The Academy's Evolution Site
The concept of biological evolution is a fundamental concept in biology. 에볼루션 게이밍 are involved in helping those interested in science to understand evolution theory and how it is incorporated throughout all fields of scientific research.
This site offers a variety of resources for teachers, students, and general readers on 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 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 in addition to providing a framework for understanding the history of species, and how they respond to changing environmental conditions.
The earliest attempts to depict the biological world focused on categorizing organisms into distinct categories which had been distinguished by physical and metabolic characteristics1. These methods, based on the sampling of various parts of living organisms or sequences of short DNA fragments, significantly increased the variety that could be included in a tree of life2. The trees are mostly composed of eukaryotes, while bacterial diversity is vastly underrepresented3,4.
In avoiding the necessity of direct observation and experimentation genetic techniques have made it possible to depict the Tree of Life in a more precise way. Particularly, molecular methods allow us to build trees using sequenced markers like the small subunit ribosomal gene.
The Tree of Life has been significantly expanded by genome sequencing. However there is still a lot of diversity to be discovered. This is particularly true of microorganisms, which can be difficult to cultivate and are often only represented in a single specimen5. A recent study of all genomes known to date has produced a rough draft version 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 specific area and determine if specific habitats require special protection. This information can be utilized in many ways, including finding new drugs, battling diseases and enhancing crops. It is also valuable in conservation efforts. It helps biologists determine those areas that are most likely contain cryptic species with potentially important metabolic functions that could be at risk from anthropogenic change. While funds to protect biodiversity are essential, the best method to preserve the world's biodiversity is to equip the people of developing nations with the necessary knowledge to take action locally and encourage conservation.
Phylogeny
A phylogeny is also known as an evolutionary tree, shows the relationships between various groups of organisms. Scientists can build a phylogenetic diagram that illustrates the evolution of taxonomic groups based on molecular data and morphological differences or similarities. The phylogeny of a tree plays an important role in understanding the relationship between genetics, biodiversity and evolution.
A basic phylogenetic Tree (see Figure PageIndex 10 Determines the relationship between organisms that have similar characteristics and have evolved from an ancestor that shared traits. These shared traits can be either analogous or homologous. Homologous traits share their underlying evolutionary path and analogous traits appear similar but do not have the same origins. Scientists group similar traits together into a grouping referred to as a the clade. For instance, all of the organisms that make up a clade share the trait of having amniotic egg and evolved from a common ancestor who had these eggs. A phylogenetic tree is then constructed by connecting the clades to determine the organisms which are the closest to each other.
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. Molecular data allows researchers to determine the number of species that have an ancestor common to them and estimate their evolutionary age.
The phylogenetic relationship can be affected by a number of factors such as the phenomenon of phenotypicplasticity. This is a type of behavior that alters due to unique environmental conditions. This can cause a trait to appear more similar to one species than to the other and obscure the phylogenetic signals. However, this problem can be solved through the use of techniques such as cladistics that incorporate a combination of homologous and analogous 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 decisions about which species to protect from extinction. In the end, it's the preservation of phylogenetic diversity that will lead to an ecosystem that is balanced and complete.
Evolutionary Theory
The central theme in evolution is that organisms change over time as a result of 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 believed that an organism would evolve slowly according to its requirements, the Swedish botanist Carolus Linnaeus (1707-1778) who conceived the modern hierarchical taxonomy 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, concepts from various fields, including natural selection, genetics & particulate inheritance, were brought together to form a modern theorizing of evolution. This describes how evolution occurs by the variation in genes within a population and how these variants alter over time due to natural selection. This model, which is known as genetic drift or mutation, gene flow, and sexual selection, is a cornerstone of the current evolutionary biology and is mathematically described.
Recent advances 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 even migration between populations. These processes, as well as others such as directional selection or 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 the change in phenotype over time (the expression of that genotype in an individual).
Students can better understand the concept of phylogeny by using evolutionary thinking into all areas of biology. A recent study by Grunspan and colleagues, for example, showed that teaching about the evidence that supports evolution increased students' understanding of evolution in a college-level biology class. For more information on how to teach evolution, see The Evolutionary Potential in All Areas of Biology or Thinking Evolutionarily as a Framework for Integrating 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 a thing that happened in the past, it's an ongoing process, taking place today. Bacteria mutate and resist antibiotics, viruses evolve and are able to evade new medications and animals change their behavior to a changing planet. The resulting changes are often visible.
It wasn't until late 1980s that biologists understood that natural selection could be observed in action as well. The key to this is that different traits confer the ability to survive at different rates as well as reproduction, and may be passed down from generation to generation.
In the past, if one particular allele, the genetic sequence that controls coloration - was present in a group of interbreeding organisms, it could rapidly become more common than all other alleles. As time passes, 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.
The ability to observe evolutionary change is much easier when a species has a rapid turnover of its generation like 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 fifty thousand generations have been observed.
Lenski's research has shown that a mutation can profoundly alter the efficiency with which a population reproduces--and so the rate at which it alters. It also proves that evolution takes time--a fact that some people find difficult to accept.
Another example of microevolution is the way mosquito genes for resistance to pesticides appear more frequently in areas where insecticides are employed. This is due to pesticides causing an enticement that favors individuals who have resistant genotypes.
The rapid pace of evolution taking place has led to a growing awareness of its significance in a world shaped by human activities, including climate change, pollution and the loss of habitats which prevent many species from adapting. Understanding the evolution process can aid you in making better decisions regarding the future of the planet and its inhabitants.