The Academy's Evolution Site
Biology is one of the most important concepts in biology. The Academies have been for a long time involved in helping people who are interested in science understand the theory of evolution and how it influences all areas of scientific exploration.
This site provides a range of sources for teachers, students and general readers of evolution. 에볼루션 카지노 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 religions and cultures as a symbol of unity and love. 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 changes in environmental conditions.
Early approaches to depicting the biological world focused on separating species into distinct categories that were distinguished by their physical and metabolic characteristics1. These methods rely on the sampling of different parts of organisms or short fragments of DNA have significantly increased the diversity of a tree of Life2. These trees are mostly populated of eukaryotes, while bacterial diversity is vastly underrepresented3,4.
Genetic techniques have greatly broadened our ability to depict the Tree of Life by circumventing the requirement for direct observation and experimentation. In particular, molecular methods enable us to create trees using sequenced markers, such as the small subunit of ribosomal RNA gene.
Despite the massive growth of the Tree of Life through genome sequencing, much biodiversity still awaits discovery. This is especially true of microorganisms, which are difficult to cultivate and are usually only represented in a single sample5. A recent analysis of all genomes produced an unfinished draft of the Tree of Life. This includes a variety of archaea, bacteria and other organisms that have not yet been isolated, or their diversity is not thoroughly understood6.
The expanded Tree of Life is particularly beneficial in assessing the biodiversity of an area, assisting to determine whether specific habitats require special protection. The information can be used in a range of ways, from identifying the most effective treatments to fight disease to enhancing the quality of crops. This information is also extremely valuable in conservation efforts. It can help biologists identify areas most likely to have cryptic species, which may have vital metabolic functions and be vulnerable to the effects of human activity. While funds to protect biodiversity are essential, ultimately the best way to preserve the world's biodiversity is for more people living in developing countries to be empowered with the knowledge to act locally in order to promote conservation from within.
Phylogeny
A phylogeny, also known as an evolutionary tree, reveals the connections between groups of organisms. Scientists can create an phylogenetic chart which shows the evolution of taxonomic groups using molecular data and morphological differences or similarities. The role of phylogeny is crucial in understanding the relationship between genetics, biodiversity and evolution.
A basic phylogenetic Tree (see Figure PageIndex 10 Finds the connections between organisms with similar traits and evolved from an ancestor with common traits. These shared traits can be homologous, or analogous. Homologous characteristics are identical in their evolutionary paths. Analogous traits could appear like they are but they don't have the same ancestry. Scientists combine similar traits into a grouping referred to as a clade. For instance, all of the species in a clade share the characteristic of having amniotic eggs and evolved from a common ancestor who had eggs. A phylogenetic tree is then built by connecting the clades to identify the species that are most closely related to one another.
To create a more thorough and precise phylogenetic tree scientists use molecular data from DNA or RNA to identify the connections between organisms. This information is more precise than morphological data and gives evidence of the evolutionary background of an organism or group. The analysis of molecular data can help researchers identify the number of species that share an ancestor common to them and estimate their evolutionary age.
The phylogenetic relationships of organisms can be affected by a variety of factors, including phenotypic flexibility, a kind of behavior that alters in response to specific environmental conditions. This can cause a particular trait to appear more similar in one species than other species, which can obscure the phylogenetic signal. This problem can be mitigated by using cladistics, which incorporates an amalgamation of analogous and homologous features in the tree.
Furthermore, phylogenetics may help predict the duration and rate of speciation. This information can aid conservation biologists to make decisions about which species they should protect from extinction. It is ultimately the preservation of phylogenetic diversity which will create a complete and balanced ecosystem.
Evolutionary Theory
The main idea behind evolution is that organisms acquire various characteristics over time due to their interactions with their surroundings. Many scientists have proposed theories of evolution, including the Islamic naturalist Nasir al-Din al-Tusi (1201-274) who believed that an organism could develop according to its own needs as well as the Swedish taxonomist Carolus Linnaeus (1707-1778), who created the modern hierarchical taxonomy as well as Jean-Baptiste Lamarck (1844-1829), who suggested that the usage or non-use of traits can cause changes that are passed on to the next generation.
In the 1930s and 1940s, theories from a variety of fields--including genetics, natural selection and particulate inheritance - came together to create the modern synthesis of evolutionary theory, which defines how evolution occurs through the variation of genes within a population, and how these variants change in time as a result of natural selection. This model, known as genetic drift, mutation, gene flow, and sexual selection, is a cornerstone of current evolutionary biology, and can be mathematically described.
Recent advances in the field of evolutionary developmental biology have shown how variation can be introduced to a species via mutations, genetic drift or reshuffling of genes in sexual reproduction, and even migration between populations. These processes, along with other ones like directional selection and gene erosion (changes in the frequency of genotypes over time) can lead to evolution. Evolution is defined by changes in the genome over time as well as changes in the phenotype (the expression of genotypes within individuals).
Students can better understand the concept of phylogeny by using evolutionary thinking into all aspects of biology. A recent study conducted by Grunspan and colleagues, for instance revealed that teaching students about the evidence supporting evolution increased students' acceptance of evolution in a college biology course. For 에볼루션코리아 on how to teach evolution look up The Evolutionary Potential in all Areas of Biology or Thinking Evolutionarily A Framework for Infusing Evolution into Life Sciences Education.
Evolution in Action
Traditionally, scientists have studied evolution through looking back, studying fossils, comparing species, and studying living organisms. Evolution is not a past event; it is an ongoing process that continues to be observed today. Viruses evolve to stay away from new drugs and bacteria evolve to resist antibiotics. Animals alter their behavior because of a changing environment. The results are often evident.
It wasn't until late 1980s that biologists began to realize that natural selection was at work. The key to this is that different traits can confer the ability to survive at different rates as well as reproduction, and may be passed down from one generation to the next.
In the past, if one allele - the genetic sequence that determines color - appeared in a population of organisms that interbred, it could be more common than other allele. In time, this 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 see evolution when a species, such as bacteria, has a high generation turnover. Since 1988, Richard Lenski, a biologist, has studied twelve populations of E.coli that descend from a single strain. The samples of each population were taken frequently and more than 500.000 generations of E.coli have passed.
Lenski's research has revealed that a mutation can dramatically alter the speed at which a population reproduces--and so the rate at which it changes. It also demonstrates that evolution takes time, a fact that many are unable to accept.
Another example of microevolution is the way mosquito genes that confer resistance to pesticides show up more often in populations where insecticides are used. Pesticides create a selective pressure which favors those who have resistant genotypes.
The rapid pace at which evolution can take place has led to a growing recognition of its importance in a world that is shaped by human activity, including climate change, pollution and the loss of habitats that prevent the species from adapting. Understanding the evolution process can assist you in making better choices regarding the future of the planet and its inhabitants.