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The Academy's Evolution Site

Biology is a key concept in biology. The Academies have been for a long time involved in helping those interested in science understand the concept of evolution and how it affects all areas of scientific research.

This site provides a wide range of tools for teachers, students, and general readers on evolution. It contains 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 unity in many cultures. It can be used in many practical ways in addition to providing a framework to understand the history of species and how they react to changes in environmental conditions.

Early approaches to depicting the biological world focused on categorizing species into distinct categories that had been identified by their physical and metabolic characteristics1. These methods rely on the collection of various parts of organisms or short DNA fragments have significantly increased the diversity of a Tree of Life2. These trees are largely composed by eukaryotes and the diversity of bacterial species is greatly underrepresented3,4.

Genetic techniques have greatly broadened our ability to visualize the Tree of Life by circumventing the requirement for direct observation and experimentation. We can construct trees using molecular methods such as the small subunit ribosomal gene.

Despite the massive expansion of the Tree of Life through genome sequencing, much biodiversity still remains to be discovered. This is particularly the case for microorganisms which are difficult to cultivate, and which are usually only found in one sample5. A recent analysis of all genomes resulted in a rough draft of a Tree of Life. This includes a large number of bacteria, archaea and other organisms that have not yet been identified or whose diversity has not been well understood6.

This expanded Tree of Life is particularly beneficial in assessing the biodiversity of an area, assisting to determine whether specific habitats require special protection. This information can be used in a range of ways, from identifying the most effective medicines to combating disease to enhancing the quality of crops. It is also useful in conservation efforts. It can help biologists identify the areas that are most likely to contain cryptic species with potentially important metabolic functions that could be at risk of anthropogenic changes. Although funding to protect biodiversity are essential but the most effective way to protect the world's biodiversity is for more people living in developing countries to be empowered with the necessary knowledge to act locally to promote conservation from within.

Phylogeny

A phylogeny (also known as an evolutionary tree) depicts the relationships between species. 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 evolutionary relationships between taxonomic groups. Phylogeny is essential in understanding the evolution of biodiversity, evolution and genetics.

A basic phylogenetic Tree (see Figure PageIndex 10 ) identifies the relationships between organisms with similar traits that evolved from common ancestors. These shared traits are either homologous or analogous. Homologous traits are similar in terms of their evolutionary path. Analogous traits might appear like they are but they don't have the same ancestry. Scientists combine similar traits into a grouping referred to as a Clade. For example, 에볼루션 무료 바카라 에볼루션 게이밍 (visit www.swanmei.com) all of the species in a clade have the characteristic of having amniotic egg and evolved from a common ancestor who had eggs. The clades are then linked to form a phylogenetic branch to determine the organisms with the closest relationship.

To create a more thorough and precise phylogenetic tree scientists make use of molecular data from DNA or RNA to establish the relationships among organisms. This information is more precise and provides evidence of the evolutionary history of an organism. Molecular data allows researchers to determine the number of organisms who share the same ancestor and estimate their evolutionary age.

The phylogenetic relationships of organisms can be affected by a variety of factors including phenotypic plasticity, a type of behavior that alters in response to unique environmental conditions. This can cause a characteristic to appear more like a species other species, which can obscure the phylogenetic signal. However, this problem can be reduced by the use of techniques such as cladistics which include a mix of homologous and analogous features into the tree.

Additionally, phylogenetics can help predict the duration and rate at which speciation occurs. This information can aid conservation biologists in making decisions about which species to save from the threat of extinction. In the end, it is the conservation of phylogenetic diversity that will lead to an ecosystem that is complete and balanced.

Evolutionary Theory

The fundamental concept of evolution is that organisms acquire different features over time based on their interactions with their environments. Several theories of evolutionary change have been developed by a variety of scientists such as the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who believed that an organism would evolve gradually according to its needs and needs, the Swedish botanist Carolus Linnaeus (1707-1778) who developed the modern hierarchical taxonomy, as well as Jean-Baptiste Lamarck (1744-1829) who suggested that the use or misuse of traits can cause changes that could be passed on to offspring.

In the 1930s and 1940s, ideas from various fields, including genetics, natural selection and particulate inheritance--came together to create the modern evolutionary theory which explains how evolution happens through the variations of genes within a population, and how those variants change in time as a result of natural selection. This model, which includes mutations, genetic drift as well as gene flow and sexual selection is mathematically described mathematically.

Recent developments in the field of evolutionary developmental biology have demonstrated that variations can be introduced into a species through mutation, genetic drift, and reshuffling of genes during sexual reproduction, and 에볼루션 also through the movement of populations. These processes, as well as 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 change in the genome of the species over time and also the change in phenotype over time (the expression of that genotype within the individual).

Students can better understand phylogeny by incorporating evolutionary thinking throughout 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 in the course of a college biology. To find out more about how to teach about evolution, read The Evolutionary Potential in all Areas of Biology and Thinking Evolutionarily A Framework for Infusing Evolution in Life Sciences Education.

Evolution in Action

Traditionally, scientists have studied evolution by studying fossils, comparing species and studying living organisms. Evolution is not a distant event; it is an ongoing process that continues to be observed today. Viruses reinvent themselves to avoid new medications and bacteria mutate to resist antibiotics. Animals adapt their behavior as a result of a changing world. The changes that result are often easy to see.

It wasn't until late 1980s that biologists understood that natural selection can be observed in action as well. The main reason is that different traits confer a different rate of survival as well as reproduction, and may 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 population of interbreeding species, it could quickly become more prevalent than other alleles. As time passes, this could mean that the number of moths with 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.

It is easier to track evolution when the species, like bacteria, has a high generation turnover. Since 1988 the biologist Richard Lenski has been tracking twelve populations of E. Coli that descended from a single strain; samples from each population are taken regularly and over 500.000 generations have passed.

Lenski's research has demonstrated that mutations can alter the rate of change and the rate at which a population reproduces. It also proves that evolution is slow-moving, a fact that some people are unable to accept.

Microevolution can be observed in the fact that mosquito genes that confer resistance to pesticides are more prevalent in populations where insecticides have been used. Pesticides create an enticement that favors those who have resistant genotypes.

The speed of evolution taking place has led to an increasing appreciation of its importance in a world that is shaped by human activities, including climate change, pollution and the loss of habitats which prevent many species from adjusting. Understanding the evolution process can help us make better decisions about the future of our planet, as well as the life of its inhabitants.