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The Academy's Evolution Site

Biology is one of the most central concepts in biology. The Academies have been active for a long time in helping those interested in science comprehend the theory of evolution and how it affects all areas of scientific research.

This site provides a wide range of resources for students, teachers and general readers of 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 of the interconnectedness of life. It is seen in a variety of cultures and spiritual beliefs as symbolizing unity and love. It also has practical applications, like providing a framework to understand the evolution of species and how they respond to changes in environmental conditions.

Early approaches to depicting the biological world focused on categorizing organisms into distinct categories which had been distinguished by their physical and metabolic characteristics1. These methods, which rely on sampling of different parts of living organisms or small fragments of their DNA, significantly expanded the diversity that could be represented in a tree of life2. However the trees are mostly composed of eukaryotes; bacterial diversity is still largely unrepresented3,4.

Genetic techniques have significantly expanded our ability to visualize the Tree of Life by circumventing the need for direct observation and experimentation. Particularly, molecular techniques enable us to create trees by using sequenced markers such as the small subunit of ribosomal RNA gene.

Despite the massive growth of the Tree of Life through genome sequencing, a large amount of biodiversity is waiting to be discovered. This is especially the case for microorganisms which are difficult to cultivate, and which are usually only found in one sample5. A recent analysis of all genomes resulted in an unfinished draft of the Tree of Life. This includes a wide range of archaea, bacteria, and other organisms that have not yet been isolated or the diversity of which is not fully understood6.

This expanded Tree of Life is particularly useful for 에볼루션바카라 assessing the biodiversity of an area, which can help to determine whether specific habitats require protection. The information is useful in many ways, including finding new drugs, battling diseases and improving crops. The information is also useful in conservation efforts. It can aid biologists in identifying the areas most likely to contain cryptic species that could have important metabolic functions that could be vulnerable to anthropogenic change. Although funding to protect biodiversity are essential however, the most effective method to preserve the world's biodiversity is for more people in developing countries to be empowered with the knowledge to take action locally to encourage conservation from within.

Phylogeny

A phylogeny, also called an evolutionary tree, illustrates the relationships between groups of organisms. Using molecular data, morphological similarities and differences, or ontogeny (the process of the development of an organism) scientists can construct a phylogenetic tree that illustrates the evolution of taxonomic categories. Phylogeny is essential in understanding the evolution of biodiversity, evolution and genetics.

A basic phylogenetic Tree (see Figure PageIndex 10 Finds the connections between organisms that have similar traits and evolved from an ancestor that shared traits. These shared traits could be analogous or homologous. Homologous traits are similar in terms of their evolutionary path. Analogous traits might appear similar however they do not have the same origins. Scientists put similar traits into a grouping called a clade. All members of a clade have a common characteristic, like amniotic egg production. They all derived from an ancestor that had these eggs. The clades then join to create a phylogenetic tree to determine the organisms with the closest relationship to.

For a more precise and 에볼루션 슬롯게임 accurate phylogenetic tree, scientists use molecular data from DNA or RNA to determine the relationships among organisms. This information is more precise and gives evidence of the evolution of an organism. The use of molecular data lets researchers identify the number of species that share an ancestor common to them and estimate their evolutionary age.

The phylogenetic relationships of a species can be affected by a variety of factors such as the phenotypic plasticity. This is a kind of behaviour that can change in response to particular environmental conditions. This can cause a characteristic to appear more similar in one species than another, clouding the phylogenetic signal. This problem can be addressed by using cladistics, which incorporates a combination of analogous and homologous features in the tree.

In addition, phylogenetics can aid in predicting the time and pace of speciation. This information can aid conservation biologists to make decisions about the species they should safeguard from extinction. In the end, it's the preservation of phylogenetic diversity that will lead to an ecologically balanced and complete ecosystem.

Evolutionary Theory

The fundamental concept of evolution is that organisms acquire distinct characteristics over time as a result of their interactions with their environment. Many scientists have developed theories of evolution, such as the Islamic naturalist Nasir al-Din al-Tusi (1201-274) who believed that a living thing would develop according to its own needs, the Swedish taxonomist Carolus Linnaeus (1707-1778) who developed the modern hierarchical system of taxonomy, as well as Jean-Baptiste Lamarck (1844-1829), who suggested that the usage or non-use of certain traits can result in changes that are passed on to the next generation.

In the 1930s and 1940s, theories from various fields, including natural selection, 에볼루션 무료 바카라 genetics, and particulate inheritance -- came together to form the modern evolutionary theory which explains how evolution is triggered by the variations of genes within a population, and how these variants change over time as a result of natural selection. This model, which incorporates mutations, 에볼루션 카지노 genetic drift, gene flow and sexual selection can be mathematically described mathematically.

Recent developments in the field of evolutionary developmental biology have demonstrated that variations can be introduced into a species via genetic drift, mutation, and reshuffling genes during sexual reproduction, and 바카라 에볼루션 also through the movement of 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 lead towards evolution. Evolution is defined by changes in the genome over time as well as changes in phenotype (the expression of genotypes in individuals).

Students can gain a better understanding of the concept of phylogeny by using evolutionary thinking throughout all areas of biology. A recent study by Grunspan and colleagues, for example demonstrated that teaching about the evidence supporting evolution increased students' acceptance of evolution in a college-level biology class. For more information about how to teach evolution, see The Evolutionary Power of Biology in All Areas of Biology or Thinking Evolutionarily as a Framework for Integrating Evolution into Life Sciences Education.

Evolution in Action

Traditionally scientists have studied evolution by studying fossils, comparing species, and studying living organisms. Evolution is not a past event, but a process that continues today. Viruses reinvent themselves to avoid new medications and bacteria mutate to resist antibiotics. Animals alter their behavior because of a changing world. The changes that occur are often visible.

It wasn't until late 1980s that biologists understood that natural selection can be observed in action as well. The main reason 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 particular allele--the genetic sequence that determines coloration--appeared in a group of interbreeding species, it could quickly become more prevalent than the other alleles. Over time, this would mean that the number of moths sporting black pigmentation could increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.

Observing evolutionary change in action is easier when a species has a fast generation turnover such as bacteria. Since 1988 the biologist Richard Lenski has been tracking twelve populations of E. coli that descended from a single strain; samples from each population are taken every day and more than fifty thousand generations have been observed.

Lenski's research has shown that a mutation can profoundly alter the speed at which a population reproduces--and so the rate at which it changes. It also shows that evolution takes time, a fact that some find hard 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. Pesticides create an enticement that favors those who have resistant genotypes.

The rapidity of evolution has led to a greater appreciation of its importance especially in a planet shaped largely by human activity. This includes the effects of climate change, pollution and habitat loss that hinders many species from adapting. Understanding the evolution process can help us make smarter choices about the future of our planet as well as the life of its inhabitants.