The Academy's Evolution Site
Biological evolution is a central concept in biology. The Academies are involved in helping those interested in the sciences comprehend the evolution theory and how it is incorporated in all areas of scientific research.
This site provides a range of tools for students, teachers, and general readers on evolution. It includes important video clips from NOVA and the WGBH-produced science programs on DVD.
Tree of Life
The Tree of Life is an ancient symbol of the interconnectedness of all life. It appears in many cultures and spiritual beliefs as symbolizing unity and love. It also has many practical applications, like providing a framework for understanding the history of species and how they react to changes in the environment.
Early attempts to describe the biological world were based on categorizing organisms based on their metabolic and physical characteristics. These methods rely on the collection of various parts of organisms or DNA fragments, have greatly increased the diversity of a Tree of Life2. However the trees are mostly made up of eukaryotes. Bacterial diversity is not represented in a large way3,4.
By avoiding the need for direct experimentation and observation, genetic techniques have enabled us to represent the Tree of Life in a much more accurate way. In particular, molecular methods enable us to create trees using sequenced markers like the small subunit ribosomal gene.
Despite the rapid growth of the Tree of Life through genome sequencing, a large amount of biodiversity is waiting to be discovered. This is particularly true for microorganisms, which are difficult to cultivate and are often only represented in a single specimen5. A recent analysis of all known genomes has produced a rough draft of the Tree of Life, including numerous bacteria and archaea that have not been isolated and whose diversity is poorly understood6.
This expanded Tree of Life can be used to determine the diversity of a particular area and determine if certain habitats require special protection. This information can be used in a variety of ways, from identifying new remedies to fight diseases to enhancing the quality of crops. It is also beneficial for conservation efforts. It can aid biologists in identifying those areas that are most likely contain cryptic species with potentially important metabolic functions that may be vulnerable to anthropogenic change. While conservation funds are important, the best method to preserve the world's biodiversity is to empower more people in developing nations with the information they require to act locally and promote conservation.
Phylogeny
A phylogeny, also known as an evolutionary tree, shows the connections between groups of organisms. Scientists can build a phylogenetic chart that shows the evolution of taxonomic categories using molecular information and morphological differences or similarities. 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 share similar traits that have evolved from common ancestors. These shared traits may be homologous, or analogous. Homologous traits are identical in their evolutionary origins while analogous traits appear like they do, but don't have the same origins. Scientists group similar traits into a grouping called 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 linked to form a phylogenetic branch that can determine the organisms with the closest relationship.
Scientists use DNA or RNA molecular information to construct a phylogenetic graph which is more precise and detailed. This information is more precise and gives evidence of the evolution history of an organism. Researchers can utilize Molecular Data to calculate the age of evolution of organisms and determine the number of organisms that share an ancestor common to all.
Phylogenetic relationships can be affected by a number of factors that include the phenomenon of phenotypicplasticity. This is a type of behavior that alters as a result of specific environmental conditions. This can cause a particular trait to appear more similar to one species than other species, which can obscure the phylogenetic signal. However, this issue can be cured by the use of methods like cladistics, which incorporate a combination of similar and homologous traits into the tree.
In addition, phylogenetics helps determine the duration and rate at which speciation takes place. This information can assist conservation biologists in making choices about which species to protect from disappearance. Ultimately, it is the preservation of phylogenetic diversity which will lead to an ecosystem that is complete and balanced.
Evolutionary Theory
The fundamental concept of evolution is that organisms acquire various characteristics over time based on their interactions with their environments. Many scientists have developed theories of evolution, including the Islamic naturalist Nasir al-Din al-Tusi (1201-274) who believed that an organism would evolve according to its individual needs, the Swedish taxonomist Carolus Linnaeus (1707-1778) who developed 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
In the 1930s and 1940s, theories from a variety of fields -- including genetics, natural selection, and particulate inheritance - came together to create the modern synthesis of evolutionary theory which explains how evolution happens through the variations of genes within a population, and how those variants change over time due to natural selection. This model, which is known as genetic drift or mutation, gene flow, and sexual selection, is a key element of the current evolutionary biology and can be mathematically described.
Recent developments in evolutionary developmental biology have revealed the ways in which variation can be introduced to a species by mutations, genetic drift and reshuffling of genes during sexual reproduction and migration between populations. These processes, as well as others, such as directionally-selected selection and erosion of genes (changes in the frequency of genotypes over time) can lead to evolution. Evolution is defined by changes in the genome over time, as well as changes in the phenotype (the expression of genotypes within individuals).
Incorporating evolutionary thinking into all areas of biology education can increase students' understanding of phylogeny and evolution. A recent study conducted by Grunspan and colleagues, for instance demonstrated that teaching about the evidence for evolution increased students' acceptance of evolution in a college-level biology class. For more details on how to teach about evolution, see The Evolutionary Power of Biology in all Areas of Biology or Thinking Evolutionarily as a Framework for Integrating Evolution into Life Sciences Education.
Evolution in Action
Scientists have traditionally looked at evolution through the past, studying fossils, and comparing species. They also observe living organisms. However, evolution isn't something that happened in the past. It's an ongoing process happening right now. Viruses evolve to stay away from new drugs and bacteria evolve to resist antibiotics. Animals alter their behavior as a result of a changing world. The results are often evident.
It wasn't until the 1980s when biologists began to realize that natural selection was in play. The key is that different characteristics result in different rates of survival and reproduction (differential fitness) and can be transferred from one generation to the next.
In the past, if one particular allele - the genetic sequence that defines color in a group of interbreeding organisms, it might quickly become more prevalent than all other alleles. In time, this could 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.
Observing evolutionary change in action is easier when a 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 population are taken every day and more than 50,000 generations have now been observed.
Lenski's research has demonstrated that mutations can alter the rate of change and the rate at which a population reproduces. It also shows that evolution is slow-moving, a fact that some people are unable to accept.
Another example of microevolution is the way mosquito genes that are resistant to pesticides show up more often in areas in which insecticides are utilized. This is due to pesticides causing an enticement that favors those with resistant genotypes.
에볼루션 슬롯 of evolution has led to an increasing appreciation of its importance, especially in a world that is largely shaped by human activity. This includes climate change, pollution, and habitat loss that hinders many species from adapting. Understanding evolution will help you make better decisions regarding the future of the planet and its inhabitants.