The Academy's Evolution Site
Biology is a key concept 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 permeates all areas of scientific exploration.
This site provides teachers, students and general readers with a variety 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 is used in many cultures and spiritual beliefs as a symbol of unity and love. It also has many practical uses, like providing a framework to understand the history of species and how they respond to changes in the environment.
The first attempts at depicting the biological world focused on categorizing species into distinct categories that were distinguished by their physical and metabolic characteristics1. These methods, which rely on the sampling of different parts of living organisms or sequences of small fragments of their DNA, significantly expanded the diversity that could be included in a tree of life2. These trees are mostly populated by eukaryotes, and bacterial diversity is vastly underrepresented3,4.
By avoiding the need for direct experimentation and observation, genetic techniques have enabled us to represent the Tree of Life in a more precise way. We can construct trees using molecular techniques, such as the small-subunit ribosomal gene.
Despite the dramatic growth of the Tree of Life through genome sequencing, much biodiversity still is waiting to be discovered. This is especially the case for microorganisms which are difficult to cultivate, and which are usually only found in one sample5. A recent analysis of all genomes that are known has produced a rough draft version of the Tree of Life, including a large number of bacteria and archaea that are not isolated and their diversity is not fully understood6.
This expanded Tree of Life is particularly useful for assessing the biodiversity of an area, assisting to determine whether specific habitats require protection. This information can be utilized in a variety of ways, from identifying the most effective remedies to fight diseases to improving the quality of crops. The information is also incredibly valuable for conservation efforts. It helps biologists discover areas that are likely to be home to cryptic species, which could have important metabolic functions, and could be susceptible to the effects of human activity. Although funds to protect biodiversity are crucial but the most effective 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 act locally to promote conservation from within.
Phylogeny
A phylogeny (also known as an evolutionary tree) depicts the relationships between different organisms. Using molecular data, morphological similarities and differences, or ontogeny (the course of development of an organism) scientists can create an phylogenetic tree that demonstrates the evolutionary relationships between taxonomic groups. Phylogeny plays a crucial role in understanding the relationship between genetics, biodiversity and evolution.
A basic phylogenetic Tree (see Figure PageIndex 10 ) identifies the relationships between organisms that share similar traits that have evolved from common ancestors. 에볼루션게이밍 shared traits could be analogous, or homologous. Homologous traits are similar in their evolutionary path. Analogous traits could appear similar but they don't have the same ancestry. Scientists organize similar traits into a grouping known as a the clade. For instance, all of the organisms in a clade share the trait of having amniotic egg and evolved from a common ancestor which had eggs. The clades are then linked to form a phylogenetic branch to determine which organisms have the closest connection to each other.
For a more precise and precise phylogenetic tree scientists make use of molecular data from DNA or RNA to identify the connections between organisms. This data is more precise than morphological information and provides evidence of the evolutionary history of an organism or group. Researchers can use Molecular Data to determine the evolutionary age of organisms and determine how many organisms have a common ancestor.
The phylogenetic relationship can be affected by a number of factors that include phenotypicplasticity. This is a type of behavior that alters in response to specific environmental conditions. This can cause a trait to appear more similar to one species than other species, which can obscure the phylogenetic signal. However, this issue can be solved through the use of methods like cladistics, which include a mix of similar and homologous traits into the tree.
In addition, phylogenetics helps determine the duration and speed of speciation. This information can aid conservation biologists in making decisions about which species to save from the threat of extinction. In the end, it is the preservation of phylogenetic diversity that will result in an ecosystem that is balanced and complete.
Evolutionary Theory
The central theme of evolution is that organisms acquire different features over time due to their interactions with their surroundings. Many scientists have come up with theories of evolution, such as the Islamic naturalist Nasir al-Din al-Tusi (1201-274) who believed that an organism would evolve according to its own needs and needs, the Swedish taxonomist Carolus Linnaeus (1707-1778), who created the modern hierarchical taxonomy as well as Jean-Baptiste Lamarck (1844-1829), who believed that the use or absence of traits can lead to changes that are passed on to the next generation.
In the 1930s and 1940s, theories from a variety of fields--including natural selection, genetics, and particulate inheritance--came together to form the modern synthesis of evolutionary theory that explains how evolution happens through the variations of genes within a population and how those variants change over time as a result of natural selection. This model, called genetic drift or mutation, gene flow and sexual selection, is a cornerstone of the current evolutionary biology and can be mathematically described.
Recent advances in evolutionary developmental biology have revealed the ways in which variation can be introduced to a species by genetic drift, mutations and reshuffling of genes during sexual reproduction, and even migration between populations. These processes, along with others, such as the directional selection process and the erosion of genes (changes in the frequency of genotypes over time) can result in evolution. Evolution is defined by changes in the genome over time, as well as changes in the phenotype (the expression of genotypes in an individual).
Incorporating evolutionary thinking into all aspects of biology education could increase student understanding of the concepts of phylogeny and evolutionary. In a recent study by Grunspan and colleagues. It was found that teaching students about the evidence for evolution increased their understanding of evolution in a college-level course in biology. To find out more about how to teach about evolution, please read The Evolutionary Potential in all Areas of Biology and Thinking Evolutionarily: A Framework for Infusing Evolution into Life Sciences Education.
Evolution in Action
Scientists have studied evolution through looking back in the past, studying fossils, and comparing species. They also observe living organisms. However, evolution isn't something that happened in the past, it's an ongoing process that is happening in the present. The virus reinvents itself to avoid new antibiotics and bacteria transform to resist antibiotics. Animals alter their behavior in the wake of the changing environment. The results are usually evident.
It wasn't until the late 1980s that biologists began to realize that natural selection was in play. The main reason is that different traits result in an individual rate of survival and reproduction, and they can be passed down from generation to generation.
In the past, if one allele - the genetic sequence that determines color - was present in a population of organisms that interbred, it might become more prevalent than any other allele. Over time, that would mean that the number of black moths in the 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 rapid generation turnover like 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 on a regular basis and over 50,000 generations have now been observed.
Lenski's research has shown that mutations can drastically alter the speed at the rate at which a population reproduces, and consequently, the rate at which it changes. It also demonstrates that evolution takes time, a fact that is hard for some to accept.
Microevolution can be observed in the fact that mosquito genes that confer resistance to pesticides are more prevalent in populations that have used insecticides. This is because the use of pesticides causes a selective pressure that favors people with resistant genotypes.
The rapidity of evolution has led to a greater appreciation of its importance particularly in a world shaped largely by human activity. This includes the effects of climate change, pollution and habitat loss, which prevents many species from adapting. Understanding evolution can aid you in making better decisions about the future of our planet and its inhabitants.