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The Academy's Evolution Site

Biological evolution is one of the most central concepts in biology. The Academies are involved in helping those who are interested in the sciences learn about the theory of evolution and how it can be applied in all areas of scientific research.

This site provides students, teachers and general readers with a variety of learning resources on evolution. It also includes important 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 all life. It is an emblem of love and unity across many cultures. It also has practical applications, like providing a framework to understand the history of species and how they react to changes in the environment.

The earliest attempts to depict the biological world focused on categorizing organisms into distinct categories which were identified by their physical and metabolic characteristics1. These methods, based on the sampling of different parts of living organisms or short fragments of their DNA, significantly expanded the diversity that could be represented in a tree of life2. However, these trees are largely composed of eukaryotes; bacterial diversity remains vastly underrepresented3,4.

Genetic techniques have significantly expanded our ability to represent the Tree of Life by circumventing the requirement for direct observation and experimentation. We can create trees using molecular techniques such as the small subunit ribosomal gene.

Despite the rapid expansion of the Tree of Life through genome sequencing, much biodiversity still is waiting to be discovered. This is especially true of microorganisms, which can be difficult to cultivate and are typically only represented in a single specimen5. A recent analysis of all genomes resulted in a rough draft of a Tree of Life. This includes a wide range 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 is particularly useful for assessing the biodiversity of an area, assisting to determine if specific habitats require special protection. The information can be used in a range of ways, from identifying new treatments to fight disease to enhancing the quality of crop yields. This information is also beneficial for conservation efforts. It helps biologists discover areas that are likely to be home to cryptic species, which may perform important metabolic functions, and could be susceptible to the effects of human activity. While funds to protect biodiversity are important, the best method to protect the biodiversity of the world is to equip more people in developing nations with the information they require to act locally and promote conservation.

Phylogeny

A phylogeny (also called an evolutionary tree) shows the relationships between species. By using molecular information similarities and differences in morphology or ontogeny (the process of the development of an organism), scientists can build a phylogenetic tree that illustrates the evolution of taxonomic groups. Phylogeny is essential in understanding evolution, biodiversity and genetics.

A basic phylogenetic Tree (see Figure PageIndex 10 ) identifies the relationships between organisms that share similar traits that have evolved from common ancestral. These shared traits can be analogous, or homologous. Homologous traits are similar in their evolutionary roots and analogous traits appear similar but do not have the same ancestors. Scientists group similar traits into a grouping known as a the clade. All organisms in a group share a characteristic, for example, amniotic egg production. They all came from an ancestor who had these eggs. A phylogenetic tree is then built by connecting the clades to determine the organisms who are the closest to each other.

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

The phylogenetic relationship can be affected by a number of factors, including phenotypicplasticity. This is a type of behavior that alters due 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 addressed by using cladistics. This is a method that incorporates a combination of homologous and analogous traits in the tree.

Furthermore, phylogenetics may help predict the duration and rate of speciation. This information can assist conservation biologists in making choices about which species to safeguard from disappearance. In the end, it is the conservation of phylogenetic diversity that will result in an ecosystem that is balanced and complete.

Evolutionary Theory

The main idea behind 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 variety of scientists such as the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who envisioned an organism developing slowly according to its requirements and needs, the Swedish botanist Carolus Linnaeus (1707-1778) who developed the modern hierarchical taxonomy Jean-Baptiste Lamarck (1744-1829) who suggested that use or disuse 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 form the modern evolutionary theory synthesis, which defines how evolution occurs through the variation of genes within a population and 에볼루션 코리아 how those variants change in time as a result of natural selection. This model, which encompasses mutations, genetic drift in gene flow, and sexual selection, can be mathematically described.

Recent discoveries in the field of evolutionary developmental biology have demonstrated that genetic variation can be introduced into a species through mutation, genetic drift, and reshuffling genes during sexual reproduction, as well as through migration between populations. These processes, along with others like directional selection and genetic erosion (changes in the frequency of an individual's genotype over time) can lead to evolution that is defined as changes in the genome of the species over time and the change in phenotype over time (the expression of that genotype in an individual).

Students can gain a better understanding of the concept of phylogeny through incorporating evolutionary thinking in all aspects of biology. In a recent study conducted by Grunspan and colleagues. It was found that teaching students about the evidence for evolution boosted their understanding of evolution during a college-level course in biology. For more information on how to teach evolution, see 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 by looking back--analyzing fossils, comparing species and observing living organisms. But evolution isn't just something that occurred in the past; it's an ongoing process, that is taking place today. Viruses evolve to stay away from new drugs and bacteria evolve to resist antibiotics. Animals alter their behavior as a result of a changing environment. The results are usually evident.

But it wasn't until the late-1980s that biologists realized that natural selection can be seen in action, as well. The key is the fact that different traits confer the ability to survive at different rates and reproduction, and can be passed on from one generation to another.

In the past, if a certain allele - the genetic sequence that determines colour - appeared in a population of organisms that interbred, it might become more common than any other allele. Over time, this would mean that the number of moths that have black pigmentation may increase. The same is true for 에볼루션 바카라 사이트 many other characteristics--including morphology and behavior--that vary among populations of organisms.

It is easier to observe evolution when a species, 에볼루션 슬롯 such as 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 from each population are taken every day, and over fifty thousand generations have been observed.

Lenski's research has revealed that a mutation can profoundly alter the speed at which a population reproduces and, consequently, the rate at which it alters. It also proves that evolution takes time, a fact that some find difficult to accept.

Another example of microevolution is that mosquito genes that confer resistance to pesticides show up more often in populations in which insecticides are utilized. This is due to the fact that the use of pesticides creates a selective pressure that favors those with resistant genotypes.

The rapidity of evolution has led to a greater awareness of its significance, especially in a world shaped largely by human activity. This includes the effects of climate change, pollution and habitat loss that prevents many species from adapting. Understanding evolution will assist you in making better choices regarding the future of the planet and its inhabitants.