The Academy's Evolution Site
The concept of biological evolution is among the most fundamental concepts in biology. The Academies have been active for a long time in helping people who are interested in science comprehend the theory of evolution and how it influences all areas of scientific exploration.
This site provides teachers, students and general readers with a range of educational resources on evolution. It contains 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 a symbol of love and harmony in a variety of cultures. It also has many practical uses, like providing a framework to understand the evolution of species and how they respond to changes in environmental conditions.
Early attempts to describe 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 bacterial diversity is vastly underrepresented3,4.
Genetic techniques have significantly expanded our ability to depict 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 biodiversity to be discovered. This is especially true for microorganisms that are difficult to cultivate, and which are usually only found in a single specimen5. A recent analysis of all genomes resulted in a rough draft of the Tree of Life. This includes a variety of archaea, bacteria, and other organisms that haven't yet been identified or their diversity is not fully understood6.
The expanded Tree of Life is particularly beneficial in assessing the biodiversity of an area, helping to determine if specific habitats require special protection. This information can be utilized in many ways, including finding new drugs, battling diseases and enhancing crops. The information is also valuable for conservation efforts. It can help biologists identify areas most likely to have cryptic species, which may have important metabolic functions and are susceptible to the effects of human activity. Although funds to protect biodiversity are essential, ultimately the best way to preserve the world's biodiversity is for more people 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. 에볼루션 바카라 체험 can construct a phylogenetic chart that shows the evolution of taxonomic groups using molecular data and morphological differences or similarities. Phylogeny is crucial in understanding biodiversity, evolution and genetics.
A basic phylogenetic tree (see Figure PageIndex 10 ) identifies the relationships between organisms that share similar traits that evolved from common ancestral. These shared traits could be homologous, or analogous. Homologous traits are the same in their evolutionary path. Analogous traits could appear similar however they do not share the same origins. Scientists put similar traits into a grouping known as a clade. For example, all of the organisms that make up a clade share the trait of having amniotic eggs and evolved from a common ancestor who had eggs. The clades are then linked to create a phylogenetic tree to identify organisms that have the closest relationship.
For a more precise and accurate phylogenetic tree scientists rely on molecular information from DNA or RNA to identify the relationships between organisms. This information is more precise and gives evidence of the evolution history of an organism. Researchers can use Molecular Data to determine the evolutionary age of organisms and identify how many species have an ancestor common to all.
The phylogenetic relationships between organisms can be influenced by several factors, including phenotypic plasticity a kind of behavior that alters in response to unique environmental conditions. This can cause a particular trait to appear more like a species other species, which can obscure the phylogenetic signal. This issue can be cured by using cladistics, which is a a combination of homologous and analogous features in the tree.
Furthermore, phylogenetics may aid in predicting the duration and rate of speciation. This information will assist conservation biologists in making choices about which species to protect from the threat of extinction. In the end, it is the preservation of phylogenetic diversity that will result in an ecosystem that is balanced and complete.
Evolutionary Theory
The fundamental concept in evolution is that organisms change over time due to their interactions with their environment. Several theories of evolutionary change have been developed by a wide 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 requirements, the Swedish botanist Carolus Linnaeus (1707-1778) who designed the modern hierarchical taxonomy, as well as Jean-Baptiste Lamarck (1744-1829) who suggested that the use or misuse of traits can cause changes that can be passed on to offspring.
In the 1930s and 1940s, ideas from a variety of fields--including genetics, natural selection and particulate inheritance -- came together to form the modern evolutionary theory, which defines how evolution is triggered by the variations of genes within a population and how those variations change over time as a result of natural selection. This model, called genetic drift, mutation, gene flow and sexual selection, is the foundation of the current evolutionary biology and can be mathematically described.
Recent developments in the field of evolutionary developmental biology have shown that variations can be introduced into a species via genetic drift, mutation, and reshuffling of genes in sexual reproduction, as well as by migration between populations. These processes, in conjunction with other ones like the directional selection process and the erosion of genes (changes in frequency of genotypes over time), can lead towards evolution. Evolution is defined by changes in the genome over time and changes in the phenotype (the expression of genotypes in an individual).
Incorporating evolutionary thinking into all aspects of biology education can increase students' understanding of phylogeny and evolution. In a recent study conducted by Grunspan and colleagues., it was shown that teaching students about the evidence for evolution boosted their understanding of evolution during the course of a college biology. To learn more about how to teach about evolution, please look up The Evolutionary Potential of All Areas of Biology and Thinking Evolutionarily: A Framework for Infusing Evolution into Life Sciences Education.
Evolution in Action
Traditionally, scientists have studied evolution by studying fossils, comparing species and studying living organisms. Evolution is not a distant event, but an ongoing process that continues to be observed today. Bacteria mutate and resist antibiotics, viruses re-invent themselves and escape new drugs and animals change their behavior to the changing environment. The changes that result are often evident.
It wasn't until late 1980s that biologists realized that natural selection can be seen in action, as well. The reason is that different traits have different rates of survival and reproduction (differential fitness), and can be passed down from one generation to the next.
In the past, if one particular allele--the genetic sequence that defines color in a group of interbreeding species, it could quickly become more common than the other alleles. In time, this could mean that the number of moths with black pigmentation 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 evolution 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 descend from a single strain. Samples of each population have been taken regularly and more than 500.000 generations of E.coli have been observed to have passed.
Lenski's research has demonstrated that mutations can alter the rate at which change occurs and the rate of a population's reproduction. It also shows that evolution is slow-moving, a fact that many are unable to accept.
Microevolution can also be seen in the fact that mosquito genes for pesticide resistance are more common in populations where insecticides are used. This is due to pesticides causing an exclusive pressure that favors those who have resistant genotypes.
The rapid pace of evolution taking place has led to a growing awareness of its significance in a world that is shaped by human activity, including climate changes, pollution and the loss of habitats which prevent many species from adapting. Understanding evolution will help you make better decisions about the future of the planet and its inhabitants.