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 who are interested in the sciences understand evolution theory and how it can be applied throughout all fields of scientific research.
This site offers a variety of resources for teachers, students and general readers of evolution. It has 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 all life. It appears in many cultures and spiritual beliefs as an emblem of unity and love. It also has important practical uses, like providing a framework to understand the history of species and how they respond to changing environmental conditions.
Early attempts to describe the world of biology were based on categorizing organisms based on their physical and metabolic characteristics. These methods rely on the sampling of different parts of organisms or short fragments of DNA, have significantly increased the diversity of a Tree of Life2. These trees are mostly populated by eukaryotes, and bacterial diversity is vastly underrepresented3,4.
By avoiding the need for direct experimentation and observation, genetic techniques have made it possible to represent the Tree of Life in a much more accurate way. Particularly, molecular techniques allow us to construct trees by using sequenced markers such as the small subunit ribosomal RNA gene.
Despite the dramatic expansion of the Tree of Life through genome sequencing, much biodiversity still awaits discovery. This is especially true of microorganisms that are difficult to cultivate and are often only represented in a single specimen5. A recent study of all genomes that are known has created a rough draft of the Tree of Life, including a large number of bacteria and archaea that have not been isolated and which are not well understood.
This expanded Tree of Life can be used to assess the biodiversity of a particular area and determine if specific habitats require special protection. 에볼루션 바카라 사이트 can be used in a range of ways, from identifying the most effective medicines to combating disease to enhancing the quality of the quality of crops. This information is also extremely useful to conservation efforts. It helps biologists determine the areas most likely to contain cryptic species with potentially significant metabolic functions that could be at risk of anthropogenic changes. Although funds to protect biodiversity are crucial but the most effective way to protect the world's biodiversity is for more people living in developing countries to be empowered with the necessary knowledge to act locally to promote conservation from within.
Phylogeny
A phylogeny (also called an evolutionary tree) depicts the relationships between organisms. Scientists can build a phylogenetic chart that shows the evolutionary relationship of taxonomic groups using molecular data 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 evolved from common ancestral. These shared traits can be analogous, or homologous. Homologous traits are identical in their evolutionary origins while analogous traits appear like they do, but don't have the same origins. Scientists combine similar traits into a grouping known as a Clade. For instance, all of the organisms that make up a clade share the trait of having amniotic egg and evolved from a common ancestor who had eggs. The clades are then linked to form a phylogenetic branch that can determine the organisms with the closest relationship to.
Scientists make use of molecular DNA or RNA data to create a phylogenetic chart which is more precise and precise. This information is more precise and provides evidence of the evolutionary history of an organism. Molecular data allows researchers to identify the number of species that have an ancestor common to them and estimate their evolutionary age.
The phylogenetic relationship can be affected by a variety of factors, including the phenotypic plasticity. This is a type of behavior that alters due to particular environmental conditions. 에볼루션 무료체험 can cause a particular trait to appear more similar in one species than other species, which can obscure the phylogenetic signal. However, this issue can be reduced by the use of techniques like cladistics, which combine homologous and analogous features into the tree.
In addition, phylogenetics helps predict the duration and rate of speciation. This information can aid conservation biologists to make decisions about which species they should protect from the threat of extinction. Ultimately, it is the preservation of phylogenetic diversity which 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 come up with theories of evolution, including the Islamic naturalist Nasir al-Din al-Tusi (1201-274), who believed that an organism could develop according to its own requirements, the Swedish taxonomist Carolus Linnaeus (1707-1778) who developed the modern hierarchical taxonomy, as well as Jean-Baptiste Lamarck (1844-1829), who believed that the usage or non-use of traits can lead to changes that are passed on to the next generation.
In the 1930s and 1940s, ideas from a variety of fields--including genetics, natural selection 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 those variations change in time as a result of 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 discoveries in the field of evolutionary developmental biology have demonstrated that variation can be introduced into a species by mutation, genetic drift and reshuffling genes during sexual reproduction, and also through migration between populations. These processes, along with other ones like directional selection and genetic erosion (changes in the frequency of an individual's genotype over time) can lead to evolution which is defined by change in the genome of the species over time and the change in phenotype over time (the expression of that genotype in the individual).
Incorporating evolutionary thinking into all aspects of biology education could increase student understanding of the concepts of phylogeny and evolutionary. In a study by Grunspan et al. It was found that teaching students about the evidence for evolution increased their acceptance of evolution during an undergraduate biology course. To learn more about how to teach about evolution, please look up The Evolutionary Potential of all Areas of Biology and Thinking Evolutionarily: A Framework for Infusing Evolution in Life Sciences Education.
Evolution in Action
Scientists have studied evolution by looking 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 in the present. Bacteria transform and resist antibiotics, viruses reinvent themselves and elude new medications and animals alter their behavior in response to the changing environment. The changes that result are often visible.
It wasn't until late 1980s that biologists began to realize that natural selection was in play. The key is the fact that different traits result in a different rate of survival and reproduction, and can be passed down from one generation to another.
In the past when one particular allele--the genetic sequence that determines coloration--appeared in a group of interbreeding organisms, it might quickly become more common than all other alleles. As time passes, that could mean 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.
It is easier to observe evolutionary change when the species, like bacteria, has a high generation turnover. Since 1988, Richard Lenski, a biologist, has studied twelve populations of E.coli that descend from a single strain. Samples from each population have been taken regularly and more than 500.000 generations of E.coli have been observed to have passed.
Lenski's research has demonstrated that mutations can alter the rate of change and the efficiency of a population's reproduction. It also shows evolution takes time, which is hard for some to accept.
Microevolution can be observed in the fact that mosquito genes that confer resistance to pesticides are more prevalent in areas that have used insecticides. This is because the use of pesticides creates a pressure that favors individuals with resistant genotypes.
The speed of evolution taking place has led to an increasing appreciation of its importance in a world shaped by human activities, including climate change, pollution, and the loss of habitats that hinder many species from adapting. Understanding evolution can help you make better decisions regarding the future of the planet and its inhabitants.