The Academy's Evolution Site
Biological evolution is a central 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 teachers, students and general readers with a range of learning resources on 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, represents the interconnectedness of all life. It appears in many cultures and spiritual beliefs as a symbol of unity and love. It also has important practical applications, such as providing a framework for understanding the history of species and how they respond to changes in environmental conditions.
Early attempts to describe the world of biology were founded on categorizing organisms on their physical and metabolic characteristics. These methods, which relied on the sampling of different parts of living organisms or sequences of small DNA fragments, greatly increased the variety of organisms that could be included in the tree of life2. However, these trees are largely comprised of eukaryotes, and bacterial diversity remains vastly underrepresented3,4.
Genetic techniques have significantly expanded our ability to depict the Tree of Life by circumventing the requirement for direct observation and experimentation. We can construct trees using molecular techniques, such as the small-subunit ribosomal gene.
Despite the rapid growth of the Tree of Life through genome sequencing, a lot of biodiversity is waiting to be discovered. This is particularly relevant to microorganisms that are difficult to cultivate and which are usually only present in a single sample5. A recent analysis of all genomes known to date has produced a rough draft version of the Tree of Life, including many bacteria and archaea that have not been isolated and whose diversity is poorly understood6.
This expanded Tree of Life is particularly useful for assessing the biodiversity of an area, helping to determine if specific habitats require special protection. This information can be used in a range of ways, from identifying new remedies to fight diseases to enhancing crops. The information is also beneficial in conservation efforts. It helps biologists determine those areas that are most likely contain cryptic species with potentially important metabolic functions that may be at risk of anthropogenic changes. While funds to protect biodiversity are important, the best way to conserve the world's biodiversity is to equip more people in developing countries with the necessary knowledge to take action locally and encourage conservation.
Phylogeny
A phylogeny (also called an evolutionary tree) depicts the relationships between species. By using molecular information as well as morphological similarities and distinctions or ontogeny (the process of the development of an organism), scientists can build a phylogenetic tree which illustrates the evolution of taxonomic groups. Phylogeny is crucial in understanding biodiversity, evolution and genetics.
A basic phylogenetic Tree (see Figure PageIndex 10 ) is a method of identifying the relationships between organisms that share similar traits that evolved from common ancestors. These shared traits could be homologous, or analogous. Homologous traits are similar in terms of their evolutionary path. 에볼루션 바카라 무료체험 might appear similar however they do not have the same origins. Scientists organize 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. They evolved from a common ancestor who had eggs. The clades are then connected to form a phylogenetic branch that can identify organisms that have the closest connection to each other.
To create a more thorough and accurate phylogenetic tree scientists rely on molecular information from DNA or RNA to determine the relationships between organisms. This information is more precise and gives evidence of the evolution history of an organism. Researchers can utilize Molecular Data to estimate the age of evolution of living organisms and discover how many organisms share the same ancestor.
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 in one species than another, obscuring the phylogenetic signal. However, this problem can be reduced by the use of methods like cladistics, which include a mix of analogous and homologous features into the tree.
Additionally, phylogenetics can help predict the time and pace of speciation. This information can aid conservation biologists to decide the species they should safeguard from extinction. Ultimately, it is the preservation of phylogenetic diversity that will result in a complete and balanced ecosystem.
Evolutionary Theory
The central theme in evolution is that organisms alter over time because of their interactions with their environment. Many scientists have developed theories of evolution, such as the Islamic naturalist Nasir al-Din al-Tusi (1201-274), who believed that a living thing would develop according to its own needs and needs, the Swedish taxonomist Carolus Linnaeus (1707-1778) who conceived the modern hierarchical taxonomy, as well as Jean-Baptiste Lamarck (1844-1829), who suggested that the use or non-use of traits can cause changes that are passed on to the
In the 1930s and 1940s, ideas from various fields, including genetics, natural selection and particulate inheritance - came together to form the modern evolutionary theory that explains how evolution occurs through the variations of genes within a population and how those variations change in time as a result of natural selection. This model, which encompasses genetic drift, mutations as well as gene flow and sexual selection, can be mathematically described mathematically.
Recent discoveries in the field of evolutionary developmental biology have revealed that variations can be introduced into a species via mutation, genetic drift, and reshuffling genes during sexual reproduction, as well as through the movement of populations. These processes, as well as others such as directionally-selected selection and erosion of genes (changes in frequency of genotypes over time) can result in evolution. Evolution is defined by changes in the genome over time and changes in the phenotype (the expression of genotypes within individuals).
Incorporating evolutionary thinking into all areas of biology education can increase students' understanding of phylogeny and evolution. A recent study conducted by Grunspan and colleagues, for instance revealed that teaching students about the evidence for evolution increased students' understanding of evolution in a college biology class. 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 into Life Sciences Education.
Evolution in Action
Scientists have studied evolution by looking in the past, studying fossils, and comparing species. They also study living organisms. Evolution isn't a flims event; it is an ongoing process that continues to be observed today. Viruses reinvent themselves to avoid new medications and bacteria mutate to resist antibiotics. Animals alter their behavior in the wake of a changing world. The results are usually easy to see.
But it wasn't until the late 1980s that biologists understood that natural selection can be observed in action as well. The main reason is that different traits can confer the ability to survive at different rates and reproduction, and they can be passed on from generation to generation.
In the past, if an allele - the genetic sequence that determines colour - appeared in a population of organisms that interbred, it could be more common than other allele. Over time, this would mean that the number of moths with black pigmentation in a group may 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 easier when a species has a rapid turnover of its generation such as bacteria. Since 1988 the biologist Richard Lenski has been tracking twelve populations of E. Coli that descended from a single strain; samples of each are taken regularly, and over fifty thousand generations have passed.
Lenski's work has shown that mutations can alter the rate of change and the effectiveness at which a population reproduces. It also shows that evolution is slow-moving, a fact that some people find hard to accept.
Microevolution can be observed in the fact that mosquito genes for resistance to pesticides are more prevalent in populations where insecticides are used. This is due to pesticides causing an enticement that favors individuals who have resistant genotypes.
The rapidity of evolution has led to a greater recognition of its importance particularly in a world shaped largely by human activity. This includes climate change, pollution, and habitat loss that hinders many species from adapting. Understanding the evolution process will help us make better choices about the future of our planet as well as the lives of its inhabitants.