The Academy's Evolution Site
The concept of biological evolution is among the most fundamental concepts in biology. The Academies have been for a long time involved in helping those interested in science understand the concept of evolution and how it influences all areas of scientific exploration.
This site provides teachers, students and general readers with a range of learning resources about evolution. It includes key video clips from NOVA and WGBH's science programs on DVD.
Tree of Life
The Tree of Life, an ancient symbol, represents the interconnectedness of all life. 에볼루션 바카라사이트 is seen in a variety of cultures and spiritual beliefs as an emblem of unity and love. It also has many practical applications, like providing a framework to understand the history of species and how they respond to changing environmental conditions.
Early approaches to depicting the biological world focused on the classification of organisms into distinct categories that were distinguished by their physical and metabolic characteristics1. These methods, which rely on the sampling of different parts of living organisms or small fragments of their DNA, significantly increased the variety that could be included in a tree of life2. However, these trees are largely made up of eukaryotes. Bacterial diversity is not represented in a large way3,4.
Genetic techniques have greatly expanded our ability to visualize the Tree of Life by circumventing the requirement for direct observation and experimentation. Trees can be constructed by using molecular methods such as the small subunit ribosomal gene.
The Tree of Life has been significantly expanded by genome sequencing. However, there is still much diversity to be discovered. This is particularly true of microorganisms, which can be difficult to cultivate and are typically only represented in a single sample5. 에볼루션 카지노 사이트 of all genomes known to date has produced a rough draft of the Tree of Life, including a large number of archaea and bacteria that have not been isolated and whose diversity is poorly understood6.
This expanded Tree of Life can be used to assess the biodiversity of a specific area and determine if particular habitats require special protection. The information can be used in a range of ways, from identifying new medicines to combating disease to enhancing the quality of crop yields. This information is also useful for conservation efforts. It can aid biologists in identifying the areas most likely to contain cryptic species that could have important metabolic functions that may be at risk of anthropogenic changes. While funds to protect biodiversity are essential, the best method to protect the world's biodiversity is to equip more people in developing nations with the information they require to act locally and promote conservation.
Phylogeny
A phylogeny (also known as an evolutionary tree) depicts the relationships between different organisms. By using molecular information, morphological similarities and differences or ontogeny (the process of the development of an organism) scientists can create a phylogenetic tree which illustrates the evolutionary relationship between taxonomic groups. Phylogeny is crucial in understanding biodiversity, evolution and genetics.
A basic phylogenetic tree (see Figure PageIndex 10 Determines the relationship between organisms with similar traits and evolved from a common ancestor. These shared traits are either analogous or homologous. Homologous traits are the same in their evolutionary journey. Analogous traits may look like they are, but they do not have the same ancestry. Scientists group similar traits into a grouping called a Clade. All members of a clade share a characteristic, like amniotic egg production. They all came from an ancestor that had these eggs. The clades are then linked to form a phylogenetic branch to determine the organisms with the closest relationship.
Scientists use molecular DNA or RNA data to construct a phylogenetic graph which is more precise and detailed. This data is more precise than morphological data and provides evidence of the evolutionary history of an organism or group. Researchers can use Molecular Data to determine the age of evolution of living organisms and discover how many organisms share a common ancestor.
The phylogenetic relationships between organisms can be influenced by several factors, including phenotypic plasticity a kind of behavior that changes in response to specific environmental conditions. This can cause a characteristic to appear more similar to a species than to another and obscure the phylogenetic signals. This problem can be mitigated by using cladistics, which is a the combination of homologous and analogous traits in the tree.
In addition, phylogenetics can aid in predicting the duration and rate of speciation. This information can aid conservation biologists in deciding which species to save from extinction. It is ultimately the preservation of phylogenetic diversity which will lead to an ecosystem that is complete and balanced.
Evolutionary Theory
The main idea behind evolution is that organisms change over time as a result of their interactions with their environment. Many scientists have proposed theories of evolution, such as the Islamic naturalist Nasir al-Din al-Tusi (1201-274), who believed that a living thing would develop according to its own requirements 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 believed that the use or absence of traits can cause changes that can be passed on to future generations.
In the 1930s & 1940s, ideas from different fields, such as natural selection, genetics & particulate inheritance, were brought together to create a modern theorizing of evolution. This describes how evolution occurs by the variation of genes in the population, and how these variations alter over time due to natural selection. This model, which includes mutations, genetic drift as well as gene flow and sexual selection can be mathematically described.
Recent developments in the field of evolutionary developmental biology have revealed that variation can be introduced into a species by mutation, genetic drift, and reshuffling of genes during sexual reproduction, as well as through the movement of populations. These processes, as well as others such as directionally-selected selection and erosion of genes (changes in 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 an individual).
Students can better understand phylogeny by incorporating evolutionary thinking into all aspects of biology. A recent study by Grunspan and colleagues, for instance revealed that teaching students about the evidence that supports evolution helped students accept the concept of evolution in a college biology course. For more information on how to teach about evolution, please read The Evolutionary Potential in All Areas of Biology and Thinking Evolutionarily A Framework for Infusing Evolution in Life Sciences Education.
Evolution in Action
Traditionally scientists have studied evolution through looking back, studying fossils, comparing species, and observing living organisms. Evolution is not a past moment; it is an ongoing process that continues to be observed today. Viruses reinvent themselves to avoid new medications and bacteria mutate to resist antibiotics. Animals adapt their behavior as a result of the changing environment. The results are usually easy to see.
It wasn't until late 1980s that biologists began to realize that natural selection was also in action. The key is the fact that different traits confer an individual rate of survival and reproduction, and they can be passed down from one generation to another.
In the past, when one particular allele - the genetic sequence that defines color in a population of interbreeding organisms, it might quickly become more prevalent than other alleles. Over time, that would 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.
The ability to observe evolutionary change is easier when a species has a rapid turnover of its generation like bacteria. Since 1988, Richard Lenski, a biologist, has been tracking twelve populations of E.coli that descend from one strain. Samples from each population have been taken frequently and more than 500.000 generations of E.coli have passed.
Lenski's research has demonstrated that mutations can alter the rate of change and the rate at which a population reproduces. It also proves that evolution takes time--a fact that some people find hard to accept.
Another example of microevolution is that mosquito genes that are resistant to pesticides show up more often in areas in which insecticides are utilized. This is due to the fact that the use of pesticides creates a selective pressure that favors those with resistant genotypes.
The speed of evolution taking place has led to a growing awareness of its significance in a world shaped by human activity, including climate change, pollution and the loss of habitats that prevent many species from adjusting. Understanding evolution can aid you in making better decisions about the future of the planet and its inhabitants.