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The Academy's Evolution Site

Biology is one of the most important concepts in biology. The Academies have long been involved in helping those interested in science understand the theory of evolution and how it influences every area of scientific inquiry.

This site provides students, teachers and general readers with a wide range of learning resources about evolution. It includes key video clip from NOVA and WGBH produced science programs on DVD.

Tree of Life

The Tree of Life is an ancient symbol of the interconnectedness of all life. It is a symbol of love and unity in many cultures. It has many practical applications as well, including providing a framework to understand the evolution of species and how they respond to changes in environmental conditions.

The first attempts at depicting the biological world focused on separating organisms into distinct categories which were identified by their physical and metabolic characteristics1. These methods, which depend on the sampling of different parts of organisms or short fragments of DNA have greatly increased the diversity of a tree of Life2. However the trees are mostly made up of eukaryotes. Bacterial diversity is still largely unrepresented3,4.

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 allow us to build trees by using sequenced markers, such as the small subunit of ribosomal RNA gene.

The Tree of Life has been dramatically expanded through genome sequencing. However there is a lot of diversity to be discovered. This is particularly relevant to microorganisms that are difficult to cultivate and are typically found in a single specimen5. A recent analysis of all genomes produced a rough draft of a Tree of Life. This includes a variety of bacteria, archaea and other organisms that have not yet been identified or the diversity of which is not well understood6.

This expanded Tree of Life is particularly beneficial in assessing the biodiversity of an area, assisting to determine if certain habitats require protection. This information can be utilized in a variety of ways, from identifying new medicines to combating disease to enhancing the quality of the quality of crops. It is also valuable to conservation efforts. It can aid biologists in identifying areas that are likely to be home to species that are cryptic, which could have vital metabolic functions and be vulnerable to changes caused by humans. Although funding to protect biodiversity are essential however, 에볼루션 코리아 바카라 무료 (Wikimapia.org) the most effective method to preserve the world's biodiversity is for more people living in developing countries to be equipped with the knowledge to act locally to promote conservation from within.

Phylogeny

A phylogeny, also known as an evolutionary tree, shows the relationships between groups of organisms. Using molecular data as well as morphological similarities and distinctions or ontogeny (the process of the development of an organism) scientists can create an phylogenetic tree that demonstrates the evolution of taxonomic categories. Phylogeny plays a crucial role in understanding genetics, biodiversity and evolution.

A basic phylogenetic Tree (see Figure PageIndex 10 Identifies the relationships between organisms that have similar traits and have evolved from a common ancestor. These shared traits may be homologous, or analogous. Homologous traits are identical in their underlying evolutionary path while analogous traits appear similar but do not have the identical origins. Scientists arrange similar traits into a grouping known as a the clade. All members of a clade share a characteristic, like amniotic egg production. They all derived from an ancestor who had these eggs. A phylogenetic tree can be constructed by connecting the clades to identify the species who are the closest to each other.

For a more precise and accurate phylogenetic tree, scientists use molecular data from DNA or RNA to establish the relationships among organisms. This information is more precise and gives evidence of the evolution of an organism. Molecular data allows researchers to identify the number of species who share a common ancestor and to estimate their evolutionary age.

Phylogenetic relationships can be affected by a number of factors such as the phenotypic plasticity. This is a type behaviour that can change due to unique environmental conditions. This can cause a characteristic to appear more resembling to one species than to the other and obscure the phylogenetic signals. However, this issue can be reduced by the use of techniques such as cladistics that include a mix of similar and homologous traits into the tree.

Additionally, 에볼루션코리아 phylogenetics can aid in predicting the length and speed of speciation. This information can aid conservation biologists to make decisions about which species they should protect from extinction. In the end, it's the conservation of phylogenetic diversity that will lead to an ecosystem that is complete and balanced.

Evolutionary Theory

The central theme of evolution is that organisms acquire distinct characteristics over time due to 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 conceived the modern hierarchical taxonomy as well as Jean-Baptiste Lamarck (1844-1829), who suggested that the use 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, 에볼루션 슬롯 including genetics, natural selection, and particulate inheritance--came together to form the modern evolutionary theory synthesis, which defines how evolution is triggered by the variations of genes within a population, and how those variations change over time due to natural selection. This model, which includes mutations, genetic drift in gene flow, and sexual selection, can be mathematically described.

Recent discoveries in the field of evolutionary developmental biology have demonstrated the ways in which variation can be introduced to a species by genetic drift, mutations, reshuffling genes during sexual reproduction, and even migration between populations. These processes, along with others such as 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 and changes in phenotype (the expression of genotypes in an individual).

Incorporating evolutionary thinking into all aspects of biology education could increase students' understanding of phylogeny and evolution. A recent study conducted by Grunspan and colleagues, for instance, showed that teaching about the evidence that supports evolution increased students' understanding of evolution in a college-level biology class. For more details about how to teach evolution read The Evolutionary Power of Biology in all Areas of Biology or Thinking Evolutionarily: a Framework for Integrating Evolution into Life Sciences Education.

Evolution in Action

Traditionally scientists have studied evolution by looking back, studying fossils, comparing species and observing living organisms. Evolution is not a distant event, but an ongoing process that continues to be observed today. Bacteria mutate and resist antibiotics, viruses re-invent themselves and are able to evade new medications, and animals adapt their behavior to a changing planet. The changes that result are often apparent.

It wasn't until late 1980s that biologists realized that natural selection could be observed in action as well. The key is that various traits confer different rates of survival and reproduction (differential fitness) and are passed down from one generation to the next.

In the past, if one allele - the genetic sequence that determines colour appeared in a population of organisms that interbred, it could be 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.

The ability to observe evolutionary change is much easier when a species has a rapid turnover of its generation, as with bacteria. Since 1988, Richard Lenski, a biologist, has studied twelve populations of E.coli that are descended from one strain. Samples from each population have been taken regularly, 에볼루션사이트 and more than 50,000 generations of E.coli have passed.

Lenski's work has shown that mutations can alter the rate of change and the efficiency at which a population reproduces. It also demonstrates that evolution takes time, which is difficult for some to accept.

Microevolution can also be seen in the fact that mosquito genes for resistance to pesticides are more prevalent in areas that have used insecticides. This is due to pesticides causing an exclusive pressure that favors those with resistant genotypes.

The rapidity of evolution has led to an increasing appreciation of its importance especially in a planet which is largely shaped by human activities. This includes the effects of climate change, pollution and habitat loss that hinders many species from adapting. Understanding evolution will assist you in making better choices about the future of our planet and its inhabitants.