The Academy's Evolution Site

The concept of biological evolution is a fundamental concept in biology. The Academies have been active for a long time in helping those interested in science understand the theory of evolution and how it affects all areas of scientific exploration.

This site provides teachers, students and general readers with a variety of learning resources on evolution. It includes key video clip from NOVA and WGBH produced science programs on DVD.

Tree of Life

The Tree of Life is an ancient symbol that symbolizes the interconnectedness of all life. It is seen in a variety of spiritual traditions and cultures as symbolizing unity and love. It can be used in many practical ways as well, such as providing a framework to understand the evolution of species and how they react to changing environmental conditions.

Early attempts to represent the biological world were founded on categorizing organisms on their metabolic and physical characteristics. These methods depend on the sampling of different parts of organisms or short fragments of DNA, have greatly increased the diversity of a Tree of Life2. These trees are largely composed by eukaryotes, and bacteria are largely underrepresented3,4.

Genetic techniques have greatly expanded our ability to visualize the Tree of Life by circumventing the requirement for direct observation and experimentation. Particularly, molecular methods enable us to create trees by using sequenced markers, such as the small subunit ribosomal RNA gene.

Despite the massive expansion of the Tree of Life through genome sequencing, a large amount of biodiversity remains to be discovered. This is particularly true for microorganisms that are difficult to cultivate, and which are usually only found in a single specimen5. 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 have not yet been isolated or the diversity of which is not thoroughly understood6.

This expanded Tree of Life is particularly beneficial in assessing the biodiversity of an area, which can help to determine whether specific habitats require protection. The information can be used in a range of ways, from identifying the most effective medicines to combating disease to improving the quality of crops. The information is also beneficial in conservation efforts. It can aid biologists in identifying areas most likely to be home to cryptic species, which could perform important metabolic functions, and could be susceptible to changes caused by humans. While funds to protect biodiversity are essential however, the most effective method to preserve the world's biodiversity is for more people in developing countries to be empowered with the knowledge to act locally to promote conservation from within.

Phylogeny


A phylogeny (also called an evolutionary tree) illustrates the relationship between different organisms. Using molecular data similarities and differences in morphology or ontogeny (the course of development of an organism) scientists can construct an phylogenetic tree that demonstrates the evolutionary relationships between taxonomic categories. 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 ) determines the relationship between organisms with similar traits that evolved from common ancestral. These shared traits can be analogous or homologous. Homologous characteristics are identical in their evolutionary journey. Analogous traits might appear like they are but they don't share the same origins. Scientists group similar traits together into a grouping referred to as a the clade. All members of a clade have a common trait, such as amniotic egg production. They all evolved from an ancestor that had these eggs. The clades then join to form a phylogenetic branch that can identify organisms that have the closest relationship.

Scientists utilize DNA or RNA molecular information to construct a phylogenetic graph that is more precise and detailed. This information is more precise and gives evidence of the evolutionary history of an organism. Researchers can use Molecular Data to calculate the age of evolution of organisms and identify the number of organisms that share the same ancestor.

The phylogenetic relationships between species can be affected by a variety of factors including phenotypic plasticity, a type of behavior that alters in response to specific environmental conditions. This can cause a particular trait to appear more similar to one species than another, obscuring the phylogenetic signal. However, this problem can be cured by the use of methods such as cladistics which include a mix of homologous and analogous features into the tree.

Additionally, Related Homepag predict the duration and rate at which speciation takes place. This information can aid conservation biologists to decide which species they should protect from the threat of extinction. In the end, it's the conservation of phylogenetic variety that will result in an ecosystem that is complete and balanced.

Evolutionary Theory

The fundamental concept in evolution is that organisms change over time as a result of their interactions with their environment. Many theories of evolution have been proposed by a wide range of scientists such as the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who envisioned an organism developing gradually according to its needs as well as 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 causes changes that could be passed on to the offspring.

In the 1930s & 1940s, concepts from various areas, including genetics, natural selection, and particulate inheritance, merged to form a modern synthesis of evolution theory. This describes how evolution happens through the variations in genes within the population and how these variations 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 current evolutionary biology, and can be mathematically described.

Recent discoveries in evolutionary developmental biology have shown the ways in which variation can be introduced to a species through genetic drift, mutations or reshuffling of genes in sexual reproduction and the movement between populations. These processes, as well as other ones like directionally-selected selection and erosion of genes (changes to the frequency of genotypes over time) can result in 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).

Students can better understand the concept of phylogeny through incorporating evolutionary thinking into all aspects of biology. In a recent study conducted by Grunspan and co., it was shown that teaching students about the evidence for evolution boosted their understanding of evolution in an undergraduate biology course. For more information on how to teach about evolution, see The Evolutionary Potential of All Areas of Biology and Thinking Evolutionarily: A Framework for Infusing Evolution into Life Sciences Education.

Evolution in Action

Scientists have traditionally studied evolution through looking back in the past--analyzing fossils and comparing species. They also study living organisms. But evolution isn't a thing that happened in the past, it's an ongoing process happening today. Viruses evolve to stay away from new drugs and bacteria evolve to resist antibiotics. Animals alter their behavior as a result of a changing world. The results are usually evident.

It wasn't until late 1980s that biologists realized that natural selection could be seen in action, as well. The key is the fact that different traits confer a different rate of survival as well as reproduction, and may be passed down from one generation to the next.

In the past, if one allele - the genetic sequence that determines color - was present in a population of organisms that interbred, it could become more prevalent than any other allele. Over 에볼루션카지노 , this would mean that the number of moths sporting black pigmentation in a population could increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.

The ability to observe evolutionary change 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. bacteria that descend from a single strain; samples from each population are taken on a regular basis and over fifty thousand generations have passed.

Lenski's research has revealed that a mutation can profoundly alter the efficiency with which a population reproduces--and so, the rate at which it evolves. It also demonstrates that evolution takes time, a fact that some are unable to accept.

에볼루션 블랙잭 can be observed in the fact that mosquito genes that confer resistance to pesticides are more prevalent in areas where insecticides have been used. Pesticides create an exclusive pressure that favors individuals who have resistant genotypes.

The rapid pace of evolution taking place has led to an increasing recognition of its importance in a world that is shaped by human activity, including climate change, pollution, and the loss of habitats which prevent the species from adapting. Understanding evolution will help us make better decisions about the future of our planet, and the life of its inhabitants.