The Academy's Evolution Site
The concept of biological evolution is among the most fundamental concepts in biology. The Academies are involved in helping those interested in science understand evolution theory and how it is permeated throughout all fields of scientific research.
This site provides students, teachers and general readers with a range of learning resources on evolution. It includes important video clips from NOVA and the 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 an emblem of unity and love. It also has many practical uses, like providing a framework for understanding the evolution of species and how they react to changes in environmental conditions.
The first attempts at depicting the world of biology focused on separating organisms into distinct categories which were distinguished by their physical and metabolic characteristics1. These methods depend on the sampling of different parts of organisms or short fragments of DNA have greatly increased the diversity of a Tree of Life2. However, these trees are largely made up of eukaryotes. Bacterial diversity is not represented in a large way3,4.
By avoiding the necessity for direct experimentation and observation genetic techniques have enabled us to depict the Tree of Life in a much more accurate way. Trees can be constructed using molecular methods, such as the small-subunit ribosomal gene.
Despite the rapid expansion of the Tree of Life through genome sequencing, a lot of biodiversity is waiting to be discovered. This is particularly true of microorganisms that are difficult to cultivate and are often only present in a single sample5. Recent analysis of all genomes resulted in an initial draft of the Tree of Life. This includes a wide range of bacteria, archaea and other organisms that have not yet been identified or their diversity is not well understood6.
The expanded Tree of Life can be used to assess the biodiversity of a specific area and determine if specific habitats require special protection. The information is useful in a variety of ways, such as identifying new drugs, combating diseases and improving crops. The information is also incredibly useful for conservation efforts. It can aid biologists in identifying areas that are likely to be home to cryptic species, which could have vital metabolic functions and be vulnerable to changes caused by humans. Although funding to safeguard biodiversity are vital, ultimately the best 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 take action locally to encourage conservation from within.
Phylogeny
A phylogeny, also called an evolutionary tree, shows the relationships between various groups of organisms. By using molecular information, morphological similarities and differences, or ontogeny (the process of the development of an organism), scientists can build an phylogenetic tree that demonstrates the evolutionary relationship between taxonomic categories. Phylogeny is crucial in understanding evolution, biodiversity and genetics.
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 share their evolutionary roots while analogous traits appear like they do, 무료
에볼루션 바카라 무료체험 (
Qa.Holoo.Co.Ir) but don't have the same origins. Scientists arrange similar traits into a grouping called a Clade. For instance, all of the organisms in a clade share the characteristic of having amniotic egg and evolved from a common ancestor which had these eggs. The clades are then connected 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 에볼루션 무료 바카라,
yogicentral.Science, RNA to determine the connections between organisms. This data is more precise than the morphological data and provides evidence of the evolution history of an individual or group. The analysis of molecular data can help researchers identify the number of species that share a common ancestor and to estimate their evolutionary age.
Phylogenetic relationships can be affected by a variety of factors such as phenotypicplasticity. This is a kind of behavior that alters in response to unique environmental conditions. This can cause a characteristic to appear more similar to a species than another and obscure the phylogenetic signals. This problem can be addressed by using cladistics, which incorporates the combination of homologous and analogous traits in the tree.
Additionally, phylogenetics can help predict the time and pace of speciation. This information will assist conservation biologists in making decisions about which species to safeguard from extinction. In the end, it is the conservation of phylogenetic variety which will create an ecosystem that is balanced and complete.
Evolutionary Theory
The main idea behind evolution is that organisms alter over time because of their interactions with their environment. A variety of theories about evolution have been proposed by a wide variety of scientists including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who proposed that a living organism develop gradually according to its requirements, the Swedish botanist Carolus Linnaeus (1707-1778) who developed modern hierarchical taxonomy, and Jean-Baptiste Lamarck (1744-1829) who suggested that use or disuse of traits cause changes that could be passed on to the offspring.
In the 1930s and 1940s, concepts from various fields, such as genetics, natural selection, and particulate inheritance, merged to form a modern theorizing of evolution. This defines how evolution happens through the variation in genes within the population and how these variations change over time as a result of natural selection. This model, known as genetic drift or
에볼루션 바카라 mutation, gene flow and sexual selection, is a key element of modern evolutionary biology and is mathematically described.
Recent discoveries in the field of evolutionary developmental biology have shown that variation can be introduced into a species through mutation, genetic drift and reshuffling of genes during sexual reproduction, and also through migration between populations. These processes, as well as others such as directional selection or genetic erosion (changes in the frequency of a genotype over time), can lead to evolution, which is defined by change in the genome of the species over time, and the change in phenotype over time (the expression of that genotype within the individual).
Incorporating evolutionary thinking into all areas of biology education can improve students' understanding of phylogeny and evolutionary. A recent study conducted by Grunspan and colleagues, for instance revealed that teaching students about the evidence supporting evolution helped students accept the concept of evolution in a college biology class. For more details on how to teach evolution read The Evolutionary Potential in All Areas of Biology or Thinking Evolutionarily A Framework for Infusing Evolution into Life Sciences Education.
Evolution in Action
Traditionally, scientists have studied evolution by looking back, studying fossils, comparing species and studying living organisms. But evolution isn't just something that happened in the past; it's an ongoing process, that is taking place in the present. Bacteria mutate and resist antibiotics, viruses re-invent themselves and escape new drugs, and animals adapt their behavior to the changing environment.