The Academy's Evolution Site
The concept of biological evolution is a fundamental concept in biology. The Academies have long been involved in helping those interested in science comprehend the theory of evolution and how it permeates all areas of scientific research.
This site provides a range of sources for teachers, students as well as general readers about evolution. It contains the most important video clips from NOVA and WGBH's science programs on DVD.
Tree of Life
The Tree of Life is an ancient symbol that symbolizes the interconnectedness of life. It is seen in a variety of cultures and spiritual beliefs as a symbol of unity and love. It can be used in many practical ways in addition to providing a framework for understanding the evolution of species and how they react to changes in environmental conditions.
The first attempts to depict the biological world were founded on categorizing organisms on their physical and metabolic characteristics. These methods, which are based on the collection of various parts of organisms or short fragments of DNA, have significantly increased the diversity of a Tree of Life2. These trees are largely composed of eukaryotes, while the diversity of bacterial species is greatly underrepresented3,4.
Genetic techniques have greatly broadened our ability to depict the Tree of Life by circumventing the need for direct observation and experimentation. We can create trees by using molecular methods such as the small subunit ribosomal gene.
Despite the rapid growth of the Tree of Life through genome sequencing, a lot of biodiversity is waiting to be discovered. This is especially true of microorganisms, which are difficult to cultivate and are typically only represented in a single specimen5. A recent study of all genomes known to date has created a rough draft of the Tree of Life, including many archaea and bacteria that have not been isolated and whose diversity is poorly understood6.
The expanded Tree of Life is particularly useful in assessing the diversity of an area, which can help to determine if specific habitats require protection. This information can be used in a variety of ways, from identifying new medicines to combating disease to enhancing the quality of the quality of crops. The information is also incredibly beneficial to conservation efforts. It can help biologists identify the areas that are most likely to contain cryptic species that could have important metabolic functions that may be at risk of anthropogenic changes. Although funds to safeguard biodiversity are vital, ultimately the best way to ensure the preservation of biodiversity around the world 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 is also known as an evolutionary tree, reveals the relationships between various groups of organisms. Using molecular data as well as morphological similarities and distinctions or ontogeny (the course of development of an organism) scientists can construct a phylogenetic tree which illustrates the evolution of taxonomic groups. Phylogeny plays a crucial role in understanding biodiversity, genetics and evolution.
A basic phylogenetic Tree (see Figure PageIndex 10 Determines the relationship 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 their evolutionary origins and analogous traits appear like they do, but don't have the identical origins. Scientists put similar traits into a grouping known as a Clade. All organisms in a group have a common trait, such as amniotic egg production. They all came 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.
Scientists utilize DNA or RNA molecular data to build a phylogenetic chart that is more precise and precise. This information is more precise and provides evidence of the evolutionary history of an organism. Researchers can utilize Molecular Data to estimate the evolutionary age of living organisms and discover the number of organisms that share a common ancestor.
The phylogenetic relationship can be affected by a variety of factors, including phenotypicplasticity. This is a type behavior that alters due to unique environmental conditions. This can cause a trait to appear more similar to one species than to another, obscuring the phylogenetic signals. However, this issue can be cured by the use of techniques like cladistics, which combine similar and homologous traits into the tree.
Additionally, phylogenetics can help determine the duration and speed at which speciation takes place. This information will assist conservation biologists in deciding which species to safeguard from the threat of extinction. In the end, it is the preservation of phylogenetic diversity that will lead to 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 proposed by a wide range of scientists such as the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who proposed that a living organism develop slowly according to its requirements, the Swedish botanist Carolus Linnaeus (1707-1778) who conceived the modern hierarchical taxonomy Jean-Baptiste Lamarck (1744-1829) who suggested that the use or non-use of traits cause changes that can be passed onto 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, which defines how evolution occurs through the variation of genes within a population and how these variants change over time due to natural selection. This model, called genetic drift or mutation, gene flow and sexual selection, is the foundation of modern evolutionary biology and can be mathematically explained.
Recent discoveries in the field of evolutionary developmental biology have revealed that variation can be introduced into a species through mutation, genetic drift, and reshuffling genes during sexual reproduction, as well as by migration between populations. These processes, in conjunction with other ones like directional selection and gene erosion (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 the phenotype (the expression of genotypes within individuals).
Incorporating evolutionary thinking into all aspects of biology education can improve student understanding of the concepts of phylogeny and evolution. A recent study by Grunspan and colleagues, for instance demonstrated that teaching about the evidence that supports evolution helped students accept the concept of evolution in a college biology class. For more details about how to teach evolution look up The Evolutionary Potential in All Areas of Biology or Thinking Evolutionarily as a Framework for Infusing Evolution into Life Sciences Education.
Evolution in Action
Traditionally, scientists have studied evolution through looking back--analyzing fossils, comparing species and observing living organisms. But evolution isn't just something that happened in the past; it's an ongoing process that is taking place in the present. Bacteria transform and resist antibiotics, viruses evolve and escape new drugs, and animals adapt their behavior in response to a changing planet. The results are usually visible.
But it wasn't until the late 1980s that biologists realized that natural selection can be observed in action as well. The main reason is that different traits confer the ability to survive at different rates and reproduction, and can be passed on from one generation to the next.
In the past, if an allele - the genetic sequence that determines color - appeared in a population of organisms that interbred, it could become more prevalent than any other allele. As time passes, that could mean the number of black moths within a population could increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.
It is easier to see evolution when a species, such as bacteria, has a rapid generation turnover. Since 1988, Richard Lenski, a biologist, has been tracking twelve populations of E.coli that descend from a single strain. Samples of each population have been collected regularly and more than 50,000 generations of E.coli have been observed to have passed.
Lenski's research has revealed that mutations can alter the rate of change and the rate of a population's reproduction. It also shows evolution takes time, a fact that is difficult for some to accept.
에볼루션 바카라 of microevolution is how mosquito genes for resistance to pesticides show up more often in areas where insecticides are employed. That's because the use of pesticides causes a selective pressure that favors those with resistant genotypes.
The rapidity of evolution has led to a greater recognition of its importance, especially in a world which is largely shaped by human activities. This includes pollution, climate change, and habitat loss that hinders many species from adapting. Understanding the evolution process can aid you in making better decisions regarding the future of the planet and its inhabitants.