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10 Myths Your Boss Is Spreading Concerning Evolution Site
The Academy's Evolution Site

Biology is a key concept in biology. The Academies are involved in helping those who are interested in the sciences learn about the theory of evolution and how it is permeated in all areas of scientific research.

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, an ancient symbol, symbolizes the interconnectedness of all life. It is an emblem of love and harmony in a variety of cultures. It also has many practical applications, such as providing a framework to understand the history of species and how they respond to changes in the environment.

Early attempts to describe the world of biology were based on categorizing organisms based on their physical and metabolic characteristics. These methods, which rely on the sampling of different parts of living organisms, or small fragments of their DNA significantly expanded the diversity that could be included in the tree of life2. These trees are largely composed by eukaryotes and bacteria are largely underrepresented3,4.

By avoiding the necessity for direct experimentation and observation genetic techniques have made it possible to represent the Tree of Life in a more precise way. Particularly, molecular methods enable us to create trees by using sequenced markers like the small subunit ribosomal RNA gene.

The Tree of Life has been greatly expanded thanks to genome sequencing. However there is a lot of diversity to be discovered. This is particularly true of microorganisms, which are difficult to cultivate and are usually only present in a single sample5. Recent analysis of all genomes has produced an initial draft of the Tree of Life. This includes a large number of archaea, bacteria, and other organisms that haven't yet been identified or their diversity is not fully understood6.

The expanded Tree of Life can be used to assess the biodiversity of a specific region and determine if specific habitats require special protection. The information can be used in a range of ways, from identifying new medicines to combating disease to enhancing the quality of crops. It is also beneficial for conservation efforts. It can help biologists identify areas most likely to have cryptic species, which could have vital metabolic functions and be vulnerable to the effects of human activity. While funding to protect biodiversity are important, the most effective method to preserve the world's biodiversity is to equip more people in developing countries with the necessary knowledge to act locally and support conservation.

Phylogeny

A phylogeny, also known as an evolutionary tree, shows the connections between various groups of organisms. Scientists can create a phylogenetic diagram that illustrates the evolution of taxonomic groups using molecular data and morphological differences or similarities. The phylogeny of a tree plays an important role in understanding the relationship between genetics, biodiversity and evolution.

A basic phylogenetic Tree (see Figure PageIndex 10 ) identifies the relationships between organisms with similar traits that evolved from common ancestral. These shared traits may be homologous, or analogous. Homologous characteristics are identical in their evolutionary path. Analogous traits might appear similar however they do not share the same origins. Scientists combine similar traits into a grouping known as a clade. For example, all of the species in a clade share the characteristic of having amniotic eggs and evolved from a common ancestor that had eggs. The clades then join to create a phylogenetic tree to identify organisms that have the closest connection to each other.

Scientists utilize molecular DNA or RNA data to create a phylogenetic chart that is more accurate and precise. This information is more precise than morphological data and provides evidence of the evolutionary background of an organism or group. The analysis of molecular data can help researchers determine the number of species that have the same ancestor and estimate their evolutionary age.

The phylogenetic relationships of a species can be affected by a variety of factors, including the phenotypic plasticity. This is a kind of behavior that changes due to specific environmental conditions. This can cause a trait to appear more resembling to one species than to the other, obscuring the phylogenetic signals. However, this problem can be cured by the use of methods such as cladistics that include a mix of homologous and analogous features into the tree.

Additionally, phylogenetics aids determine the duration and rate of speciation. This information can aid conservation biologists in making decisions about which species to protect from extinction. In the end, it's the conservation of phylogenetic diversity which will create an ecosystem that is complete and balanced.

Evolutionary Theory

The central theme of evolution is that organisms acquire distinct characteristics over time due to their interactions with their environment. Many theories of evolution have been proposed by a wide range of scientists including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who envisioned an organism developing slowly in accordance with its needs as well as the Swedish botanist Carolus Linnaeus (1707-1778) who conceived modern hierarchical taxonomy, and Jean-Baptiste Lamarck (1744-1829) who suggested that the use or misuse of traits causes changes that can be passed onto offspring.

In the 1930s & 1940s, theories from various fields, including genetics, natural selection, and particulate inheritance, merged to create a modern synthesis of evolution theory. This describes how evolution occurs by the variation in genes within the population and how these variations change with time due to natural selection. This model, which incorporates genetic drift, mutations, gene flow and sexual selection, can be mathematically described.

Recent developments in the field of evolutionary developmental biology have demonstrated that variation can be introduced into a species by mutation, genetic drift, and reshuffling of genes during sexual reproduction, and also through the movement of populations. These processes, in conjunction with others, such as the directional selection process and the erosion of genes (changes to the frequency of genotypes over time), can lead towards evolution. Evolution is defined by changes in the genome over time and changes in phenotype (the expression of genotypes within individuals).

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

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Scientists have studied evolution through looking back in the past, studying fossils, and comparing species. They also study living organisms. But evolution isn't just something that occurred in the past. It's an ongoing process that is taking place in the present. Bacteria evolve and resist antibiotics, viruses re-invent themselves and are able to evade new medications, and animals adapt their behavior to the changing environment. The changes that occur are often apparent.

However, it wasn't until late-1980s that biologists realized that natural selection could be seen in action, as well. The main reason is that different traits confer an individual rate of survival as well as reproduction, and may be passed on from one generation to the next.

In the past, if one particular allele, the genetic sequence that determines coloration--appeared in a population of interbreeding organisms, it might rapidly become more common than the other alleles. In time, this could 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.


Observing evolutionary change in action is much easier when a species has a rapid turnover of its generation such as 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 on a regular basis and over 50,000 generations have now been observed.

Lenski's research has revealed that mutations can alter the rate of change and the effectiveness of a population's reproduction. It also shows that evolution takes time, a fact that some find difficult to accept.

Another example of microevolution is that mosquito genes that confer resistance to pesticides are more prevalent in areas where insecticides are employed. That's because the use of pesticides causes a selective pressure that favors those with resistant genotypes.

The rapidity of evolution has led to a greater awareness of its significance particularly in a world shaped largely by human activity. This includes pollution, climate change, and habitat loss, which prevents many species from adapting. Understanding evolution can help us make smarter decisions regarding the future of our planet as well as the lives of its inhabitants.

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