The Academy's Evolution Site
The concept of biological evolution is a fundamental concept in biology. The Academies have been for a long time involved in helping people who are interested in science comprehend the concept of evolution and how it affects every area of scientific inquiry.
This site provides students, teachers and general readers with a range of educational resources on evolution. It includes key video clip from NOVA and WGBH produced science programs on DVD.
Tree of Life
The Tree of Life, an ancient symbol, symbolizes the interconnectedness of all life. It appears in many cultures and spiritual beliefs as symbolizing 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 respond to changing environmental conditions.
Early attempts to represent the world of biology were based on categorizing organisms based on their physical and metabolic characteristics. These methods are based on the collection of various parts of organisms or fragments of DNA have significantly increased the diversity of a tree of Life2. The trees are mostly composed by eukaryotes, and bacteria are largely underrepresented3,4.
In avoiding the necessity of direct experimentation and observation, genetic techniques have made it possible to depict the Tree of Life in a more precise way. We can create trees using molecular techniques, such as the small-subunit ribosomal gene.
Despite the massive expansion of the Tree of Life through genome sequencing, a lot of biodiversity remains to be discovered. This is especially relevant to microorganisms that are difficult to cultivate and which are usually only found in a single specimen5. A recent analysis of all genomes resulted in an initial draft of a Tree of Life. This includes a wide range of bacteria, archaea and other organisms that haven't yet been isolated, or the diversity of which is not well understood6.
This expanded Tree of Life can be used to determine the diversity of a particular area and determine if certain habitats require special protection. The information is useful in a variety of ways, including finding new drugs, battling diseases and improving crops. This information is also beneficial for conservation efforts. It can aid biologists in identifying the areas most likely to contain cryptic species with potentially significant metabolic functions that could be at risk from anthropogenic change. While conservation funds are important, the best method to protect the biodiversity of the world is to equip more people in developing nations with the necessary knowledge to act locally and support conservation.
에볼루션 바카라 , also known as an evolutionary tree, reveals the connections between different groups of organisms. Scientists can construct an phylogenetic chart which shows the evolution of taxonomic categories using molecular information and morphological differences or similarities. The concept of phylogeny is fundamental to understanding biodiversity, evolution and genetics.
A basic phylogenetic Tree (see Figure PageIndex 10 Identifies the relationships between organisms that have similar traits and have evolved from an ancestor with common traits. These shared traits are either homologous or analogous. Homologous traits are identical in their evolutionary origins and analogous traits appear similar but do not have the identical origins. Scientists arrange similar traits into a grouping known as a Clade. For instance, all of the organisms that make up a clade have the characteristic of having amniotic eggs. They evolved from a common ancestor that had eggs. The clades then join to create a phylogenetic tree to determine the organisms with the closest relationship to.
For a more precise and precise phylogenetic tree scientists rely on molecular information from DNA or RNA to determine the relationships among organisms. This information is more precise and gives evidence of the evolutionary history of an organism. Researchers can utilize Molecular Data to calculate the evolutionary age of organisms and identify how many species have an ancestor common to all.
please click for source between species can be affected by a variety of factors, including phenotypic flexibility, a kind of behavior that alters in response to unique environmental conditions. This can cause a particular trait to appear more similar in one species than other species, which can obscure the phylogenetic signal. However, this problem can be cured by the use of techniques such as cladistics which incorporate a combination of analogous and homologous features into the tree.
Additionally, phylogenetics aids determine the duration and rate of speciation. This information can aid conservation biologists to decide which species to protect from the threat of extinction. In the end, it's the conservation of phylogenetic diversity which will create 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 environment. Many theories of evolution have been proposed by a variety of scientists, including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who proposed that a living organism develop slowly according to its needs, the Swedish botanist Carolus Linnaeus (1707-1778) who designed modern hierarchical taxonomy, and Jean-Baptiste Lamarck (1744-1829) who suggested that the use or non-use of traits causes changes that could be passed onto offspring.
In the 1930s & 1940s, theories from various areas, including genetics, natural selection and particulate inheritance, were brought together to form a modern theorizing of evolution. This describes how evolution happens through the variations in genes within the population, and how these variants change with time due to natural selection. This model, which is known as genetic drift or mutation, gene flow and sexual selection, is the foundation of modern evolutionary biology and is mathematically described.
Recent discoveries in evolutionary developmental biology have revealed how variations can be introduced to a species via genetic drift, mutations or reshuffling of genes in sexual reproduction and migration between populations. These processes, as well as others, such as 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, as well as changes in phenotype (the expression of genotypes within individuals).
Incorporating evolutionary thinking into all areas of biology education can improve students' understanding of phylogeny and evolution. 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 details on how to teach evolution, see 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 through looking back--analyzing fossils, comparing species, and studying living organisms. Evolution is not a past event; it is an ongoing process that continues to be observed today. Bacteria evolve and resist antibiotics, viruses evolve and elude new medications, and animals adapt their behavior to the changing climate. The changes that result are often evident.
It wasn't until late 1980s that biologists realized that natural selection can be observed in action as well. The reason is that different characteristics result in different rates of survival and reproduction (differential fitness), and can be passed down from one generation to the next.
In the past when one particular allele - the genetic sequence that determines coloration--appeared in a population of interbreeding organisms, it might rapidly become more common than all other alleles. In time, this could mean that the number of black moths within a particular population could rise. 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 a species, such as 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 population are taken on a regular basis and over 50,000 generations have now been observed.
Lenski's work has demonstrated that a mutation can dramatically alter the efficiency with the rate at which a population reproduces, and consequently the rate at which it evolves. It also shows that evolution takes time, something that is hard for some to accept.
Microevolution is also evident in the fact that mosquito genes that confer resistance to pesticides are more common in populations that have used insecticides. This is due to pesticides causing a selective pressure which favors those with resistant genotypes.
The rapidity of evolution has led to a greater appreciation of its importance, especially in a world which is largely shaped by human activities. This includes the effects of climate change, pollution and habitat loss, which prevents many species from adapting. Understanding the evolution process can help you make better decisions regarding the future of the planet and its inhabitants.