The Academy's Evolution Site
Biology is a key concept in biology. The Academies are committed to helping those who are interested in science to understand evolution theory and how it is permeated across all areas of scientific research.
This site provides students, teachers and general readers with a range of learning resources on evolution. It contains the most important video clips from NOVA and WGBH-produced science programs on DVD.
Tree of Life
The Tree of Life is an ancient symbol that symbolizes the interconnectedness of life. It is an emblem of love and unity across many cultures. It also has many practical applications, like providing a framework for understanding the evolution of species and how they respond to changes in environmental conditions.
Early approaches to depicting the biological world focused on categorizing organisms into distinct categories which had been distinguished by their physical and metabolic characteristics1. 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 these trees are mainly composed of eukaryotes; bacterial diversity is still largely unrepresented3,4.
By avoiding 무료 에볼루션 for direct observation and experimentation genetic techniques have made it possible to represent the Tree of Life in a more precise way. We can construct trees using molecular techniques, such as the small-subunit ribosomal gene.
The Tree of Life has been greatly expanded thanks to genome sequencing. However there is a lot of diversity to be discovered. This is especially the case for microorganisms which are difficult to cultivate and are usually present in a single sample5. A recent study of all genomes known to date has created a rough draft of the Tree of Life, including a large number of bacteria and archaea that have not been isolated and whose diversity is poorly understood6.
This expanded Tree of Life is particularly beneficial in assessing the biodiversity of an area, which can help to determine whether specific habitats require special protection. The information can be used in a range of ways, from identifying the most effective remedies to fight diseases to enhancing the quality of crop yields. This information is also extremely useful to conservation efforts. It helps biologists discover areas that are likely to be home to cryptic species, which could have vital metabolic functions, and could be susceptible to human-induced change. While funds to protect biodiversity are crucial but the most effective way to preserve the world's biodiversity is for more people in developing countries to be equipped with the knowledge to take action locally to encourage conservation from within.
Phylogeny
A phylogeny, also known as an evolutionary tree, reveals the connections between different groups of organisms. By using molecular information similarities and differences in morphology, or ontogeny (the course of development of an organism) scientists can construct a phylogenetic tree which illustrates the evolutionary relationships between taxonomic categories. Phylogeny is essential in understanding the evolution of biodiversity, evolution and genetics.
A basic phylogenetic tree (see Figure PageIndex 10 ) identifies the relationships between organisms with similar traits that evolved from common ancestors. These shared traits can be either homologous or analogous. Homologous traits are identical in their evolutionary origins while analogous traits appear like they do, but don't have the same origins. Scientists put similar traits into a grouping called a Clade. All organisms in a group share a trait, such as amniotic egg production. They all evolved from an ancestor with these eggs. The clades are then connected to create a phylogenetic tree to determine the organisms with the closest relationship to.
For a more precise and precise phylogenetic tree scientists rely on molecular information from DNA or RNA to determine the relationships among organisms. This data is more precise than morphological information and provides 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 how many species have the same ancestor.
Phylogenetic relationships can be affected by a variety of factors, including the phenomenon of phenotypicplasticity. This is a kind of behavior that alters due to unique environmental conditions. This can cause a characteristic to appear more similar to one species than another, clouding the phylogenetic signal. However, this issue can be reduced by the use of techniques like cladistics, which combine analogous and homologous features into the tree.
Furthermore, phylogenetics may aid in predicting the length and speed of speciation. This information can assist conservation biologists make decisions about which species they should protect from extinction. In the end, it's the preservation of phylogenetic diversity that will lead to an ecosystem that is complete and balanced.
Evolutionary Theory
The fundamental concept of evolution is that organisms develop different features over time as a result of their interactions with their environment. A variety of theories about 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 according to its requirements, the Swedish botanist Carolus Linnaeus (1707-1778) who designed the modern hierarchical taxonomy Jean-Baptiste Lamarck (1744-1829) who suggested that the use or misuse of traits causes changes that could be passed on to the offspring.
In the 1930s and 1940s, ideas from various fields, including natural selection, genetics, and particulate inheritance - came together to create the modern evolutionary theory which explains how evolution occurs through the variations of genes within a population, and how those variations change in time as a result of natural selection. This model, which incorporates genetic drift, mutations, gene flow and sexual selection can be mathematically described mathematically.
Recent developments in evolutionary developmental biology have shown how variation can be introduced to a species by genetic drift, mutations or reshuffling of genes in sexual reproduction and migration between populations. These processes, as well as others such as directional selection or genetic erosion (changes in the frequency of an individual's genotype over time), can lead to evolution that is defined as changes in the genome of the species over time and also the change in phenotype as time passes (the expression of the genotype within the individual).
Incorporating evolutionary thinking into all aspects of biology education can improve students' understanding of phylogeny and evolutionary. A recent study conducted by Grunspan and colleagues, for example, showed that teaching about the evidence supporting evolution increased students' understanding of evolution in a college-level biology course. For more information on how to teach about evolution, please see The Evolutionary Potential in All Areas of Biology and Thinking Evolutionarily: A Framework for Infusing Evolution in Life Sciences Education.
Evolution in Action
Scientists have traditionally looked at evolution through the past, analyzing fossils and comparing species. They also study living organisms. 에볼루션 사이트 is not a past moment; it is an ongoing process. Bacteria mutate and resist antibiotics, viruses evolve and escape new drugs and animals change their behavior to the changing environment. The changes that result are often visible.
It wasn't until late 1980s that biologists realized that natural selection could be seen in action, as well. The key to this is that different traits can confer the ability to survive at different rates and reproduction, and they can be passed down from one generation to another.
In the past, if one allele - the genetic sequence that determines color - was present in a population of organisms that interbred, it could become more prevalent than any other allele. As time passes, that could mean the number of black moths in a 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 evolution when a species, such as bacteria, has a high generation turnover. Since 1988, Richard Lenski, a biologist, has been tracking twelve populations of E.coli that are descended from one strain. Samples from each population were taken regularly and more than 500.000 generations of E.coli have been observed to have passed.
Lenski's work has demonstrated that a mutation can dramatically alter the rate at the rate at which a population reproduces, and consequently, the rate at which it evolves. It also demonstrates that evolution takes time, a fact that some people are unable to accept.
Another example of microevolution is how mosquito genes for resistance to pesticides show up more often in populations in which insecticides are utilized. This is due to the fact that the use of pesticides creates a pressure that favors those who have resistant genotypes.
The rapidity of evolution has led to an increasing appreciation of its importance particularly in a world that is largely shaped by human activity. This includes pollution, climate change, and habitat loss, which prevents many species from adapting. Understanding evolution can help us make smarter decisions about the future of our planet as well as the lives of its inhabitants.
