자유게시판

The Academy's Evolution Site

Biology is a key concept in biology. The Academies are committed to helping those who are interested in science to learn about the theory of evolution and how it is incorporated across all areas of scientific research.

This site provides students, teachers and general readers with a wide range of educational resources on evolution. It contains key 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 seen in a variety of religions and cultures as an emblem of unity and love. It has many practical applications as well, such as providing a framework to understand the history of species, and how they react to changing environmental conditions.

Early approaches to depicting the biological world focused on separating organisms into distinct categories which had been distinguished by physical and metabolic characteristics1. These methods are based on the sampling of different parts of organisms or DNA fragments have greatly increased the diversity of a Tree of Life2. However these trees are mainly composed of eukaryotes; bacterial diversity is still largely unrepresented3,4.

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

The Tree of Life has been significantly expanded by genome sequencing. However there is still a lot of biodiversity to be discovered. This is particularly relevant to microorganisms that are difficult to cultivate, and which are usually only found in a single specimen5. A recent analysis of all genomes resulted in a rough draft of a Tree of Life. This includes a variety of archaea, bacteria and other organisms that have not yet been isolated, or their diversity is not fully understood6.

This expanded Tree of Life can be used to determine the diversity of a specific region and determine if specific habitats need special protection. The information is useful in a variety of ways, such as identifying new drugs, combating diseases and enhancing crops. It is also valuable to conservation efforts. It can aid biologists in identifying areas that are likely to be home to species that are cryptic, which could have vital metabolic functions and are susceptible to the effects of human activity. While conservation funds are important, the most effective method to preserve the world's biodiversity is to empower more people in developing nations with the information they require to take action locally and encourage conservation.

Phylogeny

A phylogeny is also known as an evolutionary tree, shows 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 an phylogenetic tree that demonstrates the evolutionary relationship between taxonomic groups. Phylogeny plays a crucial role in understanding genetics, biodiversity and evolution.

A basic phylogenetic tree (see Figure PageIndex 10 ) identifies the relationships between organisms with similar traits that evolved from common ancestors. These shared traits are either analogous or homologous. Homologous traits are the same in terms of their evolutionary paths. Analogous traits could appear similar, but they do not have the same ancestry. Scientists group similar traits into a grouping called a the clade. All members of a clade have a common characteristic, for example, amniotic egg production. They all derived from an ancestor that had these eggs. A phylogenetic tree can be constructed by connecting the clades to identify the organisms that are most closely related to one another.

Scientists make use of DNA or RNA molecular data to create a phylogenetic chart that is more precise and precise. This information is more precise and gives evidence of the evolutionary history of an organism. Molecular data allows researchers to identify the number of species that share the same ancestor and estimate their evolutionary age.

Phylogenetic relationships can be affected by a variety of factors that include the phenomenon of phenotypicplasticity. This is a type of behavior that changes in response to particular environmental conditions. This can cause a trait to appear more similar to one species than to the other, obscuring the phylogenetic signals. This problem can be addressed by using cladistics. This is a method that incorporates an amalgamation of homologous and analogous traits in the tree.

Additionally, phylogenetics can aid in predicting the time and pace of speciation. This information will assist conservation biologists in making decisions about which species to protect from the threat of extinction. In the end, it's the conservation of phylogenetic diversity which will create an ecosystem that is complete and balanced.

Evolutionary Theory

The fundamental concept in evolution is that organisms change over time due to their interactions with their environment. Many scientists have come up with theories of evolution, such as the Islamic naturalist Nasir al-Din al-Tusi (1201-274) who believed that an organism could develop according to its own needs and 에볼루션 바카라 무료체험 needs, the Swedish taxonomist Carolus Linnaeus (1707-1778) who conceived the modern taxonomy system that is hierarchical, 에볼루션 바카라 무료체험 as well as Jean-Baptiste Lamarck (1844-1829), who suggested that the use or absence of certain traits can result in changes that can be passed on to future generations.

In the 1930s & 1940s, concepts from various fields, such as genetics, natural selection and particulate inheritance, came together to create a modern evolutionary theory. This explains how evolution happens through the variation in genes within the population and how these variations alter over time due to natural selection. This model, which is known as genetic drift mutation, gene flow, and sexual selection, is the foundation of modern evolutionary biology and can be mathematically described.

Recent discoveries in evolutionary developmental biology have shown how variations can be introduced to a species by mutations, genetic drift, reshuffling genes during sexual reproduction, and even migration between populations. These processes, along with others like directional selection and genetic erosion (changes in the frequency of the genotype over time) can lead to evolution that is defined as changes in the genome of the species over time and the change in phenotype over time (the expression of that genotype within the individual).

Students can better understand phylogeny by incorporating evolutionary thinking throughout all aspects of biology. In a recent study conducted by Grunspan et al., it was shown that teaching students about the evidence for evolution boosted their acceptance of evolution during a college-level course in biology. For more information on how to teach about evolution, look up The Evolutionary Potential of All Areas of Biology and Thinking Evolutionarily: A Framework for Infusing the Concept of Evolution into Life Sciences Education.

Evolution in Action

Traditionally scientists have studied evolution through looking back--analyzing fossils, comparing species, and studying living organisms. But evolution isn't a thing that occurred in the past, it's an ongoing process, happening right now. The virus reinvents itself to avoid new medications and bacteria mutate to resist antibiotics. Animals alter their behavior in the wake of a changing environment. The results are often evident.

It wasn't until the late 1980s that biologists began realize that natural selection was also in play. The key to this is that different traits can confer an individual rate of survival and reproduction, and 에볼루션 게이밍 can be passed down from one generation to another.

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. Over time, that would mean that the number of black moths in a population could increase. The same is true for 에볼루션 카지노바카라 (Setiathome.berkeley.Edu) many other characteristics--including morphology and behavior--that vary among populations of organisms.

It is easier to track evolutionary change when an organism, like bacteria, has a high generation turnover. Since 1988 the biologist Richard Lenski has been tracking twelve populations of E. coli that descended from a single strain. samples of each population are taken every day and more than 500.000 generations have passed.

Lenski's research has demonstrated that mutations can alter the rate at which change occurs and the effectiveness at which a population reproduces. It also shows that evolution is slow-moving, a fact that some are unable to accept.

Microevolution can be observed in the fact that mosquito genes that confer resistance to pesticides are more prevalent in areas that have used insecticides. This is due to the fact that the use of pesticides creates a selective pressure that favors individuals with resistant genotypes.

The rapidity of evolution has led to an increasing appreciation of its importance, especially in a world which is largely shaped by human activities. This includes the effects of climate change, pollution and habitat loss that prevents many species from adapting. Understanding evolution can help you make better decisions about the future of the planet and its inhabitants.