Are You Getting The Most You Evolution Site?

The Academy's Evolution Site

Biological evolution is a central concept in biology. The Academies are committed to helping those who are interested in the sciences comprehend the evolution theory and how it is incorporated in all areas of scientific research.

This site provides a range of resources for teachers, students as well as general readers about evolution. It also includes important video clips 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 a symbol of unity and love. It has numerous practical applications as well, such as providing a framework for understanding the evolution of species and how they react to changes in environmental conditions.

Early attempts to represent the world of biology were built on categorizing organisms based on their physical and metabolic characteristics. These methods, which are based on the sampling of different parts of organisms or fragments of DNA have greatly increased the diversity of a Tree of Life2. The trees are mostly composed by eukaryotes and the diversity of bacterial species is greatly underrepresented3,4.

By avoiding the necessity for direct experimentation and observation genetic techniques have allowed us to depict the Tree of Life in a more precise way. We can create trees using molecular methods, such as the small-subunit ribosomal gene.

The Tree of Life has been dramatically expanded through genome sequencing. However there is still a lot of diversity to be discovered. This is especially the case for microorganisms which are difficult to cultivate, and which are usually only found in one sample5. A recent analysis of all known genomes has produced a rough draft of the Tree of Life, including many archaea and bacteria that are not isolated and whose diversity is poorly understood6.

This expanded Tree of Life is particularly useful in assessing the diversity of an area, which can help to determine whether specific habitats require protection. This information can be utilized in a variety of ways, from identifying new remedies to fight diseases to improving crops. This information is also extremely beneficial to conservation efforts. It helps biologists determine the areas that are most likely to contain cryptic species with important metabolic functions that may be at risk of anthropogenic changes. While conservation funds are essential, the best method to protect the world's biodiversity is to empower more people in developing countries with the information they require to take action locally and encourage conservation.

Phylogeny

A phylogeny (also known as an evolutionary tree) illustrates the relationship between species. Scientists can build a phylogenetic chart that shows the evolution of taxonomic groups based on molecular data and morphological differences or similarities. Phylogeny is crucial in understanding evolution, biodiversity and genetics.

A basic phylogenetic tree (see Figure PageIndex 10 Determines the relationship between organisms with similar traits and evolved from a common ancestor. These shared traits are either analogous or homologous. Homologous characteristics are identical in terms of their evolutionary path. Analogous traits may look like they are but they don't share the same origins. Scientists combine similar traits into a grouping called a clade. All members of a clade have a common characteristic, like amniotic egg production. They all evolved from an ancestor who had these eggs. A phylogenetic tree is then constructed by connecting the clades to identify the organisms which are the closest to one another.

For a more detailed and accurate phylogenetic tree, scientists rely on molecular information from DNA or RNA to identify the relationships between organisms. This data is more precise than the morphological data and gives evidence of the evolutionary background of an organism or group. The use of molecular data lets researchers determine the number of organisms that share an ancestor common to them and estimate their evolutionary age.

extra resources  of organisms can be influenced by several factors, including phenotypic flexibility, an aspect of behavior that changes in response to specific environmental conditions. This can make a trait appear more similar to a species than to another which can obscure the phylogenetic signal. However, this problem can be cured by the use of techniques such as cladistics which combine analogous and homologous features into the tree.

Additionally, phylogenetics can help predict the duration and rate at which speciation takes place. This information can aid conservation biologists to make decisions about which species they should protect from the threat of extinction. Ultimately, it is the preservation of phylogenetic diversity that will create an ecologically balanced and complete ecosystem.

Evolutionary Theory

The main idea behind evolution is that organisms alter over time because of their interactions with their environment. Many scientists have proposed theories of evolution, including the Islamic naturalist Nasir al-Din al-Tusi (1201-274), who believed that an organism would evolve according to its individual requirements and needs, the Swedish taxonomist Carolus Linnaeus (1707-1778) who developed the modern hierarchical taxonomy, as well as Jean-Baptiste Lamarck (1844-1829), who suggested that the use or non-use of traits can cause changes that are passed on to the next generation.

In the 1930s & 1940s, theories from various fields, such as genetics, natural selection, and particulate inheritance, came together to form a modern theorizing of evolution. This defines how evolution occurs by the variations in genes within the population, and how these variations alter over time due to natural selection. This model, which incorporates genetic drift, mutations as well as gene flow and sexual selection can be mathematically described mathematically.

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

Incorporating evolutionary thinking into all areas of biology education can increase student understanding of the concepts of phylogeny and evolution. In a recent study conducted by Grunspan et al., it was shown that teaching students about the evidence for evolution increased their understanding of evolution in a college-level course in biology. For more information about how to teach evolution, see The Evolutionary Potential in all Areas of Biology or Thinking Evolutionarily: a Framework for Integrating Evolution into Life Sciences Education.

Evolution in Action

Traditionally scientists have studied evolution through studying fossils, comparing species, and observing living organisms. Evolution isn't a flims moment; it is a process that continues today. The virus reinvents itself to avoid new antibiotics and bacteria transform to resist antibiotics. Animals alter their behavior as a result of the changing environment. The changes that result are often visible.

It wasn't until the late 1980s that biologists began realize that natural selection was in play. The reason is that different traits have different rates of survival and reproduction (differential fitness) and are passed from one generation to the next.

In the past, when one particular allele - the genetic sequence that defines color in a group of interbreeding species, it could quickly become more prevalent than all other alleles. As time passes, that could mean that the number of black moths in a population could 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 easier when a species has a fast generation turnover, as with 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 taken regularly, and more than 500.000 generations of E.coli have passed.

Lenski's work has shown that mutations can alter the rate of change and the rate of a population's reproduction. It also shows that evolution takes time, a fact that is hard for some to accept.

Another example of microevolution is how mosquito genes that are resistant to pesticides are more prevalent in populations where insecticides are employed. Pesticides create an enticement that favors individuals who have resistant genotypes.

The rapidity of evolution has led to an increasing awareness of its significance particularly in a world shaped largely by human activity. This includes the effects of climate change, pollution and habitat loss, which prevents many species from adapting. Understanding evolution can aid you in making better decisions about the future of our planet and its inhabitants.