Why You Should Concentrate On Enhancing Evolution Site
The Academy's Evolution Site
Biological evolution is a central concept in biology. 에볼루션 바카라 사이트 are committed to helping those interested in the sciences comprehend the evolution theory and how it is incorporated throughout all fields of scientific research.
This site offers a variety of tools for teachers, students as well as general readers about evolution. It includes key video clips from NOVA and WGBH's science programs on DVD.
Tree of Life
The Tree of Life is an ancient symbol of the interconnectedness of all life. It is seen in a variety of cultures and spiritual beliefs as symbolizing unity and love. It also has important practical applications, like providing a framework to understand the evolution of species and how they react to changes in environmental conditions.
The earliest attempts to depict the world of biology focused on separating species into distinct categories that were distinguished by their physical and metabolic characteristics1. These methods, based on the sampling of different parts of living organisms or small fragments of their DNA, significantly increased the variety that could be represented in a tree of life2. However the trees are mostly comprised of eukaryotes, and bacterial diversity is not represented in a large way3,4.
Genetic techniques have greatly expanded our ability to visualize the Tree of Life by circumventing the need for direct observation and experimentation. In particular, molecular methods allow us to construct trees using sequenced markers like the small subunit of ribosomal RNA gene.
Despite the rapid growth of the Tree of Life through genome sequencing, a lot of biodiversity awaits discovery. 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 produced an unfinished draft of the Tree of Life. This includes a large number of archaea, bacteria and other organisms that haven't yet been identified or their diversity is not fully understood6.
This expanded Tree of Life can be used to assess the biodiversity of a specific region and determine if specific habitats require special protection. This information can be used in many ways, including finding new drugs, battling diseases and improving the quality of crops. The information is also incredibly useful in conservation efforts. It can aid biologists in identifying areas most likely to have species that are cryptic, which could have vital metabolic functions and be vulnerable to the effects of human activity. While funds to safeguard biodiversity are vital however, the most effective method to ensure the preservation of biodiversity around the world 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 called an evolutionary tree) shows the relationships between species. Using molecular data similarities and differences in morphology or ontogeny (the course of development of an organism) scientists can construct a phylogenetic tree which illustrates the evolutionary relationships between taxonomic categories. Phylogeny is essential in understanding evolution, biodiversity and genetics.
A basic phylogenetic Tree (see Figure PageIndex 10 Identifies the relationships between organisms with similar traits and have evolved from an ancestor with common traits. These shared traits could be analogous or homologous. Homologous traits are identical in their evolutionary roots while analogous traits appear like they do, but don't have the same origins. Scientists group similar traits together into a grouping known as a clade. For instance, all the species in a clade have the characteristic of having amniotic egg and evolved from a common ancestor who had eggs. The clades then join to form a phylogenetic branch that can determine which organisms have the closest connection to each other.
To create a more thorough and accurate phylogenetic tree scientists rely on molecular information from DNA or RNA to establish the connections between organisms. This information is more precise and provides evidence of the evolutionary history of an organism. The use of molecular data lets researchers determine the number of organisms that have an ancestor common to them and estimate their evolutionary age.
The phylogenetic relationships of organisms are influenced by many factors, including phenotypic flexibility, a kind of behavior that changes in response to unique environmental conditions. This can cause a characteristic to appear more similar to a species than to another which can obscure the phylogenetic signal. This problem can be mitigated by using cladistics. This is a method that incorporates a combination of homologous and analogous features in the tree.
In addition, phylogenetics helps determine the duration and rate at which speciation takes place. This information will assist conservation biologists in making decisions about which species to save from extinction. It is ultimately the preservation of phylogenetic diversity which will lead to a complete and balanced ecosystem.
Evolutionary Theory
The central theme in evolution is that organisms alter over time because of their interactions with their environment. A variety of theories about evolution have been developed by a wide variety of scientists such as the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who believed that an organism would evolve slowly in accordance with its needs as well as the Swedish botanist Carolus Linnaeus (1707-1778) who designed the modern hierarchical taxonomy Jean-Baptiste Lamarck (1744-1829) who suggested that the use or misuse of traits cause changes that can be passed on to offspring.
In the 1930s and 1940s, concepts from a variety of fields--including genetics, natural selection, and particulate inheritance -- came together to create the modern evolutionary theory which explains how evolution happens through the variation of genes within a population, and how those variants change in time as a result of natural selection. This model, known as genetic drift, mutation, gene flow and sexual selection, is the foundation of the current evolutionary biology and is mathematically described.
Recent discoveries in the field of evolutionary developmental biology have shown that variations can be introduced into a species by genetic drift, mutation, and reshuffling genes during sexual reproduction, as well as through migration between populations. These processes, along with other ones like the directional selection process and the erosion of genes (changes in the frequency of genotypes over time) can result in evolution. Evolution is defined by changes in the genome over time, as well as changes in the phenotype (the expression of genotypes in individuals).
Incorporating evolutionary thinking into all aspects of biology education could increase students' understanding of phylogeny and evolutionary. A recent study by Grunspan and colleagues, for example, showed that teaching about the evidence that supports evolution helped students accept the concept of evolution in a college biology course. For more information on how to teach about evolution, please see The Evolutionary Potential of All Areas of Biology and Thinking Evolutionarily: A Framework for Infusing the Concept of Evolution into Life Sciences Education.
Evolution in Action
Scientists have looked at evolution through the past--analyzing fossils and comparing species. They also study living organisms. But evolution isn't just something that occurred in the past, it's an ongoing process, that is taking place right now. Bacteria mutate and resist antibiotics, viruses reinvent themselves and escape new drugs and animals alter their behavior to the changing environment. The resulting changes are often easy to see.
It wasn't until late 1980s that biologists realized that natural selection could be observed in action as well. The key is that different traits confer different rates of survival and reproduction (differential fitness) and are passed down from one generation to the next.
In the past, if an allele - the genetic sequence that determines color - appeared in a population of organisms that interbred, it could become more common than other allele. As time passes, that 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 observe evolution when an organism, like bacteria, has a rapid generation turnover. Since 1988, Richard Lenski, a biologist, has been tracking twelve populations of E.coli that descend from a single strain. The samples of each population have been taken regularly and more than 500.000 generations of E.coli have passed.
Lenski's work has shown that mutations can alter the rate of change and the effectiveness at which a population reproduces. It also shows evolution takes time, which is difficult for some to accept.
Another example of microevolution is the way mosquito genes for resistance to pesticides are more prevalent in areas where insecticides are used. This is due to pesticides causing an enticement that favors those who have resistant genotypes.
The speed at which evolution can take place has led to a growing appreciation of its importance in a world shaped by human activity--including climate change, pollution, and the loss of habitats which prevent many species from adapting. Understanding evolution will assist you in making better choices about the future of the planet and its inhabitants.