The Academy's Evolution Site
Biological evolution is a central concept in biology. The Academies have been active for a long time in helping people who are interested in science understand the concept of evolution and how it affects all areas of scientific research.
This site provides teachers, students and general readers with a variety of learning resources about evolution. It has important 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 a symbol of love and unity across many cultures. It also has practical uses, like providing a framework to understand the evolution of species and how they respond to changing environmental conditions.
The first attempts to depict the world of biology were built on categorizing organisms based on their physical and metabolic characteristics. These methods, which rely on the sampling of various parts of living organisms or on small fragments of their DNA significantly expanded the diversity that could be represented in a tree of life2. However these trees are mainly comprised of eukaryotes, and bacterial diversity remains vastly underrepresented3,4.
Genetic techniques have significantly expanded our ability to depict the Tree of Life by circumventing the requirement for direct observation and experimentation. Particularly, molecular methods allow us to build trees using sequenced markers, such as the small subunit ribosomal gene.
Despite the massive growth of the Tree of Life through genome sequencing, a lot of biodiversity is waiting to be discovered. This is especially true for microorganisms that are difficult to cultivate, and are usually found in a single specimen5. A recent analysis of all known genomes has created a rough draft of the Tree of Life, including numerous archaea and bacteria that are not isolated and which are not well understood.
The expanded Tree of Life is particularly useful for assessing the biodiversity of an area, which can help to determine whether specific habitats require protection. The information is useful in a variety of ways, including finding new drugs, battling diseases and improving the quality of crops. This information is also valuable in conservation efforts. It helps biologists discover areas that are likely to be home to cryptic species, which may perform important metabolic functions and be vulnerable to changes caused by humans. While conservation funds are important, the best way to conserve the biodiversity of the world is to equip more people in developing countries with the knowledge they need to act locally and promote conservation.
Phylogeny
A phylogeny, also called an evolutionary tree, reveals the relationships between various groups of organisms. Using molecular data similarities and differences in morphology, or ontogeny (the process of the development of an organism), scientists can build a phylogenetic tree that illustrates the evolutionary relationships between taxonomic groups. Phylogeny is essential in understanding biodiversity, evolution and genetics.
A basic phylogenetic tree (see Figure PageIndex 10 ) identifies the relationships between organisms that share similar traits that evolved from common ancestral. These shared traits can be either analogous or homologous. Homologous traits are similar in terms of their evolutionary paths. Analogous traits could appear like they are, but they do not have the same origins. Scientists group similar traits into a grouping known as a Clade. All members of a clade share a trait, such as amniotic egg production. They all derived from an ancestor who had these eggs. The clades are then connected to create a phylogenetic tree to determine which organisms have the closest connection to each other.
To create a more thorough and precise phylogenetic tree scientists rely on molecular information from DNA or RNA to identify the connections between organisms. This information is more precise and provides evidence of the evolution of an organism. Researchers can utilize Molecular Data to determine the age of evolution of organisms and determine the number of organisms that share the same ancestor.
The phylogenetic relationships of a species can be affected by a variety of factors such as the phenotypic plasticity. This is a type of behavior that alters due to specific environmental conditions. This can cause a trait to appear more similar to one species than to another which can obscure the phylogenetic signal. This problem can be mitigated by using cladistics, which incorporates the combination of homologous and analogous features in the tree.
In addition, phylogenetics can help predict the length and speed of speciation. This information can help conservation biologists make decisions about the species they should safeguard from extinction. Ultimately, it is the preservation of phylogenetic diversity that will create an ecosystem that is complete and balanced.
Evolutionary Theory
The central theme of evolution is that organisms acquire distinct characteristics over time as a result of their interactions with their environment. Several theories of evolutionary change have been proposed by a variety of scientists including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who proposed that a living organism develop slowly in accordance with its requirements and needs, 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 cause changes that could be passed on to the offspring.
In the 1930s and 1940s, ideas from a variety of fields--including natural selection, genetics, and particulate inheritance - came together to form the current synthesis of evolutionary theory which explains how evolution is triggered by the variation of genes within a population, and how those variants change over time as a result of natural selection. This model, which is known as genetic drift or mutation, gene flow and sexual selection, is the foundation of the current evolutionary biology and can be mathematically explained.
Recent discoveries in the field of evolutionary developmental biology have demonstrated that variation can be introduced into a species via mutation, genetic drift and reshuffling of genes in sexual reproduction, and also by migration between populations. These processes, 에볼루션바카라사이트 as well as others, such as directionally-selected selection and erosion of genes (changes in frequency of genotypes over time), can lead towards evolution. Evolution is defined by changes in the genome over time and changes in the phenotype (the expression of genotypes in individuals).
Incorporating evolutionary thinking into all areas of biology education can increase students' understanding of phylogeny as well as evolution. A recent study by Grunspan and colleagues, for instance demonstrated that teaching about the evidence supporting evolution increased students' acceptance of evolution in a college biology course. To learn more about how to teach about evolution, look up The Evolutionary Potential of all Areas of Biology and Thinking Evolutionarily A Framework for Infusing Evolution in Life Sciences Education.
Evolution in Action
Traditionally scientists have studied evolution by studying fossils, comparing species, and studying living organisms. Evolution is not a distant event