The Academy's Evolution Site

Biology is one of the most important concepts in biology. The Academies have been for a long time involved in helping people who are interested in science comprehend the concept of evolution and 에볼루션 코리아 how it affects all areas of scientific exploration.

This site offers a variety of tools for teachers, students as well as general readers about evolution. It contains key video clips from NOVA and 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 unity in many cultures. It has numerous practical applications as well, including providing a framework for understanding the history of species, and how they respond to changes in environmental conditions.

Early approaches to depicting the biological world focused on categorizing species into distinct categories that were distinguished by their physical and metabolic characteristics1. These methods, 에볼루션게이밍 which rely on sampling of different parts of living organisms or on small fragments of their DNA significantly increased the variety that could be included in a tree of life2. However these trees are mainly composed of eukaryotes; bacterial diversity remains vastly underrepresented3,4.

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

Despite the dramatic expansion of the Tree of Life through genome sequencing, a lot of biodiversity remains to be discovered. This is particularly true of microorganisms that are difficult to cultivate and are typically only represented in a single sample5. A recent study of all genomes that are known has produced a rough draft of the Tree of Life, including a large number of archaea and bacteria that have not been isolated, and their diversity is not fully understood6.

The expanded Tree of Life is particularly useful in assessing the diversity of an area, assisting to determine if certain habitats require special protection. The information can be used in a variety of ways, from identifying the most effective treatments to fight disease to enhancing crop yields. This information is also extremely valuable in conservation efforts. It can help biologists identify areas that are most likely to be home to species that are cryptic, which could perform important metabolic functions and are susceptible to changes caused by humans. While funding to protect biodiversity are essential, the best method to protect the world's biodiversity is to empower more people in developing nations with the necessary knowledge to act locally and support conservation.

Phylogeny

A phylogeny is also known as an evolutionary tree, illustrates 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 construct an phylogenetic tree that demonstrates the evolutionary relationships between taxonomic groups. Phylogeny plays a crucial role in understanding biodiversity, genetics and evolution.

A basic phylogenetic tree (see Figure PageIndex 10 ) determines the relationship between organisms that share similar traits that evolved from common ancestors. These shared traits can be either homologous or analogous. Homologous traits are identical in their evolutionary roots, while analogous traits look similar, but do not share the identical origins. Scientists arrange similar traits into a grouping known as a the clade. All organisms in a group have a common characteristic, for example, amniotic egg production. They all evolved from an ancestor with these eggs. A phylogenetic tree can be constructed by connecting the clades to determine the organisms which 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 between organisms. This information is more precise and gives evidence of the evolutionary history of an organism. The use of molecular data lets researchers identify the number of species that share a common ancestor and to estimate their evolutionary age.

The phylogenetic relationships of organisms are influenced by many factors, including phenotypic flexibility, a kind of behavior that changes in response to unique environmental conditions. This can cause a characteristic to appear more resembling to one species than another which can obscure the phylogenetic signal. This problem can be addressed by using cladistics, which is a the combination of analogous and homologous features in the tree.

Additionally, phylogenetics aids determine the duration and speed at which speciation occurs. This information can aid conservation biologists to decide the species they should safeguard from the threat of extinction. Ultimately, it is the preservation of phylogenetic diversity that will create an ecosystem that is complete and balanced.

Evolutionary Theory

The central theme in evolution is that organisms change over time as a result of their interactions with their environment. A variety of theories about evolution have been developed by a wide range of scientists such as the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who envisioned an organism developing gradually according to its requirements as well as the Swedish botanist Carolus Linnaeus (1707-1778) who designed modern hierarchical taxonomy, and Jean-Baptiste Lamarck (1744-1829) who suggested that use or disuse of traits can cause changes that could be passed onto offspring.

In the 1930s and 1940s, concepts from various areas, including natural selection, genetics & particulate inheritance, came together to form a modern synthesis of evolution theory. This explains how evolution is triggered by the variation in genes within the population and how these variants change over time as a result of natural selection. This model, called genetic drift mutation, gene flow, and sexual selection, is a cornerstone of current evolutionary biology, and can be mathematically explained.

Recent discoveries in the field of evolutionary developmental biology have revealed that genetic variation can be introduced into a species through mutation, genetic drift and reshuffling genes during sexual reproduction, and also through the movement of populations. These processes, along with others like directional selection and genetic erosion (changes in the frequency of the genotype over time) can result in evolution, 에볼루션 바카라 무료체험 바카라 에볼루션 - evolutionfreebaccarat86008.Ambien-blog.com - which is defined by changes in the genome of the species over time and also by changes in phenotype over time (the expression of that genotype within the individual).

Incorporating evolutionary thinking into all aspects of biology education could increase student understanding of the concepts of phylogeny as well as evolution. A recent study by Grunspan and colleagues, for example demonstrated that teaching about the evidence supporting evolution helped students accept the concept of evolution in a college biology class. For more details about how to teach evolution read The Evolutionary Potential in all Areas of Biology or Thinking Evolutionarily as a Framework for Integrating Evolution into Life Sciences Education.

Evolution in Action

Traditionally, scientists have studied evolution through looking back, studying fossils, comparing species and studying living organisms. But evolution isn't just something that occurred in the past; it's an ongoing process taking place today. Viruses evolve to stay away from new medications and bacteria mutate to resist antibiotics. Animals alter their behavior in the wake of the changing environment. The results are often visible.

But it wasn't until the late 1980s that biologists understood that natural selection can be observed in action as well. The main reason is that different traits result in a different rate of survival and reproduction, and they can be passed down from generation to generation.

In the past, if a certain allele - the genetic sequence that determines colour appeared in a population of organisms that interbred, it could become more common than any other allele. Over time, this would mean that the number of moths that have black pigmentation may increase. 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, Richard Lenski, a biologist, has studied twelve populations of E.coli that are descended from one strain. The samples of each population have been collected frequently and more than 50,000 generations of E.coli have been observed to have passed.

Lenski's work has demonstrated that a mutation can profoundly 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 difficult for some to accept.

Microevolution is also evident in the fact that mosquito genes for resistance to pesticides are more prevalent in populations where insecticides have been used. This is because pesticides cause a selective pressure which favors individuals who have resistant genotypes.

The rapid pace at which evolution can take place has led to a growing recognition of its importance in a world that is shaped by human activity--including climate change, 에볼루션 바카라 pollution and the loss of habitats which prevent the species from adapting. Understanding evolution can help us make better decisions regarding the future of our planet, and the life of its inhabitants.