The Academy's Evolution Site
Biological evolution is one of the most important concepts in biology. The Academies have been for a long time involved in helping those interested in science comprehend the concept of evolution and how it affects all areas of scientific research.
This site provides a wide range of sources for students, teachers as well as general readers about evolution. It has the most important video clips from NOVA and the 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 a symbol of love and harmony in a variety of cultures. It has numerous practical applications as well, including providing a framework for understanding the history of species, and how they respond to changing environmental conditions.
Early attempts to describe the world of biology were based on categorizing organisms based on their physical and metabolic characteristics. 에볼루션 코리아 , which rely on sampling of different parts of living organisms or on short DNA fragments, significantly increased the variety that could be included in the tree of life2. The trees are mostly composed of eukaryotes, while bacteria are largely underrepresented3,4.
Genetic techniques have greatly expanded our ability to depict the Tree of Life by circumventing the need for direct observation and experimentation. Particularly, molecular techniques enable us to create trees using sequenced markers like the small subunit of ribosomal RNA gene.
The Tree of Life has been significantly expanded by genome sequencing. However there is still a lot of biodiversity to be discovered. This is particularly the case for microorganisms which are difficult to cultivate, and are usually present in a single sample5. 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 have not yet been identified or their diversity is not thoroughly understood6.
The expanded Tree of Life can be used to determine the diversity of a specific area and determine if particular habitats require special protection. This information can be utilized in many ways, including identifying new drugs, combating diseases and improving the quality of crops. The information is also beneficial to conservation efforts. It can help biologists identify areas that are likely to be home to cryptic species, which may have vital metabolic functions and be vulnerable to human-induced change. While funds to safeguard biodiversity are vital, ultimately the best way to ensure the preservation of biodiversity around the world is for more people living in developing countries to be equipped with the knowledge to take action locally to encourage conservation from within.
just click the following document , also called an evolutionary tree, shows the relationships between 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. Phylogeny plays a crucial role in understanding biodiversity, genetics and evolution.
A basic phylogenetic tree (see Figure PageIndex 10 ) determines the relationship between organisms with similar traits that evolved from common ancestors. These shared traits can be homologous, or analogous. Homologous characteristics are identical in terms of their evolutionary paths. Analogous traits could appear like they are but they don't have the same origins. Scientists put similar traits into a grouping referred to as a Clade. For example, all of the organisms in a clade share the characteristic of having amniotic eggs. They evolved from a common ancestor who had eggs. The clades are then connected to form a phylogenetic branch that can determine the organisms with the closest connection to each other.
To create a more thorough and precise phylogenetic tree scientists rely on molecular information from DNA or RNA to establish the relationships between organisms. This information is more precise than morphological data and provides evidence of the evolutionary background of an organism or group. Molecular data allows researchers to identify the number of species that share the same ancestor and estimate their evolutionary age.
The phylogenetic relationships of a species can be affected by a number of factors that include the phenomenon of phenotypicplasticity. This is a type behavior that alters as a result of unique environmental conditions. This can make a trait appear more similar to a species than to another and obscure the phylogenetic signals. This problem can be addressed by using cladistics, which incorporates an amalgamation of analogous and homologous features in the tree.
Additionally, phylogenetics can help determine the duration and speed at which speciation occurs. This information will assist conservation biologists in making choices about which species to protect from the threat of extinction. Ultimately, it is the preservation of phylogenetic diversity which will lead to 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. Many scientists have come up with theories of evolution, including the Islamic naturalist Nasir al-Din al-Tusi (1201-274), who believed that a living thing would evolve according to its own needs, the Swedish taxonomist Carolus Linnaeus (1707-1778), who created the modern hierarchical system of taxonomy, as well as Jean-Baptiste Lamarck (1844-1829), who believed that the usage or non-use of traits can cause changes that are passed on to the next generation.
In the 1930s and 1940s, theories from various fields, including genetics, natural selection and particulate inheritance--came together to form the current synthesis of evolutionary theory which explains how evolution occurs through the variation of genes within a population, and how these variants change over time due to natural selection. This model, which includes mutations, genetic drift, gene flow and sexual selection can be mathematically described mathematically.
Recent discoveries in the field of evolutionary developmental biology have shown that variation can be introduced into a species by genetic drift, mutation, and reshuffling of genes in sexual reproduction, and also by migration between populations. These processes, as well as others such as directional selection or genetic erosion (changes in the frequency of an individual's genotype over time), can lead to evolution that is defined as change in the genome of the species over time, and also by changes in phenotype over time (the expression of the genotype in the individual).
Incorporating evolutionary thinking into all areas of biology education can improve student understanding of the concepts of phylogeny as well as evolution. similar site by Grunspan and colleagues, for example, showed that teaching about the evidence for evolution increased students' acceptance of evolution in a college-level biology course. For more information on how to teach about evolution look up The Evolutionary Potency in all Areas of Biology or Thinking Evolutionarily A Framework for Integrating 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 study living organisms. Evolution is not a distant moment; it is an ongoing process. Bacteria evolve and resist antibiotics, viruses reinvent themselves and are able to evade new medications and animals change their behavior to the changing environment. The changes that occur are often apparent.
But it wasn't until the late-1980s that biologists realized that natural selection could be observed in action as well. The reason is that different characteristics result in different rates of survival and reproduction (differential fitness) and are passed from one generation to the next.
In the past when one particular allele - the genetic sequence that defines color in a population of interbreeding organisms, it might quickly become more common than the other alleles. As time passes, this could mean that the number of moths sporting black pigmentation in a population could increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.
Observing evolutionary change in action is easier when a species has a fast generation turnover, as with 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 more than 50,000 generations have now been observed.
Lenski's research has revealed that mutations can drastically alter the efficiency with which a population reproduces--and so, the rate at which it evolves. It also shows that evolution takes time, something that is difficult for some to accept.
Microevolution can be observed in the fact that mosquito genes for pesticide resistance are more common in populations where insecticides have been used. That's because the use of pesticides causes a selective pressure that favors individuals with resistant genotypes.
The speed at which evolution can take place has led to an increasing awareness of its significance in a world that is shaped by human activity, 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 and the life of its inhabitants.