The Academy's Evolution Site
Biology is a key concept in biology. The Academies are involved in helping those who are interested in science comprehend the evolution theory and how it is permeated in all areas of scientific research.
This site provides a range of resources for teachers, students as well as general readers about evolution. It contains important video clips from NOVA and the WGBH-produced science programs on DVD.
Tree of Life
The Tree of Life, an ancient symbol, represents the interconnectedness of all life. It is a symbol of love and unity across many cultures. It has many practical applications in addition to providing a framework for understanding the history of species, and how they respond to changes in environmental conditions.
The earliest attempts to depict the world of biology focused on categorizing species into distinct categories that were distinguished by physical and metabolic characteristics1. These methods, which relied on the sampling of various parts of living organisms or sequences of short fragments of their DNA, significantly expanded the diversity that could be represented in a tree of life2. These trees are largely composed of eukaryotes, while bacterial diversity is vastly underrepresented3,4.
In avoiding the necessity of direct experimentation and observation genetic techniques have made it possible to represent the Tree of Life in a more precise way. Particularly, molecular methods allow us to build trees by using sequenced markers like the small subunit ribosomal RNA gene.
Despite the rapid growth of the Tree of Life through genome sequencing, a large amount of biodiversity remains to be discovered. This is especially the case for microorganisms which are difficult to cultivate, and are usually found in one sample5. A recent study of all genomes that are known has created a rough draft of the Tree of Life, including many bacteria and archaea that are not isolated and their diversity is not fully understood6.
The expanded Tree of Life is particularly useful for assessing the biodiversity of an area, which can help to determine whether specific habitats require special protection. This information can be used in a variety of ways, from identifying new remedies to fight diseases to enhancing the quality of crops. This information is also extremely useful to conservation efforts. It helps biologists determine those areas that are most likely contain cryptic species with important metabolic functions that may be vulnerable to anthropogenic change. While funds to protect biodiversity are important, the most effective method to protect the world's biodiversity is to empower more people in developing countries with the knowledge they need to act locally and support conservation.
Phylogeny
A phylogeny (also called an evolutionary tree) depicts the relationships between different organisms. Scientists can construct a phylogenetic diagram that illustrates the evolution of taxonomic groups using molecular data and morphological differences or similarities. 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 that have similar traits and evolved from an ancestor with common traits. These shared traits could be homologous, or analogous. Homologous traits are the same in terms of their evolutionary journey. Analogous traits might appear similar however they do not share the same origins. Scientists group similar traits together into a grouping referred to as a clade. For instance, all of the organisms that make up a clade have the characteristic of having amniotic eggs and evolved from a common ancestor who had these eggs. The clades are then linked to form a phylogenetic branch to determine which organisms have the closest connection to each other.
Scientists utilize DNA or RNA molecular information to construct a phylogenetic graph that is more accurate and detailed. This information is more precise and gives evidence of the evolution of an organism. The use of molecular data lets researchers determine the number of organisms that have an ancestor common to them and estimate their evolutionary age.
The phylogenetic relationships between organisms can be affected by a variety of factors, including phenotypic flexibility, an aspect of behavior that changes in response to specific environmental conditions. This can cause a characteristic to appear more similar to a species than to the other which can obscure the phylogenetic signal. This issue can be cured by using cladistics, which is a a combination of homologous and analogous traits in the tree.
Furthermore, phylogenetics may help predict the duration and rate of speciation. This information can help conservation biologists decide which species they should protect from the threat of extinction. In the end, it is the preservation of phylogenetic diversity that will lead to an ecosystem that is complete and balanced.
Evolutionary Theory
The main idea behind evolution is that organisms develop various characteristics over time as a result of their interactions with their environment. Many theories of evolution have been developed by a wide range of scientists including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who believed that an organism would evolve slowly in accordance with its requirements 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 can be passed on to offspring.
In the 1930s and 1940s, concepts from various fields, including natural selection, genetics, and particulate inheritance--came together to form the current synthesis of evolutionary theory that explains how evolution is triggered by the variation of genes within a population, and how those variants change over time due to natural selection. This model, known as genetic drift, mutation, gene flow and sexual selection, is a cornerstone of modern evolutionary biology and can be mathematically described.
Recent developments in the field of evolutionary developmental biology have demonstrated that variation can be introduced into a species via mutation, genetic drift and reshuffling of genes in sexual reproduction, and also by migration between populations. These processes, in conjunction with others such as the directional selection process and the erosion of genes (changes in frequency of genotypes over time), can lead towards evolution. Evolution is defined by changes in the genome over time and changes in the phenotype (the expression of genotypes in individuals).
Incorporating evolutionary thinking into all aspects of biology education can increase student understanding of the concepts of phylogeny and evolutionary. In a recent study conducted by Grunspan et al. It was found that teaching students about the evidence for evolution increased 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 in All Areas of Biology and Thinking Evolutionarily A Framework for Infusing Evolution in Life Sciences Education.
Evolution in Action
Scientists have studied evolution through looking back in the past, analyzing fossils and comparing species. They also observe living organisms. Evolution is not a past moment; it is an ongoing process. Viruses evolve to stay away from new antibiotics and bacteria transform to resist antibiotics. Animals adapt their behavior in the wake of a changing environment. The results are usually easy to see.
It wasn't until late 1980s that biologists realized that natural selection could be observed in action as well. The key is that different traits confer different rates of survival and reproduction (differential fitness) and can be passed from one generation to the next.
In the past, if one particular allele - the genetic sequence that determines coloration--appeared in a group of interbreeding species, it could quickly become more common than all other alleles. As time passes, this could mean that the number of moths sporting black pigmentation in a group may increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.
Observing evolutionary change in action is easier when a particular species has a rapid generation turnover like bacteria. Since 1988, Richard Lenski, a biologist, has tracked twelve populations of E.coli that descend from a single strain. Samples from each population were taken frequently and more than 50,000 generations of E.coli have passed.
Lenski's work has demonstrated that a mutation can dramatically alter the rate at which a population reproduces--and so, the rate at which it alters. It also shows that evolution takes time, which is hard for some to accept.
Another example of microevolution is that mosquito genes for resistance to pesticides appear more frequently in populations where insecticides are used. This is due to the fact that the use of pesticides creates a selective pressure that favors individuals who have resistant genotypes.
The rapidity of evolution has led to an increasing recognition of its importance particularly in a world shaped largely by human activity. This includes climate change, pollution, and habitat loss, which prevents many species from adapting. Understanding 에볼루션 룰렛 can help you make better decisions about the future of our planet and its inhabitants.