The Academy's Evolution Site
The concept of biological evolution is a fundamental concept in biology. The Academies have been active for a long time in helping those interested in science comprehend the concept of evolution and how it influences all areas of scientific research.
This site provides a wide range of tools for students, teachers as well as general readers about evolution. It includes key video clips from NOVA and the WGBH-produced science programs on DVD.
Tree of Life
The Tree of Life, an ancient symbol, symbolizes the interconnectedness of all life. It is an emblem of love and unity in many cultures. It has many practical applications as well, such as providing a framework to understand the history of species and how they respond to changes in environmental conditions.
The first attempts at depicting the world of biology focused on separating organisms into distinct categories that had been distinguished by physical and metabolic characteristics1. These methods, which rely on the sampling of different parts of living organisms, or short DNA fragments, significantly increased the variety that could be represented in the tree of life2. However the trees are mostly composed of eukaryotes; bacterial diversity is still largely unrepresented3,4.
In avoiding the necessity of direct observation and experimentation, genetic techniques have allowed us to represent the Tree of Life in a more precise manner. Particularly, molecular techniques allow us to build trees 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 biodiversity to be discovered. This is especially true of microorganisms that are difficult to cultivate and are often only represented in a single specimen5. A recent study of all genomes that are known has produced a rough draft version of the Tree of Life, including many archaea and bacteria that have not been isolated, and which are not well understood.
The expanded Tree of Life can be used to evaluate the biodiversity of a specific region and determine if specific habitats need special protection. This information can be used in a variety of ways, such as finding new drugs, battling diseases and enhancing crops. This information is also extremely beneficial to conservation efforts. It helps biologists determine the areas that are most likely to contain cryptic species with potentially significant metabolic functions that could be at risk from anthropogenic change. Although funding to protect biodiversity are crucial however, the most effective method 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 called an evolutionary tree, reveals the relationships between different groups of organisms. Using molecular data, morphological similarities and differences or ontogeny (the process of the development of an organism), scientists can build a phylogenetic tree that illustrates the evolutionary relationships between taxonomic groups. Phylogeny is essential in understanding the evolution of biodiversity, evolution and genetics.
A basic phylogenetic Tree (see Figure PageIndex 10 ) identifies the relationships between organisms that share similar traits that have evolved from common ancestral. These shared traits are either homologous or analogous. Homologous traits are similar in their underlying evolutionary path while analogous traits appear similar, but do not share the same origins. Scientists combine similar traits into a grouping called a clade. Every organism in a group have a common trait, such as amniotic egg production. They all derived from an ancestor who had these eggs. The clades are then connected to form a phylogenetic branch to determine the organisms with the closest relationship to.
Scientists use molecular DNA or RNA data to construct a phylogenetic graph that is more precise and precise. This information is more precise and gives evidence of the evolution history of an organism. Researchers can utilize Molecular Data to estimate the evolutionary age of living organisms and discover the number of organisms that have the same ancestor.
The phylogenetic relationships of organisms are influenced by many factors, including phenotypic plasticity a type of behavior that alters in response to specific environmental conditions. This can cause a particular trait to appear more similar in one species than another, obscuring the phylogenetic signal. This problem can be mitigated by using cladistics, which is a a combination of analogous and homologous features in the tree.
In addition, phylogenetics can help predict the duration and rate of speciation. This information can assist conservation biologists decide the species they should safeguard from the threat of extinction. In the end, it's the preservation of phylogenetic diversity which will create an ecosystem that is balanced and complete.
Evolutionary Theory
The fundamental concept of evolution is that organisms acquire different features over time due to their interactions with their surroundings. Several theories of evolutionary change have been proposed by a wide variety of scientists including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who envisioned an organism developing slowly in accordance with its needs as well as the Swedish botanist Carolus Linnaeus (1707-1778) who designed the modern hierarchical taxonomy Jean-Baptiste Lamarck (1744-1829) who suggested that use or disuse of traits causes changes that could be passed onto offspring.
In the 1930s and 1940s, concepts from a variety of fields -- including genetics, natural selection and particulate inheritance -- came together to create the modern evolutionary theory that explains how evolution occurs through the variation of genes within a population and how those variations change over time due to natural selection. This model, called genetic drift mutation, gene flow, and sexual selection, is a cornerstone of the current evolutionary biology and can be mathematically explained.
Recent discoveries in evolutionary developmental biology have revealed how variation can be introduced to a species through genetic drift, mutations or reshuffling of genes in sexual reproduction, and even migration between populations. These processes, as well as others such as directional selection or genetic erosion (changes in the frequency of an individual's genotype over time) can result in evolution that is defined as change in the genome of the species over time, and also the change in phenotype over time (the expression of that genotype within the individual).
Incorporating evolutionary thinking into all areas of biology education can improve student understanding of the concepts of phylogeny and evolution. In a recent study conducted by Grunspan et al. It was found that teaching students about the evidence for evolution boosted their understanding of evolution in the course of a college biology. To learn more about how to teach about evolution, see The Evolutionary Potential of all Areas of Biology and Thinking Evolutionarily: A Framework for Infusing Evolution in Life Sciences Education.
Evolution in Action
Scientists have looked at evolution through the past, analyzing fossils and comparing species. They also observe living organisms. However, 바카라 에볼루션 isn't something that occurred in the past. It's an ongoing process taking place today. Viruses reinvent themselves to avoid new drugs and bacteria evolve to resist antibiotics. Animals adapt their behavior because of a changing environment. The results are often apparent.
It wasn't until late 1980s that biologists began to realize that natural selection was at work. The main reason is that different traits result in an individual rate of survival as well as reproduction, and may be passed down from generation to generation.
In the past, if one allele - the genetic sequence that determines colour - was present in a population of organisms that interbred, it could become more prevalent than any other allele. In time, this could mean the number of black moths in a particular population could rise. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.
It is easier to see evolution when a species, such as bacteria, has a rapid generation turnover. 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 on a regular basis and more than fifty thousand generations have been observed.
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 proves that evolution takes time, a fact that many find hard to accept.
Microevolution can be observed in the fact that mosquito genes for pesticide resistance are more prevalent in populations where insecticides are used. This is because pesticides cause an enticement that favors individuals who have resistant genotypes.
The rapid pace of evolution taking place has led to a growing appreciation of its importance in a world that is shaped by human activity--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 regarding the future of our planet, as well as the life of its inhabitants.