The Academy's Evolution Site
Biological evolution is a central concept in biology. The Academies have been active for a long time in helping those interested in science comprehend the theory of evolution and how it affects every area of scientific inquiry.
This site provides teachers, students and general readers with a variety of learning resources about evolution. It contains key 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 a symbol of love and harmony in a variety of cultures. It also has important practical uses, like providing a framework for understanding the history of species and how they react to changing environmental conditions.
The first attempts to depict the world of biology were built on categorizing organisms based on their metabolic and physical characteristics. These methods, based on sampling of different parts of living organisms or short fragments of their DNA, significantly increased the variety that could be represented in a tree of life2. These trees are mostly populated of eukaryotes, while the diversity of bacterial species is greatly underrepresented3,4.
By avoiding the necessity for direct observation and experimentation genetic techniques have enabled us to represent the Tree of Life in a more precise manner. Trees can be constructed by using molecular methods like the small-subunit ribosomal gene.
Despite the dramatic growth of the Tree of Life through genome sequencing, a lot of biodiversity is waiting to be discovered. This is especially true of microorganisms that are difficult to cultivate and are typically only represented in a single specimen5. A recent analysis of all genomes produced an initial draft of the Tree of Life. This includes a large number of archaea, bacteria, and other organisms that have not yet been isolated, or whose diversity has not been thoroughly understood6.
The expanded Tree of Life is particularly useful for assessing the biodiversity of an area, helping to determine whether specific habitats require protection. This information can be utilized in a variety of ways, including identifying new drugs, combating diseases and improving crops. This information is also extremely beneficial for conservation efforts. It can help biologists identify areas that are likely to be home to cryptic species, which may have important metabolic functions, and could be susceptible to human-induced change. While conservation funds are essential, the best method to preserve the world's biodiversity is to equip the people of developing nations with the information they require to act locally and support conservation.
Phylogeny
A phylogeny, also called an evolutionary tree, reveals the relationships between different groups of organisms. 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 relationship between taxonomic groups. Phylogeny is essential in understanding evolution, biodiversity and genetics.
A basic phylogenetic tree (see Figure PageIndex 10 ) identifies the relationships between organisms that share similar traits that evolved from common ancestors. These shared traits can be either analogous or homologous. Homologous characteristics are identical in terms of their evolutionary journey. Analogous traits could appear like they are but they don't have the same origins. Scientists group similar traits into a grouping referred to as a clade. All organisms in a group share a characteristic, like amniotic egg production. They all derived from an ancestor that had these eggs. A phylogenetic tree is built by connecting the clades to identify the species that are most closely related to each other.
Scientists make use of molecular DNA or RNA data to construct a phylogenetic graph that is more accurate and precise. This information is more precise and provides evidence of the evolution history of an organism. Molecular data allows researchers to determine the number of species that share the same ancestor and estimate their evolutionary age.
The phylogenetic relationships between species can be affected by a variety of factors including phenotypic plasticity, an aspect of behavior that changes in response to specific environmental conditions. This can make a trait appear more similar to one species than to another, obscuring the phylogenetic signals. This problem can be addressed by using cladistics, which is a the combination of homologous and analogous features in the tree.
In addition, phylogenetics can help predict the time and pace of speciation. This information can help conservation biologists make decisions about which species to protect from the threat of extinction. In the end, it is the conservation of phylogenetic diversity that will result in an ecosystem that is complete and balanced.
Evolutionary Theory
The main idea behind evolution is that organisms develop various characteristics over time due to their interactions with their environment. Many scientists have proposed theories of evolution, including the Islamic naturalist Nasir al-Din al-Tusi (1201-274), who believed that an organism could evolve according to its own requirements, the Swedish taxonomist Carolus Linnaeus (1707-1778) who developed the modern taxonomy system that is hierarchical and Jean-Baptiste Lamarck (1844-1829), who believed that the usage or non-use of traits can lead to changes that are passed on to the next generation.
In the 1930s & 1940s, theories from various fields, including natural selection, genetics & particulate inheritance, came together to form a modern evolutionary theory. This defines how evolution is triggered by the variation in genes within a population and how these variants change with time due to natural selection. This model, called genetic drift or mutation, gene flow, and sexual selection, is a cornerstone of modern evolutionary biology and can be mathematically explained.
Recent discoveries in the field of evolutionary developmental biology have demonstrated how variations can be introduced to a species via mutations, genetic drift or reshuffling of genes in sexual reproduction and migration between populations. These processes, as well as 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 change in the genome of the species over time, and the change in phenotype over time (the expression of the genotype in an individual).
Students can gain a better understanding of the concept of phylogeny through incorporating evolutionary thinking into all aspects of biology. In a recent study conducted by Grunspan and colleagues. It was found that teaching students about the evidence for evolution increased their acceptance of evolution during a college-level course in biology. For more details about how to teach evolution read 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 studying fossils, comparing species, and studying living organisms. Evolution isn't a flims event, but an ongoing process that continues to be observed today. 에볼루션 바카라 체험 evolve to stay away from new antibiotics and bacteria transform to resist antibiotics. Animals adapt their behavior as a result of a changing environment. The changes that result are often evident.
It wasn't until late 1980s that biologists began realize that natural selection was at work. 에볼루션 바카라 체험 is that different traits can confer an individual rate of survival as well as reproduction, and may be passed on from one generation to another.
In the past, if a certain allele - the genetic sequence that determines color - appeared in a population of organisms that interbred, it might become more common than any 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.
The ability to observe evolutionary change is easier when a species has a rapid turnover of its generation such as bacteria. Since 1988, biologist Richard Lenski has been tracking twelve populations of E. coli that descended from a single strain. samples of each population are taken on a regular basis and more than 500.000 generations have passed.
Lenski's research has revealed 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, which is difficult 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 that have used insecticides. This is because the use of pesticides creates a selective pressure that favors people with resistant genotypes.
The speed at which evolution takes place has led to a growing awareness of its significance in a world that is shaped by human activity--including climate change, pollution, and the loss of habitats that hinder many species from adapting. Understanding evolution can help you make better decisions regarding the future of the planet and its inhabitants.