The Academy's Evolution Site
Biological evolution is a central concept in biology. The Academies have been for a long time involved in helping those interested in science understand the theory of evolution and how it permeates all areas of scientific exploration.
This site provides teachers, students and general readers with a wide range of learning resources about evolution. It includes 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 life. It is used in many religions and cultures as an emblem of unity and love. It has many practical applications in addition to providing a framework to understand the history of species and how they respond to changes in environmental conditions.
The first attempts to depict the biological world were built on categorizing organisms based on their physical and metabolic characteristics. These methods rely on the sampling of different parts of organisms or DNA fragments, have significantly increased the diversity of a tree of Life2. These trees are mostly populated of eukaryotes, while the diversity of bacterial species is greatly underrepresented3,4.
Genetic techniques have significantly expanded our ability to visualize the Tree of Life by circumventing the need for direct observation and experimentation. In particular, molecular methods allow us to construct trees by using sequenced markers, such as the small subunit ribosomal gene.
Despite the massive expansion of the Tree of Life through genome sequencing, a lot of biodiversity remains to be discovered. This is particularly true of microorganisms, which are difficult to cultivate and are usually only present in a single sample5. Recent analysis of all genomes resulted in an initial draft of a Tree of Life. 에볼루션 코리아 includes a variety of archaea, bacteria, and other organisms that haven't yet been isolated or the diversity of which is not well understood6.
The expanded Tree of Life can be used to assess the biodiversity of a particular area and determine if certain habitats need special protection. 에볼루션 바카라 무료 can be utilized in a range of ways, from identifying new medicines to combating disease to enhancing the quality of the quality of crops. This information is also extremely beneficial to conservation efforts. It can aid biologists in identifying those areas that are most likely contain cryptic species that could have important metabolic functions that may be vulnerable to anthropogenic change. While funds to safeguard biodiversity are vital but the most effective way to protect the world's biodiversity is for more people in developing countries to be empowered with the necessary knowledge to act locally in order to promote conservation from within.
Phylogeny
A phylogeny is also known as an evolutionary tree, reveals the connections between groups of organisms. Scientists can build an phylogenetic chart which shows the evolutionary relationship of taxonomic groups based on molecular data and morphological similarities or differences. Phylogeny is crucial in understanding the evolution of biodiversity, evolution and genetics.
A basic phylogenetic tree (see Figure PageIndex 10 ) identifies the relationships between organisms that share similar traits that have evolved from common ancestors. These shared traits are either analogous or homologous. Homologous traits are similar in their evolutionary origins, while analogous traits look similar but do not have the identical origins. Scientists put similar traits into a grouping known as a the clade. All members of a clade share a characteristic, for example, amniotic egg production. They all derived from an ancestor who had these eggs. A phylogenetic tree is constructed by connecting the clades to identify the organisms that are most closely related to one another.
Scientists utilize DNA or RNA molecular information to create a phylogenetic chart that is more precise and precise. This information is more precise than the morphological data and gives evidence of the evolutionary history of an organism or group. Molecular data allows researchers to determine the number of organisms that have the same ancestor and estimate their evolutionary age.
Phylogenetic relationships can be affected by a number of factors, including phenotypicplasticity. This is a type behaviour that can change as a result of unique environmental conditions. This can cause a characteristic to appear more similar to one species than to another and obscure the phylogenetic signals. This problem can be mitigated by using cladistics. This is a method that incorporates the combination of homologous and analogous traits in the tree.
Additionally, phylogenetics aids predict the duration and rate at which speciation takes place. This information will assist conservation biologists in making choices about which species to save from the threat of extinction. In the end, it's the conservation of phylogenetic diversity that will lead to an ecosystem that is complete and balanced.
Evolutionary Theory
The fundamental concept of evolution is that organisms develop various characteristics over time based on their interactions with their environment. Several theories of evolutionary change have been proposed by a wide variety of scientists such as the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who believed that an organism would evolve gradually according to its requirements and needs, 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 cause changes that could be passed onto offspring.
In the 1930s and 1940s, theories from various fields, including genetics, natural selection, and particulate inheritance--came together to create the modern evolutionary theory, which defines how evolution happens through the variation of genes within a population, and how those variants change in time as a result of natural selection. This model, which includes genetic drift, mutations, gene flow and sexual selection, can be mathematically described.
Recent discoveries in the field of evolutionary developmental biology have demonstrated that variations can be introduced into a species by mutation, genetic drift and reshuffling genes during sexual reproduction, as well as through migration between populations. These processes, as well as other ones like directional selection and gene erosion (changes in frequency of genotypes over time) can lead to evolution. Evolution is defined by changes in the genome over time and changes in phenotype (the expression of genotypes in individuals).
Incorporating evolutionary thinking into all aspects of biology education can increase students' understanding of phylogeny and evolutionary. In a study by Grunspan et al., it was shown that teaching students about the evidence for evolution boosted their understanding of evolution in a college-level course in biology. To find out more about how to teach about evolution, look up The Evolutionary Potential of all Areas of Biology and Thinking Evolutionarily: A Framework for Infusing Evolution in Life Sciences Education.
Evolution in Action
Traditionally scientists have studied evolution through looking back--analyzing fossils, comparing species and studying living organisms. Evolution is not a distant event; it is an ongoing process. Bacteria transform and resist antibiotics, viruses evolve and escape new drugs and animals alter their behavior to the changing climate. The results are usually easy to see.
It wasn't until late-1980s that biologists realized that natural selection can be seen in action, as well. The key is that various traits have different rates of survival and reproduction (differential fitness) and can be passed from one generation to the next.
In the past, if one particular allele--the genetic sequence that defines color in a population of interbreeding organisms, it might quickly become more prevalent than the other alleles. Over time, that would mean that the number of black moths in 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. bacteria that descend from a single strain. samples of each are taken every day and over 50,000 generations have now passed.
Lenski's research has revealed that mutations can alter the rate of change and the efficiency at which a population reproduces. It also shows that evolution takes time--a fact that many are unable to accept.
Microevolution is also evident in the fact that mosquito genes for resistance to pesticides are more prevalent in areas where insecticides have been used. Pesticides create a selective pressure which favors those who have resistant genotypes.
The rapidity of evolution has led to an increasing appreciation of its importance especially in a planet shaped largely by human activity. This includes pollution, climate change, and habitat loss that hinders many species from adapting. Understanding evolution will help you make better decisions regarding the future of the planet and its inhabitants.