The Academy's Evolution Site
Biology is one of the most important concepts in biology. The Academies are involved in helping those who are interested in the sciences comprehend the evolution theory and how it is incorporated in all areas of scientific research.
This site provides a range of sources for teachers, students, and general readers on evolution. It also includes important video clips from NOVA and WGBH produced science programs on DVD.
Tree of Life
The Tree of Life is an ancient symbol of the interconnectedness of life. It is an emblem of love and harmony in a variety of cultures. It also has important practical applications, such as providing a framework for understanding the history of species and how they respond to changes in the environment.
Early approaches to depicting the biological world focused on the classification of organisms into distinct categories that were identified by their physical and metabolic characteristics1. These methods, based on the sampling of various parts of living organisms or on sequences of short fragments of their DNA greatly increased the variety of organisms that could be included in a tree of life2. However the trees are mostly made up of eukaryotes. Bacterial diversity is not represented in a large way3,4.
In avoiding the necessity of direct experimentation and observation, genetic techniques have enabled us to depict the Tree of Life in a more precise way. Trees can be constructed using molecular methods, 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 biodiversity to be discovered. This is especially true of microorganisms, which are difficult to cultivate and are typically only found in a single sample5. 에볼루션 바카라 무료 of all known genomes has produced a rough draft version of the Tree of Life, including a large number of archaea and bacteria that have not been isolated, and whose diversity is poorly understood6.
The expanded Tree of Life is particularly useful for assessing the biodiversity of an area, which can help to determine whether specific habitats require protection. This information can be used in many ways, including finding new drugs, battling diseases and improving crops. The information is also incredibly beneficial to conservation efforts. It can help biologists identify areas that are likely to be home to cryptic species, which could perform important metabolic functions, and could be susceptible to changes caused by humans. Although funds to safeguard biodiversity are vital, ultimately the best way to protect the world's biodiversity is for more people in developing countries to be empowered with the knowledge to take action locally to encourage conservation from within.
Phylogeny
A phylogeny, also known as an evolutionary tree, illustrates the connections between different groups of organisms. Scientists can build a phylogenetic chart that shows the evolutionary relationships between taxonomic groups using molecular data and morphological similarities or differences. Phylogeny plays a crucial role in understanding the relationship between genetics, biodiversity and evolution.
A basic phylogenetic tree (see Figure PageIndex 10 ) is a method of identifying the relationships between organisms that share similar traits that have evolved from common ancestral. These shared traits are either analogous or homologous. Homologous traits are similar in terms of their evolutionary path. Analogous traits may look like they are, but they do not have the same origins. Scientists arrange similar traits into a grouping referred to as a clade. For instance, all the species in a clade share the trait of having amniotic eggs. They evolved from a common ancestor that had these eggs. A phylogenetic tree can be constructed by connecting the clades to determine the organisms which are the closest to each other.
To create a more thorough and accurate phylogenetic tree scientists make use of molecular data from DNA or RNA to identify the connections between organisms. This information is more precise than morphological information and gives evidence of the evolutionary history of an individual or group. Researchers can use Molecular Data to calculate the evolutionary age of organisms and determine how many species have an ancestor common to all.
The phylogenetic relationships between species are influenced by many factors, including phenotypic flexibility, an aspect of behavior that alters in response to specific environmental conditions. This can cause a trait to appear more similar to one species than another, obscuring the phylogenetic signals. This problem can be mitigated by using cladistics, which is a the combination of homologous and analogous features in the tree.
Additionally, phylogenetics aids predict the duration and rate at which speciation occurs. This information can aid conservation biologists in deciding which species to save from the threat of extinction. In the end, it's the conservation of phylogenetic variety that will result in an ecosystem that is balanced and complete.
Evolutionary Theory
The fundamental concept in evolution is that organisms change over time as a result of their interactions with their environment. 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 taxonomy system that is hierarchical as well as Jean-Baptiste Lamarck (1844-1829), who suggested that the use or non-use of traits can cause changes that are passed on to the next generation.
In the 1930s & 1940s, concepts from various fields, such as natural selection, genetics & particulate inheritance, merged to form a modern theorizing of evolution. This defines how evolution happens through the variations in genes within the population, and how these variations change over time as a result of natural selection. This model, which is known as genetic drift mutation, gene flow and sexual selection, is the foundation of the current evolutionary biology and can be mathematically described.
Recent discoveries in the field of evolutionary developmental biology have demonstrated that genetic variation can be introduced into a species by mutation, genetic drift and reshuffling of genes during sexual reproduction, and also by migration between populations. These processes, in conjunction with others such as the directional selection process and the erosion of genes (changes in the frequency of genotypes over time) can result in evolution. Evolution is defined by changes in the genome over time and changes in phenotype (the expression of genotypes in individuals).
Incorporating evolutionary thinking into all aspects of biology education could increase student understanding of the concepts of phylogeny as well as evolution. A recent study by Grunspan and colleagues, for example demonstrated that teaching about the evidence that supports evolution increased students' acceptance of evolution in a college-level biology course. For more information on how to teach about evolution, please look up The Evolutionary Potential of All Areas of Biology and Thinking Evolutionarily A Framework for Infusing the Concept of Evolution into Life Sciences Education.
Evolution in Action
Traditionally, scientists have studied evolution by looking back, studying fossils, comparing species and observing living organisms. But evolution isn't just something that happened in the past, it's an ongoing process, that is taking place right now. The virus reinvents itself to avoid new medications and bacteria mutate to resist antibiotics. Animals adapt their behavior as a result of the changing environment. 에볼루션 슬롯 that result are often evident.
It wasn't until late 1980s when biologists began to realize that natural selection was in action. The key is the fact that different traits confer an individual rate of survival and reproduction, and they can be passed on 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 could be more prevalent than any other allele. As time passes, this could mean that the number of moths that have black pigmentation in a group could increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.
It is easier to see evolutionary change when a species, such as bacteria, has a high generation turnover. Since 1988, biologist Richard Lenski has been tracking twelve populations of E. coli that descended from a single strain; samples of each are taken every day and over fifty thousand generations have been observed.
Lenski's research has revealed that mutations can alter the rate of change and the effectiveness of a population's reproduction. It also demonstrates that evolution takes time, something that is hard for some to accept.
Another example of microevolution is how mosquito genes that confer resistance to pesticides show up more often in areas in which insecticides are utilized. This is due to pesticides causing an exclusive pressure that favors individuals who have resistant genotypes.
The speed at which evolution can take place has led to a growing appreciation of its importance in a world that is shaped by human activity--including climate changes, pollution and the loss of habitats that prevent the species from adapting. Understanding evolution will help us make better choices about the future of our planet, as well as the lives of its inhabitants.