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The Academy's Evolution Site

Biological evolution is one of the most important concepts in biology. The Academies are committed to helping those interested in science learn about the theory of evolution and how it can be applied in all areas of scientific research.

This site provides a range of sources for students, teachers as well as general readers about evolution. It includes important video clips from NOVA and the WGBH-produced science programs on DVD.

Tree of Life

The Tree of Life, an ancient symbol, symbolizes the interconnectedness of all life. It appears in many religions and cultures as symbolizing unity and love. It also has practical uses, like providing a framework to understand the history of species and how they respond to changing environmental conditions.

The first attempts to depict the biological world were based on categorizing organisms based on their physical and metabolic characteristics. These methods, which are based on the sampling of different parts of organisms or fragments of DNA, have significantly increased the diversity of a Tree of Life2. However, these trees are largely made up of eukaryotes. Bacterial diversity is not represented in a large way3,4.

By avoiding the necessity for direct experimentation and observation genetic techniques have made it possible to depict the Tree of Life in a more precise manner. Particularly, molecular techniques allow us to construct trees by using sequenced markers such as the small subunit of ribosomal RNA gene.

Despite the dramatic growth of the Tree of Life through genome sequencing, much biodiversity still awaits discovery. This is especially true of microorganisms, which can be difficult to cultivate and are often only present in a single specimen5. A recent study of all known genomes has created a rough draft of the Tree of Life, including numerous archaea and bacteria that are not isolated and whose diversity is poorly understood6.

The expanded Tree of Life is particularly beneficial in assessing the biodiversity of an area, assisting to determine if specific habitats require protection. This information can be utilized in many ways, including finding new drugs, fighting diseases and enhancing crops. The information is also beneficial in conservation efforts. It can help biologists identify areas that are most likely to have cryptic species, which may have vital metabolic functions and be vulnerable to the effects of human activity. Although funding to protect biodiversity are crucial however, the most effective method to protect the world's biodiversity is for more people living in developing countries to be empowered 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 different groups of organisms. Scientists can build a phylogenetic chart that shows the evolutionary relationships between taxonomic categories using molecular information and morphological similarities or differences. Phylogeny is essential in understanding evolution, biodiversity and 에볼루션 무료 바카라 genetics.

A basic phylogenetic Tree (see Figure PageIndex 10 Determines the relationship between organisms that have similar characteristics and have evolved from an ancestor with common traits. These shared traits could be analogous or 에볼루션 코리아 homologous. Homologous traits share their underlying evolutionary path, while analogous traits look similar but do not have the identical origins. Scientists group similar traits into a grouping called a Clade. For instance, all of the species in a clade share the characteristic of having amniotic egg and evolved from a common ancestor that had eggs. The clades are then linked to form a phylogenetic branch that can determine which organisms have the closest connection to each other.

For a more detailed and accurate phylogenetic tree scientists use molecular data from DNA or RNA to determine the relationships among organisms. This data is more precise than morphological data and provides evidence of the evolutionary background of an organism or group. Researchers can use Molecular Data to calculate the age of evolution of living organisms and discover how many species share a common ancestor.

Phylogenetic relationships can be affected by a variety of factors that include phenotypicplasticity. This is a type behavior that alters in response to particular environmental conditions. This can cause a trait to appear more resembling to one species than another and obscure the phylogenetic signals. This issue can be cured by using cladistics, which incorporates an amalgamation of homologous and analogous features in the tree.

Additionally, phylogenetics can help predict the time and pace of speciation. This information can help conservation biologists make decisions about which species to protect from the threat of extinction. In the end, it's the conservation of phylogenetic variety that will result in an ecosystem that is balanced and complete.

Evolutionary Theory

The fundamental concept in evolution is that organisms alter over time because of their interactions with their environment. A variety of theories about evolution have been proposed by a wide range of scientists, including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who proposed that a living organism develop slowly in accordance with its requirements and needs, the Swedish botanist Carolus Linnaeus (1707-1778) who designed the modern hierarchical taxonomy Jean-Baptiste Lamarck (1744-1829) who suggested that use or disuse of traits cause changes that could be passed on to the offspring.

In the 1930s & 1940s, concepts from various fields, 에볼루션 바카라 체험 including genetics, natural selection and particulate inheritance, merged to form a contemporary evolutionary theory. This explains how evolution occurs by the variations in genes within the population and how these variations change with time due to natural selection. This model, which incorporates mutations, genetic drift in gene flow, and sexual selection can be mathematically described.

Recent advances in evolutionary developmental biology have revealed how variations can be introduced to a species by mutations, genetic drift, reshuffling genes during sexual reproduction, and even migration between populations. These processes, 에볼루션 무료 바카라 as well as others such as directional selection and gene erosion (changes in frequency of genotypes over time) can result in evolution. Evolution is defined by changes in the genome over time, as well as changes in the phenotype (the expression of genotypes within individuals).

Incorporating evolutionary thinking into all areas of biology education can improve students' understanding of phylogeny as well as evolution. A recent study by Grunspan and colleagues, for instance revealed that teaching students about the evidence supporting evolution increased students' acceptance of evolution in a college-level biology class. To learn more about how to teach about evolution, please read The Evolutionary Potential of all Areas of Biology and Thinking Evolutionarily A Framework for Infusing the Concept of Evolution into Life Sciences Education.

Evolution in Action

Traditionally, scientists have studied evolution by looking back, studying 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 right now. Bacteria mutate and resist antibiotics, viruses reinvent themselves and are able to evade new medications and animals alter their behavior to the changing environment. The resulting changes are often visible.

But it wasn't until the late-1980s that biologists realized that natural selection can be seen in action, as well. The key is that various traits have different rates of survival and reproduction (differential fitness), and can be transferred from one generation to the next.

In the past, if one allele - the genetic sequence that determines colour - was found in a group of organisms that interbred, it could be more common than any other allele. Over time, that would mean the number of black moths in a population could increase. The same is true for 바카라 에볼루션 many other characteristics--including morphology and behavior--that vary among populations of organisms.

It is easier to see evolutionary change when the species, like bacteria, has a high generation turnover. Since 1988, Richard Lenski, a biologist, has been tracking twelve populations of E.coli that are descended from a single strain. Samples of each population were taken frequently and more than 50,000 generations of E.coli have been observed to have passed.

Lenski's research has demonstrated that mutations can alter the rate at which change occurs and the rate of a population's reproduction. It also proves that evolution takes time, a fact that some people are unable to accept.

Microevolution can also be seen in the fact that mosquito genes for pesticide resistance are more common in populations that have used insecticides. This is because pesticides cause an exclusive pressure that favors those who have resistant genotypes.

The rapidity of evolution has led to a growing recognition of its importance particularly in a world that is largely shaped by human activity. This includes pollution, climate change, and habitat loss, which prevents many species from adapting. Understanding evolution can help you make better decisions about the future of the planet and its inhabitants.