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The Academy's Evolution Site

The concept of biological evolution is among the most central concepts in biology. The Academies have long been involved in helping those interested in science understand the theory of evolution and how it influences all areas of scientific research.

This site provides students, teachers and general readers with a wide range of learning resources about evolution. It has the most important video clips from NOVA and the WGBH-produced science programs on DVD.

Tree of Life

The Tree of Life is an ancient symbol that symbolizes the interconnectedness of life. It is an emblem of love and harmony in a variety of cultures. 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 earliest attempts to depict the biological world focused on separating organisms into distinct categories which had been identified by their physical and metabolic characteristics1. These methods rely on the sampling of different 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 bacteria are largely underrepresented3,4.

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

Despite the massive growth of the Tree of Life through genome sequencing, much biodiversity still is waiting to be discovered. This is especially the case for microorganisms which are difficult to cultivate and are usually found in a single specimen5. A recent analysis of all genomes has produced an unfinished draft of a Tree of Life. This includes a variety of bacteria, archaea and other organisms that have not yet been isolated or the diversity of which is not thoroughly understood6.

This expanded Tree of Life is particularly useful for assessing the biodiversity of an area, assisting to determine whether specific habitats require protection. This information can be utilized in many ways, including finding new drugs, battling diseases and improving crops. It is also valuable to conservation efforts. It can help biologists identify the areas most likely to contain cryptic species that could have important metabolic functions that may be vulnerable to anthropogenic change. While funds to protect biodiversity are essential but the most effective way to preserve 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 (also known as an evolutionary tree) illustrates the relationship between different organisms. Scientists can construct a phylogenetic chart that shows the evolutionary relationships between taxonomic categories using molecular information and morphological similarities or differences. The concept of phylogeny is fundamental to understanding the evolution of biodiversity, evolution and genetics.

A basic phylogenetic Tree (see Figure PageIndex 10 Finds the connections between organisms that have similar characteristics and have evolved from an ancestor that shared traits. These shared traits are either homologous or analogous. Homologous traits are identical in their evolutionary origins while analogous traits appear similar but do not have the identical origins. Scientists combine similar traits into a grouping called a the clade. For instance, all the species in a clade share the characteristic of having amniotic egg and evolved from a common ancestor who had eggs. A phylogenetic tree is built by connecting the clades to identify the species who are the closest to each other.

Scientists utilize molecular DNA or RNA data to create a phylogenetic chart that is more precise and precise. This information is more precise and provides evidence of the evolution history of an organism. The analysis of molecular data can help researchers determine the number of species who share the same ancestor and estimate their evolutionary age.

The phylogenetic relationships between organisms can be influenced by several factors, including phenotypic flexibility, a type of behavior that alters in response to unique environmental conditions. This can cause a trait to appear more similar to one species than another, clouding the phylogenetic signal. However, this problem can be solved through the use of methods like cladistics, 에볼루션코리아 (Evolution-Site22242.Blogginaway.com) which incorporate a combination of analogous and homologous features into the tree.

In addition, phylogenetics can aid in predicting the time and pace of speciation. This information can aid conservation biologists to decide the species they should safeguard from extinction. Ultimately, it is the preservation of phylogenetic diversity which will result in an ecosystem that is complete and balanced.

Evolutionary Theory

The fundamental concept of evolution is that organisms acquire different features over time as a result of their interactions with their environments. A variety of theories about evolution have been developed by a variety 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 needs and needs, the Swedish botanist Carolus Linnaeus (1707-1778) who conceived modern hierarchical taxonomy, and Jean-Baptiste Lamarck (1744-1829) who suggested that the use or misuse of traits can cause changes that can be passed on to offspring.

In the 1930s and 1940s, theories from various fields, including genetics, natural selection and particulate inheritance - came together to form the modern evolutionary theory which explains how evolution is triggered by the variation of genes within a population and how those variants change over time due to natural selection. This model, which includes mutations, genetic drift, gene flow and sexual selection is mathematically described mathematically.

Recent discoveries in the field of evolutionary developmental biology have demonstrated that variation can be introduced into a species through mutation, genetic drift and reshuffling of genes during sexual reproduction, as well as through the movement of populations. These processes, as well as other ones 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 에볼루션바카라사이트 the change in phenotype as time passes (the expression of that genotype in the individual).

Students can better understand phylogeny by incorporating evolutionary thinking in all aspects of biology. A recent study by Grunspan and 에볼루션 바카라 사이트 colleagues, for 에볼루션사이트 instance demonstrated that teaching about the evidence that supports evolution increased students' understanding of evolution in a college-level biology class. For more information on 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

Scientists have traditionally looked at evolution through the past, 에볼루션 무료체험 studying fossils, and comparing species. They also observe living organisms. Evolution is not a distant event, but an ongoing process that continues to be observed today. Bacteria evolve and resist antibiotics, viruses reinvent themselves and escape new drugs and animals alter their behavior in response to the changing environment. The changes that result are often evident.

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

In the past when one particular allele, the genetic sequence that defines color in a population of interbreeding organisms, it might quickly become more common than other alleles. Over time, that would mean that the number of black moths within a particular population could rise. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.

Monitoring evolutionary changes in action is easier when a species has a fast generation turnover like bacteria. Since 1988, Richard Lenski, a biologist, has tracked twelve populations of E.coli that descend from one strain. Samples of each population were taken frequently and more than 500.000 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 alters. It also demonstrates that evolution takes time--a fact that some people find hard to accept.

Another example of microevolution is how mosquito genes that confer resistance to pesticides are more prevalent in areas in which insecticides are utilized. Pesticides create an exclusive pressure that favors those with resistant genotypes.

The rapidity of evolution has led to a greater appreciation of its importance particularly in a world shaped largely by human activity. This includes pollution, climate change, and habitat loss that hinders many species from adapting. Understanding the evolution process will aid you in making better decisions regarding the future of the planet and its inhabitants.