An Evolution Site Success Story You'll Never Be Able To
The Academy's Evolution Site
The concept of biological evolution is among the most fundamental concepts in biology. The Academies are committed to helping those who are interested in the sciences learn about the theory of evolution and how it can be applied across all areas of scientific research.
This site offers a variety of resources for teachers, students as well as general readers about evolution. It contains key video clips from NOVA and WGBH produced science programs on DVD.
Tree of Life
The Tree of Life is an ancient symbol that symbolizes the interconnectedness of life. It is an emblem of love and harmony in a variety of cultures. It can be used in many practical ways as well, including providing a framework for understanding the history of species and how they respond to changing environmental conditions.
Early attempts to represent the biological world were built on categorizing organisms based on their metabolic and physical characteristics. These methods, based on the sampling of various parts of living organisms, or short fragments of their DNA, significantly increased the variety that could be included in a tree of life2. These trees are largely composed by eukaryotes and the diversity of bacterial species is greatly underrepresented3,4.
Genetic techniques have significantly expanded our ability to visualize the Tree of Life by circumventing the requirement for direct observation and experimentation. We can construct trees using molecular methods like the small-subunit ribosomal gene.
The Tree of Life has been greatly expanded thanks to genome sequencing. However there is still a lot of biodiversity to be discovered. This is particularly true for microorganisms that are difficult to cultivate and are often only present in a single specimen5. A recent analysis of all genomes has produced a rough draft of a Tree of Life. This includes a wide range of archaea, bacteria, and other organisms that haven't yet been identified or their diversity is not thoroughly understood6.
The expanded Tree of Life is particularly useful for assessing the biodiversity of an area, helping to determine if certain habitats require special protection. This information can be used in a variety of ways, including identifying new drugs, combating diseases and improving the quality of crops. This information is also extremely valuable in conservation efforts. It helps biologists discover areas that are likely to be home to cryptic species, which could perform important metabolic functions, and could be susceptible to the effects of human activity. Although funds to safeguard biodiversity are vital however, the most effective method to preserve the world's biodiversity 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 known as an evolutionary tree, illustrates the relationships between groups of organisms. Utilizing molecular data similarities and differences in morphology, or ontogeny (the process of the development of an organism) scientists can construct a phylogenetic tree which illustrates the evolution of taxonomic categories. The concept of phylogeny is fundamental to understanding evolution, biodiversity and genetics.
A basic phylogenetic Tree (see Figure PageIndex 10 Identifies the relationships between organisms that have similar characteristics and have evolved from an ancestor that shared traits. These shared traits are either homologous or analogous. Homologous traits are identical in their evolutionary roots while analogous traits appear like they do, but don't have the same origins. Scientists arrange similar traits into a grouping referred to as a Clade. All members of a clade share a characteristic, like amniotic egg production. They all derived from an ancestor that had these eggs. A phylogenetic tree can be constructed by connecting clades to determine the organisms that are most closely related to one another.
To create a more thorough and accurate 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 evolution history of an organism. Researchers can utilize Molecular Data to calculate the age of evolution of living organisms and discover how many species share the same ancestor.
The phylogenetic relationship can be affected by a number of factors such as phenotypicplasticity. This is a type behaviour that can change in response to particular environmental conditions. This can cause a particular trait to appear more similar in one species than another, obscuring the phylogenetic signal. This issue can be cured by using cladistics. This is a method that incorporates a combination of analogous and homologous features in the tree.
Furthermore, phylogenetics may help predict the length and speed of speciation. This information can help conservation biologists decide which species to protect from extinction. Ultimately, it is the preservation of phylogenetic diversity which will create a complete and balanced ecosystem.
Evolutionary Theory
The central theme of evolution is that organisms develop different features over time due to their interactions with their surroundings. Many scientists have proposed theories of evolution, such as the Islamic naturalist Nasir al-Din al-Tusi (1201-274) who believed that an organism could evolve according to its own requirements as well as the Swedish taxonomist Carolus Linnaeus (1707-1778) who developed the modern taxonomy system that is hierarchical, as well as Jean-Baptiste Lamarck (1844-1829), who suggested that the usage or non-use of certain traits can result in changes that can be passed on to future generations.
In the 1930s & 1940s, theories from various fields, such as genetics, natural selection, and particulate inheritance, came together to form a contemporary synthesis of evolution theory. This describes how evolution occurs by the variation of genes in the population and how these variants change with time due to natural selection. This model, called genetic drift or mutation, gene flow and sexual selection, is a cornerstone of the current evolutionary biology and can be mathematically described.
Recent developments in evolutionary developmental biology have revealed the ways in which variation can be introduced to a species by mutations, genetic drift, reshuffling genes during sexual reproduction and the movement 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 changes in the genome of the species over time, and also the change in phenotype as time passes (the expression of that genotype in the individual).
Incorporating evolutionary thinking into all aspects of biology education can increase students' understanding of phylogeny and evolution. In a recent study conducted by Grunspan et al., it was shown that teaching students about the evidence for evolution increased their acceptance of evolution during an undergraduate biology course. To find out more about how to teach about evolution, please see The Evolutionary Potential of All Areas of Biology and Thinking Evolutionarily: A Framework for Infusing Evolution in Life Sciences Education.
Evolution in Action
Scientists have traditionally looked at evolution through the past--analyzing fossils and comparing species. They also observe living organisms. Evolution is not a past event, but a process that continues today. The virus reinvents itself to avoid new medications and bacteria mutate to resist antibiotics. Animals adapt their behavior as a result of a changing environment. The results are often apparent.
It wasn't until late 1980s that biologists understood that natural selection can be seen in action, as well. 에볼루션 바카라사이트 is that different characteristics result in different rates of survival and reproduction (differential fitness), and can be transferred from one generation to the next.
In the past, if one allele - the genetic sequence that determines colour was present in a population of organisms that interbred, it might become more common than other allele. As time passes, that could mean that the number of black moths in a particular population could rise. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.
Observing evolutionary change in action is much easier when a species has a rapid generation turnover, as with bacteria. 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 regularly, and over 50,000 generations have now been observed.
Lenski's work has shown that mutations can alter the rate of change and the efficiency at which a population reproduces. It also shows evolution takes time, something that is difficult for some to accept.
Microevolution can also be seen in the fact that mosquito genes that confer resistance to pesticides are more prevalent in populations where insecticides are used. That's because the use of pesticides creates a pressure that favors individuals who have resistant genotypes.
The rapid pace at which evolution takes place has led to a growing recognition of its importance in a world that is shaped by human activities, including climate change, pollution and the loss of habitats that hinder many species from adapting. Understanding the evolution process can help us make smarter choices about the future of our planet as well as the lives of its inhabitants.