The Academy's Evolution Site
The concept of biological evolution is a fundamental concept in biology. The Academies have been for a long time involved in helping those interested in science comprehend the concept of evolution and how it influences all areas of scientific exploration.
This site provides students, teachers 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, an ancient symbol, represents the interconnectedness of all life. It is an emblem of love and unity across many cultures. 에볼루션 카지노 has many practical applications, like providing a framework to understand the evolution of species and how they react to changes in environmental conditions.
Early approaches to depicting the biological world focused on the classification of organisms into distinct categories that had been distinguished by physical and metabolic characteristics1. These methods, based on sampling of different parts of living organisms, or short fragments of their DNA significantly increased the variety that could be represented in the tree of life2. The trees are mostly composed of eukaryotes, while bacterial diversity is vastly underrepresented3,4.
Genetic techniques have greatly broadened our ability to represent the Tree of Life by circumventing the requirement for direct observation and experimentation. Particularly, molecular techniques allow us to construct trees by using sequenced markers such as the small subunit ribosomal gene.
The Tree of Life has been significantly expanded by genome sequencing. However there is still a lot of diversity to be discovered. This is particularly relevant to microorganisms that are difficult to cultivate, and are usually found in a single specimen5. A recent analysis of all genomes has produced an initial draft of a Tree of Life. This includes a variety of bacteria, archaea and other organisms that have not yet been identified or whose diversity has not been fully understood6.
This expanded Tree of Life is particularly beneficial in assessing the biodiversity of an area, which can help to determine whether specific habitats require special protection. This information can be used in a range of ways, from identifying the most effective remedies to fight diseases to improving the quality of crops. This information is also extremely useful in conservation efforts. It can help biologists identify those areas that are most likely contain cryptic species with important metabolic functions that may be at risk of anthropogenic changes. While conservation funds are important, the most effective method to protect the world's biodiversity is to equip the people of developing nations with the knowledge they need to act locally and support conservation.
Phylogeny
A phylogeny, also called an evolutionary tree, illustrates the relationships between groups of organisms. 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 evolution of taxonomic groups. Phylogeny plays a crucial role in understanding genetics, biodiversity and evolution.
A basic phylogenetic tree (see Figure PageIndex 10 Finds the connections between organisms with similar traits and have evolved from a common ancestor. These shared traits may be analogous, or homologous. Homologous traits are similar in their evolutionary origins and analogous traits appear like they do, but don't have the same ancestors. Scientists group similar traits together into a grouping known as a the clade. For instance, all the organisms in a clade share the characteristic of having amniotic eggs and evolved from a common ancestor which had eggs. The clades are then linked to create a phylogenetic tree to identify organisms that have the closest relationship to.
For a more detailed and accurate phylogenetic tree, scientists make use of molecular data from DNA or RNA to determine the relationships among organisms. This information is more precise and provides evidence of the evolution of an organism. The analysis of molecular data can help researchers identify the number of species who share an ancestor common to them and estimate their evolutionary age.
The phylogenetic relationships of organisms can be influenced by several factors, including phenotypic plasticity an aspect of behavior that changes in response to specific environmental conditions. This can make a trait appear more similar to a species than to the other which can obscure the phylogenetic signal. This problem can be addressed by using cladistics. This is a method that incorporates the combination of homologous and analogous features in the tree.
In addition, phylogenetics helps predict the duration and rate at which speciation takes place. This information can help conservation biologists decide which species to protect from the threat of extinction. It is ultimately the preservation of phylogenetic diversity that will lead to an ecologically balanced and complete ecosystem.
Evolutionary Theory
The main idea behind evolution is that organisms acquire different features over time due to their interactions with their environment. Many scientists have proposed theories of evolution, including the Islamic naturalist Nasir al-Din al-Tusi (1201-274) who believed that a living thing would evolve according to its individual requirements, the Swedish taxonomist Carolus Linnaeus (1707-1778) who developed the modern hierarchical taxonomy as well as Jean-Baptiste Lamarck (1844-1829), who suggested that the use or non-use of certain traits can result in changes that are passed on to the next generation.
In the 1930s & 1940s, ideas from different fields, including genetics, natural selection and particulate inheritance, were brought together to form a modern evolutionary theory. This explains how evolution happens through the variation in genes within the population and how these variants change with time due to natural selection. This model, which includes genetic drift, mutations in gene flow, and sexual selection is mathematically described mathematically.
Recent developments in the field of evolutionary developmental biology have demonstrated that variation can be introduced into a species by genetic drift, mutation, and reshuffling genes during sexual reproduction, as well as by migration between populations. These processes, as well as other ones like the directional selection process and the erosion of genes (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 the phenotype (the expression of genotypes in an individual).
Students can gain a better understanding of the concept of phylogeny by using evolutionary thinking throughout all aspects of biology. A recent study by Grunspan and colleagues, for instance demonstrated that teaching about the evidence that supports evolution helped students accept the concept of evolution in a college biology course. For more information on how to teach evolution look up 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
Traditionally scientists have studied evolution by studying fossils, comparing species, and observing living organisms. However, evolution isn't something that occurred in the past. It's an ongoing process taking place today. Viruses evolve to stay away from new medications and bacteria mutate to resist antibiotics. Animals alter their behavior as a result of the changing environment. The changes that result are often apparent.
It wasn't until the 1980s that biologists began to realize that natural selection was also in play. The key to this is that different traits confer the ability to survive at different rates and reproduction, and can be passed on from generation to generation.
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 all other alleles. As time passes, this could mean that the number of moths that have black pigmentation in a group may 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 much easier when a species has a rapid turnover of its generation like bacteria. Since 1988, Richard Lenski, a biologist, has tracked twelve populations of E.coli that descend from one strain. Samples of each population were taken regularly, and more than 50,000 generations of E.coli have been observed to have passed.
Lenski's work has demonstrated that mutations can drastically alter the speed at which a population reproduces--and so the rate at which it changes. It also shows that evolution takes time, something that is difficult for some to accept.
Another example of microevolution is that mosquito genes that confer resistance to pesticides are more prevalent in populations in which insecticides are utilized. This is due to pesticides causing an exclusive pressure that favors those with resistant genotypes.
The rapidity of evolution has led to a growing appreciation of its importance particularly in a world shaped largely by human activity. This includes climate change, pollution, and habitat loss that prevents many species from adapting. Understanding evolution can assist you in making better choices regarding the future of the planet and its inhabitants.