The Academy's Evolution Site
Biological evolution is one of the most important concepts in biology. The Academies have long been involved in helping those interested in science comprehend the theory of evolution and how it influences every area of scientific inquiry.
This site provides a range of sources for teachers, students and general readers of evolution. It has the most 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 cultures and spiritual beliefs as an emblem of unity and love. It has numerous practical applications in addition to providing a framework for understanding the history of species, and how they respond 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, which depend on the collection of various parts of organisms or fragments of DNA have significantly increased the diversity of a Tree of Life2. However, these trees are largely composed of eukaryotes; bacterial diversity is still largely unrepresented3,4.
Genetic techniques have greatly broadened our ability to represent the Tree of Life by circumventing the need for direct observation and experimentation. In particular, molecular methods allow us to build trees using sequenced markers such as the small subunit ribosomal gene.
Despite the dramatic growth of the Tree of Life through genome sequencing, a large amount of biodiversity remains to be discovered. This is especially true for microorganisms that are difficult to cultivate and which are usually only found in one sample5. Recent analysis of all genomes produced a rough draft of the Tree of Life. This includes a wide range of archaea, bacteria and other organisms that haven't yet been identified or whose diversity has not been fully understood6.
This expanded Tree of Life is particularly useful for assessing the biodiversity of an area, helping to determine if specific habitats require protection. This information can be utilized in a variety of ways, from identifying new remedies to fight diseases to enhancing the quality of crops. It is also useful for conservation efforts. It helps biologists discover areas that are likely to be home to species that are cryptic, which could have vital metabolic functions, and could be susceptible to changes caused by humans. Although funding to protect biodiversity are essential but the most effective way to preserve the world's biodiversity is for more people in developing countries to be empowered with the knowledge to take action locally to encourage conservation from within.
Phylogeny
A phylogeny (also called an evolutionary tree) illustrates the relationship between different organisms. Scientists can create a phylogenetic chart that shows the evolutionary relationships between taxonomic categories using molecular information and morphological differences or similarities. Phylogeny plays a crucial role in understanding genetics, biodiversity and evolution.
A basic phylogenetic Tree (see Figure PageIndex 10 Finds the connections between organisms that have similar traits and evolved from an ancestor that shared traits. These shared traits could be analogous or homologous. Homologous traits are the same in terms of their evolutionary journey. Analogous traits could appear like they are but they don't have the same origins. Scientists group similar traits into a grouping known as a Clade. For example, all of the organisms that make up a clade share the trait of having amniotic egg and evolved from a common ancestor which had eggs. The clades then join to form a phylogenetic branch to identify organisms that have the closest relationship to.
For a more precise and accurate phylogenetic tree, scientists use molecular data from DNA or RNA to identify the relationships between organisms. This information is more precise and provides evidence of the evolutionary history of an organism. Researchers can utilize Molecular Data to determine the age of evolution of living organisms and discover how many species have the same ancestor.
The phylogenetic relationships between organisms can be influenced by several factors, including phenotypic flexibility, a kind of behavior that alters in response to specific environmental conditions. This can cause a characteristic to appear more resembling to one species than another, obscuring the phylogenetic signals. This problem can be addressed by using cladistics, which incorporates the combination of analogous and homologous features in the tree.
Additionally, phylogenetics can aid in predicting the length and speed of speciation. This information can assist conservation biologists make decisions about which species they should protect from extinction. It is ultimately the preservation of phylogenetic diversity which will lead to an ecosystem that is complete and balanced.
에볼루션 슬롯게임 Evolution behind evolution is that organisms alter over time because of their interactions with their environment. A variety of theories about evolution have been developed by a wide range of scientists, including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who believed that an organism would evolve slowly in accordance with its requirements, the Swedish botanist Carolus Linnaeus (1707-1778) who conceived modern hierarchical taxonomy, and Jean-Baptiste Lamarck (1744-1829) who suggested that the use or non-use of traits can cause changes that could be passed on to offspring.
In the 1930s and 1940s, theories from a variety of fields--including natural selection, genetics, and particulate inheritance -- came together to form the modern evolutionary theory synthesis, which defines how evolution happens through the variations of genes within a population and how these variants change in time as a result of natural selection. This model, which incorporates mutations, genetic drift in gene flow, and sexual selection can be mathematically described.
Recent advances in evolutionary developmental biology have demonstrated how variation can be introduced to a species via genetic drift, mutations and reshuffling of genes during sexual reproduction, and even migration between populations. These processes, as well as other ones like 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 as well as changes in phenotype (the expression of genotypes within individuals).
Incorporating evolutionary thinking into all aspects of biology education can increase students' understanding of phylogeny and evolutionary. In a recent study by Grunspan and colleagues., it was shown that teaching students about the evidence for evolution boosted their understanding of evolution during the course of a college biology. For more information on how to teach 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 by looking in the past, analyzing fossils and comparing species. They also observe living organisms. Evolution is not a distant event; it is a process that continues today. Viruses evolve to stay away from new drugs and bacteria evolve to resist antibiotics. Animals alter their behavior as a result of the changing environment. The changes that result are often evident.
It wasn't until late 1980s that biologists began to realize that natural selection was also in action. The reason is that different traits have different rates of survival and reproduction (differential fitness) and are transferred from one generation to the next.
In the past, when one particular allele--the genetic sequence that controls coloration - was present in a population of interbreeding species, it could rapidly become more common than other alleles. In time, this could mean the number of black moths in a population could increase. 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 an organism, like bacteria, has a rapid generation turnover. Since 1988 biologist Richard Lenski has been tracking twelve populations of E. Coli that descended from a single strain; samples of each are taken on a regular basis and over 500.000 generations have passed.
Lenski's research has demonstrated that mutations can alter the rate at which change occurs and the rate of a population's reproduction. It also proves that evolution takes time, a fact that some people are unable to accept.
Microevolution can be observed in the fact that mosquito genes for resistance to pesticides are more prevalent in areas that have used insecticides. That's because the use of pesticides creates a pressure that favors individuals who have resistant genotypes.
The speed at which evolution can take place has led to an increasing awareness of its significance in a world shaped by human activity--including climate changes, pollution and the loss of habitats that prevent many species from adjusting. Understanding evolution can aid you in making better decisions regarding the future of the planet and its inhabitants.