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The Academy's Evolution Site

Biology is one of the most central concepts in biology. The Academies have been for a long time involved in helping people who are 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 variety of learning resources about evolution. It has key video clips from NOVA and the WGBH-produced science programs on DVD.

Tree of Life

The Tree of Life, an ancient symbol, represents the interconnectedness of all life. It appears in many spiritual traditions and cultures as an emblem of unity and love. It also has practical uses, like providing a framework for understanding the history of species and how they react to changing environmental conditions.

Early approaches to depicting the biological world focused on the classification of organisms into distinct categories which had been identified by their physical and metabolic characteristics1. These methods, which rely on 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 a tree of life2. However, these trees are largely comprised of eukaryotes, and 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. In particular, molecular methods allow us to construct trees by using sequenced markers such as 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 which are usually only found in one sample5. A recent study of all genomes that are known has created a rough draft of the Tree of Life, including many archaea and bacteria that are not isolated and whose diversity is poorly understood6.

This expanded Tree of Life can be used to evaluate the biodiversity of a specific area and determine if certain habitats require special protection. This information can be utilized in a variety of ways, from identifying the most effective medicines to combating disease to enhancing crop yields. It is also beneficial in conservation efforts. It helps biologists discover areas that are most likely to have species that are cryptic, which could have vital metabolic functions and are susceptible to changes caused by humans. While funding to protect biodiversity are important, the most effective way to conserve the biodiversity of the world is to equip more people in developing countries with the knowledge they need to act locally and promote conservation.

Phylogeny

A phylogeny, also called an evolutionary tree, reveals the connections between different groups of organisms. Utilizing molecular data similarities and differences in morphology or 바카라 에볼루션 ontogeny (the course of development of an organism) scientists can construct a phylogenetic tree which illustrates the evolutionary relationship between taxonomic categories. The role of phylogeny is crucial in understanding biodiversity, genetics and evolution.

A basic phylogenetic tree (see Figure PageIndex 10 ) determines the relationship between organisms with similar traits that evolved from common ancestors. These shared traits could be analogous or homologous. Homologous traits are similar in their underlying evolutionary path while analogous traits appear like they do, but don't have the same ancestors. Scientists put similar traits into a grouping referred to as a the clade. All organisms in a group have a common characteristic, like amniotic egg production. They all derived from an ancestor with these eggs. A phylogenetic tree can be built by connecting the clades to determine the organisms which are the closest to one another.

To create a more thorough and accurate phylogenetic tree scientists rely on molecular information from DNA or RNA to identify the relationships among organisms. This information is more precise than the morphological data and gives evidence of the evolutionary history of an individual or group. The analysis of molecular data can help researchers identify the number of organisms who share an ancestor common to them and estimate their evolutionary age.

The phylogenetic relationships between organisms can be influenced by several factors, including phenotypic plasticity an aspect of behavior that changes in response to specific environmental conditions. This can cause a characteristic to appear more similar in one species than another, clouding the phylogenetic signal. However, this problem can be cured by the use of methods such as cladistics which combine similar and homologous traits into the tree.

Additionally, phylogenetics can help determine the duration and speed at which speciation occurs. This information can help conservation biologists make decisions about which species they should protect from 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 central theme of evolution is that organisms develop various characteristics over time as a result of their interactions with their environment. Many scientists have proposed theories of evolution, such as the Islamic naturalist Nasir al-Din al-Tusi (1201-274), who believed that an organism would evolve according to its own needs as well as the Swedish taxonomist Carolus Linnaeus (1707-1778), who created the modern taxonomy system that is hierarchical, as well as Jean-Baptiste Lamarck (1844-1829), who suggested that the use or 에볼루션게이밍 non-use of certain traits can result in changes that are passed on to the

In the 1930s & 1940s, concepts from various fields, such as natural selection, genetics & particulate inheritance, merged to form a modern evolutionary theory. This describes how evolution is triggered by the variation in genes within the population, and how these variants change with time due to natural selection. This model, 에볼루션 called genetic drift mutation, gene flow and sexual selection, is a key element of the current evolutionary biology and is mathematically described.

Recent developments in evolutionary developmental biology have demonstrated how variation can be introduced to a species through 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 a genotype over time), can lead to evolution that is defined as changes in the genome of the species over time and also by changes in phenotype as time passes (the expression of the genotype in the individual).

Incorporating evolutionary thinking into all aspects of biology education could increase students' understanding of phylogeny as well as evolution. In a recent study conducted by Grunspan and colleagues., it was shown that teaching students about the evidence for evolution boosted their acceptance of evolution during an undergraduate biology course. To learn more about how to teach about evolution, read 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--analyzing fossils, comparing species and studying living organisms. However, evolution isn't something that occurred in the past. It's an ongoing process happening today. Bacteria evolve and resist antibiotics, viruses re-invent themselves and 에볼루션 바카라 사이트 코리아 (marvelvsdc.faith) escape new drugs, and animals adapt their behavior to the changing climate. The results are usually easy to see.

It wasn't until the 1980s when biologists began to realize that natural selection was in action. The key is the fact that different traits confer a different rate of survival and reproduction, and 에볼루션 바카라 무료 can be passed on 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 could rapidly become more common than other alleles. As time passes, that could mean the number of black moths within the population 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 much easier when a species has a fast generation turnover, as with bacteria. Since 1988 biologist Richard Lenski has been tracking twelve populations of E. coli that descended from a single strain; samples of each are taken on a regular basis and more than 50,000 generations have now passed.

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

Another example of microevolution is the way mosquito genes for resistance to pesticides appear more frequently in areas where insecticides are used. This is because the use of pesticides creates a selective pressure that favors people who have 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 the effects of climate change, 에볼루션게이밍 pollution and habitat loss that prevents many species from adapting. Understanding the evolution process can assist you in making better choices about the future of our planet and its inhabitants.