The Academy's Evolution Site
Biological evolution is one of the most important concepts in biology. The Academies have been for a long time involved in helping people who are interested in science understand the concept of evolution and how it influences all areas of scientific research.
This site provides students, teachers and general readers with a range of learning resources about evolution. It has important video clips from NOVA and WGBH's science programs on DVD.
Tree of Life
The Tree of Life is an ancient symbol of the interconnectedness of all life. It is a symbol of love and harmony in a variety of cultures. It also has practical applications, such as providing a framework to understand the history of species and how they respond to changes in environmental conditions.
Early attempts to represent the biological world were built on categorizing organisms based on their metabolic and physical characteristics. These methods, which relied on sampling of different parts of living organisms or sequences of short DNA fragments, significantly expanded the diversity that could be included in the tree of life2. These trees are largely composed by eukaryotes and bacterial diversity is vastly underrepresented3,4.
In avoiding the necessity of direct observation and experimentation, genetic techniques have enabled us to depict the Tree of Life in a much more accurate way. We can construct trees using molecular techniques such as the small subunit ribosomal gene.
Despite the massive expansion of the Tree of Life through genome sequencing, much biodiversity still is waiting to be discovered. This is especially relevant to microorganisms that are difficult to cultivate, and are typically present in a single sample5. Recent analysis of all genomes has produced an unfinished draft of a Tree of Life. This includes a large number of archaea, bacteria and other organisms that have not yet been isolated, or whose diversity has not been thoroughly understood6.
The expanded Tree of Life can be used to assess the biodiversity of a specific region and determine if particular habitats need special protection. This information can be used in a variety of ways, including finding new drugs, battling diseases and improving crops. This information is also extremely beneficial to conservation efforts. It can help biologists identify areas that are most likely to have species that are cryptic, which could perform important metabolic functions and be vulnerable to the effects of human activity. Although funds to protect biodiversity are essential, ultimately the best way to preserve 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 called an evolutionary tree, illustrates the relationships between different groups of organisms. By using molecular information similarities and differences in morphology or ontogeny (the course of development of an organism), scientists can build a phylogenetic tree which illustrates the evolutionary relationship between taxonomic groups. The phylogeny of a tree plays an important role in understanding the relationship between genetics, biodiversity and evolution.
A basic phylogenetic Tree (see Figure PageIndex 10 Finds the connections between organisms that have similar characteristics and have evolved from a common ancestor. These shared traits could be either homologous or analogous. Homologous traits are similar in their evolutionary journey. Analogous traits could appear similar but they don't have the same ancestry. Scientists group similar traits into a grouping referred to as a the clade. All members of a clade have a common trait, such as amniotic egg production. They all derived from an ancestor with these eggs. A phylogenetic tree can be constructed by connecting the clades to identify the species that are most closely related to one another.
Scientists utilize DNA or RNA molecular data to create a phylogenetic chart that is more precise and detailed. This information is more precise and gives evidence of the evolution history of an organism. 에볼루션바카라 can utilize Molecular Data to calculate the evolutionary age of organisms and identify how many species share a common ancestor.
Phylogenetic relationships can be affected by a variety of factors that include the phenomenon of phenotypicplasticity. This is a type of behavior that changes due to unique environmental conditions. This can cause a characteristic to appear more similar in one species than another, clouding the phylogenetic signal. However, this issue can be reduced by the use of methods such as cladistics which include a mix of homologous and analogous features into the tree.
In addition, phylogenetics helps determine the duration and speed at which speciation takes place. This information can help conservation biologists make decisions about which species to protect from the threat of extinction. It is ultimately the preservation of phylogenetic diversity which will create an ecosystem that is complete and balanced.
에볼루션사이트 in evolution is that organisms change over time due to their interactions with their environment. Many theories of evolution have been proposed by a wide range of scientists including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who proposed that a living organism develop slowly according to its requirements and needs, the Swedish botanist Carolus Linnaeus (1707-1778) who designed the modern hierarchical taxonomy Jean-Baptiste Lamarck (1744-1829) who suggested that the use or misuse of traits causes changes that could be passed on to offspring.
In the 1930s and 1940s, theories from a variety of fields--including genetics, natural selection and particulate inheritance -- came together to form the modern synthesis of evolutionary theory which explains how evolution is triggered by the variations of genes within a population, and how those variants change over time as a result of natural selection. This model, which includes genetic drift, mutations in gene flow, and sexual selection can be mathematically described.
Recent advances in evolutionary developmental biology have shown the ways in which variation can be introduced to a species through genetic drift, mutations and reshuffling of genes during sexual reproduction, and even migration between populations. These processes, along with others such as directional selection or genetic erosion (changes in the frequency of the genotype over time) can result in evolution which is defined by changes in the genome of the species over time, and also by changes in phenotype over time (the expression of that genotype in an individual).
Students can better understand phylogeny by incorporating evolutionary thinking throughout all aspects of biology. A recent study by Grunspan and colleagues, for instance, showed that teaching about the evidence for evolution increased students' acceptance of evolution in a college-level biology class. To find out more about how to teach about evolution, see The Evolutionary Potential in all Areas of Biology and Thinking Evolutionarily: A Framework for Infusing the Concept of Evolution into Life Sciences Education.
Evolution in Action
Scientists have studied evolution by looking in the past, studying fossils, and comparing species. They also observe living organisms. Evolution is not a distant event; it is an ongoing process. Viruses reinvent themselves to avoid new drugs and bacteria evolve to resist antibiotics. Animals adapt their behavior as a result of a changing environment. The resulting changes are often easy to see.
It wasn't until the late 1980s when 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 down from one generation to the next.
In the past when one particular allele--the genetic sequence that determines coloration--appeared in a population of interbreeding organisms, it could rapidly become more common than the other alleles. In time, this could mean that the number of moths with 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 easier when a particular species has a rapid turnover of its generation, as with bacteria. Since 1988, Richard Lenski, a biologist, has tracked twelve populations of E.coli that descend from a single strain. The samples of each population have been collected regularly and more than 50,000 generations of E.coli have passed.
Lenski's research has shown that a mutation can profoundly alter the speed at the rate at which a population reproduces, and consequently the rate at which it evolves. It also shows evolution takes time, a fact that is hard for some to accept.
Another example of microevolution is how mosquito genes for resistance to pesticides show up more often in populations where insecticides are employed. This is due to the fact that the use of pesticides causes a selective pressure that favors those who have resistant genotypes.
The rapidity of evolution has led to a growing awareness of its significance especially in a planet which is largely shaped by human activities. This includes the effects of climate change, pollution and habitat loss that prevents many species from adapting. Understanding the evolution process can help us make smarter decisions about the future of our planet, and the life of its inhabitants.