The Academy's Evolution Site
Biological evolution is a central concept in biology. The Academies are committed to helping those interested in science comprehend the evolution theory and how it is incorporated throughout all fields of scientific research.
This site provides teachers, students and general readers with a variety of educational resources on evolution. It contains key video clips from NOVA and 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 spiritual traditions and cultures as a symbol of unity and love. It can be used in many practical ways in addition to providing a framework to understand the evolution of species and how they react to changing environmental conditions.
Early attempts to describe the world of biology were founded on categorizing organisms on their physical and metabolic characteristics. These methods, based on sampling of different parts of living organisms, or sequences of short fragments of their DNA greatly increased the variety of organisms that could be included in a tree of life2. However 에볼루션 바카라 무료 are mainly comprised of eukaryotes, and bacterial diversity is not represented in a large way3,4.
In avoiding the necessity of direct experimentation and observation genetic techniques have enabled us to depict the Tree of Life in a more precise way. Particularly, molecular techniques allow us to build trees using sequenced markers like the small subunit of ribosomal RNA gene.
Despite the rapid expansion of the Tree of Life through genome sequencing, a large amount of biodiversity remains to be discovered. This is particularly true for microorganisms that are difficult to cultivate, and are typically found in a single specimen5. A recent analysis of all genomes known to date has created a rough draft of the Tree of Life, including a large number of archaea and bacteria that have not been isolated and their diversity is not fully understood6.
The expanded Tree of Life is particularly beneficial in assessing the biodiversity of an area, assisting to determine if certain habitats require special protection. This information can be utilized in a range of ways, from identifying the most effective medicines to combating disease to enhancing crops. The information is also incredibly valuable to conservation efforts. It can help biologists identify areas most likely to be home to species that are cryptic, which could have vital metabolic functions and be vulnerable to human-induced change. While conservation funds are important, the most effective method to preserve the world's biodiversity is to empower more people in developing countries with the information they require to act locally and support conservation.
Phylogeny
A phylogeny, also called an evolutionary tree, illustrates the relationships between different groups of organisms. By using molecular information as well as morphological similarities and distinctions, or ontogeny (the course of development of an organism) scientists can construct a phylogenetic tree that illustrates the evolutionary relationship between taxonomic groups. The phylogeny of a tree plays an important role in understanding genetics, biodiversity and evolution.
A basic phylogenetic Tree (see Figure PageIndex 10 ) identifies the relationships between organisms with similar traits that have evolved from common ancestral. These shared traits may be homologous, or analogous. Homologous traits share their evolutionary roots while analogous traits appear similar but do not have the identical origins. Scientists group similar traits into a grouping known as a Clade. For instance, all the organisms in a clade share the trait of having amniotic eggs and evolved from a common ancestor who had these eggs. A phylogenetic tree is constructed by connecting the clades to identify the species that are most closely related to each other.
Scientists use DNA or RNA molecular information to build a phylogenetic chart which is more precise and precise. This information is more precise than morphological information and provides evidence of the evolutionary history of an organism or group. Molecular data allows researchers to identify the number of organisms who share a common ancestor and to estimate their evolutionary age.
The phylogenetic relationships of a species can be affected by a variety of factors, including phenotypicplasticity. This is a type of behaviour that can change due to specific environmental conditions. This can cause a trait to appear more resembling to one species than another which can obscure the phylogenetic signal. However, this issue can be cured by the use of methods like cladistics, which combine similar and homologous traits into the tree.
Furthermore, phylogenetics may aid in predicting the time and pace of speciation. This information can assist conservation biologists in deciding which species to safeguard from disappearance. Ultimately, it is the preservation of phylogenetic diversity that will lead to a complete and balanced ecosystem.
Evolutionary Theory
The main idea behind evolution is that organisms alter over time because of their interactions with their environment. Many scientists have proposed theories of evolution, including the Islamic naturalist Nasir al-Din al-Tusi (1201-274) who believed that an organism could evolve according to its individual needs as well as the Swedish taxonomist Carolus Linnaeus (1707-1778) who conceived the modern hierarchical system of taxonomy as well as Jean-Baptiste Lamarck (1844-1829), who suggested that the use or non-use of certain traits can result in changes that are passed on to the
In the 1930s and 1940s, concepts from a variety of fields--including genetics, natural selection, and particulate inheritance--came together to form the current synthesis of evolutionary theory, which defines how evolution occurs through the variations of genes within a population and how those variants change in time as a result of natural selection. This model, which incorporates mutations, genetic drift, gene flow and sexual selection, can be mathematically described mathematically.
Recent advances in the field of evolutionary developmental biology have shown how variations can be introduced to a species through genetic drift, mutations or reshuffling of genes in sexual reproduction, and even migration between populations. These processes, in conjunction with 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 as 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 as well as evolution. 에볼루션 룰렛 by Grunspan and colleagues, for instance demonstrated that teaching about the evidence supporting evolution helped students accept the concept of evolution in a college biology class. For more information about how to teach evolution, see The Evolutionary Potency in All Areas of Biology or Thinking Evolutionarily A Framework for Integrating Evolution into Life Sciences Education.
Evolution in Action
Traditionally, scientists have studied evolution by looking back--analyzing fossils, comparing species and observing living organisms. But evolution isn't just something that occurred in the past. It's an ongoing process that is that is taking place today. Bacteria transform and resist antibiotics, viruses re-invent themselves and escape new drugs and animals alter their behavior to the changing climate. The changes that occur are often evident.
It wasn't until late 1980s that biologists began realize that natural selection was in action. The key is that different traits have different rates of survival and reproduction (differential fitness) and are passed down from one generation to the next.
In the past, if an allele - the genetic sequence that determines colour appeared in a population of organisms that interbred, it could become more common than other allele. In time, this could mean that the number of moths with black pigmentation may increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.
It is easier to observe evolution when a species, such as bacteria, has a rapid generation turnover. Since 1988, Richard Lenski, a biologist, has studied twelve populations of E.coli that are descended from a single strain. Samples from each population have been collected regularly and more than 50,000 generations of E.coli have been observed to have passed.
Lenski's research has revealed that mutations can alter the rate of change and the effectiveness at which a population reproduces. It also demonstrates that evolution takes time--a fact that many find difficult to accept.
Another example of microevolution is that mosquito genes for resistance to pesticides are more prevalent in areas where insecticides are employed. This is because the use of pesticides creates a selective pressure that favors people who have resistant genotypes.
The rapidity of evolution has led to a greater recognition of its importance especially in a planet which is largely shaped by human activities. This includes climate change, pollution, and habitat loss that prevents many species from adapting. Understanding the evolution process can help us make better decisions about the future of our planet and the life of its inhabitants.