The Academy's Evolution Site
Biology is one of the most fundamental concepts in biology. The Academies have been active for a long time in helping those interested in science understand the concept of evolution and how it permeates all areas of scientific research.
This site provides a wide range of resources for students, teachers and general readers of evolution. It also includes important 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 life. It is seen in a variety of spiritual traditions and cultures as an emblem of unity and love. It has many practical applications as well, such as providing a framework for understanding the evolution of species and how they respond to changes in environmental conditions.
Early attempts to represent the world of biology were based on categorizing organisms based on their physical and metabolic characteristics. These methods, which rely 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 largely made up of eukaryotes. Bacterial diversity is still largely unrepresented3,4.
By avoiding the necessity for direct experimentation and observation genetic techniques have made it possible to depict the Tree of Life in a more precise manner. Trees can be constructed using molecular methods like the small-subunit ribosomal gene.
Despite the dramatic expansion of the Tree of Life through genome sequencing, much biodiversity still awaits discovery. This is particularly true of microorganisms, which can be difficult to cultivate and are typically only present in a single sample5. Recent analysis of all genomes resulted in an initial draft of the Tree of Life. This includes a variety of bacteria, archaea and other organisms that haven't yet been isolated or their diversity is not well understood6.
This expanded Tree of Life is particularly useful for assessing the biodiversity of an area, helping to determine if certain habitats require special protection. This information can be utilized in a variety of ways, such as finding new drugs, battling diseases and improving the quality of crops. This information is also extremely beneficial to conservation efforts. It helps biologists determine those areas that are most likely contain cryptic species with significant metabolic functions that could be vulnerable to anthropogenic change. While funds to protect biodiversity are essential, ultimately the best way to ensure the preservation of biodiversity around the world is for more people in developing countries to be empowered with the knowledge to take action locally to encourage conservation from within.
Phylogeny
A phylogeny (also known as an evolutionary tree) shows the relationships between species. Utilizing molecular data, morphological similarities and differences, or ontogeny (the process of the development of an organism) scientists can create an phylogenetic tree that demonstrates the evolutionary relationship between taxonomic groups. Phylogeny is essential in understanding the evolution of biodiversity, evolution and genetics.
A basic phylogenetic tree (see Figure PageIndex 10 Determines the relationship between organisms that have similar traits and have evolved from a common ancestor. These shared traits could be either analogous or homologous. Homologous traits are similar in their evolutionary roots and analogous traits appear like they do, but don't have the identical origins. Scientists put similar traits into a grouping referred to as a Clade. For example, all of the organisms in a clade have the characteristic of having amniotic egg and evolved from a common ancestor that had these eggs. The clades are then linked to create a phylogenetic tree to identify organisms that have the closest connection to each other.
Scientists use molecular DNA or RNA data to create a phylogenetic chart that is more accurate and detailed. This information is more precise and provides evidence of the evolution of an organism. The analysis of molecular data can help researchers identify the number of organisms that share an ancestor common to them and estimate their evolutionary age.
The phylogenetic relationships of organisms can be affected by a variety of factors, including phenotypic plasticity an aspect of behavior that alters in response to specific environmental conditions. This can cause a trait to appear more like a species another, clouding the phylogenetic signal. This issue can be cured by using cladistics. This is a method that incorporates a combination of homologous and analogous traits in the tree.
Additionally, phylogenetics aids determine the duration and speed at which speciation takes place. This information can assist conservation biologists make decisions about which species to protect from the threat of extinction. Ultimately, it is the preservation of phylogenetic diversity that will result in a complete and balanced ecosystem.
Evolutionary Theory
The central theme in evolution is that organisms alter over time because of their interactions with their environment. 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 slowly according to its needs as well as the Swedish botanist Carolus Linnaeus (1707-1778) who developed modern hierarchical taxonomy, and Jean-Baptiste Lamarck (1744-1829) who suggested that the use or misuse of traits causes changes that could be passed onto offspring.
In the 1930s and 1940s, theories from various fields, such as natural selection, genetics & particulate inheritance, were brought together to create a modern theorizing of evolution. This describes how evolution happens through the variations in genes within the population, and how these variations alter over time due to natural selection. This model, which includes mutations, genetic drift as well as gene flow and sexual selection, can be mathematically described mathematically.
Recent discoveries in evolutionary developmental biology have shown how variations can be introduced to a species via mutations, genetic drift or reshuffling of genes in sexual reproduction, and even migration between populations. These processes, along with others such as directional selection or genetic erosion (changes in the frequency of the 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 the individual).
Students can gain a better understanding of phylogeny by incorporating evolutionary thinking in all areas of biology. In a recent study conducted by Grunspan and co. It was found that teaching students about the evidence for evolution increased their understanding of evolution in the course of a college 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 Evolution into Life Sciences Education.
Evolution in Action
Traditionally scientists have studied evolution through looking back, studying fossils, comparing species and observing living organisms. But evolution isn't just something that occurred in the past, it's an ongoing process that is taking place in the present. Viruses evolve to stay away from new medications and bacteria mutate to resist antibiotics. Animals alter their behavior as a result of a changing environment. The changes that occur are often apparent.
It wasn't until late 1980s when biologists began to realize that natural selection was also in play. The key is the fact that different traits can confer an individual rate of survival and reproduction, and can be passed down from one generation to another.
In the past, if one particular allele, the genetic sequence that determines coloration--appeared in a population of interbreeding species, it could rapidly become more common than other alleles. As time passes, this could mean that the number of moths that have black pigmentation could increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.
Monitoring evolutionary changes in action is 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 regularly and over 500.000 generations have passed.
Lenski's work has demonstrated that mutations can drastically alter the efficiency with which a population reproduces and, consequently, the rate at which it evolves. It also shows that evolution takes time--a fact that many find difficult to accept.
Microevolution is also evident in the fact that mosquito genes that confer resistance to pesticides are more prevalent in areas where insecticides have been used. That's because the use of pesticides creates a selective pressure that favors those with resistant genotypes.
The rapidity of evolution has led to a growing recognition of its importance particularly in a world that is largely shaped by human activity. 에볼루션 바카라사이트 includes climate change, pollution, and habitat loss, which prevents many species from adapting. Understanding the evolution process will assist you in making better choices regarding the future of the planet and its inhabitants.