The Academy's Evolution Site
The concept of biological evolution is among the most central concepts in biology. The Academies are involved in helping those interested in science comprehend the evolution theory and how it can be applied throughout all fields of scientific research.
This site provides students, teachers and general readers with a range of learning resources about evolution. It contains key video clips from NOVA and WGBH's science programs on DVD.
Tree of Life
The Tree of Life, an ancient symbol, represents the interconnectedness of all life. It is a symbol of love and harmony in a variety of cultures. It has many practical applications in addition to providing a framework for understanding the history of species, and how they respond to changing environmental conditions.
The earliest attempts to depict the biological world focused on the classification of species into distinct categories that had been identified by their physical and metabolic characteristics1. These methods, which rely on sampling of different parts of living organisms or on short fragments of their DNA, greatly increased the variety of organisms that could be represented in the tree of life2. The trees are mostly composed by eukaryotes, and bacteria are largely underrepresented3,4.
Genetic techniques have greatly expanded our ability to represent the Tree of Life by circumventing the requirement for direct observation and experimentation. Particularly, 에볼루션 무료체험 allow us to construct trees by using sequenced markers like the small subunit ribosomal gene.
Despite the massive growth of the Tree of Life through genome sequencing, a lot of biodiversity is waiting to be discovered. This is especially true of microorganisms that are difficult to cultivate and are usually only present in a single sample5. A recent analysis of all genomes that are known has produced a rough draft of the Tree of Life, including many bacteria and archaea that have not been isolated, and their diversity is not fully understood6.
This expanded Tree of Life can be used to determine the diversity of a specific region and determine if particular habitats require special protection. This information can be used in a variety of ways, from identifying new medicines to combating disease to enhancing the quality of crops. It is also valuable in conservation efforts. It helps biologists discover areas most likely to have cryptic species, which could have important metabolic functions, and could be susceptible to the effects of human activity. While conservation funds are important, the best method to protect the world's biodiversity is to equip more people in developing nations with the necessary knowledge to act locally and promote conservation.
Phylogeny
A phylogeny (also called an evolutionary tree) depicts the relationships between different organisms. 에볼루션 코리아 can create an phylogenetic chart which shows the evolution of taxonomic groups based on molecular data and morphological similarities or differences. The concept of phylogeny is fundamental to understanding the evolution of biodiversity, evolution and genetics.
A basic phylogenetic tree (see Figure PageIndex 10 ) determines the relationship between organisms that share similar traits that evolved from common ancestral. These shared traits can be either analogous or homologous. Homologous traits are similar in their evolutionary path. Analogous traits may look similar, but they do not share the same origins. Scientists combine similar traits into a grouping known as a the clade. All members of a clade have a common characteristic, like amniotic egg production. They all derived from an ancestor who had these eggs. The clades are then linked to create a phylogenetic tree to identify organisms that have the closest relationship.
For a more detailed and accurate phylogenetic tree scientists make use of molecular data from DNA or RNA to identify the relationships between organisms. This data is more precise than morphological information and provides evidence of the evolution history of an individual or group. Researchers can utilize Molecular Data to calculate the evolutionary age of organisms and determine the number of organisms that share the same ancestor.
The phylogenetic relationship can be affected by a number of factors that include phenotypicplasticity. This is a kind of behavior that changes in response to specific environmental conditions. This can make a trait appear more resembling to one species than to another which can obscure the phylogenetic signal. This problem can be mitigated by using cladistics, which is a the combination of homologous and analogous traits in the tree.
In addition, phylogenetics can aid in predicting the duration and rate of speciation. This information can assist conservation biologists make decisions about the species they should safeguard from the threat of extinction. In the end, it's the preservation of phylogenetic diversity that will create an ecosystem that is complete and balanced.
Evolutionary Theory
The main idea behind evolution is that organisms alter over time because of their interactions with their environment. Several theories of evolutionary change have been developed by a wide range of scientists, including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who believed that an organism would evolve slowly in accordance with its needs, the Swedish botanist Carolus Linnaeus (1707-1778) who conceived modern hierarchical taxonomy, and Jean-Baptiste Lamarck (1744-1829) who suggested that use or disuse of traits can cause changes that can be passed onto offspring.
In the 1930s and 1940s, theories from various fields, such as natural selection, genetics & particulate inheritance, came together to form a contemporary evolutionary theory. This describes how evolution happens through the variation of genes in the population, and how these variations alter over time due to natural selection. This model, which includes mutations, genetic drift, gene flow and sexual selection is mathematically described.
Recent discoveries in the field of evolutionary developmental biology have demonstrated that genetic variation can be introduced into a species through mutation, genetic drift and reshuffling genes during sexual reproduction, as well as through migration between populations. These processes, along with others like directional selection and genetic erosion (changes in the frequency of the genotype over time) can lead to evolution, which is defined by change in the genome of the species over time, and also the change in phenotype as time passes (the expression of that genotype in an individual).
Incorporating evolutionary thinking into all areas of biology education could increase student understanding of the concepts of phylogeny as well as evolution. A recent study by Grunspan and colleagues, for example revealed that teaching students about the evidence for evolution increased students' acceptance of evolution in a college biology course. To find out more about how to teach about evolution, look up The Evolutionary Potential of All Areas of Biology and Thinking Evolutionarily: A Framework for Infusing the Concept of Evolution into Life Sciences Education.
Evolution in Action
Scientists have studied evolution through looking back in the past--analyzing fossils and comparing species. They also observe living organisms. Evolution isn't a flims event, but an ongoing process. Viruses reinvent themselves to avoid new drugs and bacteria evolve to resist antibiotics. Animals alter their behavior as a result of a changing world. The resulting changes are often evident.
It wasn't until the 1980s that biologists began realize that natural selection was at work. The key is the fact that different traits can confer a different rate of survival as well as reproduction, and may be passed down from one generation to the next.
In the past, if one allele - the genetic sequence that determines colour - was present in a population of organisms that interbred, it might become more common than any other allele. In time, this could mean that the number of black moths in a particular population could rise. 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 easier when a particular species has a rapid turnover of its generation like bacteria. 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 on a regular basis and over fifty thousand generations have passed.
Lenski's research has revealed that a mutation can dramatically alter the speed at the rate at which a population reproduces, and consequently the rate at which it alters. It also demonstrates that evolution takes time, something that is difficult for some to accept.
Microevolution is also evident in the fact that mosquito genes for pesticide resistance are more prevalent in populations where insecticides are used. This is due to the fact that the use of pesticides causes a selective pressure that favors those with resistant genotypes.
The rapidity of evolution has led to an increasing appreciation of its importance particularly in a world shaped largely by human activity. This includes pollution, climate change, and habitat loss, which prevents many species from adapting. Understanding the evolution process can help us make smarter choices about the future of our planet, and the life of its inhabitants.