular Data to estimate the evolutionary age of organisms and identify the number of organisms that have a common ancestor.
The phylogenetic relationships of organisms are influenced by many factors including phenotypic plasticity, a type of behavior that changes in response to unique environmental conditions. This can cause a characteristic to appear more similar to one species than another, obscuring the phylogenetic signal. This issue can be cured by using cladistics, which is a a combination of homologous and analogous traits in the tree.
In addition, phylogenetics can help predict the duration and rate of speciation. This information can help conservation biologists decide the species they should safeguard from extinction. In the end, it's the preservation of phylogenetic diversity which will result in an ecosystem that is complete and balanced.
Evolutionary Theory
The fundamental concept in evolution is that organisms change over time due to their interactions with their environment. Many scientists have proposed theories of evolution, including the Islamic naturalist Nasir al-Din al-Tusi (1201-274) who believed that an organism could evolve according to its individual requirements and needs, the Swedish taxonomist Carolus Linnaeus (1707-1778), who created the modern hierarchical taxonomy and Jean-Baptiste Lamarck (1844-1829), who suggested that the use or non-use of certain traits can result in changes that are passed on to the next generation.
In the 1930s & 1940s, concepts from various areas, including genetics, natural selection and particulate inheritance, merged to create a modern theorizing of evolution. This defines how evolution occurs by the variation in genes within a population and how these variants alter over time due to natural selection. This model, known as genetic drift or mutation, gene flow, and sexual selection, is a key element of modern evolutionary biology and can be mathematically explained.
Recent developments 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 even migration between populations. These processes, along with others such as directionally-selected selection and erosion of genes (changes in the frequency of genotypes over time), can lead towards evolution. Evolution is defined by changes in the genome over time as well as changes in phenotype (the expression of genotypes in individuals).
Incorporating evolutionary thinking into all areas of biology education can improve students' understanding of phylogeny as well as evolution. In a recent study by Grunspan and colleagues., it was shown that teaching students about the evidence for evolution boosted their understanding of evolution in a college-level course in biology. For more information about how to teach evolution look up The Evolutionary Potency in all Areas of Biology or Thinking Evolutionarily: a Framework for Integrating Evolution into Life Sciences Education.
Evolution in Action
Traditionally, scientists have studied evolution by looking back--analyzing fossils, comparing species and studying living organisms. Evolution isn't a flims moment; it is a process that continues today. The virus reinvents itself to avoid new drugs and bacteria evolve to resist antibiotics. Animals adapt their behavior as a result of a changing world. The changes that occur are often evident.
It wasn't until late 1980s that biologists began realize that natural selection was also in play. The key is that different traits have 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 determines coloration--appeared in a population of interbreeding species, it could rapidly become more common than other alleles. Over time, this would mean that the number of moths that have black pigmentation in a group could increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.
Monitoring evolutionary changes in action is easier when a particular species has a fast generation turnover like bacteria. Since 1988 biologist Richard Lenski has been tracking twelve populations of E. bacteria that descend from a single strain. samples of each population are taken on a regular basis, and over fifty thousand generations have passed.
Lenski's research has revealed that a mutation can dramatically alter the efficiency with which a population reproduces and, consequently the rate at which it evolves. It also proves that evolution is slow-moving, a fact that some people find hard to accept.
Another example of microevolution is the way mosquito genes that are resistant to pesticides appear more frequently in areas in which insecticides are utilized. That's because the use of pesticides causes a selective pressure that favors individuals who have resistant genotypes.
The rapidity of evolution has led to a greater appreciation of its importance, especially in a world that is largely shaped by human activity. This includes pollution, climate change, and habitat loss, which prevents many species from adapting. Understanding evolution can assist you in making better choices about the future of our planet and its inhabitants.
