The Academy's Evolution Site
Biological evolution is one of the most fundamental concepts 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 all areas of scientific exploration.
This site provides a wide range of sources for students, teachers, and general readers on evolution. It contains 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 all life. It is a symbol of love and harmony in a variety of cultures. It also has important practical uses, like providing a framework for understanding the evolution of species and how they respond to changes in environmental conditions.
The first attempts at depicting the world of biology focused on separating organisms into distinct categories which had been distinguished by their physical and metabolic characteristics1. These methods, which rely on the collection of various parts of organisms, or DNA fragments have greatly increased the diversity of a Tree of Life2. However, these trees are largely comprised of eukaryotes, and bacterial diversity is still largely unrepresented3,4.
Genetic techniques have greatly broadened our ability to depict the Tree of Life by circumventing the need 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 greatly expanded thanks to genome sequencing. However there is still a lot of diversity to be discovered. This is especially true of microorganisms that are difficult to cultivate and are often only found in a single sample5. A recent study of all genomes that are known has created a rough draft of the Tree of Life, including a large number of bacteria and archaea that have not been isolated, and which are not well understood.
This expanded Tree of Life is particularly beneficial in assessing the biodiversity of an area, assisting to determine if certain habitats require special protection. The information is useful in many ways, including finding new drugs, battling diseases and enhancing crops. This information is also beneficial in conservation efforts. It can help biologists identify those areas that are most likely contain cryptic species with potentially important metabolic functions that may be vulnerable to anthropogenic change. While conservation funds are important, the most effective method to preserve the world's biodiversity is to equip more people in developing countries with the information they require to act locally and support conservation.
Phylogeny
A phylogeny, also called an evolutionary tree, shows the connections 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 create a phylogenetic tree that illustrates the evolutionary relationships between taxonomic groups. The role of phylogeny is crucial in understanding biodiversity, genetics and evolution.
A basic phylogenetic Tree (see Figure PageIndex 10 ) determines the relationship between organisms with similar traits that evolved from common ancestral. These shared traits could be analogous, or homologous. Homologous traits are identical in their underlying evolutionary path, while analogous traits look similar but do not have the same origins. Scientists arrange similar traits into a grouping known as a clade. For instance, all the organisms in a clade share the trait of having amniotic egg and evolved from a common ancestor that had these eggs. The clades are then linked to create a phylogenetic tree to determine which organisms have the closest relationship to.
For a more precise and accurate phylogenetic tree scientists make use of molecular data from DNA or RNA to identify the relationships among organisms. This data is more precise than morphological data and provides evidence of the evolutionary background of an organism or group. Researchers can use Molecular Data to calculate the evolutionary age of living organisms and discover the number of organisms that have the same ancestor.
The phylogenetic relationships of a species can be affected by a number of factors such as the phenomenon of phenotypicplasticity. This is a kind of behaviour that can change due to specific environmental conditions. This can cause a trait to appear more similar to a species than another and obscure the phylogenetic signals. This issue can be cured by using cladistics, which is a the combination of homologous and analogous traits in the tree.
Furthermore, phylogenetics may help predict the duration and rate of speciation. 에볼루션카지노사이트 can assist conservation biologists in making decisions about which species to save from disappearance. In the end, it is the preservation of phylogenetic diversity that will result in an ecosystem that is balanced and complete.
Evolutionary Theory
The fundamental concept in evolution is that organisms alter over time because of 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 could develop according to its own needs, the Swedish taxonomist Carolus Linnaeus (1707-1778) who conceived the modern taxonomy system that is hierarchical and Jean-Baptiste Lamarck (1844-1829), who suggested that the use or non-use of traits can cause changes that are passed on to the
In the 1930s & 1940s, ideas from different fields, including genetics, natural selection and particulate inheritance, came together to form a contemporary evolutionary theory. This explains how evolution occurs by the variation in genes within the population, and how these variants change over time as a result of natural selection. This model, called genetic drift mutation, gene flow, and sexual selection, is a cornerstone of current evolutionary biology, and can be mathematically explained.
Recent developments in the field of evolutionary developmental biology have demonstrated how variations can be introduced to a species through mutations, genetic drift, reshuffling genes during sexual reproduction and the movement between populations. These processes, along with others like directional selection and genetic erosion (changes in the frequency of a 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 that genotype in the individual).
Students can gain a better understanding of the concept of phylogeny by using evolutionary thinking into all areas of biology. A recent study by Grunspan and colleagues, for instance, showed that teaching about the evidence supporting evolution increased students' understanding of evolution in a college biology course. For more details on how to teach evolution look up The Evolutionary Potential in All Areas of Biology or Thinking Evolutionarily: a Framework for Infusing Evolution into Life Sciences Education.
Evolution in Action
Scientists have traditionally studied evolution by looking in the past, analyzing fossils and comparing species. They also observe living organisms. Evolution isn't a flims moment; it is an ongoing process that continues to be observed today. Bacteria mutate and resist antibiotics, viruses re-invent themselves and elude new medications, and animals adapt their behavior to a changing planet. The results are usually evident.
It wasn't until late 1980s that biologists began to realize that natural selection was in play. The main reason is that different traits result in an individual rate of survival and reproduction, and can be passed on from one generation to the next.
In the past, if one particular allele - the genetic sequence that determines coloration--appeared in a group of interbreeding organisms, it might quickly become more prevalent than the other alleles. In time, this could mean that the number of black moths in a population could increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.
The ability to observe evolutionary change is easier when a particular species has a rapid generation turnover such as bacteria. Since 1988, Richard Lenski, a biologist, has been tracking twelve populations of E.coli that are descended from a single strain. Samples of each population have been taken regularly, and more than 50,000 generations of E.coli have been observed to have passed.
Lenski's research has revealed that a mutation can dramatically alter the efficiency with which a population reproduces--and so the rate at which it alters. Going In this article demonstrates that evolution takes time, a fact that some people are unable to accept.
Another example of microevolution is that mosquito genes that confer resistance to pesticides are more prevalent in populations in which insecticides are utilized. This is due to pesticides causing an exclusive pressure that favors those who have resistant genotypes.
The speed at which evolution takes place has led to an increasing appreciation of its importance in a world shaped by human activity--including climate change, pollution and the loss of habitats that prevent many species from adjusting. Understanding evolution can help us make smarter decisions regarding the future of our planet, as well as the life of its inhabitants.