The Academy's Evolution Site
The concept of biological evolution is a fundamental concept in biology. The Academies are involved in helping those interested in science to learn about the theory of evolution and how it can be applied across all areas of scientific research.
This site offers a variety of resources for teachers, students and general readers of evolution. It contains the most important video clips from NOVA and WGBH's science programs on DVD.
Tree of Life
The Tree of Life, an ancient symbol, symbolizes the interconnectedness of all life. It is an emblem of love and unity across many cultures. It has numerous practical applications as well, such as providing a framework for understanding the history of species, and how they react to changing environmental conditions.
Early approaches to depicting the biological world focused on the classification of organisms into distinct categories which were distinguished by their physical and metabolic characteristics1. These methods, which rely on the sampling of various parts of living organisms, or sequences of small fragments of their DNA, significantly expanded the diversity that could be included in the tree of life2. However these trees are mainly comprised of eukaryotes, and bacterial diversity remains vastly underrepresented3,4.
Genetic techniques have greatly expanded our ability to represent the Tree of Life by circumventing the need for direct observation and experimentation. Particularly, molecular techniques enable us to create 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 diversity to be discovered. This is especially true of microorganisms, which can be difficult to cultivate and are often only represented in a single sample5. A recent study of all genomes known to date has produced a rough draft version of the Tree of Life, including numerous archaea and bacteria 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. The information can be used in a range of ways, from identifying the most effective medicines to combating disease to enhancing the quality of crops. This information is also valuable for conservation efforts. It can help biologists identify areas most likely to be home to cryptic species, which may have vital metabolic functions, and could be susceptible to human-induced change. While funds to protect biodiversity are essential, the best method to preserve the world's biodiversity is to equip more people in developing nations with the knowledge they need to act locally and promote conservation.
Phylogeny
A phylogeny (also known as an evolutionary tree) illustrates the relationship between organisms. By using molecular information similarities and differences in morphology or ontogeny (the process of the development of an organism) scientists can create a phylogenetic tree which illustrates the evolutionary relationships between taxonomic categories. The role of phylogeny is crucial in understanding genetics, biodiversity and evolution.
A basic phylogenetic tree (see Figure PageIndex 10 Identifies the relationships between organisms with similar traits and evolved from a common ancestor. These shared traits could be analogous or homologous. Homologous traits are similar in their underlying evolutionary path while analogous traits appear similar but do not have the identical origins. Scientists combine similar traits into a grouping called a Clade. For example, all of the organisms in a clade share the characteristic of having amniotic eggs. 에볼루션바카라사이트 evolved from a common ancestor that had eggs. A phylogenetic tree is constructed by connecting the clades to identify the organisms which are the closest to one another.
Scientists make use of DNA or RNA molecular data to construct a phylogenetic graph which is more precise and precise. This data is more precise than morphological information and provides evidence of the evolution history of an individual or group. Researchers can utilize Molecular Data to calculate the age of evolution of organisms and identify the number of organisms that share an ancestor common to all.
The phylogenetic relationships of organisms are influenced by many factors, including phenotypic plasticity a kind of behavior that changes in response to unique environmental conditions. This can cause a particular trait to appear more similar in one species than other species, which can obscure the phylogenetic signal. However, this problem can be reduced by the use of techniques such as cladistics that incorporate a combination of analogous and homologous features into the tree.
Additionally, phylogenetics can help determine the duration and rate of speciation. This information can aid conservation biologists to decide which species they should protect from extinction. In the end, it's the preservation of phylogenetic diversity which will create an ecologically balanced and complete ecosystem.
에볼루션카지노 of evolution is that organisms develop different features over time based on their interactions with their surroundings. Many scientists have come up with theories of evolution, including the Islamic naturalist Nasir al-Din al-Tusi (1201-274), who believed that an organism would evolve according to its individual requirements as well as the Swedish taxonomist Carolus Linnaeus (1707-1778) who conceived the modern hierarchical taxonomy, as well as Jean-Baptiste Lamarck (1844-1829), who believed that the usage or non-use of certain traits can result in changes that are passed on to the next generation.
In the 1930s & 1940s, theories from various areas, including genetics, natural selection and particulate inheritance, were brought together to create a modern theorizing of evolution. This describes how evolution happens through the variation in genes within the population, and how these variants alter over time due to natural selection. This model, which encompasses genetic drift, mutations as well as gene flow and sexual selection is mathematically described.
Recent discoveries in the field of evolutionary developmental biology have shown that variations 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 the genotype over time) can result in evolution that is defined as change in the genome of the species over time and also the change in phenotype as time passes (the expression of that genotype within the individual).
Students can better understand the concept of phylogeny through incorporating evolutionary thinking into all areas of biology. A recent study by Grunspan and colleagues, for example, showed that teaching about the evidence for evolution increased students' understanding of evolution in a college-level 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 Infusing Evolution into Life Sciences Education.
Evolution in Action
Traditionally, scientists have studied evolution by looking back, studying fossils, comparing species, and studying living organisms. But evolution isn't a thing that happened in the past; it's an ongoing process happening right now. Bacteria transform and resist antibiotics, viruses re-invent themselves and are able to evade new medications and animals alter their behavior to the changing environment. The results are usually easy to see.
However, it wasn't until late 1980s that biologists understood that natural selection can be seen in action, as well. The key is that different characteristics result in different rates of survival and reproduction (differential fitness) and can be transferred 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 might quickly become more prevalent than all other alleles. 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.
Observing evolutionary change 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. bacteria that descend from a single strain. samples from each population are taken on a regular basis and over 500.000 generations have been observed.
Lenski's work has demonstrated 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 takes time, something that is hard for some to accept.
Microevolution can also be seen in the fact that mosquito genes that confer resistance to pesticides are more common in populations where insecticides have been used. 에볼루션바카라사이트 is because the use of pesticides causes a selective pressure that favors individuals who have resistant genotypes.
The speed at which evolution can take place has led to an increasing awareness of its significance in a world that is shaped by human activity, including climate changes, pollution and the loss of habitats which prevent many species from adapting. Understanding evolution can help us make smarter decisions regarding the future of our planet and the lives of its inhabitants.