The Academy's Evolution Site

Biological evolution is a central concept in biology. The Academies have been for a long time involved in helping people who are interested in science understand the theory of evolution and how it influences all areas of scientific exploration.

This site provides students, teachers and general readers with a variety of learning resources on evolution. It contains key 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 across many cultures. It also has practical applications, such as providing a framework to understand the history of species and how they react to changing environmental conditions.

Early attempts to represent the world of biology were built on categorizing organisms based on their metabolic and physical characteristics. These methods, which are based on the collection of various parts of organisms or short fragments of DNA, have significantly increased the diversity of a Tree of Life2. These trees are largely composed by eukaryotes and bacterial diversity is vastly underrepresented3,4.

By avoiding the necessity for direct experimentation and observation genetic techniques have allowed us to represent the Tree of Life in a much more accurate way. We can create trees using molecular methods, such as the small-subunit ribosomal gene.

The Tree of Life has been greatly expanded thanks to genome sequencing. However there is still a lot of diversity to be discovered. This is particularly true of microorganisms, which can be difficult to cultivate and are usually only present in a single specimen5. A recent study of all known genomes has created a rough draft of the Tree of Life, including numerous archaea and bacteria that have not been isolated, and whose diversity is poorly understood6.

This expanded Tree of Life can be used to evaluate the biodiversity of a specific area and determine if specific habitats need special protection. The information is useful in a variety of ways, including finding new drugs, battling diseases and 에볼루션 무료체험 improving the quality of crops. This information is also valuable to conservation efforts. It can help biologists identify areas most likely to be home to cryptic species, which may have vital metabolic functions and are susceptible to the effects of human activity. While conservation funds are important, the most effective way to conserve the world's biodiversity is to empower more people in developing countries with the information they require to take action locally and encourage conservation.

Phylogeny

A phylogeny (also known as an evolutionary tree) depicts the relationships between species. By using molecular information as well as morphological similarities and distinctions or ontogeny (the process of the development of an organism) scientists can construct an phylogenetic tree that demonstrates the evolutionary relationship between taxonomic groups. The role of phylogeny is crucial in understanding biodiversity, genetics and evolution.

A basic phylogenetic Tree (see Figure PageIndex 10 Identifies the relationships between organisms that have similar traits and 에볼루션 무료체험 have evolved from an ancestor that shared traits. These shared traits may be analogous or homologous. Homologous characteristics are identical in their evolutionary path. Analogous traits might appear like they are however they do not have the same ancestry. Scientists put similar traits into a grouping called a Clade. All organisms in a group have a common characteristic, for example, amniotic egg production. They all came from an ancestor with these eggs. The clades then join to form a phylogenetic branch to determine the organisms with the closest relationship to.

Scientists utilize DNA or 에볼루션 게이밍 RNA molecular data to construct a phylogenetic graph that is more accurate and detailed. This information is more precise and gives evidence of the evolution of an organism. The analysis of molecular data can help researchers identify the number of species who share the same ancestor and estimate their evolutionary age.

Phylogenetic relationships can be affected by a variety of factors that include the phenomenon of phenotypicplasticity. This is a kind of behaviour that can change as a result of specific environmental conditions. This can cause a characteristic to appear more like a species another, clouding the phylogenetic signal. This problem can be mitigated by using cladistics, 에볼루션 카지노 사이트 which is a the combination of homologous and analogous features in the tree.

Additionally, phylogenetics can help determine the duration and speed at which speciation occurs. This information can assist conservation biologists in making decisions about which species to save from the threat of extinction. In the end, it's the preservation of phylogenetic diversity that will lead to an ecosystem that is balanced and complete.

Evolutionary Theory

The central theme of evolution is that organisms acquire various characteristics over time due to their interactions with their surroundings. Many scientists have come up with 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 individual requirements, 에볼루션 바카라 무료체험 the Swedish taxonomist Carolus Linnaeus (1707-1778), who created the modern hierarchical system of taxonomy, as well as Jean-Baptiste Lamarck (1844-1829), who believed that the use or absence of traits can cause changes that can be passed on to future generations.

In the 1930s and 1940s, ideas from a variety of fields -- including genetics, natural selection, and particulate inheritance--came together to form the modern synthesis of evolutionary theory that explains how evolution is triggered by the variation of genes within a population, and how those variants change in time as a result of natural selection. This model, known as genetic drift, mutation, gene flow, and sexual selection, is a key element of modern evolutionary biology and can be mathematically described.

Recent discoveries in the field of evolutionary developmental biology have shown the ways in which variation can be introduced to a species via genetic drift, mutations or reshuffling of genes in sexual reproduction and the movement between populations. These processes, along with other ones like directionally-selected selection and erosion of genes (changes to the frequency of genotypes over time), can lead towards evolution. Evolution is defined by changes in the genome over time as well as changes in phenotype (the expression of genotypes in an individual).

Students can better understand the concept of phylogeny through incorporating evolutionary thinking throughout all areas of biology. In a recent study by Grunspan et al., it was shown that teaching students about the evidence for evolution boosted their acceptance of evolution during the course of a college biology. For more information on how to teach about evolution, look up The Evolutionary Potential in all Areas of Biology and Thinking Evolutionarily A Framework for Infusing Evolution into Life Sciences Education.

Evolution in Action

Scientists have traditionally studied evolution through looking back in the past, studying fossils, and comparing species. They also study living organisms. Evolution isn't a flims event; it is an ongoing process that continues to be observed today. Viruses evolve to stay away from new medications and bacteria mutate to resist antibiotics. Animals adapt their behavior as a result of the changing environment. The changes that result are often evident.

However, it wasn't until late 1980s that biologists understood that natural selection could be seen in action, as well. The key to this is that different traits can confer a different rate of survival and reproduction, and they can be passed down from generation to generation.

In the past, if one allele - the genetic sequence that determines colour - was found in a group of organisms that interbred, it might become more prevalent than any other allele. Over time, that would mean the number of black moths within a particular population could rise. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.

Monitoring evolutionary changes in action is much easier when a species has a rapid generation turnover, as with 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 every day and over fifty thousand generations have passed.

Lenski's work has demonstrated that mutations can drastically alter the rate at which a population reproduces--and so the rate at which it alters. It also shows that evolution takes time, a fact that is hard for some to accept.

Another example of microevolution is the way mosquito genes for resistance to pesticides appear more frequently in areas where insecticides are used. Pesticides create an enticement that favors individuals who have resistant genotypes.

The rapidity of evolution has led to a growing appreciation of its importance particularly in a world which is largely shaped by human activities. This includes pollution, climate change, and habitat loss that prevents many species from adapting. Understanding evolution can help you make better decisions about the future of our planet and its inhabitants.