The Academy's Evolution Site
Biology is one of the most important concepts in biology. The Academies are committed to helping those interested in science learn about the theory of evolution and how it is incorporated in all areas of scientific research.
This site provides a range of tools for teachers, students and general readers of evolution. It has important video clips from NOVA and WGBH's 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 harmony in a variety of cultures. It has numerous practical applications in addition to providing a framework to understand the history of species, and how they react to changes in environmental conditions.
The first attempts to depict the biological world were based on categorizing organisms based on their physical and metabolic characteristics. These methods, which depend on the sampling of different parts of organisms, or DNA fragments, have significantly increased the diversity of a tree of Life2. These trees are largely composed of eukaryotes, while bacteria are largely underrepresented3,4.
Genetic techniques have significantly expanded our ability to represent the Tree of Life by circumventing the need for direct observation and experimentation. We can create trees using molecular methods like the small-subunit ribosomal gene.
Despite the rapid expansion of the Tree of Life through genome sequencing, much biodiversity still is waiting to be discovered. This is particularly true for microorganisms, which can be difficult to cultivate and are typically only present in a single sample5. A recent study of all known genomes has produced a rough draft version of the Tree of Life, including a large number of archaea and bacteria that have not been isolated, and their diversity is not fully understood6.
This expanded Tree of Life is particularly useful for assessing the biodiversity of an area, helping to determine if certain habitats require special protection. This information can be used in a variety of ways, including identifying new drugs, combating diseases and improving crops. 에볼루션카지노 is also extremely beneficial for conservation efforts. It helps biologists discover areas that are likely to have cryptic species, which may have important metabolic functions, and could be susceptible to changes caused by humans. Although funds to safeguard biodiversity are vital however, the most effective method to ensure the preservation of biodiversity around the world is for more people living in developing countries to be empowered with the necessary knowledge to act locally to promote conservation from within.
Phylogeny
A phylogeny (also known as an evolutionary tree) depicts the relationships between species. Scientists can build an phylogenetic chart which shows the evolution of taxonomic groups using molecular data and morphological differences or similarities. The role of phylogeny is crucial in understanding genetics, biodiversity and evolution.
A basic phylogenetic tree (see Figure PageIndex 10 Determines the relationship between organisms with similar characteristics and have evolved from a common ancestor. These shared traits can be either homologous or analogous. Homologous traits are the same in their evolutionary path. Analogous traits might appear similar, but they do not have the same origins. Scientists group similar traits into a grouping called a Clade. All members of a clade have a common trait, such as amniotic egg production. They all derived from an ancestor that had these eggs. A phylogenetic tree is then built by connecting the clades to identify the species which are the closest to each other.
Scientists make use of DNA or RNA molecular data to build a phylogenetic chart that is more accurate and precise. This information is more precise and gives evidence of the evolution of an organism. Molecular data allows researchers to determine the number of species who share a common ancestor and to estimate their evolutionary age.
The phylogenetic relationships between species are influenced by many factors, including phenotypic flexibility, an aspect of behavior that changes in response to specific environmental conditions. This can cause a characteristic to appear more similar to one species than to the other, obscuring the phylogenetic signals. This problem can be mitigated by using cladistics. This is a method that incorporates an amalgamation of homologous and analogous traits in the tree.
In addition, phylogenetics helps determine the duration and rate at which speciation takes place. This information can aid conservation biologists in making choices about which species to safeguard from extinction. In the end, it's the preservation of phylogenetic diversity that will result in 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 scientists have developed theories of evolution, including the Islamic naturalist Nasir al-Din al-Tusi (1201-274), who believed that an organism would develop according to its own needs, the Swedish taxonomist Carolus Linnaeus (1707-1778) who developed the modern hierarchical system of taxonomy, as well as Jean-Baptiste Lamarck (1844-1829), who suggested that the usage or non-use of traits can lead to changes that are passed on to the next generation.
In the 1930s and 1940s, theories from a variety of fields--including genetics, natural selection and particulate inheritance - came together to create the modern synthesis of evolutionary theory, which defines how evolution is triggered by the variation of genes within a population and how those variants change in time as a result of natural selection. This model, which incorporates mutations, genetic drift, gene flow and sexual selection, can be mathematically described.
Recent discoveries in the field of evolutionary developmental biology have shown that variation can be introduced into a species by mutation, genetic drift, and reshuffling of genes in sexual reproduction, as well as through the movement of populations. These processes, along with others such as directionally-selected selection and erosion of genes (changes in frequency of genotypes over time) can result in evolution. Evolution is defined by changes in the genome over time and changes in phenotype (the expression of genotypes within 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 instance demonstrated that teaching about the evidence for evolution increased students' understanding of evolution in a college biology class. For more information on how to teach evolution, see The Evolutionary Power of Biology in All Areas of Biology or Thinking Evolutionarily A Framework for Infusing Evolution into Life Sciences Education.
Evolution in Action
Traditionally, scientists have studied evolution through looking back--analyzing fossils, comparing species and studying living organisms. However, evolution isn't something that occurred in the past; it's an ongoing process that is taking place right now. Bacteria evolve and resist antibiotics, viruses re-invent themselves and elude new medications and animals alter their behavior in response to the changing climate. The results are often apparent.
It wasn't until late 1980s that biologists began realize that natural selection was also in action. The main reason is that different traits confer the ability to survive at different rates and reproduction, and can be passed on from one generation to the next.
In the past, when one particular allele--the genetic sequence that determines coloration--appeared in a population of interbreeding organisms, it could rapidly become more common than the other alleles. Over time, that would mean that the number of black moths in a population could increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.
It is easier to track evolution when a species, such as bacteria, has a high generation turnover. Since 1988, Richard Lenski, a biologist, has studied twelve populations of E.coli that descend from a single strain. Samples of each population have been collected regularly and more than 50,000 generations of E.coli have been observed to have passed.
Lenski's research has revealed that a mutation can profoundly alter the efficiency with 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 some find hard to accept.
sources of microevolution is the way mosquito genes that are resistant to pesticides are more prevalent in areas in which insecticides are utilized. This is due to pesticides causing a selective pressure which favors those who have resistant genotypes.
The rapidity of evolution has led to a greater recognition of its importance, especially in a world which is largely shaped by human activities. This includes the effects of climate change, pollution and habitat loss that prevents many species from adapting. Understanding evolution can help us make smarter decisions regarding the future of our planet and the lives of its inhabitants.