Are You Getting The Most You Evolution Site?
The Academy's Evolution Site
Biological evolution is a central concept in biology. The Academies are involved in helping those interested in science learn about the theory of evolution and how it is permeated throughout all fields of scientific research.
This site provides teachers, students and general readers with a wide range of learning resources on evolution. It contains key video clips 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 is seen in a variety of spiritual traditions and cultures as an emblem of unity and love. It also has practical uses, like providing a framework for understanding the history of species and how they react to changes in environmental conditions.
Early attempts to represent the world of biology 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 small DNA fragments, significantly increased the variety that could be represented in the tree of life2. The trees are mostly composed by eukaryotes and bacterial diversity is vastly underrepresented3,4.
Genetic techniques have greatly broadened our ability to visualize the Tree of Life by circumventing the need for direct observation and experimentation. In particular, molecular methods enable us to create trees by using sequenced markers such as the small subunit ribosomal RNA gene.
Despite the rapid growth of the Tree of Life through genome sequencing, a lot of biodiversity is waiting to be discovered. This is especially true for microorganisms that are difficult to cultivate and which are usually only found in a single specimen5. A recent analysis of all genomes produced an initial draft of the Tree of Life. This includes a large number of archaea, bacteria, and other organisms that haven't yet been identified or whose diversity has not been fully understood6.
The expanded Tree of Life can be used to evaluate the biodiversity of a specific region and determine if certain habitats need special protection. The information is useful in many ways, including finding new drugs, battling diseases and improving the quality of crops. This information is also extremely valuable to conservation efforts. It helps biologists determine the areas most likely to contain cryptic species with important metabolic functions that could be at risk of anthropogenic changes. While funds to protect biodiversity are essential but the most effective way to ensure the preservation of biodiversity around the world is for more people 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, reveals the connections between various groups of organisms. Scientists can construct an phylogenetic chart which shows the evolutionary relationship of taxonomic categories using molecular information and morphological differences or similarities. Phylogeny is essential in understanding evolution, biodiversity and genetics.
A basic phylogenetic tree (see Figure PageIndex 10 Identifies the relationships between organisms that have similar traits and evolved from a common ancestor. These shared traits may be analogous or homologous. Homologous traits are the same in their evolutionary path. Analogous traits could appear similar but they don't have the same origins. Scientists group similar traits into a grouping called a clade. For example, all of the organisms that make up a clade have the characteristic of having amniotic eggs and evolved from a common ancestor which had eggs. The clades then join to create a phylogenetic tree to identify organisms that have the closest relationship.
에볼루션 블랙잭 Evolution KR use molecular DNA or RNA data to create a phylogenetic chart that is more precise and precise. This data is more precise than the morphological data and gives evidence of the evolutionary background of an organism or group. Researchers can utilize Molecular Data to calculate the evolutionary age of living organisms and discover how many species share an ancestor common to all.
The phylogenetic relationship can be affected by a number of factors such as the phenomenon of phenotypicplasticity. This is a kind of behaviour that can change due to unique environmental conditions. This can cause a characteristic to appear more similar to one species than another and obscure the phylogenetic signals. However, this problem can be cured by the use of techniques such as cladistics which combine similar and homologous traits into the tree.
Additionally, phylogenetics can help determine the duration and rate at which speciation occurs. This information can assist conservation biologists in making decisions about which species to save from the threat of extinction. In the end, it is the conservation of phylogenetic variety which will create an ecosystem that is complete and balanced.
Evolutionary Theory
The main idea behind evolution is that organisms acquire different features over time as a result of their interactions with their environments. A variety of theories about evolution have been developed by a wide range of scientists such as 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 modern hierarchical taxonomy, and Jean-Baptiste Lamarck (1744-1829) who suggested that the use or misuse of traits can cause changes that could be passed on to the offspring.
In the 1930s and 1940s, theories from a variety of fields--including genetics, natural selection, and particulate inheritance--came together to create the modern evolutionary theory synthesis which explains how evolution is triggered by the variation of genes within a population and how those variations change in time due to natural selection. This model, called genetic drift mutation, gene flow and sexual selection, is a key element of modern evolutionary biology and can be mathematically explained.
Recent developments in the field of evolutionary developmental biology have revealed the ways in which variation can be introduced to a species through genetic drift, mutations, reshuffling genes during sexual reproduction and the movement between populations. These processes, as well as other ones like directional selection and genetic erosion (changes in the frequency of a 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 over time (the expression of the genotype within the individual).
Incorporating evolutionary thinking into all areas of biology education could increase student understanding of the concepts of phylogeny and evolution. A recent study conducted by Grunspan and colleagues, for instance demonstrated that teaching about the evidence supporting evolution increased students' understanding of evolution in a college-level biology course. For more information on how to teach evolution read The Evolutionary Potential in all Areas of Biology or Thinking Evolutionarily: a Framework for Infusing Evolution into Life Sciences Education.
Evolution in Action
Scientists have studied evolution through looking back in the past--analyzing fossils and comparing species. They also observe living organisms. Evolution isn't a flims event; it is an ongoing process that continues to be observed today. Bacteria evolve and resist antibiotics, viruses reinvent themselves and are able to evade new medications, and animals adapt their behavior to the changing climate. The results are often visible.
It wasn't until late-1980s that biologists realized that natural selection can be observed in action as well. The key is that different traits have different rates of survival and reproduction (differential fitness), and can be transferred 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 species, it could quickly become more common than other alleles. In time, this could mean that the number of black moths within a 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 observe evolution when the species, like 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 are taken on a regular basis and more than 500.000 generations have been observed.
Lenski's research has shown that a mutation can profoundly alter the rate at the rate at which a population reproduces, and consequently the rate at which it alters. It also shows evolution takes time, a fact that is hard for some to accept.
Another example of microevolution is the way mosquito genes that are resistant to pesticides show up more often in areas where insecticides are employed. This is due to pesticides causing an exclusive pressure that favors those with resistant genotypes.
The rapidity of evolution has led to a greater appreciation of its importance particularly in a world shaped largely by human activity. This includes the effects of climate change, pollution and habitat loss, which prevents many species from adapting. Understanding the evolution process can aid you in making better decisions about the future of our planet and its inhabitants.