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The Academy's Evolution Site

Biological evolution is one of the most fundamental concepts in biology. The Academies have been for a long time 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 on evolution. It also includes important 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 an emblem of love and harmony in a variety of cultures. It also has many practical applications, like providing a framework to understand the history of species and how they respond to changes in environmental conditions.

Early attempts to represent the world of biology were founded on categorizing organisms on their physical and metabolic characteristics. These methods, which relied on sampling of different parts of living organisms or on small DNA fragments, significantly increased the variety that could be represented in the tree of life2. These trees are mostly populated by eukaryotes, and bacteria are largely underrepresented3,4.

Genetic techniques have greatly expanded our ability to represent the Tree of Life by circumventing the need for direct observation and experimentation. Particularly, molecular methods allow us to construct trees using sequenced markers such as the small subunit of ribosomal RNA gene.

Despite the rapid expansion of the Tree of Life through genome sequencing, a large amount of biodiversity awaits discovery. This is particularly true of microorganisms, which can be difficult to cultivate and are typically only represented in a single sample5. Recent analysis of all genomes has produced an initial draft of the Tree of Life. This includes a variety of bacteria, 에볼루션 무료체험 archaea and other organisms that haven't yet been isolated or whose diversity has not been fully understood6.

The expanded Tree of Life can be used to assess the biodiversity of a specific region and determine if particular habitats need special protection. The information can be used in a range of ways, from identifying new medicines to combating disease to enhancing the quality of crop yields. This information is also extremely beneficial to conservation efforts. It can aid biologists in identifying areas most likely to be home to cryptic species, which could perform important metabolic functions and be vulnerable to the effects of human activity. Although funds to safeguard biodiversity are vital but the most effective way to protect the world's biodiversity is for more people in developing countries to be equipped with the knowledge to take action locally to encourage conservation from within.

Phylogeny

A phylogeny is also known as an evolutionary tree, illustrates the relationships between different groups of organisms. By using molecular information as well as morphological similarities and distinctions, or ontogeny (the process of the development of an organism) scientists can construct a phylogenetic tree that illustrates the evolution of taxonomic categories. Phylogeny plays a crucial role in understanding biodiversity, 에볼루션 genetics and evolution.

A basic phylogenetic Tree (see Figure PageIndex 10 ) is a method of identifying the relationships between organisms that share similar traits that evolved from common ancestral. These shared traits can be either analogous or homologous. Homologous traits are similar in their evolutionary path. Analogous traits could appear like they are but they don't share the same origins. Scientists combine similar traits into a grouping referred to as a Clade. For instance, all of the organisms in a clade share the trait of having amniotic eggs and evolved from a common ancestor which had these eggs. The clades then join to form a phylogenetic branch that can identify organisms that have the closest connection to each other.

For a more detailed and accurate phylogenetic tree scientists rely on molecular information from DNA or RNA to establish the connections between organisms. This information is more precise and provides evidence of the evolutionary history of an organism. Molecular data allows researchers to identify the number of organisms that share a common ancestor and to estimate their evolutionary age.

The phylogenetic relationships of a species can be affected by a number of factors that include the phenotypic plasticity. This is a type behavior that changes due to particular environmental conditions. This can cause a characteristic to appear more like a species other species, which can obscure the phylogenetic signal. This problem can be mitigated by using cladistics, which is a the combination of analogous and homologous features in the tree.

Additionally, phylogenetics can help predict the duration and rate of speciation. This information will assist conservation biologists in making decisions about which species to protect from extinction. It is ultimately the preservation of phylogenetic diversity which will result in an ecosystem that is complete and balanced.

Evolutionary Theory

The central theme in evolution is that organisms change over time as a result of their interactions with their environment. A variety of theories about evolution have been proposed by a wide variety of scientists, including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who envisioned an organism developing slowly according to its requirements as well as the Swedish botanist Carolus Linnaeus (1707-1778) who designed modern hierarchical taxonomy, and Jean-Baptiste Lamarck (1744-1829) who suggested that the use or misuse of traits cause changes that could be passed onto offspring.

In the 1930s & 1940s, concepts from various fields, including genetics, natural selection and particulate inheritance, merged to create a modern synthesis of evolution theory. This defines how evolution is triggered by the variation of genes in the population and 에볼루션 사이트 how these variants alter over time due to natural selection. This model, called genetic drift or mutation, gene flow and sexual selection, is a key element of modern evolutionary biology and 에볼루션 게이밍바카라사이트 (Bramsen-Fitzgerald.Technetbloggers.De) is mathematically described.

Recent discoveries in the field of evolutionary developmental biology have revealed how variation can be introduced to a species by genetic drift, mutations or reshuffling of genes in sexual reproduction, and even migration between populations. These processes, along with other ones like directional selection and genetic erosion (changes in the frequency of the genotype over time), can lead to evolution that is defined as change in the genome of the species over time, and the change in phenotype over time (the expression of the genotype in an individual).

Students can gain a better understanding of the concept of phylogeny through incorporating evolutionary thinking into all areas of biology. In a study by Grunspan and colleagues., it was shown 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 about evolution, read The Evolutionary Potential in 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 through studying fossils, comparing species and observing living organisms. Evolution is not a distant 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 as a result of a changing environment. The changes that result are often easy to see.

It wasn't until the late 1980s when biologists began to realize that natural selection was in action. The key is that different traits have different rates of survival and reproduction (differential fitness), and can be passed down from one generation to the next.

In the past when one particular allele, the genetic sequence that controls coloration - was present in a group of interbreeding organisms, it could quickly become more prevalent than all other alleles. Over time, this would mean that the number of moths sporting black pigmentation in a group 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 rapid generation turnover like bacteria. Since 1988, Richard Lenski, a biologist, has tracked twelve populations of E.coli that are descended from a single strain. Samples from each population have been collected regularly, and more than 50,000 generations of E.coli have passed.

Lenski's research has revealed that a mutation can dramatically alter the efficiency with which a population reproduces and, consequently the rate at which it changes. It also shows evolution takes time, something that is difficult for some to accept.

Microevolution can also be seen in the fact that mosquito genes that confer resistance to pesticides are more prevalent in areas where insecticides have been used. Pesticides create a selective pressure which favors those who have resistant genotypes.

The rapidity of evolution has led to an increasing recognition of its importance particularly in a world which is largely shaped by human activities. This includes climate change, pollution, and habitat loss that prevents many species from adapting. Understanding the evolution process can help us make better decisions regarding the future of our planet and the lives of its inhabitants.