The Academy's Evolution Site
Biological evolution is a central concept in biology. The Academies are committed to helping those interested in science to comprehend the evolution theory and how it is permeated across all areas of scientific research.
This site provides students, teachers and general readers with a variety of learning resources on evolution. It contains key video clips from NOVA and the WGBH-produced science programs on DVD.
Tree of Life
The Tree of Life, an ancient symbol, represents the interconnectedness of all life. It appears in many spiritual traditions and cultures as a symbol of unity and love. It also has important practical uses, like providing a framework for understanding the evolution of species and how they respond to changes in environmental conditions.
Early attempts to represent the world of biology were founded on categorizing organisms on their physical and metabolic characteristics. These methods, which relied on the sampling of various parts of living organisms or on small fragments of their DNA, significantly expanded the diversity that could be represented in a tree of life2. These trees are largely composed of eukaryotes, while the diversity of bacterial species is greatly underrepresented3,4.
By avoiding the need for 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 by using sequenced markers, such as the small subunit ribosomal RNA gene.
Despite the rapid growth of the Tree of Life through genome sequencing, much biodiversity still remains to be discovered. This is especially true of microorganisms that are difficult to cultivate and are typically only found in a single sample5. A recent analysis of all genomes known to date has created a rough draft of the Tree of Life, including numerous bacteria and archaea that have not been isolated, and whose diversity is poorly understood6.
The expanded Tree of Life can be used to evaluate the biodiversity of a particular area and determine if certain habitats need special protection. This information can be utilized in a range of ways, from identifying new remedies to fight diseases to improving the quality of crops. This information is also extremely useful in conservation efforts. It can help biologists identify the areas that are most likely to contain cryptic species with important metabolic functions that could be vulnerable to anthropogenic change. While conservation funds are important, the most effective method to protect the world's biodiversity is to empower more people in developing nations with the knowledge they need to take action locally and encourage conservation.
Phylogeny
A phylogeny (also known as an evolutionary tree) shows the relationships between species. Scientists can build a phylogenetic chart that shows the evolution of taxonomic groups using molecular data and morphological similarities or differences. Phylogeny is crucial in understanding evolution, biodiversity and genetics.
A basic phylogenetic Tree (see Figure PageIndex 10 ) identifies the relationships between organisms with similar traits that have evolved from common ancestors. These shared traits are either homologous or analogous. Homologous traits are similar in terms of their evolutionary journey. Analogous traits could appear like they are but they don't have the same origins. Scientists put similar traits into a grouping known as a Clade. Every organism in a group have a common characteristic, for example, amniotic egg production. They all evolved from an ancestor with these eggs. A phylogenetic tree is then built by connecting the clades to identify the species who are the closest to each other.
Scientists utilize DNA or RNA molecular information to create a phylogenetic chart which is more precise and precise. This information is more precise and provides evidence of the evolution history of an organism. Researchers can utilize Molecular Data to calculate the evolutionary age of living organisms and discover how many organisms have a common ancestor.
The phylogenetic relationships of a species can be affected by a number of factors such as the phenomenon of phenotypicplasticity. This is a type of behavior that alters in response to specific environmental conditions. This can cause a trait to appear more similar in one species than another, clouding the phylogenetic signal. 에볼루션 슬롯 can be cured by using cladistics. This is a method that incorporates an amalgamation of homologous and analogous features in the tree.
Furthermore, phylogenetics may help predict the time and pace of speciation. This information can aid conservation biologists to make decisions about which species they should protect from the threat of extinction. In the end, it is the conservation of phylogenetic variety which will create an ecosystem that is balanced and complete.
Evolutionary Theory
The central theme in evolution is that organisms change 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 would evolve according to its own needs and needs, the Swedish taxonomist Carolus Linnaeus (1707-1778), who created the modern hierarchical taxonomy and Jean-Baptiste Lamarck (1844-1829), who suggested that the use or absence of certain traits can result in changes that are passed on to the
In the 1930s and 1940s, theories from various fields, including genetics, natural selection and particulate inheritance -- came together to form the modern evolutionary theory which explains how evolution is triggered by the variations of genes within a population and how those variants change in time due to natural selection. This model, which is known as genetic drift mutation, gene flow and sexual selection, is the foundation of current evolutionary biology, and is mathematically described.
Recent discoveries in evolutionary developmental biology have revealed how variations can be introduced to a species through genetic drift, mutations and reshuffling of genes during sexual reproduction and the movement between populations. These processes, as well as others like directional selection and genetic erosion (changes in the frequency of an individual's genotype over time), can lead to evolution that is defined as change in the genome of the species over time and also the change in phenotype as time passes (the expression of that genotype within the individual).
Incorporating evolutionary thinking into all areas of biology education could increase student understanding of the concepts of phylogeny and evolutionary. In a recent study conducted by Grunspan et al. It was demonstrated that teaching students about the evidence for evolution boosted their understanding of evolution during an undergraduate biology course. For more information on how to teach evolution read The Evolutionary Power of Biology in All Areas of Biology or Thinking Evolutionarily as a Framework for Infusing 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 study living organisms. Evolution isn't a flims event, but an ongoing process. The virus reinvents itself to avoid new drugs and bacteria evolve to resist antibiotics. Animals alter their behavior because of the changing environment. The results are usually easy to see.
It wasn't until late 1980s that biologists understood that natural selection can be seen in action, as well. The key is that various characteristics result in different rates of survival and reproduction (differential fitness), and can be passed down from one generation to the next.
In the past, when one particular allele - the genetic sequence that determines coloration--appeared in a group of interbreeding organisms, it might quickly become more prevalent than other alleles. Over time, that would mean that the number of black moths within a population could increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.
The ability to observe evolutionary change is easier when a particular species has a rapid generation turnover such as bacteria. Since 1988, Richard Lenski, a biologist, has studied twelve populations of E.coli that descend from a single strain. The samples of each population have been collected regularly, and more than 500.000 generations of E.coli have passed.
Lenski's research has revealed that mutations can alter the rate of change and the efficiency of a population's reproduction. It also shows that evolution takes time, a fact that some people find difficult to accept.
에볼루션 슬롯 of microevolution is that mosquito genes for resistance to pesticides show up more often in areas where insecticides are used. That's because the use of pesticides creates a selective pressure that favors individuals with resistant genotypes.
The rapidity of evolution has led to a growing appreciation of its importance especially in a planet shaped largely by human activity. This includes the effects of climate change, pollution and habitat loss that prevents many species from adapting. Understanding evolution can help you make better decisions about the future of the planet and its inhabitants.
