The Academy's Evolution Site
Biological evolution is one of the most central concepts in biology. The Academies have been for a long time involved in helping those interested in science comprehend the theory of evolution and how it affects all areas of scientific research.
This site provides a wide range of tools for teachers, students as well as general readers 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 represents 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 to understand the history of species and how they react to changes in environmental conditions.
Early attempts to describe the world of biology were founded on categorizing organisms on their metabolic and physical characteristics. These methods, based on the sampling of different parts of living organisms or sequences of small fragments of their DNA, greatly increased the variety of organisms that could be included in the tree of life2. The trees are mostly composed of eukaryotes, while the diversity of bacterial species is greatly underrepresented3,4.
By avoiding the necessity for direct experimentation and observation genetic techniques have made it possible to depict the Tree of Life in a more precise manner. In particular, molecular methods allow us to construct trees by using sequenced markers such as the small subunit ribosomal RNA gene.
Despite the rapid expansion of the Tree of Life through genome sequencing, much biodiversity still remains to be discovered. This is especially true for microorganisms that are difficult to cultivate and are typically found in one sample5. A recent analysis of all genomes that are known has produced a rough draft of the Tree of Life, including many archaea and bacteria that have not been isolated, and which are not well understood.
This expanded Tree of Life can be used to evaluate the biodiversity of a specific region and determine if particular habitats need special protection. This information can be used in many ways, including identifying new drugs, combating diseases and improving the quality of crops. The information is also incredibly useful for conservation efforts. 에볼루션사이트 helps biologists discover areas that are most likely to be home to cryptic species, which could have important metabolic functions and are susceptible to changes caused by humans. While 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 equipped with the knowledge to take action locally to encourage conservation from within.
Phylogeny
A phylogeny, also called an evolutionary tree, reveals the relationships between various groups of organisms. Scientists can construct a phylogenetic diagram that illustrates the evolutionary relationship of taxonomic categories using molecular information 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 ) identifies the relationships between organisms with similar traits that have evolved from common ancestral. These shared traits can be either homologous or analogous. Homologous traits are identical in their evolutionary origins while analogous traits appear similar but do not have the identical origins. Scientists combine similar traits into a grouping known as a the clade. For instance, all the organisms in a clade share the trait of having amniotic eggs and evolved from a common ancestor that had eggs. A phylogenetic tree can be built by connecting the clades to identify the species who are the closest to each other.
Scientists use DNA or RNA molecular data to build a phylogenetic chart which is more precise and detailed. This information is more precise than the morphological data and gives evidence of the evolutionary history of an organism or group. The use of molecular data lets researchers identify the number of organisms who share an ancestor common to them and estimate their evolutionary age.
The phylogenetic relationships between species can be affected by a variety of factors, including phenotypic flexibility, a kind of behavior that changes in response to unique environmental conditions. This can cause a trait to appear more like a species another, obscuring the phylogenetic signal. This issue can be cured by using cladistics, which is a the combination of homologous and analogous features in the tree.
In addition, phylogenetics helps determine the duration and speed at which speciation takes place. This information can aid conservation biologists in deciding which species to protect from disappearance. In the end, it is the conservation of phylogenetic variety that will lead to an ecosystem that is complete and balanced.
Evolutionary Theory
The fundamental concept of evolution is that organisms develop different features over time due to their interactions with their environment. Several theories of evolutionary change have been proposed by a variety of scientists, including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who proposed that a living organism develop slowly according to its requirements, the Swedish botanist Carolus Linnaeus (1707-1778) who conceived modern hierarchical taxonomy, and Jean-Baptiste Lamarck (1744-1829) who suggested that use or disuse of traits causes changes that can be passed onto offspring.
In the 1930s and 1940s, theories from various fields, including genetics, natural selection, and particulate inheritance--came together to form the current synthesis of evolutionary theory, which defines how evolution is triggered by the variation of genes within a population and how those variations change in time as a result of natural selection. This model, which is known as genetic drift mutation, gene flow, and sexual selection, is a key element of current evolutionary biology, and can be mathematically explained.
Recent developments in evolutionary developmental biology have revealed the ways in which variation can be introduced to a species by genetic drift, mutations and reshuffling of genes during sexual reproduction and the movement between populations. These processes, along with other ones like directional selection and genetic erosion (changes in the frequency of an individual's genotype over time), can lead to evolution, which is defined by changes in the genome of the species over time and the change in phenotype as time passes (the expression of the genotype in an individual).
Students can better understand the concept of phylogeny through incorporating evolutionary thinking into all areas of biology. In a recent study by Grunspan and colleagues. It was demonstrated that teaching students about the evidence for evolution boosted their acceptance of evolution during the course of a college biology. To find out more about how to teach about evolution, please 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 through looking back, studying fossils, comparing species and observing living organisms. Evolution isn't a flims event, but a process that continues today. Bacteria mutate and resist antibiotics, viruses evolve and escape new drugs, and animals adapt their behavior to a changing planet. The results are often visible.
It wasn't until late 1980s that biologists understood that natural selection could be observed in action as well. The reason is that different traits have different rates of survival and reproduction (differential fitness), and can be transferred from one generation to the next.
In the past, if an allele - the genetic sequence that determines colour - appeared in a population of organisms that interbred, it could be more common than any other allele. As time passes, this could mean that the number of moths sporting black pigmentation in a population may increase. try this 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 the biologist Richard Lenski has been tracking twelve populations of E. Coli that descended from a single strain; samples from each population are taken regularly and over 500.000 generations have been observed.
Lenski's work has demonstrated that a mutation can dramatically alter the speed at the rate at which a population reproduces, and consequently, the rate at which it changes. It also proves that evolution is slow-moving, a fact that many find hard to accept.
Another example of microevolution is how mosquito genes for resistance to pesticides are more prevalent in areas in which insecticides are utilized. Pesticides create an exclusive pressure that favors those who have resistant genotypes.
The rapidity of evolution has led to a growing awareness of its significance especially in a planet which is largely shaped by human activities. This includes climate change, pollution, and habitat loss, which prevents many species from adapting. Understanding evolution can aid you in making better decisions about the future of our planet and its inhabitants.