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The Academy's Evolution Site

The concept of biological evolution is a fundamental concept in biology. The Academies are committed to helping those interested in science understand evolution theory and how it is permeated throughout all fields of scientific research.

This site provides teachers, students and general readers with a variety of learning resources about evolution. It includes key video clip from NOVA and WGBH produced science programs on DVD.

Tree of Life

The Tree of Life, an ancient symbol, represents the interconnectedness of all life. It is an emblem of love and unity in many cultures. It also has many practical applications, like providing a framework for understanding the evolution of species and how they react to changes in the environment.

Early attempts to describe the biological world were based on categorizing organisms based on their physical and metabolic characteristics. These methods, which rely on the sampling of different parts of organisms or short DNA fragments, have greatly increased the diversity of a tree of Life2. These trees are largely composed of eukaryotes, while bacterial diversity is vastly underrepresented3,4.

Genetic techniques have greatly expanded our ability to represent the Tree of Life by circumventing the requirement for direct observation and experimentation. Particularly, molecular techniques allow us to construct trees using sequenced markers like the small subunit of ribosomal RNA gene.

Despite the rapid growth of the Tree of Life through genome sequencing, much biodiversity still is waiting to be discovered. This is particularly relevant to microorganisms that are difficult to cultivate, and are typically present in a single sample5. Recent analysis of all genomes has produced an unfinished draft of the Tree of Life. This includes a large number of bacteria, archaea and other organisms that have not yet been identified or the diversity of which is not thoroughly understood6.

The expanded Tree of Life is particularly beneficial in assessing the biodiversity of an area, helping to determine if specific habitats require special protection. This information can be used in a range of ways, from identifying the most effective remedies to fight diseases to enhancing the quality of crops. This information is also extremely valuable in conservation efforts. It can aid biologists in identifying areas that are likely to be home to cryptic species, which may have vital metabolic functions and are susceptible to the effects of human activity. While funding to protect biodiversity are essential, the best way to conserve the world's biodiversity is to equip the people of developing nations with the necessary knowledge to act locally and support conservation.

Phylogeny

A phylogeny is also known as an evolutionary tree, shows the relationships between various groups of organisms. Using molecular data, morphological similarities and differences, or ontogeny (the process of the development of an organism), scientists can build an phylogenetic tree that demonstrates the evolution of taxonomic groups. Phylogeny plays a crucial role in understanding the relationship between genetics, biodiversity and evolution.

A basic phylogenetic tree (see Figure PageIndex 10 ) determines the relationship between organisms with similar traits that have evolved from common ancestors. These shared traits are either homologous or analogous. Homologous traits are similar in terms of their evolutionary paths. Analogous traits could appear like they are however they do not share the same origins. Scientists arrange similar traits into a grouping called a clade. For example, all of the species in a clade have the characteristic of having amniotic egg and evolved from a common ancestor that had these eggs. The clades then join to create a phylogenetic tree to determine which organisms have the closest connection to each other.

To create a more thorough and accurate phylogenetic tree scientists make use of molecular data from DNA or RNA to determine the connections between organisms. This information is more precise and gives evidence of the evolution history of an organism. Researchers can utilize Molecular Data to calculate the evolutionary age of organisms and identify the number of organisms that have a common ancestor.

The phylogenetic relationships between species can be influenced by several factors, 에볼루션바카라 including phenotypic plasticity an aspect of behavior that alters in response to unique environmental conditions. This can cause a characteristic to appear more similar to a species than another, obscuring the phylogenetic signals. However, this problem can be reduced by the use of techniques such as cladistics that combine analogous and homologous features into the tree.

In addition, phylogenetics can aid in predicting the length and speed of speciation. This information can help conservation biologists make decisions about which species to protect from the threat of extinction. It is ultimately the preservation of phylogenetic diversity which will lead to a complete and balanced ecosystem.

Evolutionary Theory

The central theme of evolution is that organisms acquire distinct characteristics over time based on their interactions with their surroundings. Many scientists have come up with theories of evolution, including the Islamic naturalist Nasir al-Din al-Tusi (1201-274) who believed that an organism could evolve according to its own needs, the Swedish taxonomist Carolus Linnaeus (1707-1778), who created the modern hierarchical system of taxonomy, as well as Jean-Baptiste Lamarck (1844-1829), who suggested that the use or non-use of certain traits can result in changes that can be passed on to future generations.

In the 1930s and 1940s, ideas from various fields, including genetics, natural selection and particulate inheritance--came together to form the modern evolutionary theory that explains how evolution happens through the variations of genes within a population, and how these variants change over time due to natural selection. This model, which encompasses genetic drift, mutations in gene flow, 에볼루션 바카라 무료체험 and sexual selection, can be mathematically described mathematically.

Recent discoveries in evolutionary developmental biology have shown how variation can be introduced to a species by genetic drift, mutations, reshuffling genes during sexual reproduction, and even migration between populations. These processes, in conjunction with others, such as directional selection and gene erosion (changes in the frequency of genotypes over time) can result in evolution. Evolution is defined as changes in the genome over time, as well as changes in phenotype (the expression of genotypes in an individual).

Students can gain a better understanding of phylogeny by incorporating evolutionary thinking in all aspects of biology. A recent study conducted by Grunspan and colleagues, for example, showed that teaching about the evidence for evolution increased students' acceptance of evolution in a college biology class. For more details about how to teach evolution look up The Evolutionary Potential in All Areas of Biology or Thinking Evolutionarily as a Framework for Infusing Evolution into Life Sciences Education.

Evolution in Action

Scientists have traditionally looked at evolution through the past, analyzing fossils and comparing species. They also study living organisms. Evolution isn't a flims event; it is an ongoing process. Bacteria transform and resist antibiotics, 에볼루션 사이트 에볼루션 바카라 사이트 무료체험 [www.switchingutilities.co.uk] viruses reinvent themselves and elude new medications and animals alter their behavior to a changing planet. The resulting changes are often easy to see.

However, it wasn't until late 1980s that biologists realized that natural selection can be seen in action, as well. The key is that various traits confer different rates of survival and reproduction (differential fitness), and can be passed from one generation to the next.

In the past, when one particular allele - the genetic sequence that controls coloration - was present in a group of interbreeding organisms, it could quickly become more common than all other alleles. As time passes, this could mean that the number of moths sporting 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.

Monitoring evolutionary changes in action is much easier when a species has a rapid generation turnover such as bacteria. Since 1988, Richard Lenski, a biologist, has tracked twelve populations of E.coli that descend from a single strain. The samples of each population have been collected frequently and more than 50,000 generations of E.coli have passed.

Lenski's research has revealed that mutations can alter the rate at which change occurs and the rate at which a population reproduces. It also shows evolution takes time, a fact that is difficult for some to accept.

Another example of microevolution is the way mosquito genes for resistance to pesticides are more prevalent in areas in which insecticides are utilized. This is due to pesticides causing an exclusive pressure that favors those who have resistant genotypes.

The rapidity of evolution has led to a greater appreciation of its importance, especially in a world that is largely shaped by human activity. This includes the effects of climate change, pollution and habitat loss that hinders many species from adapting. Understanding the evolution process will help us make better decisions about the future of our planet, as well as the lives of its inhabitants.