The Academy's Evolution Site
Biology is a key concept in biology. The Academies have been for a long time involved in helping people who are interested in science understand the theory of evolution and how it permeates every area of scientific inquiry.
This site provides teachers, students and general readers with a wide range of educational resources on evolution. It also includes important video clips from NOVA and WGBH produced science programs on DVD.
Tree of Life
The Tree of Life is an ancient symbol that symbolizes the interconnectedness of all life. It is a symbol of love and unity across many cultures. It also has many practical uses, like providing a framework to understand the evolution 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 were distinguished by physical and metabolic characteristics1. These methods rely on the collection of various parts of organisms, or DNA fragments have significantly increased the diversity of a Tree of Life2. However, these trees are largely made up of eukaryotes. Bacterial diversity remains vastly underrepresented3,4.
Genetic techniques have significantly expanded our ability to represent the Tree of Life by circumventing the need for direct observation and experimentation. We can construct trees by using molecular methods, such as the small-subunit ribosomal gene.
Despite the rapid growth of the Tree of Life through genome sequencing, much biodiversity still remains to be discovered. This is especially true for microorganisms that are difficult to cultivate and are usually found in a single specimen5. Recent analysis of all genomes resulted in an unfinished draft of the Tree of Life. This includes a variety of bacteria, archaea and other organisms that have not yet been isolated or whose diversity has not been thoroughly understood6.
This expanded Tree of Life is particularly beneficial in assessing the biodiversity of an area, which can help to determine if specific habitats require special protection. This information can be utilized in a variety of ways, such as identifying new drugs, combating diseases and enhancing crops. The information is also incredibly beneficial to conservation efforts. It can aid biologists in identifying areas that are likely to have species that are cryptic, which could perform important metabolic functions and are susceptible to the effects of human activity. Although funds to safeguard biodiversity are vital however, the most effective method to protect the world's biodiversity is for more people living in developing countries to be equipped with the knowledge to take action locally to encourage conservation from within.
Phylogeny
A phylogeny, also called an evolutionary tree, reveals the connections between groups of organisms. Scientists can construct a phylogenetic chart that shows the evolutionary relationships between taxonomic groups based on molecular data and morphological differences or similarities. Phylogeny plays a crucial role in understanding biodiversity, genetics and evolution.
A basic phylogenetic Tree (see Figure PageIndex 10 Identifies the relationships between organisms with similar characteristics and have evolved from an ancestor that shared traits. These shared traits could be either homologous or analogous. Homologous traits are identical in their evolutionary roots, while analogous traits look similar, but do not share the identical origins. Scientists group similar traits into a grouping known as a the clade. For instance, all of the species in a clade share the characteristic of having amniotic egg and evolved from a common ancestor which had these eggs. A phylogenetic tree is then constructed by connecting clades to determine the organisms who are the closest to one another.
Scientists make use of DNA or RNA molecular data to construct a phylogenetic graph that is more accurate and precise. This information is more precise than morphological data and gives evidence of the evolutionary history of an individual or group. Researchers can use Molecular Data to determine the evolutionary age of organisms and determine how many organisms have an ancestor common to all.
Phylogenetic relationships can be affected by a number of factors, including the phenotypic plasticity. This is a type behaviour that can change due to specific environmental conditions. 에볼루션사이트 can cause a characteristic to appear more like a species another, clouding the phylogenetic signal. This issue can be cured by using cladistics, which incorporates the combination of homologous and analogous features in the tree.
Furthermore, phylogenetics may aid in predicting the duration and rate of speciation. This information will assist conservation biologists in deciding which species to safeguard from disappearance. It is ultimately the preservation of phylogenetic diversity that will lead to a complete and balanced ecosystem.
Evolutionary Theory
The fundamental concept of evolution is that organisms acquire different features over time due to 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 could develop according to its own requirements and 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 usage or non-use of traits can cause changes that are passed on to the
In the 1930s & 1940s, theories from various areas, including genetics, natural selection, and particulate inheritance, came together to create a modern theorizing of evolution. This defines how evolution is triggered by the variation in genes within the population and how these variants change over time as a result of natural selection. This model, called genetic drift mutation, gene flow, and sexual selection, is a cornerstone of modern evolutionary biology and can be mathematically described.
Recent developments in the field of evolutionary developmental biology have shown that variations can be introduced into a species through mutation, genetic drift, and reshuffling genes during sexual reproduction, and also by migration between populations. These processes, in conjunction with others such as the directional selection process and the erosion of genes (changes in frequency of genotypes over time) can result in evolution. Evolution is defined by changes in the genome over time and changes in phenotype (the expression of genotypes in an individual).
Students can better understand the concept of phylogeny by using evolutionary thinking in all areas of biology. In a recent study conducted by Grunspan and colleagues., it was shown that teaching students about the evidence for evolution boosted their understanding of evolution during an undergraduate biology course. For more information on how to teach about evolution, look up The Evolutionary Potential in all Areas of Biology and Thinking Evolutionarily: A Framework for Infusing Evolution into Life Sciences Education.
Evolution in Action
Scientists have studied evolution by looking in the past, analyzing fossils and comparing species. They also observe living organisms. Evolution isn't a flims event; it is an ongoing process. Bacteria transform and resist antibiotics, viruses re-invent themselves and are able to evade new medications and animals alter their behavior to a changing planet. The results are usually visible.
It wasn't until the late 1980s that biologists began realize that natural selection was also in action. 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 one particular allele--the genetic sequence that defines color in a group of interbreeding species, it could quickly become more prevalent than the other alleles. Over time, this would mean that the number of moths with black pigmentation in a group 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 much easier when a species has a rapid generation turnover like bacteria. Since 1988, Richard Lenski, a biologist, has tracked twelve populations of E.coli that are descended from one strain. The samples of each population have been collected regularly and more than 500.000 generations of E.coli have passed.
Lenski's research has shown 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 proves that evolution is slow-moving, a fact that some people are unable to accept.
Another example of microevolution is that mosquito genes for resistance to pesticides show up more often 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 speed at which evolution takes place has led to an increasing appreciation of its importance in a world that is shaped by human activity--including climate change, pollution and the loss of habitats that prevent many species from adapting. Understanding evolution will assist you in making better choices regarding the future of the planet and its inhabitants.