The Academy's Evolution Site
Biological evolution is one of the most important concepts in biology. The Academies have long been involved in helping people who are interested in science comprehend the theory of evolution and how it affects all areas of scientific research.
에볼루션코리아 provides a wide range of resources for students, teachers as well as general readers about evolution. It includes important video clips from NOVA and WGBH-produced science programs on DVD.
Tree of Life
The Tree of Life is an ancient symbol of the interconnectedness of life. It is seen in a variety of spiritual traditions and cultures as a symbol of unity and love. It can be used in many practical ways as well, including providing a framework for understanding the history of species, and how they respond to changes in environmental conditions.
Early attempts to describe the biological world were built on categorizing organisms based on their physical and metabolic characteristics. These methods, which rely on sampling of different parts of living organisms, or sequences of small fragments of their DNA significantly expanded the diversity that could be included in the tree of life2. These trees are largely composed of eukaryotes, while bacterial diversity is vastly underrepresented3,4.
By avoiding the need for direct observation and experimentation genetic techniques have allowed us to represent the Tree of Life in a more precise way. Particularly, molecular techniques enable us to create trees using sequenced markers like the small subunit of ribosomal RNA gene.
Despite the massive expansion of the Tree of Life through genome sequencing, a lot of biodiversity awaits discovery. This is especially true of microorganisms, which are difficult to cultivate and are typically only found in a single sample5. Recent analysis of all genomes resulted in a rough draft of a Tree of Life. This includes a large number of bacteria, archaea and other organisms that have not 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 if certain habitats require special protection. The information can be used in a range of ways, from identifying new medicines to combating disease to improving the quality of crops. This information is also extremely beneficial to conservation efforts. It can aid biologists in identifying areas that are most likely to be home to species that are cryptic, which could have vital metabolic functions and be vulnerable to changes caused by humans. While funds to safeguard biodiversity are vital however, the most effective method to preserve the world's biodiversity is for more people living in developing countries to be empowered with the necessary knowledge to act locally to promote conservation from within.
Phylogeny
A phylogeny, also known as an evolutionary tree, illustrates the relationships between different groups of organisms. Scientists can create a phylogenetic chart that 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 with similar traits that evolved from common ancestral. These shared traits are either analogous or homologous. Homologous characteristics are identical in their evolutionary path. Analogous traits might appear similar, but they do not have the same ancestry. Scientists group similar traits into a grouping referred to as a the clade. For example, all of the species in a clade share the characteristic of having amniotic eggs. They evolved from a common ancestor which had eggs. A phylogenetic tree is then built by connecting the clades to identify the species that are most closely related to each other.
For a more detailed and precise phylogenetic tree scientists rely on molecular information from DNA or RNA to identify the connections between organisms. This information is more precise than the morphological data and provides evidence of the evolution background of an organism or group. The use of molecular data lets researchers identify the number of organisms that share a common ancestor and to estimate their evolutionary age.
Phylogenetic relationships can be affected by a variety of factors that include the phenomenon of phenotypicplasticity. This is a type behavior that alters in response to unique environmental conditions. This can cause a characteristic to appear more similar to one species than another, clouding the phylogenetic signal. This issue can be cured by using cladistics, which is a the combination of homologous and analogous features in the tree.
Additionally, phylogenetics can help determine the duration and rate of speciation. This information can assist conservation biologists in making decisions about which species to save from extinction. It is ultimately the preservation of phylogenetic diversity which will result in a complete and balanced ecosystem.
Evolutionary Theory
The main idea behind evolution is that organisms alter over time because of their interactions with their environment. A variety of theories about evolution have been proposed by a wide range of scientists such as the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who believed that an organism would evolve gradually according to its needs and needs, 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 & 1940s, ideas from different fields, such as natural selection, genetics & particulate inheritance, merged to create a modern theorizing of evolution. 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, known as genetic drift or mutation, gene flow and sexual selection, is a cornerstone of modern evolutionary biology and is mathematically described.
Recent discoveries in the field of evolutionary developmental biology have demonstrated the ways in which variation can be introduced to a species by genetic drift, mutations or reshuffling of genes in sexual reproduction and migration between populations. These processes, as well as other ones like the directional selection process and the erosion of genes (changes in the frequency of genotypes over time) can result in evolution. Evolution is defined by changes in the genome over time, as well as changes in the phenotype (the expression of genotypes within individuals).
Incorporating evolutionary thinking into all aspects of biology education can improve students' understanding of phylogeny and evolution. In a study by Grunspan and co. It was found 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, see The Evolutionary Potential in all Areas of Biology and Thinking Evolutionarily: A Framework for Infusing the Concept of Evolution into Life Sciences Education.
Evolution in Action
Traditionally scientists have studied evolution by looking back--analyzing fossils, comparing species and observing living organisms. Evolution isn't a flims moment; it is an ongoing process that continues to be observed today. Bacteria mutate and resist antibiotics, viruses reinvent themselves and escape new drugs and animals alter their behavior in response to the changing climate. The results are often visible.
It wasn't until late 1980s that biologists understood that natural selection can be observed in action as well. The key is the fact that different traits result in a different rate of survival as well as reproduction, and may be passed down from generation to generation.
In the past, if a certain allele - the genetic sequence that determines color - appeared in a population of organisms that interbred, it could be more prevalent than any other allele. As time passes, that could mean the number of black moths within a particular population could rise. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.
It is easier to see evolutionary change when a species, such as 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 of each population are taken every day, and over fifty thousand generations have passed.
Lenski's research has revealed that mutations can alter the rate of change and the efficiency at which a population reproduces. It also shows that evolution takes time, which is difficult for some to accept.
Microevolution is also evident in the fact that mosquito genes for resistance to pesticides are more prevalent in areas that have used insecticides. This is because the use of pesticides creates a pressure that favors people with resistant genotypes.
The rapidity of evolution has led to an increasing recognition of its importance particularly in a world which is largely shaped by human activities. This includes climate change, pollution, and habitat loss that prevents many species from adapting. Understanding evolution can help us make better choices about the future of our planet and the life of its inhabitants.