The Academy's Evolution Site
Biological evolution is a central concept in biology. The Academies have been for a long time involved in helping people who are interested in science understand the theory of evolution and how it influences all areas of scientific exploration.
This site provides a wide range of sources for teachers, students, and general readers on evolution. It also includes important video clips from NOVA and WGBH produced science programs on DVD.
에볼루션 바카라 사이트 of Life
The Tree of Life, an ancient symbol, symbolizes the interconnectedness of all life. It is seen in a variety of religions and cultures as symbolizing unity and love. It has numerous practical applications in addition to providing a framework for understanding the evolution of species and how they react to changes in environmental conditions.
The first attempts to depict the world of biology were based on categorizing organisms based on their physical and metabolic characteristics. These methods, based on sampling of different parts of living organisms or sequences of small DNA fragments, significantly expanded the diversity that could be included in a tree of life2. These trees are largely composed by eukaryotes, and bacterial diversity is vastly underrepresented3,4.
Genetic techniques have significantly expanded our ability to represent the Tree of Life by circumventing the need for direct observation and experimentation. Particularly, molecular techniques allow us to build trees using sequenced markers such as the small subunit ribosomal RNA gene.
Despite the massive expansion of the Tree of Life through genome sequencing, much biodiversity still remains to be discovered. This is especially true of microorganisms, which can be difficult to cultivate and are often only present in a single sample5. A recent study of all known genomes has created a rough draft of the Tree of Life, including a large number of bacteria and archaea that are not isolated and which are not well understood.
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 a variety of ways, including identifying new drugs, combating diseases and improving the quality of crops. This information is also extremely valuable to conservation efforts. It can aid biologists in identifying those areas that are most likely contain cryptic species with significant metabolic functions that could be at risk from anthropogenic change. Although funds to safeguard biodiversity are vital but the most effective way to protect 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) illustrates the relationship between different organisms. By using molecular information as well as morphological similarities and distinctions, or ontogeny (the course of development of an organism), scientists can build a phylogenetic tree that illustrates the evolutionary relationships between taxonomic categories. The phylogeny of a tree plays an important role in understanding genetics, biodiversity and evolution.
A basic phylogenetic tree (see Figure PageIndex 10 Identifies the relationships between organisms that have similar traits and have evolved from an ancestor with common traits. These shared traits can be analogous, or homologous. Homologous traits share their underlying evolutionary path while analogous traits appear like they do, but don't have the same ancestors. Scientists organize similar traits into a grouping referred to as a clade. Every organism in a group have a common characteristic, like amniotic egg production. They all derived from an ancestor that had these eggs. A phylogenetic tree can be built by connecting the clades to identify the species that are most closely related to one another.
Scientists utilize molecular DNA or RNA data to build a phylogenetic chart that is more precise and detailed. This information is more precise than morphological information and gives evidence of the evolutionary history of an organism or group. Researchers can use Molecular Data to calculate the age of evolution of organisms and determine how many species share a common ancestor.
Phylogenetic relationships can be affected by a variety of factors such as phenotypicplasticity. This is a type behavior that alters due to specific environmental conditions. This can cause a characteristic to appear more similar to one species than to another, obscuring the phylogenetic signals. This problem can be mitigated by using cladistics. This is a method that incorporates an amalgamation of homologous and analogous traits in the tree.
Additionally, phylogenetics aids predict the duration and rate of speciation. This information can assist conservation biologists in deciding which species to safeguard from the threat of extinction. In the end, it's the preservation of phylogenetic diversity that will create a complete and balanced ecosystem.
Evolutionary Theory
The central theme in evolution is that organisms change over time as a result of their interactions with their environment. Many scientists have proposed theories of evolution, including the Islamic naturalist Nasir al-Din al-Tusi (1201-274), who believed that an organism would evolve according to its individual requirements, the Swedish taxonomist Carolus Linnaeus (1707-1778), who created the modern taxonomy system that is hierarchical, as well as Jean-Baptiste Lamarck (1844-1829), who believed that the use or non-use of traits can lead to changes that can be passed on to future generations.
In the 1930s and 1940s, ideas from various fields, including genetics, natural selection and particulate inheritance--came together to form the modern evolutionary theory synthesis, which defines how evolution is triggered by the variation of genes within a population, and how those variations change over time due to natural selection. This model, known as genetic drift or mutation, gene flow, and sexual selection, is a key element of current evolutionary biology, and can be mathematically explained.
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 of genes in sexual reproduction, and also by migration between populations. These processes, in conjunction with other ones like directional selection and gene erosion (changes in frequency of genotypes over time) can lead to evolution. Evolution is defined by changes in the genome over time and changes in phenotype (the expression of genotypes in individuals).
Incorporating evolutionary thinking into all aspects of biology education could increase student understanding of the concepts of phylogeny and evolution. In a recent study conducted by Grunspan and co. It was found that teaching students about the evidence for evolution increased their understanding of evolution in the course of a college biology. To learn more about how to teach about evolution, look up The Evolutionary Potential in 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--analyzing fossils, comparing species, and studying living organisms. Evolution is not a past event; it is an ongoing process that continues to be observed today. 에볼루션 and resist antibiotics, viruses evolve and escape new drugs, and animals adapt their behavior in response to a changing planet. The results are usually evident.
It wasn't until 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 can be passed down from one generation to the next.
In 에볼루션 바카라 무료체험 , if an allele - the genetic sequence that determines colour - was present in a population of organisms that interbred, it could become more common than other allele. Over time, this would mean that the number of moths that have black pigmentation could increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.
It is easier to observe evolutionary change when a species, such as bacteria, has a rapid generation turnover. Since 1988 the biologist Richard Lenski has been tracking twelve populations of E. coli that descended from a single strain. samples from each population are taken every day, and over 500.000 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--a fact that some people are unable to accept.
Another example of microevolution is that mosquito genes that are resistant to pesticides show up more often in areas where insecticides are employed. That's because the use of pesticides causes a selective pressure that favors those who have resistant genotypes.
The speed at which evolution takes place has led to a growing awareness of its significance in a world shaped by human activity--including climate change, pollution and the loss of habitats that prevent the species from adapting. Understanding evolution will aid you in making better decisions regarding the future of the planet and its inhabitants.