The Academy's Evolution Site
Biology is one of the most fundamental concepts in biology. The Academies have been for a long time involved in helping people who are interested in science comprehend the concept of evolution and how it permeates all areas of scientific exploration.
This site offers a variety of resources for students, teachers as well as general readers about evolution. It includes key video clips from NOVA and WGBH-produced science programs on DVD.
Tree of Life
The Tree of Life is an ancient symbol that symbolizes the interconnectedness of life. It is an emblem of love and unity across many cultures. It also has important practical applications, such as providing a framework for understanding the history of species and how they react to changes in environmental conditions.
mouse click the following article to depict the biological world focused on categorizing organisms into distinct categories which had been distinguished by physical and metabolic characteristics1. These methods depend on the collection of various parts of organisms, or fragments of DNA have significantly increased the diversity of a tree of Life2. These trees are mostly populated by eukaryotes, and bacteria are largely underrepresented3,4.
In avoiding the necessity of direct observation and experimentation genetic techniques have enabled us to depict the Tree of Life in a much more accurate way. We can construct trees using molecular techniques such as the small subunit ribosomal gene.
Despite the dramatic growth of the Tree of Life through genome sequencing, a large amount of biodiversity remains to be discovered. This is particularly true for microorganisms that are difficult to cultivate, and are typically found in a single specimen5. A recent analysis of all genomes resulted in a rough draft of a Tree of Life. This includes a large number of bacteria, archaea and other organisms that haven't yet been isolated, or the diversity of which is not thoroughly understood6.
The expanded Tree of Life can be used to assess the biodiversity of a specific area and determine if particular habitats require special protection. click the following article can be used in a variety of ways, from identifying new remedies to fight diseases to enhancing the quality of crops. The information is also incredibly valuable in conservation efforts. It can help biologists identify areas most likely to have cryptic species, which could have important metabolic functions and are susceptible to the effects of human activity. While funds to protect biodiversity are important, the best way to conserve the world's biodiversity is to equip more people in developing nations with the knowledge they need to act locally and support conservation.
Phylogeny
A phylogeny (also known as an evolutionary tree) shows the relationships between different organisms. Scientists can construct a phylogenetic diagram that illustrates the evolutionary relationships between taxonomic groups using molecular data and morphological similarities or differences. The phylogeny of a tree plays an important role in understanding the relationship between genetics, biodiversity and evolution.
A basic phylogenetic Tree (see Figure PageIndex 10 Identifies the relationships between organisms with similar traits and have evolved from a common ancestor. These shared traits could be either analogous or homologous. Homologous traits are similar in their evolutionary roots and analogous traits appear similar, but do not share the identical origins. Scientists arrange similar traits into a grouping called a clade. For instance, all of the species in a clade have the characteristic of having amniotic egg and evolved from a common ancestor that had these eggs. The clades then join to form a phylogenetic branch that can determine the organisms with the closest relationship to.
Scientists utilize DNA or RNA molecular data to construct a phylogenetic graph that is more accurate and precise. This information is more precise and provides evidence of the evolution of an organism. The use of molecular data lets researchers identify the number of species that share the same ancestor and estimate their evolutionary age.
The phylogenetic relationships of organisms are influenced by many factors including phenotypic plasticity, a type of behavior that alters in response to unique environmental conditions. This can cause a trait to appear more similar to one species than to the other and obscure the phylogenetic signals. This problem can be mitigated by using cladistics, which is a an amalgamation of homologous and analogous traits in the tree.
Additionally, phylogenetics can help predict the time and pace of speciation. This information can aid conservation biologists in making decisions about which species to protect from extinction. Ultimately, it is the preservation of phylogenetic diversity that will create an ecologically balanced and complete ecosystem.
Evolutionary Theory
The central theme of evolution is that organisms acquire different features over time as a result of their interactions with their environments. Many theories of evolution have been proposed by a wide variety of scientists, including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who believed that an organism would evolve slowly according to its requirements and needs, the Swedish botanist Carolus Linnaeus (1707-1778) who developed the modern hierarchical taxonomy Jean-Baptiste Lamarck (1744-1829) who suggested that use or disuse of traits can cause changes that could be passed on to offspring.
In the 1930s and 1940s, theories from a variety of fields -- including genetics, natural selection and particulate inheritance--came together to form the modern synthesis of evolutionary theory that explains how evolution occurs through the variations of genes within a population, and how those variants change in 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 is mathematically described.
Recent developments in the field of evolutionary developmental biology have shown that variation can be introduced into a species via mutation, genetic drift, and reshuffling of genes in sexual reproduction, and also by migration between populations. These processes, as well as others such as the directional selection process and the erosion of genes (changes to 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 within individuals).
Students can better understand phylogeny by incorporating evolutionary thinking in all aspects of biology. A recent study conducted by Grunspan and colleagues, for example, showed that teaching about the evidence that supports evolution helped students accept the concept of evolution in a college-level biology course. 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 observing living organisms. However, evolution isn't something that happened in the past; it's an ongoing process that is that is taking place today. Viruses evolve to stay away from new medications and bacteria mutate to resist antibiotics. Animals adapt their behavior in the wake of the changing environment. The changes that result are often evident.
It wasn't until the late 1980s that biologists began realize that natural selection was also in action. The reason is that different characteristics result in different rates of survival and reproduction (differential fitness) and can be passed from one generation to the next.
In the past, if one particular allele, the genetic sequence that determines coloration--appeared in a group of interbreeding organisms, it might quickly become more common than the other alleles. Over time, that would mean the number of black moths within the population could increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.
Observing evolutionary change in action is easier when a particular species has a fast generation turnover like bacteria. 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 on a regular basis and more than 500.000 generations have passed.
Lenski's work has demonstrated that a mutation can dramatically alter the efficiency with the rate at which a population reproduces, and consequently the rate at which it changes. It also demonstrates that evolution takes time, which is hard for some to accept.
Another example of microevolution is how mosquito genes that are resistant to pesticides show up more often in populations in which insecticides are utilized. This is because the use of pesticides creates a pressure that favors people with resistant genotypes.
The rapidity of evolution has led to a greater recognition of its importance especially in a planet that is largely shaped by human activity. This includes climate change, pollution, and habitat loss, which prevents many species from adapting. Understanding the evolution process can help you make better decisions about the future of the planet and its inhabitants.