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The Academy's Evolution Site

Biology is one of the most central concepts in biology. The Academies are committed to helping those interested in science comprehend the 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 educational resources on 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 seen in a variety of spiritual traditions and cultures as an emblem of unity and love. It also has practical applications, such as providing a framework to understand the history of species and how they respond to changes in environmental conditions.

Early attempts to describe the world of biology were based on categorizing organisms based on their physical and metabolic characteristics. These methods, which are based on the collection of various parts of organisms or DNA fragments have greatly increased the diversity of a Tree of Life2. These trees are largely composed by eukaryotes and bacterial diversity is vastly underrepresented3,4.

In avoiding the necessity of direct observation and experimentation genetic techniques have enabled us to depict the Tree of Life in a more precise manner. We can create trees using molecular techniques like the small-subunit ribosomal gene.

Despite the dramatic growth of the Tree of Life through genome sequencing, a lot of biodiversity is waiting to be discovered. This is particularly true of microorganisms that are difficult to cultivate and are often only found in a single sample5. A recent study of all genomes known to date has created 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.

This expanded Tree of Life can be used to determine the diversity of a particular area and determine if certain habitats need special protection. This information can be used in many ways, including finding new drugs, fighting diseases and improving the quality of crops. The information is also incredibly valuable in conservation efforts. It can aid biologists in identifying areas that are likely to have cryptic species, which could perform important metabolic functions, and could be susceptible to changes caused by humans. While funds to safeguard biodiversity are vital, ultimately the best way to preserve the world's biodiversity is for more people living in developing countries to be empowered with the necessary 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 build a phylogenetic diagram that illustrates the evolution of taxonomic groups based on molecular data and morphological similarities or differences. Phylogeny is essential in understanding evolution, biodiversity and genetics.

A basic phylogenetic tree (see Figure PageIndex 10 ) determines the relationship between organisms that share similar traits that have evolved from common ancestors. These shared traits may be analogous or homologous. Homologous traits are the same in terms of their evolutionary journey. Analogous traits might appear similar but they don't share the same origins. Scientists organize similar traits into a grouping called a the clade. For example, all of the organisms that make up a clade have the characteristic of having amniotic egg and evolved from a common ancestor that had these eggs. A phylogenetic tree can be constructed by connecting the clades to identify the species that are most closely related to each other.

For a more precise and accurate phylogenetic tree, scientists rely on molecular information from DNA or RNA to determine the relationships between organisms. This information is more precise than the morphological data and provides evidence of the evolutionary background of an organism or group. Researchers can use Molecular Data to estimate the age of evolution of organisms and identify how many species have a common ancestor.

The phylogenetic relationships between species can be influenced by several factors, including phenotypic plasticity a kind of behavior that alters in response to specific environmental conditions. This can cause a particular trait to appear more similar to one species than other species, which can obscure the phylogenetic signal. This problem can be mitigated by using cladistics. This is a method that incorporates an amalgamation of homologous and analogous features in the tree.

Furthermore, phylogenetics may aid in predicting the time and pace of speciation. This information can help conservation biologists make decisions about which species to protect from extinction. In the end, it's the conservation of phylogenetic diversity that will lead to an ecosystem that is balanced and complete.

Evolutionary Theory

The main idea behind evolution is that organisms acquire distinct characteristics over time due to their interactions with their environments. Several theories of evolutionary change have been proposed by a wide variety of scientists, including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who believed that an organism would evolve slowly in accordance with its requirements and needs, the Swedish botanist Carolus Linnaeus (1707-1778) who developed modern hierarchical taxonomy, and Jean-Baptiste Lamarck (1744-1829) who suggested that use or disuse of traits can cause changes that can be passed on to the offspring.

In the 1930s and 1940s, 에볼루션 바카라 ideas from a variety of fields -- including genetics, natural selection, and particulate inheritance -- came together to form the current evolutionary theory synthesis that 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, 에볼루션 바카라사이트 called genetic drift or mutation, gene flow and sexual selection, is a key element of the current evolutionary biology and can be mathematically explained.

Recent advances in the field of evolutionary developmental biology have shown the ways in which variation can be introduced to a species through mutations, genetic drift, 에볼루션 룰렛 reshuffling genes during sexual reproduction, and even migration between populations. These processes, along with other ones like directional selection and genetic erosion (changes in the frequency of the genotype over time) can result in 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 within the individual).

Students can gain a better understanding of the concept of phylogeny by using evolutionary thinking into all aspects of biology. A recent study by Grunspan and colleagues, for example revealed that teaching students about the evidence supporting evolution increased students' acceptance of evolution in a college-level biology course. For more details on how to teach about evolution look up The Evolutionary Power of Biology in all Areas of Biology or Thinking Evolutionarily A Framework for Infusing Evolution into Life Sciences Education.

Evolution in Action

Traditionally, scientists have studied evolution by studying fossils, comparing species and observing living organisms. Evolution is not a distant event, but an ongoing process that continues to be observed today. Viruses reinvent themselves to avoid new medications and bacteria mutate to resist antibiotics. Animals adapt their behavior because of a changing world. The results are usually easy to see.

It wasn't until late 1980s when biologists began to realize that natural selection was also in action. The key is the fact that different traits result in an individual rate of survival and reproduction, and can be passed on from one generation to another.

In the past, if one allele - the genetic sequence that determines colour - appeared in a population of organisms that interbred, it might become more prevalent than any other allele. Over time, this would mean that the number of moths sporting black pigmentation may increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.

It is easier to observe evolution when a species, such as bacteria, has a rapid generation turnover. Since 1988, Richard Lenski, a biologist, 에볼루션 has studied twelve populations of E.coli that descend from a single strain. The samples of each population were taken regularly and more than 500.000 generations of E.coli have been observed to have passed.

Lenski's research has shown that mutations can drastically alter the efficiency with which a population reproduces--and so the rate at which it alters. It also proves that evolution is slow-moving, a fact that some find difficult to accept.

Microevolution is also evident in the fact that mosquito genes for pesticide resistance are more prevalent in populations that have used insecticides. Pesticides create an enticement that favors individuals who have resistant genotypes.

The speed at which evolution can take place has led to an increasing awareness of its significance in a world that is shaped by human activity, including climate change, pollution, and the loss of habitats which prevent many species from adapting. Understanding the evolution process will aid you in making better decisions about the future of our planet and its inhabitants.