The Academy's Evolution Site
The concept of biological evolution is among the most important concepts in biology. The Academies are involved in helping those who are interested in science to learn about the theory of evolution and how it can be applied in all areas of scientific research.
This site provides students, teachers and general readers with a wide range of educational resources on evolution. It includes key video clips from NOVA and WGBH's science programs on DVD.
Tree of Life
The Tree of Life is an ancient symbol of the interconnectedness of life. It is an emblem of love and unity across many cultures. It also has important practical applications, like providing a framework to understand the history of species and how they respond to changing environmental conditions.
Early attempts to describe the biological world were built on categorizing organisms based on their metabolic and physical characteristics. These methods, which rely on sampling of different parts of living organisms, or small fragments of their DNA, greatly increased the variety of organisms that could be included in a tree of life2. The trees are mostly composed by eukaryotes, and bacteria are largely underrepresented3,4.
Genetic techniques have greatly expanded our ability to represent the Tree of Life by circumventing the need for direct observation and experimentation. In particular, molecular methods allow us to build trees using sequenced markers such as the small subunit ribosomal gene.
에볼루션바카라사이트 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 found in one sample5. 에볼루션 바카라 of all genomes resulted in 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 well understood6.
This expanded Tree of Life can be used to assess the biodiversity of a particular area and determine if specific habitats need special protection. The information is useful in many ways, including finding new drugs, battling diseases and improving the quality of crops. It is also valuable for conservation efforts. It can help biologists identify areas that are likely to be home to cryptic species, which could perform important metabolic functions and are susceptible to human-induced change. While funding to protect biodiversity are essential, the best way to conserve the world's biodiversity is to equip more people in developing nations with the necessary knowledge to act locally and support conservation.
Phylogeny
A phylogeny, also called an evolutionary tree, shows the relationships between groups of organisms. Scientists can build a phylogenetic diagram that illustrates the evolutionary relationships between taxonomic categories using molecular information and morphological similarities or differences. Phylogeny plays a crucial role in understanding the relationship between genetics, biodiversity and evolution.
A basic phylogenetic Tree (see Figure PageIndex 10 ) is a method of identifying the relationships between organisms with similar traits that evolved from common ancestors. These shared traits may be analogous or homologous. Homologous traits share their evolutionary origins while analogous traits appear like they do, but don't have the identical origins. Scientists arrange similar traits into a grouping known as a clade. Every organism in a group have a common characteristic, for example, amniotic egg production. They all derived from an ancestor with these eggs. The clades are then connected to create a phylogenetic tree to determine which organisms have the closest relationship to.
Scientists make use of molecular DNA or RNA data to construct a phylogenetic graph that is more accurate and detailed. This data is more precise than morphological data and provides evidence of the evolutionary history of an organism or group. Researchers can utilize Molecular Data to estimate the age of evolution of living organisms and discover how many species share a common ancestor.
The phylogenetic relationships of organisms are influenced by many factors including phenotypic plasticity, an aspect of behavior that alters in response to unique environmental conditions. This can cause a characteristic to appear more similar to a species than to another and obscure the phylogenetic signals. This problem can be addressed by using cladistics, which incorporates the combination of homologous and analogous features in the tree.
In addition, phylogenetics helps determine the duration and speed at which speciation occurs. This information can help conservation biologists make decisions about which species they should protect from extinction. In the end, it is the preservation of phylogenetic diversity that will result in an ecosystem that is complete and balanced.
Evolutionary Theory
The main idea behind evolution is that organisms change over time due to their interactions with their environment. Several theories of evolutionary change have been proposed by a variety of scientists such as the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who envisioned an organism developing slowly in accordance with its requirements and needs, the Swedish botanist Carolus Linnaeus (1707-1778) who conceived the modern hierarchical taxonomy, as well as Jean-Baptiste Lamarck (1744-1829) who suggested that use or disuse of traits can cause changes that can be passed on to the offspring.
In the 1930s & 1940s, theories from various fields, such as genetics, natural selection and particulate inheritance, merged to create a modern synthesis of evolution theory. This defines how evolution is triggered by the variation of genes in the population and how these variants alter over time due to natural selection. This model, which is known as genetic drift mutation, gene flow, and sexual selection, is the foundation of modern evolutionary biology and can be mathematically explained.
Recent discoveries in the field of evolutionary developmental biology have shown that variations can be introduced into a species through genetic drift, mutation, and reshuffling genes during sexual reproduction, and also by migration between populations. These processes, along with other ones like the directional selection process and the erosion of genes (changes in frequency of genotypes over time) can lead to evolution. Evolution is defined as changes in the genome over time as well as changes in the phenotype (the expression of genotypes in individuals).
Students can better understand the concept of phylogeny through incorporating evolutionary thinking into all aspects of biology. A recent study conducted by Grunspan and colleagues, for example revealed that teaching students about the evidence supporting evolution increased students' understanding of evolution in a college-level biology class. To find out more about how to teach about evolution, please see The Evolutionary Potential of all Areas of Biology and Thinking Evolutionarily A Framework for Infusing Evolution into Life Sciences Education.
Evolution in Action
Scientists have studied evolution through looking back in the past, analyzing fossils and comparing species. They also study living organisms. But evolution isn't a thing that occurred in the past. It's an ongoing process, happening in the present. Bacteria mutate and resist antibiotics, viruses evolve and are able to evade new medications, and animals adapt their behavior to the changing climate. The changes that result are often visible.
However, it wasn't until late 1980s that biologists realized that natural selection can be observed in action as well. The main reason is that different traits confer an individual rate of survival and reproduction, and can be passed on 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 rapidly become more common than the other alleles. 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.
Observing evolutionary change in action is easier when a particular species has a rapid turnover of its generation like 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 regularly and over fifty thousand generations have been observed.
Lenski's research has revealed that mutations can alter the rate at which change occurs and the rate of a population's reproduction. It also shows that evolution takes time, a fact that some people find difficult to accept.
Microevolution can also be seen in the fact that mosquito genes for resistance to pesticides are more common in populations where insecticides are used. This is due to the fact that the use of pesticides creates a pressure that favors individuals with resistant genotypes.
The rapidity of evolution has led to a growing appreciation of its importance especially in a planet that is largely shaped by human activity. This includes pollution, climate change, and habitat loss that prevents many species from adapting. Understanding the evolution process will aid you in making better decisions about the future of the planet and its inhabitants.