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The Academy's Evolution Site
The concept of biological evolution is among the most fundamental concepts in biology. The Academies have long been involved in helping those interested in science comprehend the theory of evolution and how it permeates all areas of scientific research.
This site provides students, teachers 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 is an ancient symbol that represents the interconnectedness of all life. It is a symbol of love and unity in many cultures. It also has many practical uses, like providing a framework to understand the history of species and how they respond to changes in environmental conditions.
Early attempts to represent the biological world were based on categorizing organisms based on their metabolic and physical characteristics. These methods, based on sampling of different parts of living organisms, or small fragments of their DNA, greatly increased the variety of organisms that could be included in a tree of life2. However these trees are mainly comprised of eukaryotes, and bacterial diversity remains vastly underrepresented3,4.
By avoiding the necessity for direct observation and 에볼루션 룰렛 블랙잭 [This Internet site] experimentation, genetic techniques have made it possible to represent the Tree of Life in a much more accurate way. In particular, molecular methods allow us to build trees using sequenced markers such as the small subunit of ribosomal RNA gene.
The Tree of Life has been dramatically expanded through genome sequencing. However there is still a lot of biodiversity to be discovered. This is especially true of microorganisms that are difficult to cultivate and are typically only found in a single specimen5. Recent analysis of all genomes has produced a rough draft of a Tree of Life. This includes a large number of archaea, bacteria and other organisms that have not yet been identified or their diversity is not fully understood6.
This expanded Tree of Life is particularly useful in assessing the diversity of an area, assisting to determine if certain habitats require special protection. This information can be used in a range of ways, from identifying the most effective remedies to fight diseases to enhancing the quality of crops. This information is also useful to conservation efforts. It can aid biologists in identifying areas most likely to be home to species that are cryptic, which could have important metabolic functions and are susceptible to changes caused by humans. While funds to protect biodiversity are essential, the best way to conserve the world's biodiversity is to empower 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) illustrates the relationship between different organisms. Using molecular data similarities and differences in morphology, or ontogeny (the process of the development of an organism), scientists can build a phylogenetic tree which illustrates the evolutionary relationships between taxonomic categories. Phylogeny plays a crucial role in understanding biodiversity, genetics and evolution.
A basic phylogenetic Tree (see Figure PageIndex 10 ) is a method of identifying the relationships between organisms with similar traits that have evolved from common ancestors. These shared traits may be analogous, or homologous. Homologous characteristics are identical in their evolutionary paths. Analogous traits might appear similar, but they do not have the same origins. Scientists group similar traits together into a grouping referred to as a the clade. All members of a clade share a characteristic, for example, amniotic egg production. They all derived from an ancestor with these eggs. A phylogenetic tree is then constructed by connecting the clades to identify the species that are most closely related to each other.
Scientists use molecular DNA or RNA data to construct a phylogenetic graph that is more accurate and precise. This information is more precise and provides evidence of the evolution history of an organism. Researchers can use Molecular Data to calculate the evolutionary age of organisms and identify how many species share an ancestor common to all.
The phylogenetic relationships between species can be influenced by several factors, including phenotypic plasticity a type of behavior that alters in response to specific environmental conditions. This can cause a characteristic to appear more similar to one species than another, obscuring the phylogenetic signal. This problem can be addressed by using cladistics, which is a an amalgamation of analogous and homologous features in the tree.
In addition, phylogenetics can aid in predicting the time and pace of speciation. This information will assist conservation biologists in making choices about which species to safeguard from disappearance. In the end, it is 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 change over time due to their interactions with their environment. Many theories of evolution have been developed by a variety of scientists including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who envisioned an organism developing gradually according to its requirements and needs, the Swedish botanist Carolus Linnaeus (1707-1778) who developed modern hierarchical taxonomy, and Jean-Baptiste Lamarck (1744-1829) who suggested that the use or non-use of traits can cause changes that can be passed on to the offspring.
In the 1930s and 1940s, concepts from various fields, including genetics, natural selection, and particulate inheritance, merged to create a modern theorizing of evolution. This defines how evolution occurs by the variations in genes within the population, and how these variations change with time due to natural selection. This model, which encompasses genetic drift, mutations in gene flow, and sexual selection, can be mathematically described.
Recent discoveries in the field of evolutionary developmental biology have demonstrated how variations can be introduced to a species by 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 lead to evolution which is defined by change in the genome of the species over time and also by changes in phenotype as time passes (the expression of the genotype within the individual).
Incorporating evolutionary thinking into all aspects of biology education could increase students' understanding of phylogeny as well as evolution. A recent study conducted by Grunspan and colleagues, for instance demonstrated that teaching about the evidence that supports evolution increased students' understanding of evolution in a college-level biology class. To find out more about how to teach about evolution, look up The Evolutionary Potential in All Areas of Biology and Thinking Evolutionarily A Framework for Infusing Evolution in Life Sciences Education.
Evolution in Action
Scientists have traditionally studied evolution by looking in the past--analyzing fossils and comparing species. They also observe living organisms. Evolution isn't a flims moment; it is a process that continues today. Bacteria mutate and resist antibiotics, viruses reinvent themselves and escape new drugs and animals alter their behavior to a changing planet. The changes that result are often visible.
However, it wasn't until late 1980s that biologists understood that natural selection can be seen in action, as well. The key to this is that different traits confer a different rate of survival and reproduction, and can be passed on from generation to generation.
In the past, if one allele - the genetic sequence that determines color - appeared in a population of organisms that interbred, 에볼루션 게이밍 블랙잭, https://git.luoui.com:2443/Evolution3503, it could become more prevalent than any other allele. As time passes, that could mean 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.
It is easier to track evolution when a species, such as bacteria, has a high generation turnover. Since 1988 biologist Richard Lenski has been tracking twelve populations of E. Coli that descended from a single strain; samples from each population are taken every day and more than 50,000 generations have now been observed.
Lenski's research has shown that mutations can drastically alter the speed at which a population reproduces--and so the rate at which it alters. It also shows that evolution takes time, a fact that is hard for some to accept.
Another example of microevolution is that mosquito genes that are resistant to pesticides are more prevalent in populations in which insecticides are utilized. This is because the use of pesticides creates a selective pressure that favors those with resistant genotypes.
The rapidity of evolution has led to an increasing awareness of its significance particularly in a world which is largely shaped by human activities. This includes the effects of climate change, pollution and habitat loss that prevents many species from adapting. Understanding the evolution process can aid you in making better decisions regarding the future of the planet and its inhabitants.