15 Reasons You Shouldn't Ignore Evolution Site
The Academy's Evolution Site
Biological evolution is a central concept in biology. The Academies are committed to helping those who are interested in science learn about the theory of evolution and how it can be applied across all areas of scientific research.
This site provides students, teachers and general readers with a 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 is an ancient symbol that symbolizes the interconnectedness of life. It is an emblem of love and unity in many cultures. 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 at depicting the biological world focused on categorizing organisms into distinct categories that had been distinguished by their physical and metabolic characteristics1. These methods depend on the sampling of different parts of organisms, or fragments of DNA have significantly increased the diversity of a tree of Life2. However, these trees are largely made up of eukaryotes. Bacterial diversity is not represented in a large way3,4.
In avoiding the necessity of direct observation and experimentation genetic techniques have enabled us to represent the Tree of Life in a more precise way. Particularly, molecular techniques enable us to create trees by using sequenced markers like the small subunit of ribosomal RNA gene.
Despite the rapid expansion of the Tree of Life through genome sequencing, much biodiversity still remains to be discovered. This is especially true for microorganisms that are difficult to cultivate, and which are usually only found in a single specimen5. A recent analysis of all genomes known to date has produced a rough draft of the Tree of Life, including a large number of bacteria and archaea that have not been isolated and their diversity is not fully understood6.
The expanded Tree of Life is particularly beneficial in assessing the biodiversity of an area, helping to determine if certain habitats require protection. The information can be used in a range 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. 에볼루션 블랙잭 Evolution KR can aid biologists in identifying areas most likely to be home to species that are cryptic, which could perform important metabolic functions, and could be susceptible to human-induced change. While funding to protect biodiversity are important, the best method to preserve the biodiversity of the world is to equip more people in developing countries with the knowledge they need to act locally and promote conservation.
Phylogeny
A phylogeny (also called an evolutionary tree) illustrates the relationship between species. By using molecular information as well as morphological similarities and distinctions, or ontogeny (the course of development of an organism), scientists can build an phylogenetic tree that demonstrates the evolutionary relationships between taxonomic groups. Phylogeny is crucial in understanding evolution, biodiversity and genetics.
A basic phylogenetic Tree (see Figure PageIndex 10 Identifies the relationships between organisms that have similar characteristics and have evolved from an ancestor that shared traits. These shared traits can be either homologous or analogous. Homologous characteristics are identical in terms of their evolutionary journey. Analogous traits could appear like they are, but they do not have the same origins. Scientists combine similar traits into a grouping known as a Clade. All members of a clade have a common characteristic, for example, amniotic egg production. They all evolved from an 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 make use of molecular DNA or RNA data to create a phylogenetic chart that is more precise 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.
Phylogenetic relationships can be affected by a number of factors, including the phenomenon of phenotypicplasticity. This is a type of behavior that changes due to specific environmental conditions. This can cause a particular trait to appear more similar to one species than another, clouding the phylogenetic signal. However, this problem can be reduced by the use of methods like cladistics, which combine analogous and homologous features into the tree.
Additionally, phylogenetics can aid in predicting the time and pace of speciation. This information can assist conservation biologists make decisions about which species they should protect from extinction. Ultimately, it is the preservation of phylogenetic diversity which will create an ecologically balanced and complete ecosystem.
Evolutionary Theory
The central theme of evolution is that organisms develop various characteristics over time due to their interactions with their environments. Many scientists have developed theories of evolution, such as the Islamic naturalist Nasir al-Din al-Tusi (1201-274) who believed that an organism could evolve according to its individual needs, the Swedish taxonomist Carolus Linnaeus (1707-1778) who developed the modern hierarchical system of taxonomy and Jean-Baptiste Lamarck (1844-1829), who suggested that the usage or non-use of traits can cause changes that are passed on to the
In the 1930s and 1940s, ideas from various fields, including natural selection, genetics, and particulate inheritance - came together to create the modern synthesis of evolutionary theory which explains how evolution is triggered by the variations of genes within a population, and how these variants change over time due to natural selection. This model, which is known as genetic drift or mutation, gene flow, and sexual selection, is the foundation of current evolutionary biology, and can be mathematically explained.
Recent discoveries in the field of evolutionary developmental biology have revealed that variation can be introduced into a species by mutation, genetic drift and reshuffling of genes during sexual reproduction, and also by migration between populations. These processes, in conjunction with other ones like directional selection and gene erosion (changes in the frequency of genotypes over time), can lead towards evolution. Evolution is defined as changes in the genome over time and changes in the phenotype (the expression of genotypes in 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 demonstrated that teaching about the evidence supporting evolution helped students accept the concept of evolution in a college biology class. For more information about how to teach evolution look up The Evolutionary Potency in all Areas of Biology or Thinking Evolutionarily as a Framework for Infusing Evolution into Life Sciences Education.
Evolution in Action
Scientists have traditionally studied evolution by looking in the past--analyzing fossils and comparing species. They also observe living organisms. Evolution is not a past event, but an ongoing process. Bacteria mutate and resist antibiotics, viruses evolve and escape new drugs and animals alter their behavior in response to the changing environment. The results are often visible.
It wasn't until the 1980s that biologists began to realize that natural selection was in action. The key is that different traits have different rates of survival and reproduction (differential fitness), and can be passed down from one generation to the next.
In the past, if an allele - the genetic sequence that determines color - appeared in a population of organisms that interbred, it might become more common than other allele. Over time, this would mean that the number of moths sporting black pigmentation in a group could increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.
It is easier to see evolutionary change when an organism, like bacteria, has a rapid generation turnover. Since 1988, Richard Lenski, a biologist, has tracked twelve populations of E.coli that are descended from a single strain. The samples of each population were taken regularly, and more than 50,000 generations of E.coli have passed.
Lenski's work has demonstrated that a mutation can profoundly alter the speed at which a population reproduces--and so, the rate at which it changes. It also proves that evolution takes time, a fact that some people are unable to accept.
Another example of microevolution is that mosquito genes that confer resistance to pesticides are more prevalent in areas where insecticides are used. This is because pesticides cause a selective pressure which favors those with resistant genotypes.
The rapid pace of evolution taking place has led to an increasing appreciation of its importance in a world that is shaped by human activities, including climate changes, pollution and the loss of habitats that hinder many species from adapting. Understanding the evolution process will help us make better decisions about the future of our planet, and the lives of its inhabitants.