The Academy's Evolution Site
The concept of biological evolution is a fundamental concept in biology. The Academies are involved in helping those interested in science to understand evolution theory and how it is incorporated across all areas of scientific research.
This site provides students, teachers and general readers with a variety of learning resources about evolution. It includes key video clip 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 used in many spiritual traditions and cultures as symbolizing unity and love. It also has many practical applications, like providing a framework to understand the history of species and how they respond to changes in the environment.
Early approaches to depicting the world of biology focused on the classification of organisms into distinct categories that had been distinguished by physical and metabolic characteristics1. These methods, which rely on the sampling of different parts of organisms or short fragments of DNA have greatly increased the diversity of a Tree of Life2. However the trees are mostly composed of eukaryotes; bacterial diversity is not represented in a large way3,4.
By avoiding the need for direct observation and experimentation, genetic techniques have made it possible to represent the Tree of Life in a more precise manner. Particularly, molecular techniques allow us to build trees using sequenced markers, such as the small subunit ribosomal RNA gene.
Despite the rapid growth of the Tree of Life through genome sequencing, a large amount of biodiversity is waiting to be discovered. This is especially true of microorganisms that are difficult to cultivate and are often only represented in a single specimen5. A recent analysis of all genomes produced an initial draft of the Tree of Life. This includes a large number of bacteria, archaea and other organisms that haven't yet been isolated, or whose diversity has not been thoroughly understood6.
The expanded Tree of Life is particularly beneficial in assessing the biodiversity of an area, helping to determine whether specific habitats require special protection. This information can be used in a range of ways, from identifying the most effective medicines to combating disease to enhancing the quality of crops. It is also valuable for conservation efforts. It can help biologists identify areas most likely to have species that are cryptic, which could have vital metabolic functions, and could be susceptible to changes caused by humans. Although funding to protect biodiversity are crucial however, the most effective method to protect the world's biodiversity is for more people in developing countries to be equipped with the knowledge to take action locally to encourage conservation from within.
Phylogeny
A phylogeny, also known as an evolutionary tree, reveals the relationships between various groups of organisms. Utilizing 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 evolutionary relationships between taxonomic categories. Phylogeny is essential in 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 are either homologous or analogous. Homologous characteristics are identical in terms of their evolutionary path. Analogous traits may look similar, but they do not have the same ancestry. Scientists combine similar traits into a grouping known as a Clade. For instance, all of the organisms in a clade share the trait of having amniotic eggs and evolved from a common ancestor that had these eggs. A phylogenetic tree is then built by connecting the clades to identify the organisms who are the closest to one another.
For 에볼루션 카지노 사이트 detailed and accurate phylogenetic tree scientists make use of molecular data from DNA or RNA to identify the relationships among organisms. This data is more precise than morphological information and provides evidence of the evolutionary history of an organism or group. Researchers can utilize Molecular Data to determine the age of evolution of living organisms and discover how many species have the same ancestor.
The phylogenetic relationships between species can be affected by a variety of factors including phenotypic plasticity, a type of behavior that alters in response to specific environmental conditions. This can make a trait appear more similar to one species than another, obscuring the phylogenetic signals. However, this issue can be solved through the use of techniques like cladistics, which combine homologous and analogous features into the tree.
In addition, phylogenetics helps determine the duration and rate of speciation. This information can assist conservation biologists in making decisions about which species to safeguard from the threat of extinction. In the end, it is the preservation of phylogenetic diversity that will result in an ecosystem that is balanced and complete.
Evolutionary Theory
The central theme in evolution is that organisms change over time due to their interactions with their environment. Many theories of evolution have been proposed by a variety of scientists such as the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who proposed that a living organism develop slowly according to its requirements, the Swedish botanist Carolus Linnaeus (1707-1778) who designed modern hierarchical taxonomy, and Jean-Baptiste Lamarck (1744-1829) who suggested that use or disuse of traits cause changes that could be passed on to the offspring.
In the 1930s and 1940s, ideas from various fields, including natural selection, genetics, and particulate inheritance--came together to form the current evolutionary theory that explains how evolution happens through the variations of genes within a population and how those variants change over time due to natural selection. This model, known as genetic drift or mutation, gene flow, and sexual selection, is a key element of the current evolutionary biology and is mathematically described.
Recent developments in the field of evolutionary developmental biology have revealed that genetic variation can be introduced into a species by mutation, genetic drift and reshuffling of genes in sexual reproduction, and also by migration between populations. These processes, along with other ones like the directional selection process and the erosion of genes (changes in frequency of genotypes over time), can lead towards evolution. Evolution is defined by changes in the genome over time and changes in the phenotype (the expression of genotypes in individuals).
Students can gain a better understanding of the concept of phylogeny by using evolutionary thinking into all areas of biology. In a study by Grunspan et al. It was found that teaching students about the evidence for evolution boosted their acceptance of evolution during the course of a college biology. 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 Infusing Evolution into Life Sciences Education.
Evolution in Action
Scientists have traditionally studied evolution by looking in the past--analyzing fossils and comparing species. They also observe living organisms. Evolution is not a past moment; it is a process that continues today. The virus reinvents itself to avoid new drugs and bacteria evolve to resist antibiotics. Animals alter their behavior because of a changing world. The resulting changes are often easy to see.
It wasn't until late 1980s when biologists began to realize that natural selection was in action. The key is that different characteristics result in different rates of survival and reproduction (differential fitness) and are passed down from one generation to the next.
In the past, if an allele - the genetic sequence that determines colour - was present in a population of organisms that interbred, it could be more common than any other allele. In time, this could mean that the number of moths that have black pigmentation 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 fast generation turnover such as bacteria. Since 1988, biologist Richard Lenski has been tracking twelve populations of E. bacteria that descend from a single strain. samples of each population are taken every day, and over 500.000 generations have passed.
Lenski's work has shown that mutations can alter the rate at which change occurs and the effectiveness of a population's reproduction. 에볼루션 카지노 사이트 shows that evolution takes time--a fact that some are unable to accept.
Another example of microevolution is that mosquito genes that confer resistance to pesticides show up more often in areas where insecticides are used. That's because the use of pesticides creates a pressure that favors those with resistant genotypes.
The rapid pace at which evolution takes place has led to a growing appreciation of its importance in a world shaped by human activities, including climate change, pollution and the loss of habitats which prevent many species from adapting. Understanding the evolution process can help us make smarter decisions regarding the future of our planet, as well as the lives of its inhabitants.