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The Academy's Evolution Site

The concept of biological evolution is a fundamental concept in biology. The Academies have long been involved in helping people who are interested in science understand the concept of evolution and how it permeates all areas of scientific exploration.

This site provides a wide range of tools for teachers, students and general readers of evolution. It includes key video clip from NOVA and WGBH produced science programs on DVD.

Tree of Life

The Tree of Life is an ancient symbol of the interconnectedness of all life. It appears in many spiritual traditions and cultures as an emblem of unity and love. It also has important practical applications, such as providing a framework for understanding the evolution of species and how they respond to changes in the environment.

The first attempts to depict the biological world were based on categorizing organisms based on their metabolic and physical characteristics. These methods rely on the sampling of different parts of organisms, or fragments of DNA have greatly increased the diversity of a Tree of Life2. However the trees are mostly composed of eukaryotes; bacterial diversity is still largely unrepresented3,4.

In avoiding the necessity of direct observation and experimentation, genetic techniques have allowed us to depict the Tree of Life in a more precise manner. Particularly, molecular techniques enable us to create trees by using sequenced markers like the small subunit of ribosomal RNA gene.

The Tree of Life has been dramatically expanded through genome sequencing. However, there is still much biodiversity to be discovered. This is particularly the case for microorganisms which are difficult to cultivate, and are typically found in a single specimen5. A recent analysis of all genomes produced a rough draft of a Tree of Life. This includes a large number of archaea, bacteria and other organisms that haven't yet been isolated or whose diversity has not been fully understood6.

This expanded Tree of Life is particularly useful in assessing the diversity of an area, assisting to determine whether specific habitats require protection. This information can be utilized in a variety of ways, including finding new drugs, fighting diseases and improving crops. It is also valuable in conservation efforts. It can aid biologists in identifying areas that are most likely to be home to species that are cryptic, which could have vital metabolic functions, and could be susceptible to the effects of human activity. Although funding to protect biodiversity are crucial, ultimately the best way to ensure the preservation of biodiversity around the world is for more people living in developing countries to be equipped with the knowledge to act locally in order to promote conservation from within.

Phylogeny

A phylogeny (also called an evolutionary tree) illustrates the relationship between species. Scientists can construct a phylogenetic diagram that illustrates the evolutionary relationships between taxonomic groups based on molecular data and morphological differences or similarities. Phylogeny is essential in understanding biodiversity, evolution and genetics.

A basic phylogenetic Tree (see Figure PageIndex 10 Finds the connections between organisms that have similar traits and have evolved from a common ancestor. These shared traits could be analogous or homologous. Homologous traits are similar in their evolutionary roots and analogous traits appear similar but do not have the same origins. Scientists group similar traits into a grouping called a clade. Every organism in a group have a common characteristic, like amniotic egg production. They all evolved from an ancestor that had these eggs. A phylogenetic tree is then constructed by connecting clades to determine the organisms who are the closest to one another.

For a more precise and accurate phylogenetic tree, scientists rely on molecular information from DNA or RNA to identify the relationships among organisms. This data is more precise than morphological data and provides evidence of the evolution history of an individual or group. The use of molecular data lets researchers determine the number of organisms that have a common ancestor and to estimate their evolutionary age.

The phylogenetic relationships between organisms can be influenced by several 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 to another which can obscure the phylogenetic signal. However, 에볼루션 무료 바카라 바카라 (Suggested Looking at) this problem can be reduced by the use of methods such as cladistics that incorporate a combination of analogous and homologous features into the tree.

In addition, phylogenetics helps determine the duration and rate at which speciation occurs. This information can assist conservation biologists in making choices about which species to safeguard from the threat of extinction. It is ultimately the preservation 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 various characteristics over time based on their interactions with their surroundings. A variety of theories about evolution have been developed by a wide range of scientists including 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 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 can be passed onto offspring.

In the 1930s and 1940s, ideas from a variety of fields -- including genetics, natural selection and particulate inheritance--came together to form the current synthesis of evolutionary theory that explains how evolution occurs through the variations of genes within a population, and how those variations change over time due to natural selection. This model, which is known as genetic drift or mutation, gene flow, and sexual selection, is a key element of current evolutionary biology, and can be mathematically explained.

Recent discoveries 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 in sexual reproduction, and also through migration between populations. These processes, as well as others such as directional selection or genetic erosion (changes in the frequency of an individual's genotype over time) can result in evolution, which is defined by change in the genome of the species over time and the change in phenotype as time passes (the expression of that genotype in an individual).

Students can gain a better understanding of phylogeny by incorporating evolutionary thinking into all areas of biology. In a recent study conducted by Grunspan and colleagues. It was demonstrated that teaching students about the evidence for evolution increased their understanding of evolution in a college-level course in biology. For more details on how to teach about evolution, see The Evolutionary Power of Biology in all Areas of Biology or Thinking Evolutionarily as a Framework for Integrating Evolution into Life Sciences Education.

Evolution in Action

Scientists have studied evolution through looking back in the past, studying fossils, and comparing species. They also study living organisms. However, evolution isn't something that happened in the past; it's an ongoing process that is taking place right now. Bacteria evolve and resist antibiotics, viruses reinvent themselves and escape new drugs and animals alter their behavior to a changing planet. The changes that occur are often apparent.

However, it wasn't until late 1980s that biologists understood that natural selection could be seen in action, as well. The key to this is that different traits can confer a different rate of survival as well as reproduction, and may be passed down from one generation to another.

In the past when one particular allele, the genetic sequence that controls coloration - was present in a group of interbreeding species, 에볼루션 코리아 it could rapidly become more common than other alleles. Over time, that would mean that the number of black moths in a particular population could rise. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.

The ability to observe evolutionary change is easier when a species has a rapid 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 population are taken every day, and over 500.000 generations have passed.

Lenski's research has demonstrated that mutations can alter the rate of change and the efficiency of a population's reproduction. It also shows evolution takes time, something that is difficult for some to accept.

Microevolution can also be seen in the fact that mosquito genes for pesticide resistance are more prevalent in populations that have used insecticides. Pesticides create an exclusive pressure that favors those with resistant genotypes.

The rapidity of evolution has led to a greater recognition of its importance especially in a planet which is largely shaped by human activities. This includes climate change, pollution, 에볼루션 게이밍 and habitat loss that hinders many species from adapting. Understanding the evolution process can help us make smarter choices about the future of our planet and the life of its inhabitants.