The Academy's Evolution Site The concept of biological evolution is a fundamental concept in biology. The Academies are involved in helping those who are interested in science to comprehend the evolution theory and how it can be applied in all areas of scientific research. This site provides students, teachers and general readers with a variety of learning resources about evolution. It has key video clips from NOVA and WGBH's science programs on DVD. Going On this page of Life The Tree of Life, an ancient symbol, represents the interconnectedness of all life. It appears in many religions and cultures as a symbol of unity and love. It has many practical applications in addition to providing a framework to understand the evolution of species and how they react to changes in environmental conditions. Early approaches to depicting the biological world focused on categorizing organisms into distinct categories that had been identified by their physical and metabolic characteristics1. These methods, which relied on the sampling of various parts of living organisms, or sequences of short DNA fragments, significantly increased the variety that could be included in a tree of life2. These trees are mostly populated by eukaryotes, and bacterial diversity is vastly underrepresented3,4. Genetic techniques have greatly broadened our ability to represent the Tree of Life by circumventing the requirement for direct observation and experimentation. Trees can be constructed using molecular techniques like the small-subunit ribosomal gene. The Tree of Life has been dramatically expanded through genome sequencing. However there is still a lot of diversity to be discovered. This is especially relevant to microorganisms that are difficult to cultivate and are usually present in a single sample5. Recent analysis of all genomes resulted in 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 whose diversity has not been fully understood6. This expanded Tree of Life is particularly useful in assessing the diversity of an area, assisting to determine if specific habitats require special protection. The information is useful in a variety of ways, such as finding new drugs, fighting diseases and improving crops. This information is also extremely beneficial to conservation efforts. It can help biologists identify the areas most likely to contain cryptic species that could have significant metabolic functions that could be at risk of anthropogenic changes. Although funding 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 empowered with the knowledge to take action locally to encourage conservation from within. Phylogeny A phylogeny, also called an evolutionary tree, reveals the connections between groups of organisms. Scientists can create a phylogenetic chart that shows the evolutionary relationships between taxonomic categories using molecular information and morphological similarities or differences. Phylogeny is essential in understanding biodiversity, evolution and genetics. A basic phylogenetic tree (see Figure PageIndex 10 ) determines the relationship between organisms with similar traits that have evolved from common ancestors. These shared traits could be analogous or homologous. Homologous traits are similar in their evolutionary roots, while analogous traits look similar, but do not share the same origins. Scientists arrange similar traits into a grouping referred to as a clade. Every organism in a group have a common trait, such as amniotic egg production. They all derived from an ancestor who had these eggs. The clades are then connected to form a phylogenetic branch to determine the organisms with the closest relationship to. Scientists utilize DNA or RNA molecular data to construct a phylogenetic graph which is more precise and precise. This data is more precise than the morphological data and provides evidence of the evolution history of an individual or group. Researchers can use Molecular Data to calculate the age of evolution of organisms and identify how many species have an ancestor common to all. The phylogenetic relationships between organisms are influenced by many factors, including phenotypic plasticity an aspect of behavior that alters in response to specific environmental conditions. This can cause a trait to appear more similar to a species than to another, obscuring the phylogenetic signals. However, this issue can be solved through the use of techniques like cladistics, which include a mix of similar and homologous traits into the tree. In addition, phylogenetics helps determine the duration and rate at which speciation takes place. This information can aid conservation biologists in deciding which species to safeguard from disappearance. In the end, it's the conservation of phylogenetic variety that will lead to an ecosystem that is complete and balanced. Evolutionary Theory The central theme in evolution is that organisms change over time due to their interactions with their environment. Many theories of evolution 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 gradually according to its needs, the Swedish botanist Carolus Linnaeus (1707-1778) who developed the modern hierarchical taxonomy Jean-Baptiste Lamarck (1744-1829) who suggested that the use or non-use of traits cause changes that can be passed on to the offspring. In the 1930s & 1940s, theories from various fields, including natural selection, genetics & particulate inheritance, came together to form a contemporary theorizing of evolution. This defines how evolution happens through the variation in genes within a population and how these variations change over time as a result of natural selection. This model, which encompasses genetic drift, mutations in gene flow, and sexual selection, can be mathematically described mathematically. Recent discoveries in the field of evolutionary developmental biology have shown that variations can be introduced into a species by mutation, genetic drift and reshuffling genes during sexual reproduction, and also by migration between populations. These processes, in conjunction with others, such as the directional selection process and the erosion of genes (changes in frequency of genotypes over time), can lead towards evolution. Evolution is defined as 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 aspects of biology. A recent study conducted by Grunspan and colleagues, for example, showed that teaching about the evidence supporting evolution helped students accept the concept of evolution in a college biology class. To learn more about how to teach about evolution, look up The Evolutionary Potential in All Areas of Biology and Thinking Evolutionarily: A Framework for Infusing Evolution in Life Sciences Education. Evolution in Action Scientists have looked at evolution through the past, studying fossils, and comparing species. They also study living organisms. Evolution is not a distant 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 because of a changing world. The changes that result are often visible. But it wasn't until the late 1980s that biologists understood that natural selection could be observed in action as well. The key is that different characteristics result in different rates of survival and reproduction (differential fitness) and are passed down from one generation to the next. In the past, if one allele - the genetic sequence that determines colour was found in a group of organisms that interbred, it could be more prevalent than any other allele. In time, this could mean that the number of moths that have black pigmentation in a group may increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms. It is easier to track evolutionary change when a species, such as bacteria, has a rapid generation turnover. Since 1988, Richard Lenski, a biologist, has been tracking twelve populations of E.coli that are descended from a single strain. Samples of each population were taken regularly and more than 500.000 generations of E.coli have passed. Lenski's research has shown that mutations can drastically alter the speed at the rate at which a population reproduces, and consequently the rate at which it evolves. It also demonstrates that evolution takes time, a fact that many are unable to accept. Microevolution can also be seen in the fact that mosquito genes that confer resistance to pesticides are more common in populations where insecticides have been used. This is due to pesticides causing an enticement that favors individuals who have resistant genotypes. The speed at which evolution can take place has led to an increasing appreciation of its importance in a world shaped by human activities, including climate changes, pollution and the loss of habitats that prevent the species from adapting. Understanding the evolution process can aid you in making better decisions about the future of our planet and its inhabitants.
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