The Academy's Evolution Site
Biological evolution is one of the most fundamental concepts in biology. The Academies are committed to helping those who are interested in the sciences understand evolution theory and how it is incorporated throughout all fields of scientific research.
This site provides students, teachers and general readers with a variety of learning resources about evolution. It contains key video clips from NOVA and WGBH's science programs on DVD.
Tree of Life
The Tree of Life, an ancient symbol, symbolizes the interconnectedness of all life. It appears in many religions and cultures as an emblem of unity and love. It also has practical applications, such as providing a framework to understand the history of species and how they react to changes in environmental conditions.
Early approaches to depicting the world of biology focused on the classification of species into distinct categories that had been distinguished by their physical and metabolic characteristics1. These methods, which rely on the sampling of various parts of living organisms, or small DNA fragments, significantly expanded the diversity that could be represented in the tree of life2. These trees are largely composed by eukaryotes and the diversity of bacterial species is greatly underrepresented3,4.
Genetic techniques have greatly expanded our ability to depict the Tree of Life by circumventing the requirement for direct observation and experimentation. We can create trees using molecular methods like the small-subunit ribosomal gene.
The Tree of Life has been significantly expanded by genome sequencing. However there is a lot of biodiversity to be discovered. This is especially the case for microorganisms which are difficult to cultivate and are typically found in a single specimen5. A recent study of all genomes known to date has produced a rough draft version of the Tree of Life, including numerous bacteria and archaea that have not been isolated, and which are not well understood.
This expanded Tree of Life is particularly beneficial in assessing the biodiversity of an area, helping to determine whether specific habitats require protection. This information can be used in a range of ways, from identifying new medicines to combating disease to improving crops. This information is also beneficial to conservation efforts. It can aid biologists in identifying the areas most likely to contain cryptic species with important metabolic functions that could be at risk from anthropogenic change. While conservation funds are important, the best way to conserve the world's biodiversity is to empower more people in developing nations with the knowledge they need to act locally and promote conservation.
Phylogeny
A phylogeny, also called an evolutionary tree, reveals the relationships between different groups of organisms. Utilizing molecular data, morphological similarities and differences, or ontogeny (the process of the development of an organism), scientists can build a phylogenetic tree that illustrates the evolutionary relationships between taxonomic categories. Phylogeny is essential in understanding evolution, biodiversity and genetics.
A basic phylogenetic Tree (see Figure PageIndex 10 Finds the connections between organisms that have similar characteristics and have evolved from an ancestor with common traits. These shared traits could be analogous or homologous. Homologous characteristics are identical in their evolutionary paths. Analogous traits may look similar, 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 have a common characteristic, for example, amniotic egg production. They all evolved from an ancestor who had these eggs. 에볼루션 is constructed by connecting clades to identify the organisms that are most closely related to each other.
Scientists make use of molecular DNA or RNA data to create a phylogenetic chart which is more precise and detailed. This data is more precise than morphological data and provides evidence of the evolution background of an organism or group. Molecular data allows researchers to identify the number of organisms that share an ancestor common to them and estimate their evolutionary age.
The phylogenetic relationship can be affected by a number of factors such as the phenomenon of phenotypicplasticity. This is a type behaviour that can change in response to unique environmental conditions. This can cause a characteristic to appear more similar in one species than another, obscuring the phylogenetic signal. This issue can be cured by using cladistics, which is a the combination of homologous and analogous traits in the tree.
Furthermore, phylogenetics may help predict the time and pace of speciation. This information can assist conservation biologists in making decisions about which species to save from the threat of extinction. In the end, it's the preservation of phylogenetic diversity which will create an ecosystem that is complete and balanced.
Evolutionary Theory
The fundamental concept of evolution is that organisms acquire different features over time as a result of their interactions with their environment. Many scientists have come up with theories of evolution, such as the Islamic naturalist Nasir al-Din al-Tusi (1201-274), who believed that an organism would evolve according to its own needs and needs, the Swedish taxonomist Carolus Linnaeus (1707-1778), who created the modern taxonomy system that is hierarchical as well as Jean-Baptiste Lamarck (1844-1829), who believed that the use or non-use of certain traits can result in changes that are passed on to the next generation.
In the 1930s & 1940s, concepts from various areas, including genetics, natural selection, and particulate inheritance, merged to create a modern theorizing of evolution. This describes how evolution occurs by the variation in genes within a population and how these variations change with time due to natural selection. This model, which encompasses mutations, genetic drift in gene flow, and sexual selection is mathematically described.
Recent discoveries in evolutionary developmental biology have shown the ways in which variation can be introduced to a species via genetic drift, mutations, reshuffling genes during sexual reproduction and the movement between populations. These processes, as well as other ones like directionally-selected selection and erosion of genes (changes to the frequency of genotypes over time) can result in evolution. Evolution is defined as changes in the genome over time and changes in phenotype (the expression of genotypes within individuals).
Students can gain a better understanding of the concept of phylogeny through incorporating evolutionary thinking in all aspects of biology. A recent study conducted by Grunspan and colleagues, for instance revealed that teaching students about the evidence that supports evolution increased students' acceptance of evolution in a college-level biology class. For more details on how to teach evolution look up 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 looking back--analyzing fossils, comparing species, and observing living organisms. Evolution isn't a flims moment; it is an ongoing process. Bacteria evolve and resist antibiotics, viruses re-invent themselves and elude new medications and animals change their behavior to a changing planet. 에볼루션 카지노 that result are often evident.
It wasn't until late 1980s that biologists understood that natural selection could be seen in action, as well. The main reason is that different traits confer a different rate of survival and reproduction, and they can be passed down from one generation to the next.
In the past, if an allele - the genetic sequence that determines color - appeared in a population of organisms that interbred, it might become more common than other allele. Over time, this would mean that the number of moths that have 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, as with bacteria. Since 에볼루션 바카라사이트 , biologist Richard Lenski has been tracking twelve populations of E. Coli that descended from a single strain. samples of each population are taken regularly and over fifty thousand generations have been observed.
Lenski's research has shown that a mutation can profoundly alter the speed at which a population reproduces--and so the rate at which it alters. It also shows evolution takes time, something that is hard for some to accept.
Microevolution is also evident in the fact that mosquito genes for pesticide resistance are more prevalent in areas that have used insecticides. This is due to the fact that the use of pesticides causes a selective pressure that favors those who have resistant genotypes.
The rapid pace at which evolution can take place has led to an increasing recognition of its importance in a world that is shaped by human activity, including climate change, pollution and the loss of habitats that hinder many species from adjusting. Understanding evolution can help us make smarter choices about the future of our planet, as well as the lives of its inhabitants.