The Academy's Evolution Site

Biology is a key concept in biology. The Academies are committed to helping those interested in science learn about the theory of evolution and how it can be applied across all areas 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 WGBH's science programs on DVD.

Tree of Life

The Tree of Life, an ancient symbol, 에볼루션 represents the interconnectedness of all life. It appears in many spiritual traditions and cultures as an emblem of unity and love. It can be used in many practical ways in addition to providing a framework for understanding the evolution of species and how they respond to changes in environmental conditions.

The earliest attempts to depict the world of biology focused on separating organisms into distinct categories that had been identified by their physical and metabolic characteristics1. 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 a tree of life2. However, these trees are largely comprised of eukaryotes, and bacterial diversity is not represented in a large way3,4.

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

Despite the dramatic growth of the Tree of Life through genome sequencing, a lot of biodiversity remains to be discovered. This is particularly true for microorganisms that are difficult to cultivate, and which are usually only present in a single sample5. A recent analysis of all genomes has produced an initial draft of the Tree of Life. This includes a wide range of bacteria, archaea and other organisms that have not yet been isolated, or their diversity is not thoroughly understood6.

The expanded Tree of Life can be used to evaluate the biodiversity of a particular area and determine if certain habitats need special protection. This information can be used in a variety of ways, from identifying the most effective remedies to fight diseases to enhancing the quality of the quality of crops. It is also valuable for conservation efforts. It can help biologists identify areas most likely to be home to cryptic species, which may have important metabolic functions and are susceptible to the effects of human activity. While conservation funds are important, the best way to conserve the biodiversity of the world is to equip more people in developing nations with the knowledge they need to act locally and promote conservation.

Phylogeny

A phylogeny is also known as an evolutionary tree, illustrates the relationships between various groups of organisms. Scientists can build an phylogenetic chart which shows the evolutionary relationships between taxonomic categories using molecular information and morphological differences or similarities. The concept of phylogeny is fundamental to understanding evolution, biodiversity and genetics.

A basic phylogenetic tree (see Figure PageIndex 10 Identifies the relationships between organisms that have similar characteristics and have evolved from a common ancestor. These shared traits can be either homologous or analogous. Homologous traits share their underlying evolutionary path, while analogous traits look like they do, but don't have the identical origins. Scientists combine similar traits into a grouping called a Clade. For instance, all of the organisms that make up a clade share the characteristic of having amniotic eggs and evolved from a common ancestor who had eggs. The clades then join to form a phylogenetic branch that can determine which organisms have the closest relationship to.

Scientists make use of DNA or RNA molecular data to construct a phylogenetic graph that is more precise and precise. This information is more precise than morphological information and provides evidence of the evolutionary history of an organism or group. Researchers can utilize Molecular Data to determine the age of evolution of organisms and identify the number of organisms that have the same ancestor.

The phylogenetic relationships between species are influenced by many factors including phenotypic plasticity, 에볼루션 무료체험 a type of behavior that changes in response to specific environmental conditions. This can cause a characteristic to appear more similar to a species than to another which can obscure the phylogenetic signal. However, this issue can be reduced by the use of techniques like cladistics, which combine similar and homologous traits into the tree.

In addition, phylogenetics helps predict the duration and rate of speciation. This information can assist conservation biologists make decisions about the species they should safeguard from extinction. In the end, it is the conservation of phylogenetic diversity that will result in an ecosystem that is balanced and complete.

Evolutionary Theory

The main idea behind evolution is that organisms acquire various characteristics over time as a result of their interactions with their environments. Several theories of evolutionary change have been developed by a variety of scientists including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who envisioned an organism developing gradually according to its requirements, the Swedish botanist Carolus Linnaeus (1707-1778) who designed modern hierarchical taxonomy, and Jean-Baptiste Lamarck (1744-1829) who suggested that the use or misuse of traits cause changes that can be passed onto offspring.

In the 1930s and 1940s, theories from various fields, including genetics, natural selection and particulate inheritance, merged to create a modern evolutionary theory. This explains how evolution occurs by the variation in genes within a population and how these variations change over time as a result of natural selection. This model, known as genetic drift or mutation, gene flow and sexual selection, is a key element of modern evolutionary biology and can be mathematically described.

Recent developments in the field of evolutionary developmental biology have shown that variation can be introduced into a species through mutation, genetic drift and reshuffling genes during sexual reproduction, as well as by migration between 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 lead to evolution which is defined by changes in the genome of the species over time, and also by changes in phenotype as time passes (the expression of that genotype in an individual).

Incorporating evolutionary thinking into all aspects of biology education could increase student understanding of the concepts of phylogeny and evolution. A recent study conducted by Grunspan and colleagues, for example, showed that teaching about the evidence supporting evolution increased students' understanding of evolution in a college 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.

Evolution in Action

Traditionally, scientists have studied evolution by looking back, studying fossils, 에볼루션 무료체험 comparing species, and observing living organisms. However, evolution isn't something that happened in the past. It's an ongoing process happening today. Bacteria transform and resist antibiotics, viruses re-invent themselves and elude new medications and animals change their behavior in response to the changing climate. The changes that result are often visible.

But it wasn't until the late 1980s that biologists realized that natural selection can be seen in action, as well. The main reason is that different traits result in a different rate of survival and reproduction, and 에볼루션 무료체험 can be passed down from one generation to another.

In the past, when one particular allele - the genetic sequence that defines color in a population of interbreeding species, it could rapidly become more common than other alleles. In time, this could mean that the number of black moths in a particular population could rise. 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 particular species has a rapid turnover of its generation such as bacteria. Since 1988, Richard Lenski, a biologist, has studied twelve populations of E.coli that are descended from a single strain. Samples of each population have been collected regularly, 바카라 에볼루션 코리아 (postheaven.net) and more than 500.000 generations of E.coli have passed.

Lenski's work has shown that mutations can alter the rate at which change occurs and the rate of a population's reproduction. It also demonstrates that evolution takes time--a fact that many are unable 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. This is due to pesticides causing an enticement that favors individuals who have resistant genotypes.

The rapidity of evolution has led to a greater appreciation of its importance particularly in a world shaped largely by human activity. This includes the effects of climate change, pollution and habitat loss that hinders many species from adapting. Understanding evolution can assist you in making better choices about the future of the planet and its inhabitants.