The Academy's Evolution Site
Biology is one of the most important concepts in biology. The Academies have long been involved in helping people who are interested in science understand the theory of evolution and how it permeates all areas of scientific exploration.
This site offers a variety of resources for teachers, students 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 symbolizes the interconnectedness of life. It is used in many cultures and spiritual beliefs as a symbol of unity and love. It can be used in many practical ways as well, such as providing a framework to understand the evolution of species and how they react to changes in environmental conditions.
Early approaches to depicting the biological world focused on categorizing organisms into distinct categories which were identified by their physical and metabolic characteristics1. These methods, which are based on the sampling of different parts of organisms, or DNA fragments have significantly increased the diversity of a tree of Life2. However, these trees are largely made up of eukaryotes. Bacterial diversity remains vastly underrepresented3,4.
By avoiding the need for direct experimentation and observation, genetic techniques have allowed us to represent the Tree of Life in a much more accurate way. In particular, molecular methods allow us to build trees using sequenced markers such as the small subunit ribosomal RNA gene.
Despite the massive growth of the Tree of Life through genome sequencing, a lot of biodiversity remains to be discovered. This is especially the case for microorganisms which are difficult to cultivate, and are typically found in one sample5. A recent study of all genomes that are known has produced a rough draft of the Tree of Life, including numerous bacteria and archaea that are not isolated and whose diversity is poorly understood6.
The expanded Tree of Life is particularly beneficial in assessing the biodiversity of an area, which can help to determine if certain habitats require protection. This information can be utilized in a variety of ways, from identifying the most effective medicines to combating disease to enhancing crop yields. The information is also useful in conservation efforts. It can help biologists identify those areas that are most likely 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 the people of developing nations with the knowledge they need to act locally and promote conservation.
Phylogeny
A phylogeny (also called an evolutionary tree) illustrates the relationship between species. Utilizing molecular data 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. Phylogeny is crucial in understanding biodiversity, evolution and genetics.
A basic phylogenetic Tree (see Figure PageIndex 10 ) determines the relationship between organisms with similar traits that evolved from common ancestors. These shared traits could be analogous, or homologous. Homologous traits share their evolutionary origins while analogous traits appear similar, but do not share the same ancestors. Scientists group similar traits together into a grouping referred to as a the clade. All members of a clade share a characteristic, like amniotic egg production. They all derived from an ancestor who had these eggs. The clades then join to form a phylogenetic branch that can determine the organisms with the closest relationship to.
Scientists make use of DNA or RNA molecular data to create a phylogenetic chart which is more precise and detailed. This information is more precise than morphological data and provides evidence of the evolutionary history of an individual or group. Researchers can use Molecular Data to estimate the age of evolution of organisms and identify how many species share the same ancestor.
The phylogenetic relationships of a species can be affected by a variety of factors, including the phenomenon of phenotypicplasticity. This is a type of behaviour that can change as a result of particular environmental conditions. This can cause a characteristic to appear more similar in one species than another, clouding the phylogenetic signal. This issue can be cured by using cladistics, which is a an amalgamation of homologous and analogous traits in the tree.
Additionally, 에볼루션 determine the duration and rate at which speciation occurs. This information can aid conservation biologists in making choices about which species to save from disappearance. In the end, it is the preservation of phylogenetic diversity that will result in an ecosystem that is balanced and complete.
Evolutionary Theory
The central theme of evolution is that organisms develop different features over time as a result of their interactions with their environments. Many theories of evolution have been proposed by a variety of scientists, including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who proposed that a living organism develop gradually according to its needs as well as the Swedish botanist Carolus Linnaeus (1707-1778) who conceived 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 에볼루션 바카라사이트 and 1940s, theories from various fields, such as natural selection, genetics & particulate inheritance, were brought together to form a modern evolutionary theory. This explains how evolution is triggered by the variation of genes in a population and how these variants change over time as a result of natural selection. This model, which includes mutations, genetic drift, gene flow and sexual selection can be mathematically described mathematically.
Recent developments in the field of evolutionary developmental biology have revealed that 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, along with others such as directionally-selected selection and erosion of genes (changes in the frequency of genotypes over time), can lead towards evolution. Evolution is defined as changes in the genome over time and changes in phenotype (the expression of genotypes in an individual).
Students can gain a better understanding of the concept of phylogeny through incorporating evolutionary thinking in all areas of biology. In a recent study by Grunspan and co., it was shown that teaching students about the evidence for evolution boosted their understanding of evolution during an undergraduate biology course. For more details 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
Scientists have studied evolution through looking back in the past, studying fossils, and comparing species. They also study living organisms. Evolution isn't a flims moment; it is an ongoing process that continues to be observed today. Bacteria evolve and resist antibiotics, viruses reinvent themselves and are able to evade new medications, and animals adapt their behavior to the changing climate. The resulting changes are often easy to see.
But it wasn't until the late 1980s that biologists realized that natural selection could be observed in action as well. The key is the fact that different traits confer the ability to survive at different rates as well as reproduction, and may be passed down from generation to generation.
In the past, if a certain allele - the genetic sequence that determines colour - was present in a population of organisms that interbred, it could become more common than other allele. Over time, this would mean that the number of moths sporting black pigmentation in a group may increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.
Monitoring evolutionary changes in action is easier when a species has a rapid turnover of its generation like bacteria. Since 1988, biologist Richard Lenski has been tracking twelve populations of E. bacteria that descend from a single strain. samples of each are taken every day and more than 500.000 generations have passed.
Lenski's work has shown that mutations can alter the rate of change and the efficiency of a population's reproduction. It also shows that evolution is slow-moving, a fact that some people find difficult 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 are used. This is because pesticides cause an exclusive pressure that favors those with resistant genotypes.
The rapidity of evolution has led to an increasing appreciation of its importance especially in a planet which is largely shaped by human activities. This includes pollution, climate change, and habitat loss, which prevents many species from adapting. Understanding the evolution process can help us make better decisions regarding the future of our planet, as well as the lives of its inhabitants.