The Academy's Evolution Site
The concept of biological evolution is among the most central concepts in biology. The Academies have long been involved in helping those interested in science comprehend the theory of evolution and how it influences all areas of scientific exploration.
This site provides teachers, students and general readers with a wide range of learning resources 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 symbolizes the interconnectedness of life. It appears in many cultures and spiritual beliefs as a symbol of unity and love. It also has practical applications, like providing a framework for understanding the evolution of species and how they react to changes in environmental conditions.
The first attempts at depicting the biological world focused on the classification of organisms into distinct categories which had been distinguished by their physical and metabolic characteristics1. These methods depend on the collection of various parts of organisms, or DNA fragments have greatly increased the diversity of a tree of Life2. These trees are largely composed by eukaryotes, and the diversity of bacterial species is greatly underrepresented3,4.
Genetic techniques have significantly expanded our ability to visualize the Tree of Life by circumventing the need for direct observation and experimentation. Particularly, molecular methods enable us to create trees by using sequenced markers like the small subunit ribosomal gene.
Despite the dramatic expansion of the Tree of Life through genome sequencing, a large amount of biodiversity is waiting to be discovered. This is particularly true for microorganisms, which can be difficult to cultivate and are usually only present in a single specimen5. Recent analysis of all genomes has produced a rough draft of a Tree of Life. This includes a variety of archaea, bacteria and other organisms that haven't yet been identified or their diversity is not well understood6.
The expanded Tree of Life is particularly beneficial in assessing the biodiversity of an area, helping to determine if specific habitats require special protection. This information can be utilized in a variety of ways, from identifying new remedies to fight diseases to improving the quality of crops. 에볼루션 카지노 is also extremely valuable in conservation efforts. It helps biologists determine the areas most likely to contain cryptic species that could have important metabolic functions that may be at risk from anthropogenic change. While conservation funds are important, the most effective method to preserve the biodiversity of the world is to equip the people of developing nations with the necessary knowledge to act locally and promote conservation.
Phylogeny
A phylogeny is also known as an evolutionary tree, illustrates the connections between different groups of organisms. By using molecular information, morphological similarities and differences, or ontogeny (the process of the development of an organism) scientists can construct a phylogenetic tree which illustrates the evolutionary relationship between taxonomic categories. 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 with similar traits and have evolved from a common ancestor. These shared traits may be analogous or homologous. Homologous traits share their evolutionary roots while analogous traits appear similar, but do not share the same ancestors. Scientists put similar traits into a grouping called a the clade. For example, all of the organisms that make up a clade share the trait of having amniotic eggs and evolved from a common ancestor which had these eggs. A phylogenetic tree can be built by connecting the clades to identify the species who are the closest to one another.
Scientists make use of DNA or RNA molecular information to construct a phylogenetic graph that is more accurate and precise. This information is more precise than morphological information and provides evidence of the evolutionary history of an individual or group. Researchers can use Molecular Data to calculate the evolutionary age of living organisms and discover how many species share the same ancestor.
The phylogenetic relationships between species are influenced by many factors, including phenotypic flexibility, a type of behavior that alters in response to unique environmental conditions. This can cause a characteristic to appear more similar to one species than to another and obscure the phylogenetic signals. However, this problem can be cured by the use of methods like cladistics, which combine analogous and homologous features into the tree.
In addition, phylogenetics helps determine the duration and rate of speciation. This information can aid conservation biologists in deciding which species to protect from extinction. In the end, it's the conservation of phylogenetic diversity which will create an ecosystem that is complete and balanced.
Evolutionary Theory
The fundamental concept in evolution is that organisms change over time as a result of their interactions with their environment. Several theories of evolutionary change have been developed by a wide variety of scientists including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who envisioned an organism developing gradually according to its requirements, the Swedish botanist Carolus Linnaeus (1707-1778) who conceived the modern hierarchical taxonomy Jean-Baptiste Lamarck (1744-1829) who suggested that the use or non-use of traits can cause changes that could be passed on to offspring.
In the 1930s and 1940s, theories from a variety of fields--including genetics, natural selection and particulate inheritance - came together to form the modern synthesis of evolutionary theory that explains how evolution is triggered by the variations of genes within a population, and how these variants change over time as a result of natural selection. This model, which includes mutations, genetic drift, gene flow and sexual selection can be mathematically described.
Recent developments in the field of evolutionary developmental biology have revealed that variation can be introduced into a species via mutation, genetic drift, and reshuffling genes during sexual reproduction, and also by migration between populations. These processes, along with others, such as directional selection and gene erosion (changes to the frequency of genotypes over time), can lead towards evolution. Evolution is defined as changes in the genome over time and changes in the phenotype (the expression of genotypes in individuals).
Incorporating evolutionary thinking into all aspects of biology education could increase students' understanding of phylogeny and evolution. In a recent study by Grunspan and co. It was found that teaching students about the evidence for evolution increased their understanding of evolution in an undergraduate biology course. For more details on how to teach evolution, see The Evolutionary Power of Biology in All Areas of Biology or Thinking Evolutionarily as a Framework for Integrating Evolution into Life Sciences Education.
Evolution in Action
Traditionally scientists have studied evolution by looking back, studying fossils, comparing species and observing living organisms. Evolution isn't a flims moment; it is a process that continues today. Viruses evolve to stay away from new antibiotics and bacteria transform to resist antibiotics. Animals alter their behavior in the wake of a changing environment. The results are often visible.
It wasn't until late-1980s that biologists realized that natural selection could be observed in action as well. The key is the fact that different traits can confer an individual rate of survival and reproduction, and they can be passed down from one generation to the next.
In Info , if one allele - the genetic sequence that determines colour - was present in a population of organisms that interbred, it could be more common than other allele. Over time, this would mean that the number of moths that have 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.
It is easier to observe evolutionary change when an organism, like bacteria, has a rapid generation turnover. Since 1988, Richard Lenski, a biologist, has tracked twelve populations of E.coli that descend from a single strain. Samples from each population have been collected frequently and more than 50,000 generations of E.coli have passed.
Lenski's research has demonstrated that mutations can alter the rate of change and the efficiency at which a population reproduces. It also shows evolution takes time, a fact that is hard for some to accept.
Microevolution can be observed in the fact that mosquito genes for resistance to pesticides are more prevalent in populations where insecticides are used. Pesticides create an exclusive pressure that favors individuals who have resistant genotypes.
The rapidity of evolution has led to a greater appreciation of its importance particularly in a world which is largely shaped by human activities. This includes pollution, climate change, and habitat loss, which prevents many species from adapting. Understanding evolution will help us make better choices about the future of our planet, as well as the lives of its inhabitants.