The Academy's Evolution Site
The concept of biological evolution is among the most central concepts in biology. The Academies are committed to helping those interested in the sciences learn about the theory of evolution and how it is permeated in all areas of scientific research.
This site provides a wide range of tools for students, teachers, and general readers on evolution. It has the most important video clips from NOVA and WGBH-produced science programs on DVD.
Tree of Life
The Tree of Life is an ancient symbol of the interconnectedness of all life. It is an emblem of love and unity across many cultures. It also has many practical applications, like providing a framework for understanding the history of species and how they react to changes in the environment.
Early approaches to depicting the biological world focused on separating species into distinct categories that were distinguished by physical and metabolic characteristics1. These methods, based on the sampling of various parts of living organisms or on short fragments of their DNA significantly increased the variety that could be represented in a tree of life2. However, these trees are largely made up of eukaryotes. Bacterial diversity is not represented in a large way3,4.
In avoiding the necessity of direct experimentation and observation genetic techniques have allowed us to depict the Tree of Life in a more precise manner. Particularly, molecular methods allow us to build trees by using sequenced markers like the small subunit ribosomal gene.
The Tree of Life has been significantly expanded by genome sequencing. However there is a lot of diversity to be discovered. This is especially true of microorganisms that are difficult to cultivate and are usually only found in a single sample5. A recent study of all known genomes has created a rough draft of the Tree of Life, including many archaea and bacteria that have not been isolated, and their diversity is not fully understood6.
This expanded Tree of Life can be used to evaluate the biodiversity of a particular area and determine if certain habitats need special protection. This information can be used in a variety of ways, from identifying the most effective treatments to fight disease to improving crops. This information is also valuable for conservation efforts. It can aid biologists in identifying the areas most likely to contain cryptic species that could have important metabolic functions that could be at risk from anthropogenic change. 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 knowledge they need to take action locally and encourage conservation.
Phylogeny
A phylogeny, also known as an evolutionary tree, reveals the connections between groups of organisms. Using molecular data similarities and differences in morphology, or ontogeny (the process of the development of an organism) scientists can construct an phylogenetic tree that demonstrates the evolution of taxonomic groups. Phylogeny plays a crucial role in understanding the relationship between genetics, biodiversity and evolution.
A basic phylogenetic tree (see Figure PageIndex 10 ) determines the relationship between organisms that share similar traits that have evolved from common ancestors. These shared traits are either homologous or analogous. Homologous traits share their evolutionary origins, while analogous traits look similar, but do not share the same origins. Scientists group similar traits into a grouping known as a the clade. Every organism in a group share a trait, such as amniotic egg production. They all evolved from an ancestor with these eggs. A phylogenetic tree is constructed by connecting the clades to identify the species which are the closest to one another.
To create a more thorough and accurate phylogenetic tree, scientists make use of molecular data from DNA or RNA to establish the connections between organisms. This information is more precise and gives evidence of the evolution history of an organism. Researchers can utilize Molecular Data to calculate the evolutionary age of organisms and determine how many species share a common ancestor.
The phylogenetic relationships between species can be influenced by several factors, including phenotypic plasticity an aspect of behavior that alters in response to unique environmental conditions. This can cause a characteristic to appear more similar to one species than to another, obscuring the phylogenetic signals. However, this problem can be solved through the use of methods such as cladistics that include a mix of analogous and homologous features into the tree.
In addition, phylogenetics can aid in predicting the duration and rate of speciation. This information will assist conservation biologists in making choices about which species to save from extinction. In the end, it's the conservation of phylogenetic variety that will result in an ecosystem that is complete and balanced.
Evolutionary Theory
The main idea behind evolution is that organisms develop various characteristics over time due to their interactions with their environments. 에볼루션 바카라 무료 have developed theories of evolution, including the Islamic naturalist Nasir al-Din al-Tusi (1201-274) who believed that a living thing would evolve according to its individual requirements as well as the Swedish taxonomist Carolus Linnaeus (1707-1778) who developed the modern hierarchical taxonomy and 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 genetics, natural selection, and particulate inheritance--came together to form the modern evolutionary theory synthesis that explains how evolution occurs through the variation of genes within a population, and how those variants change in time due to natural selection. This model, called genetic drift mutation, gene flow and sexual selection, is a cornerstone of current evolutionary biology, and is mathematically described.
Recent developments in the field of evolutionary developmental biology have revealed that variations can be introduced into a species by mutation, genetic drift, and reshuffling of genes during sexual reproduction, and also through migration between populations. These processes, along with other ones like the directional selection process and the erosion of genes (changes in the frequency of genotypes over time), can lead towards evolution. Evolution is defined as changes in the genome over time and changes in phenotype (the expression of genotypes within individuals).
Incorporating evolutionary thinking into all areas of biology education can improve 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 boosted their understanding of evolution in a college-level course in biology. For more information on how to teach about evolution, see 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 looked at evolution through the past, analyzing fossils and comparing species. They also study living organisms. However, evolution isn't something that happened in the past; it's an ongoing process taking place in the present. Bacteria evolve and resist antibiotics, viruses re-invent themselves and are able to evade new medications, and animals adapt their behavior in response to the changing environment. The resulting changes are often evident.
It wasn't until the 1980s that biologists began to realize that natural selection was in play. The key is the fact that different traits result in an individual rate of survival as well as reproduction, and may be passed on from one generation to another.
In the past, if one particular allele - the genetic sequence that defines color in a group of interbreeding organisms, it could quickly become more prevalent than the other alleles. In time, this could mean that the number of moths that have black pigmentation in a group 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 evolution when the species, like bacteria, has a rapid generation turnover. Since 1988, Richard Lenski, a biologist, has studied twelve populations of E.coli that descend from a single strain. Samples of each population have been collected regularly and more than 500.000 generations of E.coli have been observed to have passed.
Lenski's research has revealed that a mutation can dramatically alter the speed at which a population reproduces--and so, the rate at which it evolves. It also proves that evolution takes time, a fact that some people find difficult to accept.
에볼루션 게이밍 can be observed in the fact that mosquito genes for pesticide resistance are more common in populations where insecticides have been used. This is because pesticides cause a selective pressure which favors individuals who have resistant genotypes.
에볼루션 바카라 무료 of evolution has led to an increasing appreciation of its importance, especially in a world shaped largely by human activity. This includes the effects of climate change, pollution and habitat loss that hinders many species from adapting. Understanding evolution will assist you in making better choices regarding the future of the planet and its inhabitants.