The Academy's Evolution Site
The concept of biological evolution is a fundamental concept in biology. The Academies have been active for a long time in helping those interested in science comprehend the theory of evolution and how it influences all areas of scientific research.
This site provides students, teachers and general readers with a range of learning resources on evolution. extra resources has the most important 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 all life. sneak a peek at this web-site is seen in a variety of cultures and spiritual beliefs as a symbol of unity and love. It has many practical applications as well, such as providing a framework to understand the history of species, and how they react to changing environmental conditions.
Early attempts to represent the biological world were founded on categorizing organisms on their metabolic and physical characteristics. These methods, which relied on sampling of different 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, these trees are largely comprised of eukaryotes, and bacterial diversity is still largely unrepresented3,4.
In avoiding the necessity of direct observation and experimentation, genetic techniques have enabled us to depict the Tree of Life in a more precise way. Particularly, molecular techniques allow us to build trees using sequenced markers like the small subunit ribosomal gene.
Despite the dramatic expansion of the Tree of Life through genome sequencing, much biodiversity still awaits discovery. This is particularly relevant to microorganisms that are difficult to cultivate and are usually found in one sample5. A recent analysis of all genomes produced an initial draft of the Tree of Life. This includes a large number of archaea, bacteria, and other organisms that have not yet been identified or their diversity is not thoroughly understood6.
This expanded Tree of Life can be used to evaluate the biodiversity of a particular area and determine if specific habitats need special protection. This information can be utilized in a variety of ways, such as identifying new drugs, combating diseases and improving the quality of crops. The information is also beneficial in conservation efforts. It can help biologists identify the areas most likely to contain cryptic species that could have important metabolic functions that could be at risk of anthropogenic changes. While conservation funds are important, the best way to conserve the world's biodiversity is to equip more people in developing nations with the information they require to act locally and support conservation.
Phylogeny
A phylogeny is also known as an evolutionary tree, illustrates the relationships between groups of organisms. By using molecular information, morphological similarities and differences, or ontogeny (the process of the development of an organism) scientists can construct an phylogenetic tree that demonstrates the evolutionary relationship between taxonomic groups. The phylogeny of a tree plays an important role in understanding genetics, biodiversity and evolution.
A basic phylogenetic tree (see Figure PageIndex 10 ) is a method of identifying 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 similar in their underlying evolutionary path, while analogous traits look similar but do not have the same ancestors. Scientists combine similar traits into a grouping known as a Clade. All organisms in a group have a common trait, such as amniotic egg production. They all came from an ancestor that had these eggs. The clades then join to form a phylogenetic branch to determine the organisms with the closest relationship.
To create a more thorough and accurate phylogenetic tree, scientists make use of molecular data from DNA or RNA to determine the connections between organisms. This data is more precise than the morphological data and provides evidence of the evolutionary history of an organism or group. Researchers can utilize Molecular Data to determine the age of evolution of organisms and identify how many species share a common ancestor.
Phylogenetic relationships can be affected by a number of factors such as the phenotypic plasticity. This is a type behaviour that can change due to particular environmental conditions. This can cause a characteristic to appear more resembling to one species than to another and obscure the phylogenetic signals. This problem can be mitigated by using cladistics, which is a the combination of homologous and analogous traits in the tree.
Additionally, phylogenetics can help predict the duration and rate of speciation. This information can assist conservation biologists make decisions about the species they should safeguard from extinction. It is ultimately the preservation of phylogenetic diversity which will result in an ecologically balanced and complete ecosystem.
Evolutionary Theory
The central theme of evolution is that organisms develop various characteristics over time as a result of 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 could develop according to its own requirements and needs, the Swedish taxonomist Carolus Linnaeus (1707-1778) who conceived the modern taxonomy system that is hierarchical and Jean-Baptiste Lamarck (1844-1829), who believed that the use or absence of traits can lead to changes that are passed on to the
In the 1930s and 1940s, concepts from a variety of fields--including genetics, natural selection, and particulate inheritance - came together to create the modern evolutionary theory that explains how evolution happens through the variations of genes within a population, and how those variations change in time due to natural selection. This model, which includes genetic drift, mutations, gene flow and sexual selection is mathematically described.
Recent developments in the field of evolutionary developmental biology have demonstrated that variation can be introduced into a species through mutation, genetic drift and reshuffling of genes during sexual reproduction, as well as through the movement of populations. These processes, as well as other ones like directional selection and genetic erosion (changes in the frequency of an individual's genotype over time) can result in evolution that is defined as change in the genome of the species over time, and also by changes in phenotype over time (the expression of the genotype in an individual).
Incorporating evolutionary thinking into all areas of biology education can increase student understanding of the concepts of phylogeny and evolution. In 에볼루션 바카라 무료 conducted by Grunspan and colleagues., it was shown that teaching students about the evidence for evolution boosted their understanding of evolution in an undergraduate biology course. For more details about how to teach evolution read The Evolutionary Power of Biology in All Areas of Biology or Thinking Evolutionarily as a Framework for Integrating Evolution into Life Sciences Education.
Evolution in Action
Scientists have studied evolution through looking back in the past, analyzing fossils and comparing species. They also observe living organisms. However, evolution isn't something that occurred in the past. It's an ongoing process taking place right now. Viruses reinvent themselves to avoid new antibiotics and bacteria transform to resist antibiotics. Animals adapt their behavior in the wake of the changing environment. The results are usually easy to see.
It wasn't until the late 1980s when biologists began to realize that natural selection was at work. The key is that different traits confer different rates of survival and reproduction (differential fitness) and are transferred from one generation to the next.
In the past, if one particular allele--the genetic sequence that controls coloration - was present in a group of interbreeding organisms, it could quickly become more common than other alleles. Over time, that would mean that 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.
Monitoring evolutionary changes in action is easier when a species has a rapid turnover of its generation such as bacteria. Since 1988 the biologist Richard Lenski has been tracking twelve populations of E. bacteria that descend from a single strain; samples of each population are taken regularly and over 500.000 generations have been observed.
Lenski's research has demonstrated that mutations can alter the rate at which change occurs and the effectiveness at which a population reproduces. It also shows that evolution takes time, which is hard for some to accept.
Microevolution can also be seen in the fact that mosquito genes for pesticide resistance are more common in populations that have used insecticides. This is due to pesticides causing an exclusive pressure that favors those who have resistant genotypes.
The speed at which evolution takes place has led to an increasing awareness of its significance in a world shaped by human activity--including climate change, pollution, and the loss of habitats that hinder many species from adjusting. Understanding evolution can help you make better decisions about the future of our planet and its inhabitants.