The Academy's Evolution Site
Biological evolution is a central concept in biology. The Academies have been active for a long time in helping those interested in science comprehend the theory of evolution and how it affects all areas of scientific research.
This site offers a variety of sources for students, teachers as well as general readers about evolution. It includes key 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 all life. It appears in many spiritual traditions and cultures as symbolizing unity and love. It also has important practical uses, like providing a framework for understanding the evolution of species and how they react to changing environmental conditions.
Early attempts to describe the world of biology were built on categorizing organisms based on their metabolic and physical characteristics. These methods, based on sampling of different parts of living organisms or short DNA fragments, significantly increased the variety that could be included in 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 enabled us to represent the Tree of Life in a more precise manner. In particular, molecular methods allow us to construct trees by using sequenced markers like the small subunit ribosomal gene.
The Tree of Life has been dramatically expanded through genome sequencing. However there is still a lot of biodiversity to be discovered. This is particularly the case for microorganisms which are difficult to cultivate, and are usually found in a single specimen5. Recent analysis of all genomes produced an unfinished draft of the Tree of Life. This includes a large number of archaea, bacteria and other organisms that have not yet been isolated or the diversity of which is not thoroughly understood6.
This expanded Tree of Life is particularly useful in assessing the diversity of an area, assisting to determine if certain habitats require special protection. This information can be utilized in a variety of ways, from identifying new medicines to combating disease to enhancing the quality of the quality of crops. The information is also valuable to conservation efforts. It can help biologists identify areas that are likely to have species that are cryptic, which could have vital metabolic functions, and could be susceptible to changes caused by humans. Although funds to protect biodiversity are essential, ultimately the best way to ensure the preservation of biodiversity around the world is for more people in developing countries to be empowered with the necessary knowledge to act locally in order to promote conservation from within.
Phylogeny
A phylogeny, also known as an evolutionary tree, illustrates the connections between groups of organisms. Scientists can build a phylogenetic diagram that illustrates the evolution of taxonomic categories using molecular information and morphological similarities or differences. The concept of phylogeny is fundamental to understanding biodiversity, evolution and genetics.
mouse click the following article (see Figure PageIndex 10 ) determines the relationship between organisms that share similar traits that have evolved from common ancestral. These shared traits may be analogous, or homologous. Homologous traits share their evolutionary origins, while analogous traits look like they do, but don't have the same ancestors. Scientists group similar traits together into a grouping referred to as a the clade. For instance, all of the organisms that make up a clade have the characteristic of having amniotic eggs. They evolved from a common ancestor who had these eggs. A phylogenetic tree is constructed by connecting clades to determine the organisms which are the closest to each other.
Scientists make use of DNA or RNA molecular information to build a phylogenetic chart which is more precise and detailed. This information is more precise and provides evidence of the evolution of an organism. The analysis of molecular data can help researchers determine the number of species who share the same ancestor and estimate their evolutionary age.
The phylogenetic relationships between species are influenced by many factors, including phenotypic plasticity a type 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 signal. This issue can be cured by using cladistics, which incorporates a combination of homologous and analogous traits in the tree.
Additionally, phylogenetics aids predict the duration and rate of speciation. This information can aid conservation biologists to decide which species to protect from the threat of extinction. In the end, it is the conservation of phylogenetic diversity which will create an ecosystem that is balanced and complete.
Evolutionary Theory
The main idea behind evolution is that organisms develop different features over time due to their interactions with their environment. Many scientists have developed 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 and needs, the Swedish taxonomist Carolus Linnaeus (1707-1778) who conceived the modern taxonomy system that is hierarchical, as well as Jean-Baptiste Lamarck (1844-1829), who believed that the use or non-use of certain traits can result in changes that are passed on to the
In the 1930s and 1940s, concepts from a variety of fields--including genetics, natural selection and particulate inheritance -- came together to form the modern evolutionary theory which explains how evolution occurs through the variation of genes within a population and how those variants change in time as a result of natural selection. This model, which includes genetic drift, mutations in gene flow, and sexual selection can be mathematically described mathematically.
에볼루션 바카라 체험 in the field of evolutionary developmental biology have shown that variation can be introduced into a species through mutation, genetic drift and reshuffling of genes during sexual reproduction, and also by migration between 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 lead to evolution, which is defined by change in the genome of the species over time and the change in phenotype as time passes (the expression of the genotype in an individual).
Incorporating evolutionary thinking into all aspects of biology education can increase students' understanding of phylogeny and evolution. In a study by Grunspan and co., it was shown that teaching students about the evidence for evolution increased their understanding of evolution during an undergraduate biology course. For more details about how to teach evolution, see The Evolutionary Potency in all Areas of Biology or Thinking Evolutionarily A Framework for Integrating Evolution into Life Sciences Education.
Evolution in Action
Traditionally, scientists have studied evolution through studying fossils, comparing species and observing living organisms. But evolution isn't a thing that occurred in the past; it's an ongoing process, taking place in the present. Viruses evolve to stay away from new medications and bacteria mutate to resist antibiotics. Animals adapt their behavior as a result of a changing world. The results are often visible.
It wasn't until the late 1980s that biologists began to realize that natural selection was also in play. The key is the fact that different traits can confer the ability to survive at different rates as well as reproduction, and may be passed on from one generation to the next.
In the past, if one particular allele - the genetic sequence that defines color in a group of interbreeding organisms, it could quickly become more prevalent than the other alleles. Over time, that would mean the number of black moths within a population could 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 species has a rapid turnover of its generation like bacteria. Since 1988 the biologist Richard Lenski has been tracking twelve populations of E. coli that descended from a single strain. samples of each population are taken on a regular basis, and over 500.000 generations have passed.
Lenski's research has shown that mutations can drastically alter the speed at which a population reproduces and, consequently the rate at which it alters. 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 appear more frequently in areas where insecticides are employed. Pesticides create an exclusive pressure that favors those with resistant genotypes.
The speed at which evolution takes place has led to a growing appreciation of its importance in a world that is shaped by human activity--including climate change, pollution and the loss of habitats that prevent many species from adjusting. Understanding the evolution process can aid you in making better decisions about the future of our planet and its inhabitants.