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 comprehend the theory of evolution and how it affects all areas of scientific exploration.
This site provides a range of sources for teachers, students and general readers of evolution. It includes key video clip 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. It is an emblem of love and unity in many cultures. It can be used in many practical ways as well, such as 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 based on categorizing organisms based on their physical and metabolic characteristics. These methods depend on the collection of various parts of organisms or short DNA fragments have significantly increased the diversity of a tree of Life2. The trees are mostly composed of eukaryotes, while bacteria are largely underrepresented3,4.
By avoiding the necessity for direct experimentation and observation genetic techniques have enabled us to depict the Tree of Life in a much more accurate way. Particularly, molecular techniques allow us to build trees by using sequenced markers, such as the small subunit of ribosomal RNA gene.
The Tree of Life has been significantly expanded by genome sequencing. However, there is still much diversity to be discovered. This is particularly true of microorganisms, which can be difficult to cultivate and are usually only found in a single specimen5. A recent analysis of all genomes produced a rough draft of the Tree of Life. This includes a large number of bacteria, archaea and other organisms that have not yet been identified or their diversity is not well understood6.
The expanded Tree of Life is particularly beneficial in assessing the biodiversity of an area, which can help to determine if specific habitats require special protection. This information can be utilized in a variety of ways, from identifying the most effective 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 with significant metabolic functions that could be at risk of anthropogenic changes. While funds to protect biodiversity are essential, the best method to preserve the world's biodiversity is to empower more people in developing countries with the information they require to act locally and promote conservation.
Phylogeny
A phylogeny, also known as an evolutionary tree, reveals the connections between different groups of organisms. Scientists can build an phylogenetic chart which shows the evolutionary relationship of taxonomic categories using molecular information and morphological differences or similarities. Phylogeny is crucial in understanding biodiversity, evolution and genetics.
A basic phylogenetic Tree (see Figure PageIndex 10 ) is a method of identifying the relationships between organisms with similar traits that evolved from common ancestral. 에볼루션사이트 shared traits could be homologous, or analogous. Homologous characteristics are identical in terms of their evolutionary path. Analogous traits could appear similar however they do not have the same ancestry. Scientists organize similar traits into a grouping known as a clade. All organisms in a group share a characteristic, like amniotic egg production. They all derived from an ancestor that had these eggs. The clades then join to form a phylogenetic branch that can determine the organisms with the closest relationship.
Scientists use molecular DNA or RNA data to construct a phylogenetic graph which is more precise and detailed. This data is more precise than the morphological data and provides evidence of the evolution background of an organism or group. The analysis of molecular data can help researchers determine the number of species that share a common ancestor and to estimate their evolutionary age.
The phylogenetic relationships between species 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 trait to appear more similar to a species than another, obscuring the phylogenetic signals. This problem can be addressed by using cladistics, which is a the combination of homologous and analogous features in the tree.
In addition, phylogenetics helps determine the duration and rate at which speciation occurs. 에볼루션 무료 바카라 can aid conservation biologists to decide the species they should safeguard from the threat of extinction. Ultimately, it is the preservation of phylogenetic diversity which will create a complete and balanced ecosystem.
Evolutionary Theory
The central theme of evolution is that organisms acquire distinct characteristics over time due to 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 would develop according to its own needs as well as the Swedish taxonomist Carolus Linnaeus (1707-1778) who developed the modern taxonomy system that is hierarchical as well as Jean-Baptiste Lamarck (1844-1829), who believed that the use or absence of traits can cause changes that are passed on to the next generation.
In the 1930s & 1940s, concepts from various fields, such as genetics, natural selection and particulate inheritance, merged to form a contemporary evolutionary theory. This explains how evolution happens through the variation of genes in the population, and how these variations change with time due to natural selection. This model, called genetic drift mutation, gene flow and sexual selection, is a cornerstone of current evolutionary biology, and is mathematically described.
Recent developments in the field of evolutionary developmental biology have demonstrated that variation can be introduced into a species by mutation, genetic drift, and reshuffling of genes during sexual reproduction, as well as by migration between populations. These processes, in conjunction with others, such as directional selection and gene erosion (changes in the frequency of genotypes over time), can lead towards evolution. Evolution is defined as changes in the genome over time as well as changes in phenotype (the expression of genotypes in an individual).
Incorporating evolutionary thinking into all aspects of biology education could increase students' understanding of phylogeny as well as evolution. In a study by Grunspan et al. It was demonstrated that teaching students about the evidence for evolution increased their acceptance of evolution during an undergraduate biology course. For more information on how to teach evolution, see 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 traditionally studied evolution by looking 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 that is that is taking place today. Bacteria mutate and resist antibiotics, viruses re-invent themselves and escape new drugs and animals change their behavior in response to a changing planet. The changes that result are often visible.
It wasn't until the late 1980s when biologists began to realize that natural selection was also in play. The key is that different characteristics result in different rates of survival and reproduction (differential fitness), and can be passed from one generation to the next.
In the past, if a certain allele - the genetic sequence that determines colour - appeared in a population of organisms that interbred, it could become more prevalent than any other allele. In click through the following post , this could mean that the number of moths that have black pigmentation may increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.
Observing evolutionary change in action is much easier when a species has a fast generation turnover such as bacteria. Since 1988 biologist Richard Lenski has been tracking twelve populations of E. Coli that descended from a single strain; samples from each population are taken on a regular basis and over 500.000 generations have been observed.
Lenski's work has shown that mutations can alter the rate at which change occurs and the rate of a population's reproduction. It also shows that evolution takes time, which is difficult for some to accept.
Microevolution is also evident in the fact that mosquito genes for resistance to pesticides are more prevalent in areas that have used insecticides. This is due to pesticides causing an enticement that favors those with resistant genotypes.
The rapid pace at which evolution takes place has led to an increasing recognition of its importance in a world shaped by human activity, including climate change, pollution and the loss of habitats which prevent the species from adapting. Understanding evolution can help you make better decisions about the future of the planet and its inhabitants.