The Academy's Evolution Site
Biological evolution is one of the most central concepts in biology. The Academies are involved in helping those interested in science to learn about the theory of evolution and how it is incorporated throughout all fields of scientific research.
This site provides teachers, students and general readers with a wide range of learning resources on evolution. It also includes important video clips from NOVA and WGBH produced science programs on DVD.
Tree of Life
The Tree of Life is an ancient symbol that represents the interconnectedness of all life. It is used in many cultures and spiritual beliefs as symbolizing unity and love. 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.
The earliest attempts to depict the biological world focused on the classification of organisms into distinct categories which were identified by their physical and metabolic characteristics1. These methods, based on the sampling of various parts of living organisms or on short fragments of their DNA significantly expanded the diversity that could be represented in the tree of life2. However the trees are mostly composed of eukaryotes; bacterial diversity is still largely unrepresented3,4.
By avoiding the need for direct observation and experimentation genetic techniques have made it possible to represent the Tree of Life in a more precise manner. In particular, molecular methods allow us to construct trees using sequenced markers like the small subunit ribosomal RNA gene.
Despite the rapid expansion of the Tree of Life through genome sequencing, much biodiversity still remains to be discovered. This is particularly relevant to microorganisms that are difficult to cultivate, and are typically present in a single sample5. A recent analysis of all genomes has produced a rough draft of a Tree of Life. This includes a variety of archaea, bacteria, and other organisms that haven't yet been isolated, or their diversity is not well understood6.
This expanded Tree of Life can be used to determine the diversity of a specific area and determine if certain habitats need special protection. This information can be used in a range of ways, from identifying new remedies to fight diseases to enhancing the quality of the quality of crops. This information is also extremely valuable in conservation efforts. It helps biologists determine the areas most likely to contain cryptic species with important metabolic functions that may be at risk of anthropogenic changes. Although funds to safeguard biodiversity are vital, ultimately the best way to ensure the preservation of biodiversity around the world is for more people in developing countries to be empowered with the knowledge to act locally to promote conservation from within.
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 evolutionary relationship between taxonomic categories. 무료 에볼루션 plays a crucial role in understanding the relationship between genetics, biodiversity and evolution.
A basic phylogenetic tree (see Figure PageIndex 10 ) determines the relationship between organisms that share similar traits that evolved from common ancestral. These shared traits could be either analogous or homologous. Homologous traits are similar in their evolutionary paths. Analogous traits might appear similar however they do not have the same ancestry. Scientists organize similar traits into a grouping referred to as a clade. For instance, all the organisms that make up a clade share the characteristic of having amniotic eggs and evolved from a common ancestor who had these eggs. The clades are then connected to form a phylogenetic branch to determine which organisms have the closest relationship to.
Scientists utilize DNA or RNA molecular information to create a phylogenetic chart which is more precise and precise. This data is more precise than morphological information and gives evidence of the evolutionary background of an organism or group. Researchers can utilize Molecular Data to calculate the age of evolution of organisms and determine the number of organisms that share the same ancestor.
The phylogenetic relationship can be affected by a number of factors such as the phenomenon of phenotypicplasticity. This is a type behavior that changes in response to specific environmental conditions. This can make a trait appear more similar to a species than to the other which can obscure the phylogenetic signal. However, this issue can be solved through the use of methods such as cladistics which combine analogous and homologous features into the tree.
Furthermore, phylogenetics may help predict the duration and rate of speciation. This information can assist conservation biologists decide which species they should protect from extinction. Ultimately, click the following article is the preservation of phylogenetic diversity that will lead to an ecologically balanced and complete ecosystem.
Evolutionary Theory
The fundamental concept in evolution is that organisms alter over time because of their interactions with their environment. A variety of theories about evolution have been proposed by a wide variety of scientists, including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who believed that an organism would evolve gradually according to its needs and needs, the Swedish botanist Carolus Linnaeus (1707-1778) who designed the modern hierarchical taxonomy, as well as 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 and 1940s, theories from a variety of fields -- including genetics, natural selection and particulate inheritance - came together to form the modern synthesis of evolutionary theory which explains how evolution is triggered by the variation of genes within a population and how these variants change over time due to natural selection. This model, called genetic drift mutation, gene flow and sexual selection, is the foundation of current evolutionary biology, and can be mathematically described.
Recent advances in the field of evolutionary developmental biology have shown how variations can be introduced to a species by mutations, genetic drift and reshuffling of genes during sexual reproduction, and even migration between populations. These processes, along with other ones like directional selection and genetic erosion (changes in the frequency of a genotype over time), can lead to evolution that is defined as changes in the genome of the species over time and the change in phenotype over time (the expression of that genotype in the individual).
Incorporating mouse click the following article into all areas of biology education can improve student understanding of the concepts of phylogeny and evolutionary. In a study by Grunspan and colleagues. It was found that teaching students about the evidence for evolution boosted their acceptance of evolution during an undergraduate biology course. To find out more about how to teach about evolution, see 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--analyzing fossils and comparing species. They also observe living organisms. However, evolution isn't something that happened in the past. It's an ongoing process that is taking place right now. Bacteria transform and resist antibiotics, viruses re-invent themselves and are able to evade new medications and animals change their behavior to a changing planet. The changes that result are often easy to see.
But it wasn't until the late-1980s that biologists realized that natural selection can be observed 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 a certain allele - the genetic sequence that determines color - was present in a population of organisms that interbred, it could become more common than any other allele. In time, this could mean that the number of moths sporting black pigmentation in a group 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 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 fifty thousand generations have been observed.
Lenski's research has shown that a mutation can profoundly alter the rate at the rate at which a population reproduces, and consequently, the rate at which it evolves. It also shows evolution takes time, a fact that is difficult for some to accept.
Microevolution can be observed in the fact that mosquito genes that confer resistance to pesticides are more prevalent in areas that have used insecticides. That's because the use of pesticides creates a pressure that favors individuals with resistant genotypes.
The rapidity of evolution has led to a greater appreciation of its importance particularly in a world shaped largely by human activity. This includes pollution, climate change, and habitat loss that hinders many species from adapting. Understanding evolution can help us make smarter decisions regarding the future of our planet as well as the life of its inhabitants.