The Academy's Evolution Site
Biological evolution is a central concept in biology. The Academies are involved in helping those who are interested in science learn about the theory of evolution and how it can be applied across all areas of scientific research.
This site offers a variety of resources for teachers, students and general readers of evolution. It includes key video clip from NOVA and 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 cultures and spiritual beliefs as an emblem of unity and love. It has many practical applications as well, including providing a framework to understand the history of species, and how they respond to changes in environmental conditions.
Early attempts to represent the biological world were built on categorizing organisms based on their physical and metabolic characteristics. These methods, which relied on the sampling of various parts of living organisms or sequences of small fragments of their DNA, significantly increased the variety that could be included in a tree of life2. However the trees are mostly made up of eukaryotes. Bacterial diversity remains vastly underrepresented3,4.
By avoiding the necessity for direct observation and experimentation, genetic techniques have enabled us to represent the Tree of Life in a more precise way. Trees can be constructed using molecular techniques 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 of microorganisms, which are difficult to cultivate and are typically only represented in a single sample5. Recent analysis of all genomes resulted in an unfinished draft of a Tree of Life. This includes a large number of archaea, bacteria and other organisms that have not yet been isolated, or the diversity of which is not thoroughly understood6.
The expanded Tree of Life can be used to evaluate the biodiversity of a particular area and determine if certain habitats require special protection. This information can be used in many ways, including identifying new drugs, combating diseases and improving the quality of crops. This information is also extremely beneficial for conservation efforts. It helps biologists determine the areas that are most likely to contain cryptic species that could have important metabolic functions that could be at risk from anthropogenic change. While funds to protect biodiversity are crucial, ultimately the best way to preserve the world's biodiversity is for more people living in developing countries to be equipped with the knowledge to act locally in order to promote conservation from within.
Phylogeny
A phylogeny is also known as an evolutionary tree, reveals the relationships between different groups of organisms. Using molecular data as well as morphological similarities and distinctions or ontogeny (the process of the development of an organism) scientists can create a phylogenetic tree which illustrates the evolution of taxonomic categories. The phylogeny of a tree plays an important role in understanding biodiversity, genetics and evolution.
A basic phylogenetic tree (see Figure PageIndex 10 ) identifies the relationships between organisms with similar traits that evolved from common ancestral. These shared traits could be either analogous or homologous. Homologous traits are identical in their underlying evolutionary path and analogous traits appear similar but do not have the same origins. Scientists group similar traits together into a grouping known as a Clade. For instance, all of the organisms in a clade have the characteristic of having amniotic eggs and evolved from a common ancestor who had eggs. A phylogenetic tree is built by connecting the clades to identify the species that are most closely related to one another.
Scientists make use of DNA or RNA molecular data to construct a phylogenetic graph that is more precise and precise. This data is more precise than morphological data and provides evidence of the evolutionary history of an organism or group. The analysis of molecular data can help researchers identify the number of organisms who share the same ancestor and estimate their evolutionary age.
The phylogenetic relationships between organisms are influenced by many factors, including phenotypic flexibility, an aspect of behavior that alters in response to unique environmental conditions. This can cause a particular trait to appear more like a species another, clouding the phylogenetic signal. This problem can be addressed by using cladistics. 에볼루션 슬롯게임 Evolution is a method that incorporates an amalgamation of homologous and analogous traits in the tree.
In addition, phylogenetics helps determine the duration and speed at which speciation takes place. This information can assist conservation biologists make decisions about which species they should protect from extinction. In the end, it is the conservation of phylogenetic variety which will create 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, such as the Islamic naturalist Nasir al-Din al-Tusi (1201-274) who believed that an organism would develop according to its own needs as well as the Swedish taxonomist Carolus Linnaeus (1707-1778) who conceived the modern hierarchical taxonomy and Jean-Baptiste Lamarck (1844-1829), who suggested that the use or absence of certain traits can result in changes that are passed on to the
In the 1930s and 1940s, concepts from various fields, such as genetics, natural selection and particulate inheritance, came together to create a modern evolutionary theory. This describes how evolution occurs by the variations in genes within the population and how these variations change over time as a result of natural selection. This model, known as genetic drift mutation, gene flow, and sexual selection, is the foundation of modern evolutionary biology and can be mathematically described.
Recent discoveries in the field of evolutionary developmental biology have revealed that variation can be introduced into a species through genetic drift, mutation, and reshuffling genes during sexual reproduction, as well as through the movement of populations. These processes, along with other ones like the directional selection process and the erosion of genes (changes to the frequency of genotypes over time) can lead to evolution. Evolution is defined by changes in the genome over time, as well as changes in the phenotype (the expression of genotypes in individuals).
Students can gain a better understanding of the concept of phylogeny by using evolutionary thinking in all areas of biology. In a recent study conducted by Grunspan and colleagues. It was demonstrated that teaching students about the evidence for evolution increased their acceptance of evolution during a college-level course in biology. To find out more about how to teach about evolution, please look up The Evolutionary Potential in all Areas of Biology and Thinking Evolutionarily A Framework for Infusing Evolution into Life Sciences Education.
Evolution in Action
Traditionally, scientists have studied evolution by looking back, studying fossils, comparing species, and observing living organisms. Evolution is not a distant moment; it is an ongoing process. Bacteria evolve and resist antibiotics, viruses reinvent themselves and are able to evade new medications, and animals adapt their behavior to the changing environment. The results are often visible.
It wasn't until late 1980s that biologists realized that natural selection can be seen in action, as well. The key to this is that different traits result in the ability to survive at different rates as well as reproduction, and may be passed down from generation to generation.
In the past, if an allele - the genetic sequence that determines colour was found in a group of organisms that interbred, it might become more common than other allele. Over time, this would mean that the number of moths sporting black pigmentation may increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.
It is easier to see evolutionary change when an organism, like bacteria, has a rapid generation turnover. Since 1988 the biologist Richard Lenski has been tracking twelve populations of E. bacteria that descend from a single strain; samples of each are taken regularly, and over fifty thousand generations have been observed.
Lenski's research has shown that a mutation can dramatically alter the rate at the rate at which a population reproduces, and consequently, the rate at which it changes. It also demonstrates that evolution takes time, a fact that some find hard to accept.
Another example of microevolution is that mosquito genes that confer resistance to pesticides appear more frequently in populations where insecticides are employed. Pesticides create an exclusive pressure that favors those with resistant genotypes.
The speed of evolution taking place has led to a growing recognition of its importance in a world that is shaped by human activities, including climate changes, pollution and the loss of habitats which prevent the species from adapting. Understanding evolution can help us make smarter decisions regarding the future of our planet, as well as the lives of its inhabitants.