The Academy's Evolution Site
Biology is one of the most fundamental concepts in biology. The Academies have long been involved in helping people who are interested in science comprehend the concept of evolution and how it affects all areas of scientific research.
This site provides a wide range of sources for students, teachers as well as general readers about evolution. It has important video clips from NOVA and the WGBH-produced science programs on DVD.
Tree of Life
The Tree of Life is an ancient symbol that symbolizes the interconnectedness of life. It appears in many spiritual traditions and cultures as a symbol of unity and love. It can be used in many practical ways as well, such as providing a framework to understand the history of species, and how they respond to changing environmental conditions.
The first attempts to depict the world of biology were based on categorizing organisms based on their physical and metabolic characteristics. These methods, based on sampling of different parts of living organisms or on short fragments of their DNA significantly increased the variety that could be represented in a tree of life2. However, these trees are largely made up of eukaryotes. Bacterial diversity is still largely unrepresented3,4.
In avoiding the necessity of direct experimentation and observation, genetic techniques have made it possible to depict the Tree of Life in a more precise way. In 에볼루션 룰렛 , molecular methods enable us to create trees by using sequenced markers, such as the small subunit ribosomal gene.
The Tree of Life has been greatly expanded thanks to genome sequencing. However there is still a lot of diversity to be discovered. This is particularly true for microorganisms, which can be difficult to cultivate and are usually only present in a single specimen5. Recent analysis of all genomes resulted in a rough draft of a Tree of Life. This includes a large number of bacteria, archaea and other organisms that have not yet been isolated or the diversity of which is not fully understood6.
This expanded Tree of Life is particularly useful in assessing the diversity of an area, assisting to determine if specific habitats require special protection. This information can be used in a range of ways, from identifying new remedies to fight diseases to improving crops. The information is also valuable for conservation efforts. It can aid biologists in identifying those areas that are most likely contain cryptic species with potentially important metabolic functions that may be vulnerable to anthropogenic change. While funding to protect biodiversity are important, the best way to conserve the biodiversity of the world is to equip more people in developing countries with the necessary knowledge to act locally and promote conservation.
Phylogeny
A phylogeny (also called an evolutionary tree) depicts the relationships between species. Scientists can build a phylogenetic diagram that illustrates the evolution of taxonomic categories using molecular information and morphological differences or similarities. The concept of phylogeny is fundamental to understanding biodiversity, evolution and genetics.
A basic phylogenetic Tree (see Figure PageIndex 10 ) is a method of identifying the relationships between organisms that share similar traits that have evolved from common ancestral. These shared traits could 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 combine similar traits into a grouping known as a Clade. Every organism in a group share a trait, such as amniotic egg production. They all derived from an ancestor that had these eggs. A phylogenetic tree can be constructed by connecting clades to identify the organisms which are the closest to each other.
Scientists utilize molecular DNA or RNA data to construct a phylogenetic graph which is more precise and detailed. This data is more precise than the morphological data and gives evidence of the evolutionary history of an organism or group. The analysis of molecular data can help researchers identify the number of species who share an ancestor common to them and estimate their evolutionary age.
The phylogenetic relationship can be affected by a variety of factors such as the phenomenon of phenotypicplasticity. This is a type of behavior that changes due to particular environmental conditions. This can cause a characteristic to appear more similar in one species than other species, which can obscure the phylogenetic signal. This issue can be cured by using cladistics, which is a an amalgamation of analogous and homologous features 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 safeguard from disappearance. In the end, it's the preservation of phylogenetic diversity which will lead to an ecosystem that is complete and balanced.
Evolutionary Theory
The central theme in evolution is that organisms alter over time because of their interactions with their environment. Many scientists have proposed 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 requirements, the Swedish taxonomist Carolus Linnaeus (1707-1778), who created the modern hierarchical taxonomy as well as Jean-Baptiste Lamarck (1844-1829), who believed that the use or non-use of traits can cause changes that are passed on to the
In the 1930s and 1940s, theories from various fields, such as natural selection, genetics & particulate inheritance, were brought together to form a modern theorizing of evolution. This defines how evolution happens through the variation of genes in the population and how these variations alter over time due to natural selection. This model, which includes genetic drift, mutations, gene flow and sexual selection can be mathematically described mathematically.
Recent discoveries in the field of evolutionary developmental biology have shown that genetic variation can be introduced into a species by genetic drift, mutation, and reshuffling genes during sexual reproduction, as well as through migration between populations. These processes, as well as other ones like directional selection and genetic erosion (changes in the frequency of a genotype over time) can lead to evolution, which is defined by change in the genome of the species over time and also the change in phenotype over time (the expression of the genotype in the individual).
Students can better understand the concept of phylogeny by using evolutionary thinking in 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 understanding of evolution during the course of a college biology. For more details about how to teach evolution read The Evolutionary Potency in All Areas of Biology or Thinking Evolutionarily as 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 studying living organisms. Evolution is not a past event, but an ongoing process that continues to be observed today. Bacteria transform and resist antibiotics, viruses reinvent themselves and escape new drugs, and animals adapt their behavior to the changing climate. The changes that result are often evident.
It wasn't until late 1980s that biologists understood that natural selection can be observed in action as well. The key is that various characteristics result in different rates of survival and reproduction (differential fitness) and can be passed down from one generation to the next.
In the past, when one particular allele - the genetic sequence that determines coloration--appeared in a group of interbreeding organisms, it might quickly become more prevalent than other alleles. Over time, that would mean the number of black moths within a population could increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.
It is easier to track evolution when an organism, like bacteria, has a high generation turnover. Since 1988, Richard Lenski, a biologist, has been tracking twelve populations of E.coli that are descended from a single strain. Samples from each population have been taken frequently and more than 50,000 generations of E.coli have been observed to have passed.
Lenski's work has shown that mutations can alter the rate at which change occurs and the effectiveness at which a population reproduces. It also shows evolution takes time, a fact that is hard for some to accept.
Microevolution can be observed in the fact that mosquito genes for resistance to pesticides are more common in populations that have used insecticides. That's because the use of pesticides creates a pressure that favors people with resistant genotypes.
The rapid pace of evolution taking place has led to an increasing awareness of its significance in a world shaped by human activities, including climate changes, pollution and the loss of habitats that prevent many species from adapting. Understanding the evolution process will help you make better decisions regarding the future of the planet and its inhabitants.