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 permeates every area of scientific inquiry.
This site provides students, teachers and general readers with a variety of learning resources on evolution. It includes the most 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 an emblem of love and unity in many cultures. It has many practical applications as well, such as providing a framework for understanding the history of species and how they react 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 depend on the sampling of different parts of organisms or short DNA fragments, have greatly increased the diversity of a Tree of Life2. However the trees are mostly composed of eukaryotes; bacterial diversity remains vastly underrepresented3,4.
By avoiding the need for direct experimentation and observation, genetic techniques have made it possible to represent the Tree of Life in a much more accurate way. Trees can be constructed by 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 can be difficult to cultivate and are usually only represented in a single sample5. Recent analysis of all genomes produced an unfinished draft of the Tree of Life. This includes a variety of archaea, bacteria, and other organisms that have not yet been isolated, or the diversity of which is not well understood6.
This expanded Tree of Life is particularly useful in assessing the diversity of an area, helping to determine if certain habitats require protection. This information can be used in many ways, including finding new drugs, battling diseases and improving the quality of crops. The information is also valuable in conservation efforts. It can aid biologists in identifying areas that are likely to be home to species that are cryptic, which could perform important metabolic functions and be vulnerable to human-induced change. Although funding to protect biodiversity are essential however, the most effective method to ensure the preservation of biodiversity around the world is for more people living in developing countries to be equipped with the knowledge to take action locally to encourage conservation from within.
Phylogeny
A phylogeny is also known as an evolutionary tree, reveals the connections between groups of organisms. Scientists can construct an phylogenetic chart which shows the evolutionary relationship of taxonomic groups using molecular data and morphological similarities or differences. Phylogeny is crucial in understanding biodiversity, evolution and genetics.
A basic phylogenetic Tree (see Figure PageIndex 10 ) determines the relationship between organisms with similar traits that have evolved from common ancestors. These shared traits are either homologous or analogous. Homologous characteristics are identical in their evolutionary path. Analogous traits may look like they are but they don't have the same origins. Scientists arrange similar traits into a grouping known as a Clade. For instance, all of the organisms in a clade have the characteristic of having amniotic egg and evolved from a common ancestor that had these eggs. The clades are then linked to form a phylogenetic branch that can determine the organisms with the closest connection to each other.
Scientists use DNA or RNA molecular data to build a phylogenetic chart which is more precise and precise. This information is more precise and gives evidence of the evolution history of an organism. The use of molecular data lets researchers determine the number of organisms that share a common ancestor and to estimate their evolutionary age.
The phylogenetic relationships between organisms are influenced by many factors, including phenotypic flexibility, an aspect of behavior that alters in response to unique environmental conditions. This can cause a trait to appear more resembling to one species than to another and obscure the phylogenetic signals. This problem can be mitigated by using cladistics. This is a method that incorporates a combination of homologous and analogous features in the tree.
Additionally, phylogenetics aids determine the duration and rate at which speciation takes place. This information can assist conservation biologists decide which species they should protect from the threat of extinction. In the end, it's the preservation of phylogenetic diversity which will lead to an ecologically balanced and complete ecosystem.
Evolutionary Theory
The main idea behind evolution is that organisms change over time due to their interactions with their environment. Many scientists have proposed 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 own requirements, the Swedish taxonomist Carolus Linnaeus (1707-1778) who developed the modern taxonomy system that is hierarchical and Jean-Baptiste Lamarck (1844-1829), who believed that the usage or non-use of traits can cause changes that are passed on to the
In the 1930s and 1940s, theories from various fields, including genetics, natural selection, and particulate inheritance, came together to create a modern evolutionary theory. This describes how evolution occurs by the variations in genes within the population and how these variations alter over time due to natural selection. This model, which encompasses genetic drift, mutations, gene flow and sexual selection is mathematically described mathematically.
에볼루션 카지노 사이트 in the field of evolutionary developmental biology have demonstrated that genetic variation can be introduced into a species through mutation, genetic drift, and reshuffling of genes in sexual reproduction, as well as through migration between populations. These processes, along with other ones like directional selection and gene erosion (changes in frequency of genotypes over time) can result in 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).
Incorporating evolutionary thinking into all aspects of biology education can increase student understanding of the concepts of phylogeny and evolution. In a study by Grunspan and colleagues. It was demonstrated that teaching students about the evidence for evolution increased their understanding of evolution in an undergraduate 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 Evolution into Life Sciences Education.
Evolution in Action
Traditionally scientists have studied evolution through studying fossils, comparing species and studying living organisms. However, evolution isn't something that happened in the past; it's an ongoing process that is taking place in the present. Bacteria transform and resist antibiotics, viruses reinvent themselves and are able to evade new medications and animals change their behavior to the changing climate. The results are often evident.
It wasn't until the 1980s that biologists began to realize that natural selection was also in play. The key is that different characteristics result in different rates of survival and reproduction (differential fitness), and can be passed from one generation to the next.
In the past, if one particular allele - the genetic sequence that controls coloration - was present in a population of interbreeding organisms, it might rapidly become more common than all other alleles. In time, this could mean the number of black moths in a particular population could rise. 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 fast generation turnover like bacteria. Since 1988, 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 more than 500.000 generations have been observed.
Lenski's research has shown that mutations can drastically alter the rate at which a population reproduces and, consequently, the rate at which it alters. It also shows that evolution is slow-moving, a fact that many find hard to accept.
Microevolution is also evident in the fact that mosquito genes for resistance to pesticides are more prevalent in areas where insecticides have been used. This is due to pesticides causing a selective pressure which favors those who have resistant genotypes.
The rapidity of evolution has led to a greater appreciation of its importance especially in a planet which is largely shaped by human activities. This includes the effects of climate change, pollution and habitat loss, which prevents many species from adapting. Understanding evolution will help us make better decisions about the future of our planet and the life of its inhabitants.