The Academy's Evolution Site
Biological evolution is one of the most central concepts in biology. The Academies have been for a long time involved in helping people who are interested in science comprehend the concept of evolution and how it influences all areas of scientific exploration.
This site provides a range of sources for teachers, students and general readers of 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 that represents the interconnectedness of all life. It appears in many spiritual traditions and cultures as a symbol of unity and love. It also has many practical applications, such as providing a framework to understand the history of species and how they respond to changes in environmental conditions.
Early attempts to describe the world of biology were based on categorizing organisms based on their physical and metabolic characteristics. These methods, which depend on the sampling of different parts of organisms or fragments of DNA have greatly increased the diversity of a Tree of Life2. However the trees are mostly made up of eukaryotes. Bacterial diversity is still largely unrepresented3,4.
In avoiding the necessity of direct experimentation and observation, genetic techniques have allowed us to represent the Tree of Life in a more precise way. Trees can be constructed using molecular methods 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 particularly true for microorganisms, which are difficult to cultivate and are typically only present in a single sample5. A recent analysis of all genomes known to date has created 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 useful for assessing the biodiversity of an area, helping to determine whether specific habitats require special protection. This information can be utilized in a range of ways, from identifying new treatments to fight disease to enhancing the quality of crops. The information is also beneficial to conservation efforts. It can aid biologists in identifying areas most likely to have cryptic species, which may have important metabolic functions, and could be susceptible to changes caused by humans. While funding to protect biodiversity are important, the most effective way to conserve the world's biodiversity is to empower more people in developing countries with the necessary knowledge to take action locally and encourage conservation.
Phylogeny
A phylogeny, also called an evolutionary tree, reveals the relationships between groups of organisms. Using molecular data as well as morphological similarities and distinctions or ontogeny (the course of development of an organism) scientists can create a phylogenetic tree that illustrates the evolution of taxonomic categories. The concept of phylogeny is fundamental to understanding biodiversity, evolution and genetics.
A basic phylogenetic Tree (see Figure PageIndex 10 Identifies the relationships between organisms with similar traits and have evolved from a common ancestor. These shared traits may be analogous or homologous. Homologous traits are similar in their evolutionary origins and analogous traits appear similar but do not have the same origins. Scientists arrange similar traits into a grouping known as a Clade. All members of a clade share a trait, such as amniotic egg production. 에볼루션카지노사이트 evolved from an ancestor with these eggs. A phylogenetic tree can be constructed by connecting the clades to determine the organisms that are most closely related to one another.
Scientists utilize DNA or RNA molecular data to build a phylogenetic chart which is more precise and precise. This information is more precise than morphological information and gives evidence of the evolutionary history of an organism or group. The analysis of molecular data can help researchers identify the number of organisms who share an ancestor common to them and estimate their evolutionary age.
The phylogenetic relationships between organisms are influenced by many factors, including phenotypic flexibility, a kind of behavior that changes in response to unique environmental conditions. This can cause a particular trait to appear more like a species another, clouding the phylogenetic signal. However, this problem can be reduced by the use of techniques like cladistics, which include a mix of similar and homologous traits into the tree.
Additionally, phylogenetics can help predict the time and pace of speciation. This information can assist conservation biologists in deciding which species to protect from disappearance. In the end, it is the conservation of phylogenetic variety that will lead to an ecosystem that is balanced and complete.
Evolutionary Theory
The central theme in evolution is that organisms alter over time because of their interactions with their environment. Many theories of evolution have been developed by a wide variety of scientists, including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who envisioned an organism developing slowly in accordance with its needs, the Swedish botanist Carolus Linnaeus (1707-1778) who designed modern hierarchical taxonomy, and Jean-Baptiste Lamarck (1744-1829) who suggested that use or disuse of traits causes changes that could be passed on to the offspring.
In the 1930s & 1940s, ideas from different fields, such as natural selection, genetics & particulate inheritance, merged to form a contemporary evolutionary theory. This describes how evolution is triggered by the variation of genes in the population and how these variations change with time due to natural selection. This model, which encompasses mutations, genetic drift as well as gene flow and sexual selection can be mathematically described.
Recent developments in the field of evolutionary developmental biology have revealed that genetic variation can be introduced into a species via mutation, genetic drift and reshuffling genes during sexual reproduction, as well as through migration between populations. These processes, in conjunction with others such as directionally-selected selection and erosion of genes (changes to the frequency of genotypes over time), can lead towards evolution. Evolution is defined by changes in the genome over time as well as changes in the phenotype (the expression of genotypes in individuals).
Students can gain a better understanding of the concept of phylogeny through incorporating evolutionary thinking in all areas of biology. In a study by Grunspan et al. It was demonstrated that teaching students about the evidence for evolution increased their acceptance of evolution during a college-level course in biology. 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
Scientists have traditionally studied evolution by looking in the past, studying fossils, and comparing species. They also observe living organisms. Evolution is not a distant event; it is an ongoing process. The virus reinvents itself to avoid new medications and bacteria mutate to resist antibiotics. Animals adapt their behavior because of the changing environment. The changes that result are often visible.
It wasn't until the late 1980s that biologists began to realize that natural selection was in play. The main reason is that different traits can confer a different rate of survival and reproduction, and they can be passed on from one generation to another.
In the past, if one particular allele, the genetic sequence that defines color in a population of interbreeding organisms, it might quickly become more common than all other alleles. In time, this 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 track evolutionary change when an organism, like bacteria, has a high generation turnover. Since 1988, Richard Lenski, a biologist, has studied twelve populations of E.coli that are descended from a single strain. Samples from each population have been collected regularly, and more than 500.000 generations of E.coli have passed.
Lenski's research has revealed that mutations can drastically alter the speed at which a population reproduces--and so, the rate at which it alters. It also shows that evolution takes time, which is difficult for some to accept.
Microevolution can also be seen 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 those with resistant genotypes.
The rapidity of evolution has led to a greater recognition of its importance, especially in a world shaped largely by human activity. This includes pollution, climate change, and habitat loss that prevents many species from adapting. Understanding evolution can help you make better decisions about the future of our planet and its inhabitants.