The Academy's Evolution Site
Biological evolution is one of the most central concepts in biology. The Academies have been active for a long time in helping those interested in science understand the concept of evolution and how it permeates all areas of scientific research.
This site provides students, teachers and general readers with a range of learning resources about evolution. It has key video clips from NOVA and the WGBH-produced science programs on DVD.
Tree of Life
The Tree of Life, an ancient symbol, symbolizes the interconnectedness of all life. It appears in many cultures and spiritual beliefs as a symbol of unity and love. It has numerous practical applications as well, such as providing a framework to understand the history of species, and how they respond to changes in environmental conditions.
Early approaches to depicting the biological world focused on categorizing species into distinct categories that were distinguished by their physical and metabolic characteristics1. These methods, which rely on the sampling of various parts of living organisms or sequences of short fragments of their DNA, significantly expanded the diversity that could be included in a tree of life2. However the trees are mostly comprised of eukaryotes, and bacterial diversity remains vastly underrepresented3,4.
Genetic techniques have greatly broadened our ability to depict the Tree of Life by circumventing the requirement for direct observation and experimentation. Particularly, molecular techniques allow us to build trees using sequenced markers like the small subunit ribosomal RNA gene.
The Tree of Life has been dramatically expanded through genome sequencing. However there is a lot of biodiversity to be discovered. This is particularly relevant to microorganisms that are difficult to cultivate, and which are usually only found in a single specimen5. A recent analysis of all genomes has produced an unfinished draft of a Tree of Life. This includes a variety of archaea, bacteria and other organisms that have not yet been isolated or the diversity of which is not well understood6.
The expanded Tree of Life can be used to determine the diversity of a specific area and determine if certain 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 useful to conservation efforts. It can aid biologists in identifying areas that are likely to have cryptic species, which could have important metabolic functions and be vulnerable to the effects of human activity. Although funds to protect biodiversity are crucial however, the most effective method to preserve the world's biodiversity is for more people living in developing countries to be equipped with the knowledge to take action locally to encourage conservation from within.
Phylogeny
A phylogeny (also called an evolutionary tree) depicts the relationships between different organisms. Scientists can construct an phylogenetic chart which shows the evolutionary relationships between taxonomic groups using molecular data and morphological differences or similarities. 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 have evolved from common ancestral. These shared traits may be homologous, or analogous. Homologous traits are identical in their evolutionary origins and analogous traits appear similar, but do not share the same origins. Scientists put similar traits into a grouping referred to as a the clade. All members of a clade have a common characteristic, like amniotic egg production. They all evolved from an ancestor who had these eggs. The clades are then connected to form a phylogenetic branch to determine the organisms with the closest relationship.
Scientists utilize DNA or RNA molecular information to construct a phylogenetic graph which is more precise and precise. This information is more precise and provides evidence of the evolution history of an organism. The analysis of molecular data can help researchers determine the number of species who share an ancestor common to them and estimate their evolutionary age.
에볼루션게이밍 can be affected by a number of factors that include phenotypicplasticity. This is a type behavior that changes as a result of specific environmental conditions. This can cause a particular trait to appear more similar in one species than another, obscuring the phylogenetic signal. This problem can be addressed by using cladistics. This is a method that incorporates the combination of homologous and analogous traits in the tree.
In addition, phylogenetics helps determine the duration and rate of speciation. This information will assist conservation biologists in making choices about which species to protect from extinction. Ultimately, it is the preservation of phylogenetic diversity which will create a complete and balanced ecosystem.
에볼루션게이밍 behind evolution is that organisms change over time as a result of their interactions with their environment. Many theories of evolution have been developed by a wide range of scientists such as the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who proposed that a living organism develop slowly according to its requirements, the Swedish botanist Carolus Linnaeus (1707-1778) who designed modern hierarchical taxonomy, and Jean-Baptiste Lamarck (1744-1829) who suggested that the use or non-use of traits can cause changes that could be passed on to the offspring.
In the 1930s and 1940s, concepts from various fields, including genetics, natural selection and particulate inheritance - came together to form the current evolutionary theory synthesis, which defines how evolution occurs through the variations of genes within a population and how those variants change in time due to natural selection. This model, which includes genetic drift, mutations in gene flow, and sexual selection is mathematically described mathematically.
Recent developments in the field of evolutionary developmental biology have shown how variation can be introduced to a species via mutations, genetic drift and reshuffling of genes during sexual reproduction and the movement between populations. These processes, as well as others like directional selection and genetic erosion (changes in the frequency of an individual's genotype over time) can lead to evolution that is defined as change in the genome of the species over time and also the change in phenotype over time (the expression of that genotype within the individual).
Students can gain a better understanding of phylogeny by incorporating evolutionary thinking in all aspects of biology. A recent study by Grunspan and colleagues, for instance revealed that teaching students about the evidence for evolution increased students' understanding of evolution in a college biology class. To learn more about how to teach about evolution, please look up The Evolutionary Potential in all Areas of Biology and Thinking Evolutionarily: A Framework for Infusing the Concept of Evolution into Life Sciences Education.
Evolution in Action
Traditionally, scientists have studied evolution by studying fossils, comparing species and studying living organisms. But evolution isn't a thing that happened in the past. It's an ongoing process taking place in the present. Viruses reinvent themselves to avoid new medications and bacteria mutate to resist antibiotics. Animals adapt their behavior as a result of the changing environment. 에볼루션게이밍 that result are often evident.
It wasn't until late 1980s that biologists understood that natural selection can be seen in action, as well. The key is the fact that different traits confer a different rate of survival and reproduction, and can be passed down from one generation to the next.
In the past, when one particular allele--the genetic sequence that defines color in a group of interbreeding organisms, it could quickly become more prevalent than other alleles. Over time, that would mean the number of black moths in a particular population could rise. 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 such as bacteria. Since 1988, Richard Lenski, a biologist, has been tracking twelve populations of E.coli that are descended from one strain. The samples of each population were taken regularly, and more than 500.000 generations of E.coli have passed.
Lenski's research has demonstrated that mutations can alter the rate of change and the rate of a population's reproduction. It also proves that evolution is slow-moving, a fact that some find difficult to accept.
Microevolution can also be seen in the fact that mosquito genes for pesticide resistance are more prevalent in populations where insecticides have been used. This is because the use of pesticides causes a selective pressure that favors individuals with resistant genotypes.
The rapidity of evolution has led to a greater recognition of its importance especially in a planet that is largely shaped by human activity. This includes the effects of climate change, pollution and habitat loss, which prevents many species from adapting. Understanding evolution can help us make better choices about the future of our planet, as well as the lives of its inhabitants.