The Academy's Evolution Site
Biological evolution is a central concept in biology. The Academies have been active for a long time in helping those interested in science understand the theory of evolution and how it affects every area of scientific inquiry.
This site provides a wide range of resources for students, teachers and general readers of evolution. It also includes important video clips from NOVA and WGBH produced science programs on DVD.
Tree of Life
The Tree of Life, an ancient symbol, symbolizes the interconnectedness of all life. It is a symbol of love and unity in many cultures. It can be used in many practical ways in addition to providing a framework to understand the history of species, and how they react to changing environmental conditions.
The first attempts at depicting the world of biology focused on separating species into distinct categories that had been identified by their physical and metabolic characteristics1. These methods, which rely on the sampling of various parts of living organisms, or short fragments of their DNA significantly expanded the diversity that could be included in the tree of life2. However 에볼루션 바카라 사이트 are mainly made up of eukaryotes. Bacterial diversity is not represented in a large way3,4.
By avoiding the need for direct observation and experimentation genetic techniques have enabled us to depict the Tree of Life in a more precise way. Trees can be constructed using molecular techniques such as the small subunit ribosomal gene.
Despite the massive expansion of the Tree of Life through genome sequencing, a large amount of biodiversity is waiting to be discovered. This is particularly true of microorganisms that are difficult to cultivate and are often only represented in a single sample5. A recent analysis of all genomes known to date has produced a rough draft version of the Tree of Life, including many archaea and bacteria that have not been isolated, and which are not well understood.
This expanded Tree of Life can be used to evaluate the biodiversity of a specific region and determine if certain habitats require special protection. This information can be used in a range of ways, from identifying new remedies to fight diseases to enhancing the quality of crops. 에볼루션 is also incredibly useful for conservation efforts. It can aid biologists in identifying areas most likely to have species that are cryptic, which could have vital metabolic functions and are susceptible to the effects of human activity. Although funds to protect biodiversity are essential but the most effective way to protect the world's biodiversity is for more people in developing countries to be empowered with the necessary knowledge to take action locally to encourage conservation from within.
Phylogeny
A phylogeny, also known as an evolutionary tree, illustrates the connections between groups of organisms. Using molecular data, morphological similarities and differences, or ontogeny (the process of the development of an organism) scientists can construct an phylogenetic tree that demonstrates the evolution of taxonomic categories. Phylogeny is essential in understanding evolution, biodiversity and genetics.
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 can be either homologous or analogous. Homologous traits are the same in terms of their evolutionary path. Analogous traits may look similar however they do not have the same ancestry. Scientists organize similar traits into a grouping known as a the clade. For example, all of the species in a clade have the characteristic of having amniotic eggs. They evolved from a common ancestor which had eggs. A phylogenetic tree is then built by connecting the clades to identify the organisms who are the closest to one another.
For a more precise and accurate phylogenetic tree scientists rely on molecular information from DNA or RNA to identify the relationships among organisms. This information is more precise and provides evidence of the evolution history of an organism. The analysis of molecular data can help researchers determine the number of species that have a common ancestor and to estimate their evolutionary age.
The phylogenetic relationships between species are influenced by many factors including phenotypic plasticity, an aspect of behavior that changes in response to unique environmental conditions. This can cause a trait to appear more like a species another, clouding the phylogenetic signal. 에볼루션 무료체험 can be cured by using cladistics, which incorporates a combination of analogous and homologous features in the tree.
Additionally, phylogenetics can help predict the duration and rate of speciation. This information can aid conservation biologists in making choices about which species to save from extinction. It is ultimately the preservation of phylogenetic diversity which will create a complete and balanced ecosystem.
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, such as the Islamic naturalist Nasir al-Din al-Tusi (1201-274) who believed that an organism would develop according to its own requirements and needs, the Swedish taxonomist Carolus Linnaeus (1707-1778), who created the modern hierarchical taxonomy 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, ideas from a variety of fields -- including natural selection, genetics, and particulate inheritance -- came together to form the modern evolutionary theory, which defines how evolution happens through the variations of genes within a population and how these variants change over time due to natural selection. This model, called genetic drift or mutation, gene flow and sexual selection, is a cornerstone of the current evolutionary biology and can be mathematically explained.
Recent discoveries in the field of evolutionary developmental biology have revealed that genetic variation can be introduced into a species through mutation, genetic drift and reshuffling of genes during sexual reproduction, and also through the movement of populations. These processes, as well as other ones like directional selection and genetic erosion (changes in the frequency of a genotype over time) can lead to evolution that is defined as change in the genome of the species over time, and the change in phenotype as time passes (the expression of that genotype in an individual).
Incorporating evolutionary thinking into all aspects 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 supporting evolution increased students' understanding of evolution in a college-level biology course. For more information on how to teach evolution look up The Evolutionary Potential in all Areas of Biology or Thinking Evolutionarily: a Framework for Integrating 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. Evolution isn't a flims moment; it is an ongoing process that continues to be observed today. Bacteria mutate and resist antibiotics, viruses re-invent themselves and are able to evade new medications and animals change their behavior to the changing climate. The changes that result are often evident.
But it wasn't until the late 1980s that biologists understood that natural selection can be observed in action as well. The key is that various traits have different rates of survival and reproduction (differential fitness), and can be transferred 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 might become more common than any other allele. As time passes, that could mean that the number of black moths within the population could increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.
The ability to observe evolutionary change is easier when a species has a rapid turnover of its generation like bacteria. Since 1988, Richard Lenski, a biologist, has tracked twelve populations of E.coli that descend from a single strain. Samples of each population were taken frequently and more than 500.000 generations of E.coli have passed.
Lenski's research has revealed that a mutation can profoundly alter the rate at the rate at which a population reproduces, and consequently, the rate at which it changes. It also shows evolution takes time, which is difficult for some to accept.
Another example of microevolution is the way mosquito genes for resistance to pesticides appear more frequently in populations in which insecticides are utilized. This is due to the fact that the use of pesticides creates a selective pressure that favors people with resistant genotypes.
The rapidity of evolution has led to an increasing recognition of its importance, especially in a world which is largely shaped by human activities. 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 regarding the future of the planet and its inhabitants.