The Academy's Evolution Site
Biological evolution is a central concept in biology. The Academies are committed to helping those interested in science to learn about the theory of evolution and how it is permeated throughout all fields of scientific research.
This site provides a range of sources for teachers, students and general readers of evolution. It also includes important video clips from NOVA and WGBH produced science programs on DVD.
Tree of Life
The Tree of Life, an ancient symbol, represents the interconnectedness of all life. It is a symbol of love and unity in many cultures. It also has important practical applications, such as providing a framework to understand the evolution of species and how they respond to changes in the environment.
The first attempts at depicting the biological world focused on categorizing organisms into distinct categories which were distinguished by their physical and metabolic characteristics1. These methods, which relied on the sampling of different parts of living organisms or on sequences of short DNA fragments, significantly expanded the diversity that could be included in the tree of life2. However these trees are mainly made up of eukaryotes. Bacterial diversity remains vastly underrepresented3,4.
Genetic techniques have significantly expanded our ability to depict the Tree of Life by circumventing the requirement for direct observation and experimentation. Particularly, molecular methods allow us to build trees using sequenced markers like the small subunit ribosomal RNA gene.
Despite the rapid growth of the Tree of Life through genome sequencing, a lot of biodiversity remains to be discovered. This is particularly true for microorganisms that are difficult to cultivate and are usually only present in a single sample5. A recent study of all genomes known to date has produced a rough draft of the Tree of Life, including many archaea and bacteria that have not been isolated and their diversity is not fully understood6.
The expanded Tree of Life is particularly beneficial in assessing the biodiversity of an area, helping to determine if certain habitats require special protection. This information can be used in a variety of ways, such as finding new drugs, battling diseases and improving the quality of crops. The information is also incredibly beneficial to conservation efforts. It helps biologists determine the areas that are most likely to contain cryptic species with potentially important metabolic functions that could be vulnerable to anthropogenic change. While conservation funds are important, the most effective method to protect the world's biodiversity is to empower more people in developing nations with the information they require to act locally and support conservation.
Phylogeny
A phylogeny, also known as an evolutionary tree, shows the relationships between groups of organisms. Using molecular data as well as morphological similarities and distinctions, or ontogeny (the process of the development of an organism) scientists can construct a phylogenetic tree that illustrates the evolutionary relationship between taxonomic categories. The phylogeny of a tree plays an important role in understanding genetics, biodiversity and evolution.
A basic phylogenetic Tree (see Figure PageIndex 10 ) determines the relationship between organisms that share similar traits that have evolved from common ancestors. These shared traits could be either analogous or homologous. Homologous traits are the same in terms of their evolutionary paths. Analogous traits might appear similar but they don't have the same ancestry. Scientists organize similar traits into a grouping known as a Clade. All members of a clade share a trait, such as amniotic egg production. They all came from an ancestor who had these eggs. The clades are then linked to create a phylogenetic tree to determine which organisms have the closest relationship.
For a more detailed and precise phylogenetic tree scientists rely on molecular information from DNA or RNA to identify the connections between organisms. This information is more precise than morphological information and gives evidence of the evolutionary history of an individual or group. Researchers can use Molecular Data to determine the evolutionary age of organisms and determine how many organisms share an ancestor common to all.
The phylogenetic relationship can be affected by a number of factors that include phenotypicplasticity. This is a kind of behaviour that can change as a result of specific environmental conditions. This can cause a particular trait to appear more similar to one species than another, clouding the phylogenetic signal. However, this problem can be solved through the use of techniques such as cladistics which include a mix of similar and homologous traits into the tree.
In addition, phylogenetics can help predict the time and pace of speciation. This information can assist conservation biologists in making decisions about which species to safeguard from disappearance. Ultimately, it is the preservation of phylogenetic diversity that will create a complete and balanced ecosystem.
에볼루션 바카라사이트 of evolution is that organisms develop different features over time based on their interactions with their environment. Many scientists have developed theories of evolution, including the Islamic naturalist Nasir al-Din al-Tusi (1201-274) who believed that a living thing would develop according to its own requirements and needs, the Swedish taxonomist Carolus Linnaeus (1707-1778) who conceived the modern hierarchical taxonomy and Jean-Baptiste Lamarck (1844-1829), who suggested that the use or absence of traits can cause changes that are passed on to the next generation.
In the 1930s and 1940s, theories from various fields, such as genetics, natural selection and particulate inheritance, were brought together to create a modern evolutionary theory. This describes how evolution is triggered by the variation in genes within the population and how these variations alter over time due to natural selection. This model, which encompasses mutations, genetic drift in gene flow, and sexual selection, can be mathematically described mathematically.
Recent developments in the field of evolutionary developmental biology have shown that variations can be introduced into a species by mutation, genetic drift, and reshuffling of genes during sexual reproduction, as well as through migration between populations. These processes, in conjunction with others such as the directional selection process and the erosion of genes (changes in frequency of genotypes over time) can lead to evolution. Evolution is defined by 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 areas of biology education could increase student understanding of the concepts of phylogeny as well as evolution. In a recent study by Grunspan et al. It was demonstrated that teaching students about the evidence for evolution increased their understanding of evolution during a college-level course in biology. To find out more about how to teach about evolution, look up The Evolutionary Potential of all Areas of Biology and Thinking Evolutionarily A Framework for Infusing the Concept of Evolution into Life Sciences Education.
Evolution in Action
Traditionally scientists have studied evolution through looking back--analyzing fossils, comparing species and observing living organisms. 에볼루션 바카라사이트 is not a distant event; it is a process that continues today. Bacteria transform and resist antibiotics, viruses re-invent themselves and escape new drugs, and animals adapt their behavior in response to the changing climate. The changes that occur are often apparent.
It wasn't until late 1980s that biologists understood that natural selection could be observed in action as well. The key is the fact that different traits can confer an individual rate of survival as well as reproduction, and may be passed down from one generation to the next.
In the past when one particular allele, the genetic sequence that controls coloration - was present in a population of interbreeding organisms, it might quickly become more common than the other alleles. As time passes, that could mean that the number of black moths in the population could increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.
It is easier to observe evolution when an organism, like bacteria, has a high generation turnover. 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 regularly, and over 50,000 generations have now passed.
Lenski's work has shown that mutations can alter the rate at which change occurs and the efficiency at which a population reproduces. It also demonstrates that evolution takes time, something that is hard for some to accept.
Microevolution is also evident in the fact that mosquito genes for pesticide resistance are more prevalent in areas where insecticides are used. This is because the use of pesticides creates a selective pressure that favors people with resistant genotypes.
The rapidity of evolution has led to an increasing awareness of its significance particularly in a world that is largely shaped by human activity. This includes the effects of climate change, pollution and habitat loss that hinders many species from adapting. Understanding evolution will help you make better decisions about the future of our planet and its inhabitants.