The Academy's Evolution Site
Biological evolution is a central concept in biology. The Academies have long been involved in helping those interested in science comprehend the theory of evolution and how it influences every area of scientific inquiry.
This site provides teachers, students and general readers with a range of educational resources on evolution. It includes important video clips from NOVA and WGBH-produced science programs on DVD.
Tree of Life
The Tree of Life, an ancient symbol, symbolizes the interconnectedness of all life. It is an emblem of love and unity in many cultures. 에볼루션 바카라 체험 has practical applications, like providing a framework for understanding the evolution of species and how they react to changing environmental conditions.
Early attempts to describe the biological world were built on categorizing organisms based on their metabolic and physical characteristics. These methods, which rely on sampling of different parts of living organisms, or short DNA fragments, greatly increased the variety of organisms that could be included in the tree of life2. However these trees are mainly comprised of eukaryotes, and bacterial diversity is still largely unrepresented3,4.
In avoiding the necessity of direct experimentation and observation genetic techniques have allowed us to represent the Tree of Life in a more precise manner. In particular, molecular methods allow us to build trees using sequenced markers such as the small subunit ribosomal gene.
Despite the rapid expansion of the Tree of Life through genome sequencing, a lot of biodiversity awaits discovery. This is especially the case for microorganisms which are difficult to cultivate and are usually found in one 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 whose diversity is poorly understood6.
The expanded Tree of Life can be used to assess the biodiversity of a specific region and determine if certain habitats need special protection. This information can be utilized in a range of ways, from identifying new medicines to combating disease to enhancing the quality of crops. It is also useful for conservation efforts. It helps biologists discover areas that are most likely to be home to cryptic species, which could perform important metabolic functions and are susceptible to changes caused by humans. While funds to protect biodiversity are important, the best method to preserve the world's biodiversity is to equip more people in developing countries with the information they require to take action locally and encourage conservation.
Phylogeny
A phylogeny is also known as an evolutionary tree, reveals the connections between different groups of organisms. Utilizing molecular data as well as morphological similarities and distinctions, or ontogeny (the process of the development of an organism), scientists can build an phylogenetic tree that demonstrates the evolutionary relationship between taxonomic categories. 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 Finds the connections between organisms that have similar characteristics and have evolved from an ancestor that shared traits. These shared traits may be analogous or homologous. Homologous traits are similar in their evolutionary roots, while analogous traits look similar, but do not share the identical origins. Scientists group similar traits together into a grouping known as a the clade. For instance, all of the organisms in a clade share the characteristic of having amniotic eggs and evolved from a common ancestor which had eggs. A phylogenetic tree is constructed by connecting the clades to identify the species that are most closely related to one another.
Scientists use DNA or RNA molecular data to construct a phylogenetic graph which is more precise and detailed. This information is more precise and gives evidence of the evolution of an organism. Researchers can use Molecular Data to determine the evolutionary age of living organisms and discover the number of organisms that have an ancestor common to all.
The phylogenetic relationship can be affected by a variety of factors such as the phenotypic plasticity. This is a type behavior that changes as a result of particular environmental conditions. This can cause a trait to appear more similar to one species than to another and obscure the phylogenetic signals. This issue can be cured by using cladistics, which is a an amalgamation of homologous and analogous features in the tree.
Additionally, phylogenetics aids predict the duration and rate at which speciation occurs. This information can assist conservation biologists decide which species to protect from the threat of extinction. Ultimately, it is the preservation of phylogenetic diversity that will create an ecologically balanced and complete ecosystem.
Evolutionary Theory
The main idea behind evolution is that organisms change over time as a result of their interactions with their environment. Several theories of evolutionary change have been proposed by a wide variety of scientists including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who envisioned an organism developing gradually according to its needs and needs, the Swedish botanist Carolus Linnaeus (1707-1778) who designed modern hierarchical taxonomy, and Jean-Baptiste Lamarck (1744-1829) who suggested that the use or misuse of traits causes changes that could be passed on to the offspring.
In the 1930s and 1940s, theories from a variety of fields--including genetics, natural selection, and particulate inheritance--came together to form the current synthesis of evolutionary theory which explains how evolution happens through the variations of genes within a population, and how these variants change in time due to natural selection. This model, which incorporates mutations, genetic drift, gene flow and sexual selection, can be mathematically described mathematically.
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 in sexual reproduction, as well as through the movement of populations. These processes, along with others like directional selection and genetic erosion (changes in the frequency of an individual's genotype over time), can lead to evolution, which is defined by change in the genome of the species over time and also by changes in phenotype over time (the expression of that genotype in an individual).
Incorporating evolutionary thinking into all aspects of biology education can improve student understanding of the concepts of phylogeny as well as evolution. A recent study by Grunspan and colleagues, for example revealed that teaching students about the evidence that supports evolution increased students' understanding of evolution in a college-level biology course. For more information about how to teach evolution, see The Evolutionary Potency in All Areas of Biology or Thinking Evolutionarily: a Framework for Integrating Evolution into Life Sciences Education.
Evolution in Action
Scientists have traditionally studied evolution by looking in the past, studying fossils, and comparing species. They also observe living organisms. Evolution isn't a flims event, but an ongoing process that continues to be observed today. The virus reinvents itself to avoid new medications and bacteria mutate to resist antibiotics. Animals alter their behavior as a result of a changing environment. The results are usually visible.
It wasn't until the 1980s when biologists began to realize that natural selection was at work. The key is that various traits confer different rates of survival and reproduction (differential fitness), and can be passed from one generation to the next.
In the past, if one allele - the genetic sequence that determines colour was present in a population of organisms that interbred, it could be more common than any other allele. Over 에볼루션 게이밍 , 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 like bacteria. Since 1988, biologist Richard Lenski has been tracking twelve populations of E. Coli that descended from a single strain. samples of each population are taken regularly, and over fifty thousand generations have been observed.
Lenski's research has shown that a mutation can dramatically alter the speed at which a population reproduces--and so, the rate at which it evolves. It also shows that evolution is slow-moving, a fact that some find hard to accept.
Microevolution can also be seen in the fact that mosquito genes that confer resistance to pesticides are more prevalent in areas where insecticides are used. This is because pesticides cause a selective pressure which 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 that is shaped by human activities, including climate change, pollution, and the loss of habitats which prevent the species from adapting. Understanding evolution will assist you in making better choices about the future of our planet and its inhabitants.