The Academy's Evolution Site
Biology is one of the most central concepts in biology. The Academies have long been involved in helping those interested in science understand the concept of evolution and how it affects every area of scientific inquiry.
This site provides teachers, students and general readers with a wide range of learning resources about evolution. It also includes important video clips from NOVA and WGBH produced science programs on DVD.
Tree of Life
The Tree of Life, an ancient symbol, represents the interconnectedness of all life. It appears in many religions and cultures as symbolizing unity and love. It can be used in many practical ways in addition to providing a framework for understanding the history of species and how they respond to changing environmental conditions.
Early attempts to represent the biological world were based on categorizing organisms based on their metabolic and physical characteristics. These methods, which rely on the sampling of different parts of organisms or DNA fragments have significantly increased the diversity of a Tree of Life2. However the trees are mostly made up of eukaryotes. Bacterial diversity is not represented in a large way3,4.
Genetic techniques have greatly expanded our ability to visualize the Tree of Life by circumventing the requirement for direct observation and experimentation. Trees can be constructed by using molecular methods, such as the small-subunit ribosomal gene.
Despite the massive expansion of the Tree of Life through genome sequencing, a large amount of biodiversity remains to be discovered. This is especially true of microorganisms that are difficult to cultivate and are usually only found in a single sample5. Recent analysis of all genomes resulted in an unfinished draft of a Tree of Life. This includes a large number of bacteria, archaea and other organisms that have not yet been isolated, or the diversity of which is not fully understood6.
This expanded Tree of Life can be used to determine the diversity of a specific area and determine if certain habitats need special protection. This information can be used in a variety of ways, including finding new drugs, battling diseases and improving the quality of crops. This information is also extremely useful for conservation efforts. It can aid biologists in identifying areas most likely to have cryptic species, which may have important metabolic functions and be vulnerable to the effects of human activity. Although funding to safeguard biodiversity are vital however, the most effective method to preserve the world's biodiversity is for more people in developing countries to be empowered with the necessary knowledge to act locally to promote conservation from within.
Phylogeny
A phylogeny, also called an evolutionary tree, reveals the connections between various groups of organisms. By using molecular information as well as morphological similarities and distinctions, or ontogeny (the process of the development of an organism) scientists can construct a phylogenetic tree that illustrates the evolution of taxonomic categories. Phylogeny plays a crucial role in understanding genetics, biodiversity and evolution.
A basic phylogenetic Tree (see Figure PageIndex 10 ) identifies the relationships between organisms with similar traits that evolved from common ancestral. These shared traits could be analogous, or homologous. Homologous traits are similar in terms of their evolutionary journey. Analogous traits might appear similar but they don't share the same origins. Scientists organize similar traits into a grouping known as a clade. 에볼루션 바카라 사이트 of a clade have a common trait, such as amniotic egg production. They all came from an ancestor with these eggs. The clades are then linked to form a phylogenetic branch that can determine the organisms with the closest relationship.
To create a more thorough and accurate phylogenetic tree scientists use molecular data from DNA or RNA to identify the relationships among organisms. This information is more precise and provides evidence of the evolution of an organism. The use of molecular data lets researchers identify the number of species that have the same ancestor and estimate their evolutionary age.
The phylogenetic relationships of organisms can be affected by a variety of factors including phenotypic plasticity, a kind 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. This problem can be mitigated by using cladistics. This is a method that incorporates the combination of homologous and analogous features in the tree.
Additionally, phylogenetics can help determine the duration and speed at which speciation occurs. This information can aid conservation biologists to make decisions about which species they should protect from extinction. Ultimately, it is the preservation of phylogenetic diversity which will lead to a complete and balanced ecosystem.
Evolutionary Theory
The central theme of evolution is that organisms acquire various characteristics over time due to their interactions with their surroundings. Many scientists have proposed theories of evolution, including the Islamic naturalist Nasir al-Din al-Tusi (1201-274), who believed that an organism would develop according to its own requirements as well as the Swedish taxonomist Carolus Linnaeus (1707-1778) who conceived the modern taxonomy system that is hierarchical and Jean-Baptiste Lamarck (1844-1829), who suggested that the use or absence of traits can lead to changes that can be passed on to future generations.
In the 1930s and 1940s, concepts from various areas, including natural selection, genetics & particulate inheritance, came together to form a modern theorizing of evolution. This describes how evolution occurs by the variation in genes within the population and how these variations change with time due to natural selection. This model, which encompasses mutations, genetic drift in gene flow, and sexual selection can be mathematically described.
Recent advances in the field of evolutionary developmental biology have revealed how variation can be introduced to a species via genetic drift, mutations or reshuffling of genes in sexual reproduction and the movement between populations. These processes, along with other ones like directional selection and gene erosion (changes to the frequency of genotypes over time) can result in evolution. Evolution is defined as changes in the genome over time, as well as changes in phenotype (the expression of genotypes in individuals).
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 conducted by Grunspan and colleagues, for example, showed that teaching about the evidence that supports evolution helped students accept the concept of evolution in a college biology course. To learn more about how to teach about evolution, please look up The Evolutionary Potential of All Areas of Biology and Thinking Evolutionarily: A Framework for Infusing Evolution in Life Sciences Education.
Evolution in Action
Traditionally, scientists have studied evolution by looking back, studying fossils, comparing species, and observing living organisms. But 에볼루션 바카라 무료 isn't just something that happened in the past; it's an ongoing process that is taking place in the present. The virus reinvents itself to avoid new drugs and bacteria evolve to resist antibiotics. Animals alter their behavior as a result of the changing environment. The results are usually visible.
It wasn't until the late 1980s that biologists began realize that natural selection was also in play. The key is the fact that different traits confer an individual rate of survival as well as reproduction, and may be passed on from generation to generation.
In the past, if one allele - the genetic sequence that determines color - appeared in a population of organisms that interbred, it could become more common than any other allele. Over time, this would mean that the number of moths with black pigmentation could increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.
Monitoring evolutionary changes in action is easier when a particular species has a rapid turnover of its generation such as bacteria. Since 1988, Richard Lenski, a biologist, has tracked twelve populations of E.coli that are descended from one strain. The samples of each population were taken frequently and more than 500.000 generations of E.coli have been observed to have passed.
Lenski's work has shown that mutations can alter the rate at which change occurs and the rate of a population's reproduction. It also proves that evolution is slow-moving, a fact that some are unable to accept.
Microevolution can be observed in the fact that mosquito genes that confer resistance to pesticides are more common in populations where insecticides are used. Pesticides create an exclusive pressure that favors those who have resistant genotypes.
The rapidity of evolution has led to a greater awareness of its significance particularly in a world that is largely shaped by human activity. 에볼루션 바카라 무료 includes pollution, climate change, and habitat loss that hinders many species from adapting. Understanding evolution will aid you in making better decisions regarding the future of the planet and its inhabitants.