10 Top Mobile Apps For Evolution Site
The Academy's Evolution Site
Biological evolution is a central concept in biology. The Academies are committed to helping those interested in science learn about the theory of evolution and how it is incorporated across all areas of scientific research.
This site provides teachers, students and general readers with a wide range 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 represents the interconnectedness of all life. It is used in many religions and cultures as symbolizing unity and love. It has numerous practical applications in addition to providing a framework for understanding the history 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, based on the sampling of different parts of living organisms, or sequences of small fragments of their DNA, greatly increased the variety of organisms that could be included in the tree of life2. 에볼루션 블랙잭 are largely composed of eukaryotes, while bacterial diversity is vastly underrepresented3,4.
By avoiding the necessity for direct observation and experimentation genetic techniques have allowed us to depict the Tree of Life in a more precise manner. We can create trees using molecular methods like the small-subunit ribosomal gene.
Despite the massive expansion of the Tree of Life through genome sequencing, much biodiversity still awaits discovery. This is particularly relevant to microorganisms that are difficult to cultivate, and which are usually only found in one sample5. Recent analysis of all genomes has produced an initial draft of a Tree of Life. This includes a large number of archaea, bacteria, and other organisms that have not yet been identified or the diversity of which is not thoroughly understood6.
This expanded Tree of Life can be used to assess the biodiversity of a particular area and determine if specific habitats require special protection. This information can be used in a range of ways, from identifying the most effective treatments to fight disease to improving crops. The information is also incredibly valuable in conservation efforts. It can help biologists identify the areas most likely to contain cryptic species with potentially important metabolic functions that may be vulnerable to anthropogenic change. Although funds to safeguard biodiversity are vital however, the most effective method to ensure the preservation of biodiversity around the world is for more people living in developing countries to be empowered with the necessary knowledge to act locally to promote conservation from within.
Phylogeny
A phylogeny, also known as an evolutionary tree, reveals the connections between different groups of organisms. Using molecular data, morphological similarities and differences or ontogeny (the course of development of an organism) scientists can construct a phylogenetic tree which illustrates the evolutionary relationship between taxonomic groups. Phylogeny is crucial in understanding evolution, biodiversity and genetics.
A basic phylogenetic Tree (see Figure PageIndex 10 ) determines the relationship between organisms that share similar traits that have evolved from common ancestral. These shared traits can be either analogous or homologous. Homologous traits are identical in their evolutionary origins and analogous traits appear similar but do not have the same ancestors. Scientists group similar traits into a grouping called a clade. For instance, all of the organisms in a clade share the trait 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 that are most closely related to one another.
To create a more thorough and accurate phylogenetic tree scientists make use of molecular data from DNA or RNA to determine the relationships between organisms. This data is more precise than morphological information and gives evidence of the evolutionary history of an individual or group. The use of molecular data lets researchers identify the number of organisms that share a common ancestor and to estimate their evolutionary age.
Phylogenetic relationships can be affected by a number of factors, including the phenomenon of phenotypicplasticity. This is a type behavior that alters as a result of unique environmental conditions. This can cause a trait to appear more like a species other species, which can obscure the phylogenetic signal. This issue can be cured by using cladistics. This is a method that incorporates an amalgamation of homologous and analogous features in the tree.
Furthermore, phylogenetics may aid in predicting the time and pace of speciation. This information can help conservation biologists decide which species they should protect from extinction. Ultimately, it is the preservation of phylogenetic diversity that will lead to a complete and balanced ecosystem.
Evolutionary Theory
The fundamental concept of evolution is that organisms acquire different features over time as a result of their interactions with their environments. 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 proposed that a living organism develop slowly according to its requirements, the Swedish botanist Carolus Linnaeus (1707-1778) who conceived the modern hierarchical taxonomy Jean-Baptiste Lamarck (1744-1829) who suggested that use or disuse of traits causes 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 modern evolutionary theory which explains how evolution is triggered by the variation 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 as well as gene flow and sexual selection is mathematically described mathematically.
Recent discoveries in evolutionary developmental biology have demonstrated how variation can be introduced to a species via mutations, genetic drift, reshuffling genes during sexual reproduction and the movement between populations. These processes, along with other ones like directional selection and gene erosion (changes in frequency of genotypes over time) can result in evolution. Evolution is defined by changes in the genome over time, as well as changes in phenotype (the expression of genotypes within individuals).
Incorporating evolutionary thinking into all areas of biology education can improve student understanding of the concepts of phylogeny as well as evolution. A recent study by Grunspan and colleagues, for example, showed that teaching about the evidence for evolution increased students' acceptance of evolution in a college-level biology class. For more details on how to teach evolution read The Evolutionary Potential in All Areas of Biology or Thinking Evolutionarily: a Framework for Infusing Evolution into Life Sciences Education.
Evolution in Action
Scientists have studied evolution by looking in the past, studying fossils, and comparing species. They also study living organisms. But evolution isn't just something that occurred in the past, it's an ongoing process that is happening in the present. The virus reinvents itself to avoid new medications and bacteria mutate to resist antibiotics. Animals alter their behavior as a result of a changing environment. The changes that result are often apparent.
It wasn't until late 1980s that biologists realized that natural selection can be observed in action as well. The key is the fact that different traits result in the ability to survive at different rates and reproduction, and can be passed down from one generation to the next.
In the past when one particular allele - the genetic sequence that controls coloration - was present in a group of interbreeding organisms, it might rapidly become more common than all other alleles. In time, this could mean that the number of black moths in the 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 generation turnover like 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 regularly and more than fifty thousand generations have been observed.
Lenski's research has revealed that mutations can alter the rate of change and the effectiveness of a population's reproduction. It also demonstrates that evolution takes time--a fact that many are unable to accept.
Microevolution is also evident in the fact that mosquito genes that confer resistance to pesticides are more prevalent in populations that have used insecticides. That's because the use of pesticides creates a selective pressure that favors those who have resistant genotypes.
The rapidity of evolution has led to a growing appreciation of its importance particularly in a world that is largely shaped by human activity. This includes pollution, climate change, and habitat loss that hinders many species from adapting. Understanding the evolution process will assist you in making better choices regarding the future of the planet and its inhabitants.