The Academy's Evolution Site
The concept of biological evolution is among the most important concepts in biology. The Academies are committed to helping those interested in science to comprehend the evolution theory and how it is incorporated across all areas of scientific research.
This site provides teachers, students and general readers with a range of learning resources about evolution. It includes key video clips 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 numerous practical applications as well, such as providing a framework for understanding the history of species, and how they respond to changing environmental conditions.
Early approaches to depicting the world of biology focused on the classification of organisms into distinct categories that had been distinguished by physical and metabolic characteristics1. These methods, which rely on sampling of different parts of living organisms or on small DNA fragments, significantly increased the variety that could be included in a tree of life2. However the trees are mostly made up of eukaryotes. Bacterial diversity remains vastly underrepresented3,4.
Genetic techniques have greatly expanded our ability to visualize the Tree of Life by circumventing the requirement for direct observation and experimentation. Particularly, molecular methods enable us to create trees using sequenced markers like the small subunit ribosomal gene.
The Tree of Life has been greatly expanded thanks to genome sequencing. However there is still a lot of biodiversity to be discovered. This is particularly relevant to microorganisms that are difficult to cultivate, and are usually present in a single sample5. Recent analysis of all genomes has produced a rough draft of the Tree of Life. This includes a large number of bacteria, archaea and other organisms that have not yet been isolated or their diversity is not fully understood6.
The expanded Tree of Life is particularly useful for assessing the biodiversity of an area, helping to determine whether specific habitats require protection. 에볼루션게이밍 can be used in many ways, including finding new drugs, battling diseases and enhancing crops. This information is also extremely beneficial to conservation efforts. It can aid biologists in identifying the areas that are most likely to contain cryptic species that could have important metabolic functions that may be at risk of anthropogenic changes. While conservation funds are essential, the best method to preserve the world's biodiversity is to equip more people in developing nations with the knowledge they need to act locally and support conservation.
Phylogeny
A phylogeny (also known as an evolutionary tree) illustrates the relationship between organisms. By using molecular information, morphological similarities and differences or ontogeny (the process of the development of an organism), scientists can build a phylogenetic tree which illustrates the evolution of taxonomic groups. Phylogeny plays a crucial role in understanding the relationship between genetics, biodiversity and evolution.
A basic phylogenetic Tree (see Figure PageIndex 10 Identifies the relationships between organisms that have similar traits and have evolved from an ancestor with common traits. These shared traits may be analogous or homologous. Homologous traits are similar in terms of their evolutionary paths. Analogous traits might appear similar, but they do not have the same ancestry. Scientists arrange similar traits into a grouping called a Clade. All members of a clade share a trait, such as amniotic egg production. They all derived from an ancestor that had these eggs. A phylogenetic tree is then constructed by connecting clades to identify the organisms which are the closest to each other.
Scientists utilize molecular DNA or RNA data to construct a phylogenetic graph which is more precise and precise. This data is more precise than morphological data and provides evidence of the evolutionary history of an organism or group. Molecular data allows researchers to identify the number of species who share the same ancestor and estimate their evolutionary age.
The phylogenetic relationships between organisms are influenced by many factors, including phenotypic plasticity a type of behavior that alters in response to specific environmental conditions. This can cause a characteristic to appear more similar to one species than another, obscuring the phylogenetic signals. This problem can be addressed by using cladistics, which is a the combination of analogous and homologous features in the tree.
Furthermore, phylogenetics may aid in predicting the length and speed of speciation. This information can aid conservation biologists to make decisions about which species they should protect from extinction. Ultimately, it is the preservation of phylogenetic diversity which will lead to an ecologically balanced and complete ecosystem.
Evolutionary Theory
The central theme in evolution is that organisms alter over time because of their interactions with their environment. Several theories of evolutionary change have been developed by a variety of scientists, including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who proposed that a living organism develop slowly in accordance with its requirements as well as 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 can cause changes that could be passed onto offspring.
In the 1930s and 1940s, theories from various fields, such as genetics, natural selection, and particulate inheritance, came together to create a modern evolutionary theory. This describes how evolution occurs by the variation in genes within a population and how these variations change over time as a result of natural selection. This model, which incorporates mutations, genetic drift in gene flow, and sexual selection is mathematically described.
Recent developments in the field of evolutionary developmental biology have demonstrated that variations can be introduced into a species via genetic drift, mutation, and reshuffling genes during sexual reproduction, and also through migration between populations. These processes, along with others such as directional selection or genetic erosion (changes in the frequency of an individual's 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 the genotype within the individual).
Incorporating evolutionary thinking into all aspects of biology education can improve student understanding of the concepts of phylogeny as well as evolution. In a recent study by Grunspan et al., it was shown that teaching students about the evidence for evolution increased their understanding of evolution during an undergraduate biology course. For more information on 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
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 that is taking place today. Viruses reinvent themselves to avoid new medications and bacteria mutate to resist antibiotics. Animals alter their behavior as a result of a changing environment. The results are often apparent.
But it wasn't until the late 1980s that biologists realized that natural selection can be seen in action, as well. The key to this is that different traits can confer a different rate of survival as well as reproduction, and may be passed on from one generation to the next.
In the past, if a certain allele - the genetic sequence that determines colour was found in a group of organisms that interbred, it could be more common than any other allele. As time passes, that could mean that the number of black moths within 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 particular species has a fast generation turnover like bacteria. Since 1988 the biologist Richard Lenski has been tracking twelve populations of E. bacteria that descend from a single strain. samples of each are taken regularly and over fifty thousand generations have been observed.
Lenski's research has revealed that mutations can alter the rate of change and the rate at which a population reproduces. It also proves that evolution takes time, a fact that many are unable to accept.
Microevolution can be observed in the fact that mosquito genes for pesticide resistance are more prevalent in areas that have used insecticides. That's because the use of pesticides causes a selective pressure that favors those with resistant genotypes.
The rapidity of evolution has led to a greater appreciation of its importance especially in a planet that is largely shaped by human activity. This includes climate change, pollution, and habitat loss, which prevents many species from adapting. Understanding the evolution process will assist you in making better choices about the future of the planet and its inhabitants.