The Academy's Evolution Site
Biological evolution is a central concept in biology. The Academies are committed to helping those interested in the sciences learn about the theory of evolution and how it can be applied in all areas of scientific research.
This site provides students, teachers and general readers with a range 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, represents the interconnectedness of all life. It is seen in a variety of cultures and spiritual beliefs as a symbol of unity and love. 에볼루션카지노사이트 can be used in many practical ways as well, such as providing a framework for understanding the history of species and how they react to changing environmental conditions.
Early attempts to represent the world of biology were based on categorizing organisms based on their physical and metabolic characteristics. These methods depend on the sampling of different parts of organisms or short fragments of DNA have greatly increased the diversity of a Tree of Life2. These trees are mostly populated by eukaryotes and the diversity of bacterial species is greatly underrepresented3,4.
Genetic techniques have greatly broadened our ability to visualize the Tree of Life by circumventing the requirement for direct observation and experimentation. Trees can be constructed by using molecular methods such as the small subunit ribosomal gene.
The Tree of Life has been dramatically expanded through genome sequencing. However, there is still much biodiversity to be discovered. This is particularly true for microorganisms that are difficult to cultivate and which are usually only found in one sample5. A recent analysis of all genomes has produced an initial draft of the Tree of Life. This includes a wide range of bacteria, archaea and other organisms that have not yet been identified or their diversity is not thoroughly understood6.
This expanded Tree of Life can be used to evaluate the biodiversity of a specific region and determine if specific habitats need special protection. This information can be used in a variety of ways, from identifying the most effective treatments to fight disease to improving the quality of crops. This information is also extremely beneficial for conservation efforts. It can help biologists identify areas that are likely to have cryptic species, which may have important metabolic functions and be vulnerable to changes caused by humans. While funds to protect biodiversity are essential however, the most effective method to protect the world's biodiversity is for more people in developing countries to be equipped with the knowledge to act locally in order to promote conservation from within.
Phylogeny
A phylogeny is also known as an evolutionary tree, illustrates the relationships between different groups of organisms. Scientists can construct a phylogenetic chart that shows the evolutionary relationship of taxonomic groups using 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 ) is a method of identifying the relationships between organisms that share similar traits that evolved from common ancestral. These shared traits can be analogous or homologous. Homologous characteristics are identical in terms of their evolutionary journey. Analogous traits could appear similar however they do not share the same origins. Scientists put similar traits into a grouping known as a clade. For instance, all of the organisms in a clade share the trait of having amniotic eggs and evolved from a common ancestor that had eggs. A phylogenetic tree is then constructed by connecting the clades to identify the species who are the closest to each other.
Scientists make use of DNA or RNA molecular information to create a phylogenetic chart that is more accurate and detailed. This information is more precise than morphological information and gives evidence of the evolutionary history of an individual or group. Researchers can utilize Molecular Data to calculate the age of evolution of organisms and identify the number of organisms that share an ancestor common to all.
The phylogenetic relationships of a species can be affected by a number of factors that include phenotypicplasticity. This is a kind of behavior that alters as a result of specific environmental conditions. This can cause a trait to appear more similar to one species than other species, which can obscure the phylogenetic signal. However, this problem can be reduced by the use of techniques such as cladistics which combine analogous and homologous features into the tree.
Furthermore, phylogenetics may aid in predicting the duration and rate of speciation. This information can aid conservation biologists to decide the species they should safeguard from the threat of extinction. In the end, it is the conservation of phylogenetic variety that will lead to an ecosystem that is balanced and complete.
Evolutionary Theory
The main idea behind evolution is that organisms acquire various characteristics over time due to their interactions with their surroundings. Many scientists have developed theories of evolution, including the Islamic naturalist Nasir al-Din al-Tusi (1201-274), who believed that a living thing would develop according to its own needs as well as 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 lead to changes that are passed on to the
In the 1930s and 1940s, theories from a variety of fields--including genetics, natural selection and particulate inheritance -- came together to create the modern evolutionary theory which explains how evolution happens through the variation of genes within a population, and how those variants change over time as a result of natural selection. This model, called genetic drift, mutation, gene flow, and sexual selection, is the foundation of current evolutionary biology, and is mathematically described.
Recent discoveries in the field of evolutionary developmental biology have shown that genetic variation can be introduced into a species through genetic drift, mutation, and reshuffling of genes during sexual reproduction, as well as through the movement of 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 result in evolution which is defined by change in the genome of the species over time and also the change in phenotype as time passes (the expression of that genotype in the individual).
Students can better understand the concept of phylogeny through incorporating evolutionary thinking into all aspects of biology. In a study by Grunspan et al. It was found that teaching students about the evidence for evolution increased their understanding of evolution in a college-level course in biology. For more information on how to teach about evolution, please see The Evolutionary Potential of all Areas of Biology and Thinking Evolutionarily A Framework for Infusing Evolution into Life Sciences Education.
Evolution in Action
Scientists have looked at evolution through the past, studying fossils, and comparing species. They also observe living organisms. Evolution is not a distant event; it is a process that continues today. Bacteria evolve and resist antibiotics, viruses reinvent themselves and are able to evade new medications and animals alter their behavior to the changing climate. The resulting changes are often easy to see.
It wasn't until late 1980s when biologists began to realize that natural selection was in action. The key to this is that different traits can confer an individual rate of survival and reproduction, and can be passed down from one generation to the next.
In the past, if a certain allele - the genetic sequence that determines colour - was present in a population of organisms that interbred, it might become more prevalent than any other allele. Over time, that would mean 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.
It is easier to observe evolutionary change when the species, like bacteria, has a rapid generation turnover. Since 1988, Richard Lenski, a biologist, has tracked twelve populations of E.coli that are descended from one strain. Samples from each population have been taken frequently and more than 500.000 generations of E.coli have passed.
Lenski's work has demonstrated that a mutation can profoundly alter the speed at which a population reproduces--and so the rate at which it evolves. It also shows evolution takes time, a fact that is hard for some to accept.
Microevolution can be observed in the fact that mosquito genes for resistance to pesticides are more common in populations where insecticides are used. That's because the use of pesticides causes a selective pressure that favors those who have resistant genotypes.
The speed of evolution taking place has led to an increasing appreciation of its importance in a world that is shaped by human activities, including climate change, pollution and the loss of habitats which prevent many species from adapting. Understanding evolution will help you make better decisions about the future of the planet and its inhabitants.