The Academy's Evolution Site
Biological evolution is one of the most fundamental concepts in biology. The Academies have long been involved in helping those interested in science understand the theory of evolution and how it affects all areas of scientific research.
This site provides teachers, students and general readers with a variety of educational resources on evolution. It includes key video clip from NOVA and WGBH produced science programs on DVD.
Tree of Life
The Tree of Life, an ancient symbol, represents the interconnectedness of all life. It is a symbol of love and unity in many cultures. It has many practical applications in addition to providing a framework for understanding the history of species and how they respond to changing environmental conditions.
The first attempts to depict the world of biology were based on categorizing organisms based on their physical and metabolic characteristics. These methods, based on the sampling of different parts of living organisms, or small fragments of their DNA greatly increased the variety of organisms that could be represented in the tree of life2. These trees are largely composed of eukaryotes, while the diversity of bacterial species is greatly underrepresented3,4.
By avoiding the need for direct observation and experimentation, genetic techniques have made it possible to depict the Tree of Life in a more precise way. Particularly, molecular techniques allow us to construct trees using sequenced markers like the small subunit ribosomal gene.
Despite the rapid growth of the Tree of Life through genome sequencing, a lot of biodiversity is waiting to be discovered. This is especially relevant to microorganisms that are difficult to cultivate, and are typically found in one sample5. A recent study of all genomes that are known has created a rough draft of the Tree of Life, including numerous archaea and bacteria that have not been isolated, and their diversity is not fully understood6.
This expanded Tree of Life can be used to evaluate the biodiversity of a specific region and determine if particular habitats require special protection. This information can be utilized in a range of ways, from identifying the most effective remedies to fight diseases to enhancing the quality of the quality of crops. This information is also extremely valuable in conservation efforts. It can help biologists identify areas most likely to be home to cryptic species, which may have vital metabolic functions, and could be susceptible to changes caused by humans. Although funding to protect biodiversity are essential, ultimately the best way to protect the world's biodiversity is for more people in developing countries to be equipped with the knowledge to act locally in order to promote conservation from within.
Phylogeny
A phylogeny (also known as an evolutionary tree) shows the relationships between organisms. Scientists can build a phylogenetic diagram that illustrates the evolutionary relationship of taxonomic categories using molecular information and morphological similarities or differences. The concept of phylogeny is fundamental to understanding biodiversity, evolution and genetics.
A basic phylogenetic Tree (see Figure PageIndex 10 Identifies the relationships between organisms that have similar traits and have evolved from a common ancestor. These shared traits could be analogous or homologous. Homologous characteristics are identical in their evolutionary path. Analogous traits could appear like they are, but they do not share the same origins. Scientists combine similar traits into a grouping referred to as a Clade. Every organism in a group share a characteristic, like amniotic egg production. They all derived from an ancestor with these eggs. A phylogenetic tree is then built by connecting the clades to determine the organisms that are most closely related to each other.
Scientists make use of DNA or RNA molecular data to build a phylogenetic chart that is more accurate and precise. This data is more precise than the morphological data and provides evidence of the evolution history of an organism or group. 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.
Phylogenetic relationships can be affected by a variety of factors such as the phenomenon of phenotypicplasticity. This is a type of behaviour that can change in response to unique environmental conditions. 에볼루션 바카라 can cause a particular trait to appear more similar to one species than another, clouding the phylogenetic signal. However, this issue can be reduced by the use of methods such as cladistics which include a mix of analogous and homologous features into the tree.
Additionally, phylogenetics can help predict the time and pace of speciation. This information can aid conservation biologists in making decisions about which species to safeguard from disappearance. Ultimately, it is the preservation of phylogenetic diversity that will create an ecosystem that is complete and balanced.
Evolutionary Theory
The main idea behind evolution is that organisms acquire distinct characteristics over time due to their interactions with their environment. Many scientists have proposed theories of evolution, such as the Islamic naturalist Nasir al-Din al-Tusi (1201-274), who believed that a living thing would evolve according to its own requirements and needs, the Swedish taxonomist Carolus Linnaeus (1707-1778), who created the modern hierarchical system of taxonomy and Jean-Baptiste Lamarck (1844-1829), who suggested that the use or absence of certain traits can result in changes that are passed on to the
In the 1930s and 1940s, ideas from a variety of fields -- including natural selection, genetics, and particulate inheritance - came together to form the modern evolutionary theory, which defines how evolution is triggered by the variations of genes within a population and how those variations change over time as a result of natural selection. This model, which incorporates genetic drift, mutations in gene flow, and sexual selection, can be mathematically described mathematically.
Recent advances in the field of evolutionary developmental biology have shown how variation can be introduced to a species via mutations, genetic drift, reshuffling genes during sexual reproduction, and even migration between populations. These processes, as well as others like directional selection and genetic erosion (changes in the frequency of the genotype over time) can result in evolution, which is defined by changes in the genome of the species over time, and the change in phenotype over time (the expression of that genotype in an individual).
Students can better understand the concept of phylogeny through incorporating evolutionary thinking in all areas of biology. A recent study by Grunspan and colleagues, for example revealed that teaching students about the evidence for evolution increased students' understanding of evolution in a college biology course. For more information on how to teach about evolution, please read 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 studied evolution through looking back in the past, studying fossils, and comparing species. They also study living organisms. Evolution is not a past event; it is a process that continues today. The virus reinvents itself to avoid new medications and bacteria mutate to resist antibiotics. Animals alter their behavior as a result of a changing environment. The changes that occur are often visible.
It wasn't until the 1980s that biologists began to realize that natural selection was at work. The main reason is that different traits result in the ability to survive at different rates 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 colour - appeared in a population of organisms that interbred, it could become more prevalent than any other allele. In time, this could mean the number of black moths within the population could increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.
Observing evolutionary change in action is easier when a particular 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 frequently and more than 50,000 generations of E.coli have been observed to have passed.
Lenski's work has shown that mutations can alter the rate of change and the effectiveness of a population's reproduction. It also shows that evolution takes time, something that is difficult for some to accept.
Microevolution can be observed in the fact that mosquito genes for resistance to pesticides 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 speed at which evolution can take place has led to a growing awareness of its significance in a world shaped by human activity, including climate change, pollution, and the loss of habitats that hinder many species from adapting. Understanding the evolution process can help us make smarter choices about the future of our planet as well as the life of its inhabitants.