The Academy's Evolution Site
Biological evolution is a central concept in biology. The Academies are committed to helping those who are interested in science understand evolution theory and how it can be applied across all areas of scientific research.
This site provides a wide range of resources for students, teachers as well as general readers about 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 that represents the interconnectedness of all life. It is seen in a variety of cultures and spiritual beliefs as symbolizing unity and love. It also has important practical uses, like providing a framework for understanding the evolution of species and how they respond to changes in the environment.
Early attempts to describe the world of biology were based on categorizing organisms based on their physical and metabolic characteristics. These methods, which rely on the sampling of different parts of living organisms or sequences of short fragments of their DNA, significantly increased the variety that could be included in the 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 necessity for direct experimentation and observation genetic techniques have allowed us to depict the Tree of Life in a more precise way. Particularly, molecular methods enable us to create trees by using sequenced markers such as the small subunit of ribosomal RNA gene.
Despite the massive expansion of the Tree of Life through genome sequencing, a large amount of biodiversity remains to be discovered. This is particularly true for microorganisms, which can be difficult to cultivate and are often only represented in a single specimen5. A recent analysis of all genomes resulted in a rough draft of a Tree of Life. This includes a variety of bacteria, archaea and other organisms that haven't yet been isolated, or whose diversity has not been fully understood6.
This expanded Tree of Life is particularly useful in assessing the diversity of an area, assisting to determine whether specific habitats require protection. This information can be utilized in a variety of ways, such as finding new drugs, battling diseases and enhancing crops. This information is also extremely beneficial in conservation efforts. It can aid biologists in identifying areas that are likely to have cryptic species, which may have vital metabolic functions and are susceptible to changes caused by humans. While conservation funds are important, the best method to preserve the world's biodiversity is to equip the people of developing nations with the knowledge they need to act locally and support conservation.
Phylogeny
A phylogeny is also known as an evolutionary tree, shows the connections between various groups of organisms. Scientists can construct an phylogenetic chart which shows the evolutionary relationships between taxonomic categories using molecular information and morphological differences or similarities. The role of phylogeny is crucial in understanding genetics, biodiversity and evolution.
A basic phylogenetic Tree (see Figure PageIndex 10 ) identifies the relationships between organisms that share similar traits that have evolved from common ancestral. These shared traits may be homologous, or analogous. Homologous traits are similar in their evolutionary roots, while analogous traits look similar, but do not share the identical origins. Scientists combine similar traits into a grouping known as a the clade. Every organism in a group share a characteristic, for example, amniotic egg production. They all evolved from an ancestor that had these eggs. The clades are then linked to form a phylogenetic branch that can determine the organisms with the closest connection to each other.
For 에볼루션게이밍 detailed and accurate phylogenetic tree scientists rely on molecular information from DNA or RNA to identify the connections between organisms. This information is more precise and gives evidence of the evolutionary history of an organism. The analysis of molecular data can help researchers identify the number of species who share an ancestor common to them and estimate their evolutionary age.
The phylogenetic relationship can be affected by a number of factors such as the phenotypic plasticity. This is a type behavior that changes in response to unique environmental conditions. This can cause a trait to appear more like a species another, obscuring the phylogenetic signal. However, this problem can be reduced by the use of methods like cladistics, which include a mix of analogous and homologous features into the tree.
In visit this web-site , phylogenetics can help predict the duration and rate of speciation. This information will assist conservation biologists in making choices about which species to protect from disappearance. In the end, it's the preservation of phylogenetic diversity which will create an ecosystem that is complete and balanced.
Evolutionary Theory
The fundamental concept of evolution is that organisms develop various characteristics over time as a result of their interactions with their environment. 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 own needs as well as the Swedish taxonomist Carolus Linnaeus (1707-1778) who conceived 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, concepts from various fields, including genetics, natural selection and particulate inheritance--came together to form the current evolutionary theory synthesis that explains how evolution occurs through the variations of genes within a population and how these variants change over time as a result of natural selection. This model, which is known as genetic drift mutation, gene flow, and sexual selection, is the foundation of current evolutionary biology, and is mathematically described.
Recent advances in the field of evolutionary developmental biology have shown how variations can be introduced to a species by genetic drift, mutations and reshuffling of genes during sexual reproduction and the movement between populations. These processes, along 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 by changes in the genome over time as well as changes in phenotype (the expression of genotypes in individuals).
Students can better understand the concept of phylogeny by using evolutionary thinking in all areas of biology. A recent study by Grunspan and colleagues, for example revealed that teaching students about the evidence supporting evolution increased students' understanding of evolution in a college biology course. To learn more about how to teach about evolution, please see 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 traditionally studied evolution through looking back in the past, analyzing fossils and comparing species. They also observe living organisms. However, evolution isn't something that happened in the past, it's an ongoing process, taking place today. The virus reinvents itself to avoid new drugs and bacteria evolve to resist antibiotics. Animals adapt their behavior because of a changing world. The resulting changes are often easy to see.
It wasn't until late 1980s that biologists began to realize that natural selection was at work. The main reason is that different traits confer the ability to survive at different rates and reproduction, and can be passed down from one generation to another.
In the past, when one particular allele, the genetic sequence that controls coloration - was present in a population of interbreeding organisms, it might quickly become more common than other alleles. As time passes, that could mean 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.
It is easier to see evolution when an organism, like bacteria, has a high generation turnover. Since 1988, biologist Richard Lenski has been tracking twelve populations of E. Coli that descended from a single strain; samples from each population are taken every day and more than fifty thousand generations have passed.
Lenski's work has demonstrated that a mutation can dramatically alter the speed at the rate at which a population reproduces, and consequently, the rate at which it changes. visit this web-site shows evolution takes time, which is hard for some 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 due to pesticides causing a selective pressure which favors individuals who have resistant genotypes.
The rapid pace at which evolution takes place has led to a growing recognition of its importance in a world that is shaped by human activities, including climate change, pollution, and the loss of habitats that hinder the species from adapting. Understanding evolution can assist you in making better choices about the future of our planet and its inhabitants.