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The Academy's Evolution Site

Biology is a key concept in biology. The Academies are committed to helping those interested in the sciences comprehend the evolution theory and how it is incorporated throughout all fields of scientific research.

This site provides students, teachers and general readers with a wide range of learning resources on evolution. It includes the most 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 life. It is used in many cultures and spiritual beliefs as a symbol of unity and love. It can be used in many practical ways as well, such as providing a framework for understanding the history of species, and how they respond to changes in environmental conditions.

The first attempts at depicting the world of biology focused on the classification of organisms into distinct categories that had been distinguished by physical and metabolic characteristics1. These methods, which relied on the sampling of different parts of living organisms or sequences of small fragments of their DNA greatly increased the variety of organisms that could be represented in the tree of life2. However, these trees are largely made up of eukaryotes. Bacterial diversity is not represented in a large way3,4.

Genetic techniques have greatly broadened our ability to represent the Tree of Life by circumventing the need for direct observation and experimentation. Trees can be constructed using molecular methods such as the small subunit ribosomal gene.

Despite the massive expansion of the Tree of Life through genome sequencing, a lot of biodiversity remains to be discovered. This is especially true for microorganisms that are difficult to cultivate, and are typically found in one sample5. A recent analysis of all genomes resulted in an initial draft of a Tree of Life. This includes a wide range of archaea, bacteria and other organisms that have not yet been isolated or the diversity of which is not thoroughly understood6.

The expanded Tree of Life can be used to determine the diversity of a specific region and determine if particular habitats need special protection. This information can be used in a variety of ways, from identifying the most effective treatments to fight disease to improving crop yields. This information is also valuable to conservation efforts. It can help biologists identify the areas most likely to contain cryptic species with potentially significant metabolic functions that could be at risk from anthropogenic change. While funds to protect biodiversity are important, the best method to preserve the biodiversity of the world is to equip more people in developing countries with the knowledge they need to act locally and support conservation.

Phylogeny

A phylogeny is also known as an evolutionary tree, reveals the relationships between groups of organisms. By using molecular information, morphological similarities and differences, or ontogeny (the course of development of an organism), scientists can build a phylogenetic tree that illustrates the evolutionary relationships between taxonomic categories. Phylogeny is crucial in understanding biodiversity, evolution and genetics.

A basic phylogenetic Tree (see Figure PageIndex 10 ) is a method of identifying the relationships between organisms with similar traits that have evolved from common ancestral. These shared traits can be analogous or homologous. Homologous traits are identical in their underlying evolutionary path while analogous traits appear similar, but do not share the identical origins. Scientists combine similar traits into a grouping called a clade. For instance, all the organisms in a clade share the trait of having amniotic egg and evolved from a common ancestor which had eggs. The clades then join to create a phylogenetic tree to determine the organisms with the closest connection to each other.

Scientists make use of DNA or RNA molecular data to build a phylogenetic chart that is more accurate and precise. This information is more precise and provides evidence of the evolution history of an organism. Researchers can utilize Molecular Data to calculate the age of evolution of living organisms and discover how many species have a common ancestor.

The phylogenetic relationships between organisms can be affected by a variety of factors including phenotypic plasticity, a kind of behavior that changes in response to unique environmental conditions. This can cause a characteristic to appear more similar to one species than another, obscuring the phylogenetic signal. However, this issue can be solved through the use of methods such as cladistics which incorporate a combination of similar and homologous traits into the tree.

Additionally, phylogenetics aids predict the duration and rate of speciation. This information will assist conservation biologists in deciding which species to safeguard from extinction. In the end, it's the conservation of phylogenetic variety 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. Many scientists have developed theories of evolution, such as the Islamic naturalist Nasir al-Din al-Tusi (1201-274) who believed that an organism could develop according to its own needs as well as the Swedish taxonomist Carolus Linnaeus (1707-1778), who created the modern hierarchical system of taxonomy and Jean-Baptiste Lamarck (1844-1829), who believed that the use or absence of certain traits can result in changes that can be passed on to future generations.

In the 1930s and 1940s, 에볼루션 카지노 concepts from a variety of fields -- including natural selection, genetics, and 에볼루션 바카라 무료체험; visit the next page, 에볼루션 게이밍 particulate inheritance--came together to form the current evolutionary theory synthesis that explains how evolution happens through the variations of genes within a population, and how those variants change over time due to natural selection. This model, which encompasses genetic drift, mutations in gene flow, and sexual selection, can be mathematically described mathematically.

Recent developments in the field of evolutionary developmental biology have demonstrated that variation can be introduced into a species via genetic drift, 에볼루션 무료체험코리아 (Scientific-Programs.science) mutation, and reshuffling of genes during sexual reproduction, as well as by migration between populations. These processes, as well as others like directional selection and genetic erosion (changes in the frequency of a genotype over time) can lead to evolution, which is defined by change in the genome of the species over time and also the change in phenotype over time (the expression of that genotype in the individual).

Incorporating evolutionary thinking into all areas of biology education can increase students' understanding of phylogeny and evolutionary. A recent study conducted by Grunspan and 에볼루션 바카라 무료체험 colleagues, for instance, showed that teaching about the evidence supporting evolution helped students accept the concept of evolution in a college-level biology course. To learn more about how to teach about evolution, see The Evolutionary Potential of All Areas of Biology and Thinking Evolutionarily A Framework for Infusing 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 past event; it is a process that continues today. The virus reinvents itself to avoid new antibiotics and bacteria transform to resist antibiotics. Animals alter their behavior in the wake of a changing world. The changes that result are often easy to see.

It wasn't until the late 1980s that biologists began to realize that natural selection was also in action. The key to this is that different traits can confer a different rate of survival and reproduction, and they can be passed down from generation to generation.

In the past, when one particular allele - the genetic sequence that determines coloration--appeared in a population of interbreeding species, it could quickly become more prevalent than the other alleles. In time, this could mean that the number of moths that have black pigmentation in a population may 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 much easier when a species has a rapid turnover of its generation such as bacteria. Since 1988, Richard Lenski, a biologist, has tracked twelve populations of E.coli that descend from one strain. Samples of each population have been collected frequently and more than 50,000 generations of E.coli have passed.

Lenski's research has demonstrated that mutations can alter the rate at which change occurs and the rate at which a population reproduces. It also shows that evolution is slow-moving, a fact that many find difficult to accept.

Another example of microevolution is the way mosquito genes for resistance to pesticides show up more often in areas where insecticides are used. Pesticides create a selective pressure which favors individuals who have resistant genotypes.

The rapid pace at which evolution takes place has led to a growing appreciation of its importance in a world shaped by human activity--including climate changes, pollution and the loss of habitats that prevent the species from adapting. Understanding the evolution process can help us make smarter choices about the future of our planet, as well as the lives of its inhabitants.