The Academy's Evolution Site
Biology is one of the most important concepts in biology. The Academies have been for a long time involved in helping those interested in science understand the concept of evolution and how it permeates every area of scientific inquiry.
This site offers a variety of resources for students, teachers as well as general readers about evolution. It contains 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 that represents the interconnectedness of life. It is seen in a variety of religions and cultures as symbolizing unity and love. It has numerous practical applications in addition to providing a framework for understanding the history of species, and how they respond to changes in environmental conditions.
Early approaches to depicting the biological world focused on categorizing organisms into distinct categories which had been identified by their physical and metabolic characteristics1. These methods, which rely on the collection of various parts of organisms or fragments of DNA have significantly increased the diversity of a tree of Life2. These trees are largely composed by eukaryotes and the diversity of bacterial species is greatly underrepresented3,4.
In avoiding the necessity of direct experimentation and observation genetic techniques have allowed us to depict the Tree of Life in a more precise way. In particular, molecular methods allow us to build trees by using sequenced markers like the small subunit of ribosomal RNA gene.
Despite the dramatic expansion of the Tree of Life through genome sequencing, much biodiversity still remains to be discovered. This is especially relevant to microorganisms that are difficult to cultivate, and are usually present in a single sample5. A recent analysis of all known genomes has created a rough draft of the Tree of Life, including many bacteria and archaea that have not been isolated, and which are not well understood.
This expanded Tree of Life can be used to determine the diversity of a specific region and determine if certain habitats need special protection. This information can be used in a variety of ways, including identifying new drugs, combating diseases and enhancing crops. This information is also extremely valuable in conservation efforts. It can aid biologists in identifying the areas that are most likely to 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 protect the biodiversity of the world is to equip the people of developing nations with the information they require to act locally and promote conservation.
Phylogeny
A phylogeny (also known as an evolutionary tree) illustrates the relationship between species. Scientists can create a phylogenetic chart that shows the evolutionary relationship of taxonomic groups using molecular data and morphological similarities or differences. 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 ) is a method of identifying the relationships between organisms that share similar traits that evolved from common ancestral. These shared traits could be either analogous or homologous. Homologous traits are the same in terms of their evolutionary journey. Analogous traits may look similar but they don't have the same ancestry. Scientists organize similar traits into a grouping known as a the clade. All members of a clade have a common characteristic, like amniotic egg production. They all came from an ancestor that had these eggs. A phylogenetic tree can be constructed by connecting clades to identify the species that are most closely related to each other.
Scientists make use of molecular DNA or RNA data to construct a phylogenetic graph which is more precise and detailed. 에볼루션 바카라 사이트 is more precise and gives evidence of the evolutionary history of an organism. Researchers can use Molecular Data to calculate the evolutionary age of living organisms and discover how many organisms have the same ancestor.
The phylogenetic relationships between species are influenced by many factors including phenotypic plasticity, a type of behavior that alters in response to unique environmental conditions. This can make a trait appear more resembling to one species than to another which can obscure the phylogenetic signal. This problem can be mitigated by using cladistics. This is a method that incorporates an amalgamation of homologous and analogous features in the tree.
Additionally, phylogenetics can help determine the duration and speed at which speciation occurs. This information will assist conservation biologists in making decisions about which species to protect from the threat of extinction. In the end, it's the preservation of phylogenetic diversity that will result in an ecosystem that is complete and balanced.
Evolutionary Theory
The fundamental concept of evolution is that organisms acquire distinct characteristics over time based on 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 own needs as well as 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 lead to changes that are passed on to the next generation.
In the 1930s and 1940s, ideas from various fields, including genetics, natural selection, and particulate inheritance--came together to form the modern evolutionary theory which explains how evolution is triggered by the variation of genes within a population and how those variations change in time due to natural selection. This model, called genetic drift, mutation, gene flow, and sexual selection, is a cornerstone of modern evolutionary biology and can be mathematically described.
Recent developments in the field of evolutionary developmental biology have revealed that variation can be introduced into a species through genetic drift, mutation, and reshuffling genes during sexual reproduction, as well as through migration between populations. 에볼루션 바카라 무료체험 , as well as others like directional selection and 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 the change in phenotype over time (the expression of that genotype within the individual).
Students can gain a better understanding of the concept of phylogeny by using evolutionary thinking in all areas of biology. A recent study by Grunspan and colleagues, for instance demonstrated that teaching about the evidence for evolution increased students' acceptance of evolution in a college biology class. For more information on how to teach evolution look up The Evolutionary Power of Biology 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 looking back, studying fossils, comparing species and observing living organisms. Evolution is not a distant moment; 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 changes that occur are often apparent.
However, it wasn't until late 1980s that biologists realized that natural selection can be seen in action, as well. The reason is that different characteristics result in different rates of survival and reproduction (differential fitness) and are passed from one generation to the next.
In the past, if one allele - the genetic sequence that determines colour was found in a group of organisms that interbred, it could be more common than any other allele. As time passes, this could mean that the number of moths with black pigmentation may increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.
It is easier to track evolutionary change when a species, such as bacteria, has a high generation turnover. Since 1988, Richard Lenski, a biologist, has studied twelve populations of E.coli that descend from one strain. Samples from each population have been taken regularly, and more than 500.000 generations of E.coli have been observed to have passed.
Lenski's work has demonstrated that a mutation can profoundly alter the rate at which a population reproduces and, consequently, the rate at which it alters. It also demonstrates that evolution takes time, which is difficult for some to accept.
Another example of microevolution is that mosquito genes that confer resistance to pesticides show up more often in areas where insecticides are employed. This is because the use of pesticides creates a selective pressure that favors those with resistant genotypes.
에볼루션 바카라 사이트 of evolution has led to a growing appreciation of its importance, especially in a world that is largely shaped by human activity. This includes the effects of climate change, pollution and habitat loss, which prevents many 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.