The Academy's Evolution Site
The concept of biological evolution is a fundamental concept in biology. The Academies have been active for a long time in helping people who are interested in science understand the theory of evolution and how it permeates all areas of scientific research.
This site provides teachers, students and general readers with a range of learning resources on evolution. 에볼루션 무료체험 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 seen in a variety of religions and cultures as a symbol of unity and love. It can be used in many practical ways as well, such as providing a framework for understanding the evolution of species and how they react to changes in environmental conditions.
Early approaches to depicting the biological world focused on the classification of organisms into distinct categories which had been distinguished by physical and metabolic characteristics1. These methods, based on sampling of different parts of living organisms or on sequences of short fragments of their DNA, significantly expanded the diversity that could be included in the tree of life2. However these trees are mainly composed of eukaryotes; bacterial diversity is not represented in a large way3,4.
By avoiding the need for direct experimentation and observation, genetic techniques have made it possible to represent the Tree of Life in a much more accurate way. In particular, molecular methods enable us to create trees by using sequenced markers, such as the small subunit of ribosomal RNA gene.
Despite the dramatic expansion of the Tree of Life through genome sequencing, much biodiversity still remains to be discovered. This is particularly true for microorganisms that are difficult to cultivate and which are usually only found in a single specimen5. A recent analysis of all genomes known to date has produced a rough draft version of the Tree of Life, including many bacteria and archaea that are not isolated and which are not well understood.
This expanded Tree of Life can be used to assess the biodiversity of a specific region and determine if specific habitats need special protection. This information can be utilized in a variety of ways, from identifying new treatments to fight disease to enhancing the quality of crops. The information is also incredibly beneficial for conservation efforts. It helps biologists discover areas that are likely to have species that are cryptic, which could have vital metabolic functions and be vulnerable to changes caused by humans. While funds to protect biodiversity are important, the best method to preserve the world's biodiversity is to equip the people of developing nations with the knowledge they need to act locally and promote conservation.
Phylogeny
A phylogeny is also known as an evolutionary tree, shows the connections between different groups of organisms. Scientists can build a phylogenetic chart that shows the evolutionary relationship of taxonomic groups using molecular data and morphological similarities or differences. Phylogeny is essential in understanding biodiversity, evolution 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 either homologous or analogous. Homologous traits share their evolutionary origins and analogous traits appear like they do, but don't have the same ancestors. Scientists combine 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 with these eggs. The clades then join to form a phylogenetic branch to determine which organisms have the closest connection to each other.
For a more detailed and precise phylogenetic tree scientists make use of molecular data from DNA or RNA to determine the connections between organisms. This information is more precise and provides evidence of the evolutionary history of an organism. 에볼루션 카지노 of molecular data lets researchers identify the number of species that share the same ancestor and estimate their evolutionary age.
Phylogenetic relationships can be affected by a number of factors, including the phenotypic plasticity. This is a type behavior that alters due to specific environmental conditions. This can cause a trait to appear more similar to one species than another and obscure the phylogenetic signals. This problem can be mitigated by using cladistics, which incorporates a combination of analogous and homologous features in the tree.
Additionally, phylogenetics can aid in predicting the time and pace of speciation. This information can assist conservation biologists make decisions about which species to protect from the threat of extinction. In the end, it's the conservation of phylogenetic diversity that will lead to an ecosystem that is balanced and complete.
Evolutionary Theory
The main idea behind evolution is that organisms acquire different features over time due to their interactions with their surroundings. Many theories of evolution have been proposed by a wide variety of scientists, including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who believed that an organism would evolve slowly according to its needs and needs, 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 the offspring.
In the 1930s and 1940s, concepts from various areas, including genetics, natural selection, and particulate inheritance, were brought together to create a modern synthesis of evolution theory. This defines how evolution occurs by the variation of genes in a population and how these variants change over time as a result of natural selection. This model, which is known as genetic drift, mutation, gene flow and sexual selection, is a key element of current evolutionary biology, and can be mathematically described.
Recent developments in the field of evolutionary developmental biology have shown the ways in which variation can be introduced to a species through genetic drift, mutations or reshuffling of genes in sexual reproduction and the movement between populations. These processes, along with other ones like directional selection and genetic erosion (changes in the frequency of the genotype over time) can result in evolution that is defined as changes in the genome of the species over time and also by changes in phenotype as time passes (the expression of the genotype in an individual).
Students can gain a better understanding of phylogeny by incorporating evolutionary thinking into all aspects of biology. In a recent study by Grunspan et al., it was shown that teaching students about the evidence for evolution increased their understanding of evolution in an undergraduate biology course. For more information on how to teach about evolution, please see 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 traditionally looked at evolution through the past--analyzing fossils and comparing species. They also study living organisms. But evolution isn't just something that happened in the past; it's an ongoing process happening in the present. Viruses evolve to stay away from new antibiotics and bacteria transform to resist antibiotics. Animals alter their behavior because of a changing world. The changes that result are often evident.
It wasn't until the 1980s that biologists began realize that natural selection was at work. The reason is that different traits have different rates of survival and reproduction (differential fitness) and can be passed from one generation to the next.
In the past when one particular allele, the genetic sequence that defines color in a group of interbreeding organisms, it could quickly become more prevalent than all other alleles. In time, this could mean that the number of moths with black pigmentation in a group may increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.
The ability to observe evolutionary change is much easier when a species has a fast generation turnover, as with bacteria. Since 1988 the biologist Richard Lenski has been tracking twelve populations of E. bacteria that descend from a single strain. samples of each population are taken every day, and over fifty thousand generations have been observed.
Lenski's work has shown that mutations can alter the rate of change and the rate of a population's reproduction. It also shows that evolution takes time, something that is difficult for some to accept.
Microevolution is also evident in the fact that mosquito genes for resistance to pesticides are more prevalent in populations that have used insecticides. This is because pesticides cause an exclusive pressure that favors those with resistant genotypes.
The speed at which evolution can take place has led to a growing recognition of its importance in a world that is shaped by human activity--including climate changes, pollution and the loss of habitats that prevent the species from adapting. Understanding evolution will assist you in making better choices about the future of our planet and its inhabitants.