The Academy's Evolution Site
Biology is one of the most fundamental concepts 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 about evolution. It has key video clips from NOVA and WGBH-produced science programs on DVD.
Tree of Life
The Tree of Life is an ancient symbol that represents the interconnectedness of all life. It appears in many religions and cultures as symbolizing unity and love. It has many practical applications as well, including providing a framework for understanding the history of species and how they respond to changes in environmental conditions.
Early attempts to describe the world of biology were built on categorizing organisms based on their metabolic and physical characteristics. These methods depend on the collection of various parts of organisms or short fragments of DNA have greatly increased the diversity of a Tree of Life2. However these trees are mainly comprised of eukaryotes, and bacterial diversity is still largely unrepresented3,4.
By avoiding the necessity for direct observation and experimentation genetic techniques have enabled us to depict the Tree of Life in a more precise manner. In particular, molecular methods allow us to construct trees using sequenced markers, such as the small subunit of ribosomal RNA gene.
Despite the massive expansion of the Tree of Life through genome sequencing, a large amount of biodiversity is waiting to be discovered. This is especially true for microorganisms that are difficult to cultivate and which are usually only present in a single sample5. Recent analysis of all genomes produced an unfinished draft of a Tree of Life. This includes a large number of archaea, bacteria, and other organisms that haven't yet been isolated, or their diversity is not well understood6.
This expanded Tree of Life can be used to assess the biodiversity of a specific area and determine if certain habitats need special protection. This information can be used in a variety of ways, from identifying the most effective treatments to fight disease to enhancing the quality of crops. This information is also extremely beneficial for conservation efforts. It helps biologists determine those areas that are most likely contain cryptic species that could have important metabolic functions that could be at risk from anthropogenic change. While conservation funds are important, the most effective method to preserve the world's biodiversity is to equip more people in developing countries with the necessary knowledge to act locally and promote conservation.
Phylogeny
A phylogeny (also called an evolutionary tree) illustrates the relationship between organisms. Scientists can construct an phylogenetic chart which shows the evolution of taxonomic categories using molecular information and morphological similarities or differences. The concept of phylogeny is fundamental to understanding evolution, biodiversity and genetics.
A basic phylogenetic Tree (see Figure PageIndex 10 ) is a method of identifying the relationships between organisms that share similar traits that have evolved from common ancestors. These shared traits are either analogous or homologous. Homologous traits are the same in their evolutionary path. Analogous traits may look similar however they do not have the same origins. Scientists organize similar traits into a grouping known as a the clade. For instance, all the species in a clade share the trait of having amniotic eggs and evolved from a common ancestor that had these eggs. The clades are then linked to form a phylogenetic branch that can identify organisms that have the closest relationship.
For a more precise and accurate phylogenetic tree, scientists rely on molecular information from DNA or RNA to determine the relationships between organisms. This information is more precise and provides evidence of the evolutionary history of an organism. Researchers can use Molecular Data to determine the evolutionary age of organisms and determine how many species have the same ancestor.
The phylogenetic relationships of organisms are influenced by many factors, including phenotypic plasticity a type of behavior that alters in response to unique environmental conditions. This can cause a trait to appear more resembling to one species than to another and obscure the phylogenetic signals. However, this issue can be solved through the use of techniques such as cladistics which incorporate a combination of homologous and analogous features into the tree.
In addition, phylogenetics can aid in predicting the time and pace of speciation. This information can assist conservation biologists decide the species they should safeguard from the threat of extinction. Ultimately, it is the preservation of phylogenetic diversity which will lead to an ecologically balanced and complete ecosystem.
Evolutionary Theory
The central theme in evolution is that organisms change over time as a result of their interactions with their environment. A variety of theories about evolution have been proposed by a variety of scientists such as the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who believed that an organism would evolve slowly according to its needs, the Swedish botanist Carolus Linnaeus (1707-1778) who conceived modern hierarchical taxonomy, and Jean-Baptiste Lamarck (1744-1829) who suggested that the use or non-use of traits can cause changes that could be passed on to offspring.
In 에볼루션카지노사이트 and 1940s, concepts from a variety of fields -- including genetics, natural selection, and particulate inheritance--came together to create the modern evolutionary theory synthesis which explains how evolution is triggered by the variations of genes within a population and how those variants change in time as a result of natural selection. This model, which includes genetic drift, mutations, gene flow and sexual selection can be mathematically described.
Recent developments in the field of evolutionary developmental biology have revealed that variations can be introduced into a species via genetic drift, mutation, and reshuffling of genes in sexual reproduction, as well as through the movement of populations. These processes, as well as others like directional selection and 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 the change in phenotype as time passes (the expression of that genotype in an individual).
Incorporating evolutionary thinking into all areas of biology education can improve students' understanding of phylogeny and evolutionary. A recent study conducted by Grunspan and colleagues, for example demonstrated that teaching about the evidence supporting evolution increased students' acceptance of evolution in a college biology course. For more information about how to teach evolution, see The Evolutionary Potential in All Areas of Biology or Thinking Evolutionarily: a Framework for Infusing Evolution into Life Sciences Education.
Evolution in Action
Traditionally scientists have studied evolution through studying fossils, comparing species and studying living organisms. Evolution is not a distant event; it is an ongoing process that continues to be observed today. Bacteria transform and resist antibiotics, viruses re-invent themselves and elude new medications, and animals adapt their behavior to a changing planet. The results are often apparent.
It wasn't until the late 1980s that biologists began realize that natural selection was also at work. 에볼루션 슬롯게임 is that different traits have different rates of survival and reproduction (differential fitness) and are passed down from one generation to the next.
In the past, if one particular allele, the genetic sequence that controls coloration - was present in a group of interbreeding organisms, it might quickly become more prevalent than all other alleles. As time passes, this could mean that the number of moths that have black pigmentation in a population may 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 generation turnover like bacteria. Since 1988, biologist Richard Lenski has been tracking twelve populations of E. coli that descended from a single strain. samples from each population are taken every day, and over fifty thousand generations have passed.
Lenski's research has demonstrated that mutations can alter the rate of change and the rate at which a population reproduces. It also demonstrates that evolution takes time, which is hard for some to accept.
Another example of microevolution is the way mosquito genes for resistance to pesticides show up more often in populations where insecticides are employed. Pesticides create a selective pressure which favors those with resistant genotypes.
The speed at which evolution can take place has led to an increasing appreciation of its importance in a world shaped by human activity, including climate changes, pollution and the loss of habitats that hinder many species from adjusting. Understanding the evolution process can help us make better choices about the future of our planet, as well as the lives of its inhabitants.