The Academy's Evolution Site

Biological Evolution kr is a central concept in biology. The Academies are involved in helping those interested in science comprehend the evolution theory and how it can be applied throughout all fields of scientific research.

This site provides students, teachers and general readers with a range of learning resources on evolution. It has the most important video clips from NOVA and the WGBH-produced science programs on DVD.

Tree of Life

The Tree of Life is an ancient symbol of the interconnectedness of all life. It is seen in a variety of cultures and spiritual beliefs as an emblem of unity and love. It has numerous practical applications in addition to providing a framework to understand the history of species and how they respond to changes in 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 different parts of living organisms or short fragments of their DNA, greatly increased the variety of organisms that could be represented in the tree of life2. The trees are mostly composed by eukaryotes and the diversity of bacterial species is greatly underrepresented3,4.

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

Despite the rapid expansion of the Tree of Life through genome sequencing, a large amount of biodiversity is waiting to be discovered. This is especially true of microorganisms that are difficult to cultivate and are usually only present in a single sample5. A recent study of all genomes known to date has produced a rough draft version of the Tree of Life, including a large number of archaea and bacteria that have not been isolated and which are not well understood.

The expanded Tree of Life is particularly beneficial in assessing the biodiversity of an area, which can help to determine if specific habitats require special protection. This information can be utilized in a variety of ways, including finding new drugs, battling diseases and improving the quality of crops. The information is also beneficial in conservation efforts. It helps biologists determine those areas that are most likely contain cryptic species with potentially significant metabolic functions that could be vulnerable to anthropogenic change. While funds to protect biodiversity are essential, ultimately the best way to preserve the world's biodiversity is for more people living in developing countries to be empowered with the knowledge to act locally to promote conservation from within.

Phylogeny

A phylogeny (also known as an evolutionary tree) shows the relationships between organisms. Scientists can build a phylogenetic chart that shows the evolution of taxonomic groups using molecular data and morphological similarities or differences. Phylogeny is essential in understanding evolution, biodiversity and genetics.

A basic phylogenetic tree (see Figure PageIndex 10 Finds the connections between organisms with similar traits and have evolved from an ancestor that shared traits. These shared traits can be either analogous or homologous. Homologous traits share their evolutionary roots while analogous traits appear like they do, but don't have the identical origins. Scientists group similar traits together into a grouping known as a clade. For instance, all the species in a clade share the characteristic of having amniotic eggs. They evolved from a common ancestor that had eggs. A phylogenetic tree is then built by connecting the clades to identify the species which are the closest to each other.

Scientists make use of DNA or RNA molecular data to create a phylogenetic chart that is more precise and detailed. This data is more precise than morphological information and gives evidence of the evolutionary background of an organism or group. Researchers can utilize Molecular Data to estimate the age of evolution of living organisms and discover the number of organisms that share a common ancestor.

The phylogenetic relationships of a species can be affected by a variety of factors such as the phenomenon of phenotypicplasticity. This is a type of behavior that changes in response to specific environmental conditions. This can cause a characteristic to appear more similar to one species than to another, obscuring the phylogenetic signals. This problem can be mitigated by using cladistics, which incorporates an amalgamation of homologous and analogous traits in the tree.

Additionally, phylogenetics can aid in predicting the length and speed of speciation. This information can assist conservation biologists make decisions about which species they should protect from the threat of extinction. In the end, it's the conservation of phylogenetic diversity which will create an ecosystem that is complete and balanced.

Evolutionary Theory

The main idea behind evolution is that organisms change over time due to 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 envisioned an organism developing slowly according to its needs and needs, the Swedish botanist Carolus Linnaeus (1707-1778) who developed the modern hierarchical taxonomy Jean-Baptiste Lamarck (1744-1829) who suggested that the use or non-use of traits can cause changes that can be passed onto offspring.

In the 1930s and 1940s, ideas from a variety of fields--including genetics, natural selection, and particulate inheritance--came together to create the modern evolutionary theory which explains how evolution happens through the variations of genes within a population, and how those variations change over time as a result of natural selection. This model, called genetic drift or mutation, gene flow, and sexual selection, is a cornerstone of modern evolutionary biology and is mathematically described.

Recent advances in the field of evolutionary developmental biology have demonstrated the ways in which variation can be introduced to a species via mutations, genetic drift or reshuffling of genes in sexual reproduction, and even migration between 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 result in evolution. Evolution is defined by changes in the genome over time and changes in phenotype (the expression of genotypes within individuals).

Incorporating evolutionary thinking into all aspects of biology education could increase students' understanding of phylogeny and evolutionary. In a recent study by Grunspan and colleagues. It was demonstrated that teaching students about the evidence for evolution increased their understanding of evolution during the course of a college biology. To find out more about how to teach about evolution, please see The Evolutionary Potential in All Areas of Biology and Thinking Evolutionarily A Framework for Infusing Evolution in Life Sciences Education.

Evolution in Action

Traditionally, scientists have studied evolution through looking back, studying fossils, comparing species and studying living organisms. Evolution is not a distant event