The Advanced Guide To Evolution Site

The Academy's Evolution Site

The concept of biological evolution is among the most central concepts in biology. The Academies have long been involved in helping those interested in science comprehend the theory of evolution and how it affects all areas of scientific research.

This site provides students, teachers and general readers with a wide range of learning resources on 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 that symbolizes the interconnectedness of all life. It is an emblem of love and unity across many cultures. It has many practical applications as well, including providing a framework for understanding the history of species and how they react to changing environmental conditions.

The first attempts to depict the biological world were built on categorizing organisms based on their physical and metabolic characteristics. These methods, which relied on the sampling of various parts of living organisms, or sequences of small DNA fragments, significantly expanded the diversity that could be represented in the tree of life2. These trees are mostly populated by eukaryotes and the diversity of bacterial species is greatly underrepresented3,4.

Genetic techniques have greatly broadened our ability to represent the Tree of Life by circumventing the requirement for direct observation and experimentation. We can construct trees using molecular methods like the small-subunit ribosomal gene.

The Tree of Life has been greatly expanded thanks to genome sequencing. However, there is still much biodiversity to be discovered. This is especially the case for microorganisms which are difficult to cultivate and are typically found in one sample5. A recent analysis of all genomes resulted in an unfinished draft of the Tree of Life. This includes a variety of archaea, bacteria, and other organisms that have not yet been identified or their diversity is not fully understood6.

This expanded Tree of Life is particularly useful for assessing the biodiversity of an area, which can help to determine if specific habitats require special protection. The information is useful in many ways, including finding new drugs, fighting diseases and improving crops. This information is also extremely beneficial in conservation efforts. It can help biologists identify those areas that are most likely contain cryptic species that could have important metabolic functions that could be vulnerable to anthropogenic change. Although funding to protect biodiversity are crucial however, the most effective method to protect the world's biodiversity is for more people living in developing countries to be equipped with the knowledge to take action locally to encourage conservation from within.

Phylogeny

A phylogeny (also known as an evolutionary tree) depicts the relationships between species.  에볼루션 무료 바카라  can build a phylogenetic diagram that illustrates the evolution of taxonomic categories using molecular information and morphological differences or similarities. Phylogeny is essential in understanding the evolution of biodiversity, evolution and genetics.

A basic phylogenetic tree (see Figure PageIndex 10 ) identifies the relationships between organisms with similar traits that evolved from common ancestral. These shared traits could be either homologous or analogous. Homologous traits are the same in terms of their evolutionary journey. Analogous traits may look like they are however they do not share the same origins. Scientists put similar traits into a grouping called a the clade. For instance, all of the organisms that make up a clade share the trait of having amniotic egg and evolved from a common ancestor that had eggs. The clades are then connected to form a phylogenetic branch that can determine the organisms with the closest connection to each other.

To create a more thorough and precise phylogenetic tree scientists make use of molecular data from DNA or RNA to establish the connections between organisms. This information is more precise than morphological information and provides evidence of the evolutionary background of an organism or group. Researchers can use Molecular Data to estimate the evolutionary age of living organisms and discover the number of organisms that share a common ancestor.

The phylogenetic relationships between species are influenced by many factors including phenotypic plasticity, an aspect of behavior that alters in response to unique environmental conditions. This can cause a trait to appear more like a species other species, which can obscure the phylogenetic signal. This issue can be cured by using cladistics, which incorporates an amalgamation of homologous and analogous traits in the tree.

In addition, phylogenetics helps determine the duration and rate at which speciation takes place. This information can assist conservation biologists in making choices about which species to protect from the threat of extinction. In the end, it is the conservation of phylogenetic diversity which will create an ecosystem that is balanced and complete.

Evolutionary Theory

The central theme in evolution is that organisms alter over time because of their interactions with their environment. Many theories of evolution have been proposed by a wide variety of scientists such as the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who believed that an organism would evolve slowly according to its needs as well as 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 could be passed on to the offspring.

In the 1930s and 1940s, theories from various fields, including natural selection, genetics & particulate inheritance, were brought together to create a modern evolutionary theory. This defines how evolution happens through the variation in genes within a 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 modern evolutionary biology and is mathematically described.

Recent discoveries in the field of evolutionary developmental biology have shown that variation can be introduced into a species by mutation, genetic drift and reshuffling genes during sexual reproduction, as well as through the movement of populations. These processes, along with 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 changes in the genome of the species over time and the change in phenotype as time passes (the expression of the genotype within the individual).

Students can better understand the concept of phylogeny through incorporating evolutionary thinking throughout all aspects of biology. A recent study by Grunspan and colleagues, for instance demonstrated that teaching about the evidence that supports evolution increased students' understanding of evolution in a college-level biology class. For more details about how to teach evolution read The Evolutionary Power of Biology in All Areas of Biology or Thinking Evolutionarily as a Framework for Infusing Evolution into Life Sciences Education.

Evolution in Action

Scientists have traditionally studied evolution by looking in the past--analyzing fossils and comparing species. They also study living organisms. Evolution is not a distant event, but a process that continues today. Viruses evolve to stay away from new antibiotics and bacteria transform to resist antibiotics. Animals alter their behavior as a result of a changing environment. The changes that occur are often evident.

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

In the past when one particular allele - the genetic sequence that controls coloration - was present in a population of interbreeding organisms, it could quickly become more common than the other alleles. In time, this could mean that the number of black moths within 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 from each population are taken regularly, and over fifty thousand generations have been observed.

Lenski's research has shown that mutations can drastically alter the speed at the rate at which a population reproduces, and consequently the rate at which it alters. It also demonstrates that evolution takes time, something that is difficult for some to accept.

Another example of microevolution is that mosquito genes that confer resistance to pesticides show up more often in populations where insecticides are used. That's because the use of pesticides creates a pressure that favors individuals with resistant genotypes.

The speed at which evolution can take place has led to an increasing recognition of its importance in a world that is shaped by human activity, including climate change, pollution and the loss of habitats that prevent many species from adapting. Understanding evolution can help us make smarter decisions regarding the future of our planet, as well as the life of its inhabitants.