Leland Collie

The Academy's Evolution Site

Biology is a key concept in biology. The Academies are committed to helping those interested in science learn about the theory of evolution and how it is permeated in all areas of scientific research.

This site provides teachers, students and general readers with a range of learning resources on evolution. It also includes important video clips from NOVA and WGBH produced science programs on DVD.

Tree of Life

The Tree of Life, an ancient symbol, symbolizes the interconnectedness of all life. It is used in many spiritual traditions and cultures as an emblem of unity and love. It also has practical applications, like providing a framework to understand the history of species and how they respond to changes in environmental conditions.

The earliest attempts to depict the world of biology focused on the classification of species into distinct categories that had been distinguished by physical and metabolic characteristics1. These methods, based on the sampling of various parts of living organisms, or sequences of small fragments of their DNA greatly increased the variety of organisms that could be represented in the tree of life2. The trees are mostly composed of eukaryotes, while bacterial diversity is vastly underrepresented3,4.

By avoiding the necessity for direct observation and experimentation, genetic techniques have enabled us to represent the Tree of Life in a more precise manner. We can create trees by using molecular methods, such as the small-subunit ribosomal gene.

Despite the rapid expansion of the Tree of Life through genome sequencing, a lot of biodiversity is waiting to be discovered. This is especially true for microorganisms that are difficult to cultivate and which are usually only present in a single sample5. A recent study of all known genomes has produced a rough draft of the Tree of Life, including many bacteria and 에볼루션 카지노 사이트 archaea that have not been isolated, and whose diversity is poorly understood6.

This expanded Tree of Life is particularly useful in assessing the diversity of an area, helping to determine if specific habitats require special protection. This information can be used in a variety of ways, such as identifying new drugs, combating diseases and enhancing crops. This information is also beneficial to conservation efforts. It can help biologists identify areas that are likely to have cryptic species, which may have important metabolic functions and be vulnerable to changes caused by humans. Although funding to safeguard biodiversity are vital however, the most effective method to preserve the world's biodiversity is for more people in developing countries to be empowered with the necessary knowledge to take action locally to encourage conservation from within.

Phylogeny

A phylogeny (also called an evolutionary tree) shows the relationships between organisms. Scientists can create a phylogenetic diagram that illustrates the evolution of taxonomic groups based on molecular data and morphological differences or similarities. Phylogeny is crucial in understanding the evolution of biodiversity, evolution and genetics.

A basic phylogenetic Tree (see Figure PageIndex 10 Identifies the relationships between organisms with similar traits and have evolved from a common ancestor. These shared traits could be analogous, or homologous. Homologous traits share their evolutionary roots while analogous traits appear similar but do not have the same origins. Scientists put 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 with these eggs. A phylogenetic tree is constructed by connecting clades to identify the species which are the closest to each other.

To create a more thorough and precise phylogenetic tree scientists rely on molecular information from DNA or RNA to determine the connections between organisms. This information is more precise than the morphological data and 에볼루션 코리아 provides evidence of the evolutionary history of an individual or group. The use of molecular data lets researchers determine the number of organisms who share the same ancestor and estimate their evolutionary age.

The phylogenetic relationship can be affected by a variety of factors that include phenotypicplasticity. This is a kind of behaviour that can change in response to particular environmental conditions. This can make a trait appear more resembling to one species than to the other which can obscure the phylogenetic signal. This problem can be addressed by using cladistics. This is a method that incorporates the combination of analogous and homologous features in the tree.

Furthermore, phylogenetics may aid in predicting the duration and rate of speciation. This information can aid conservation biologists in deciding which species to protect from extinction. In the end, it's the conservation of phylogenetic variety that will result in an ecosystem that is complete and balanced.

Evolutionary Theory

The central theme of evolution is that organisms develop various characteristics over time due to their interactions with their environment. Many theories of evolution have been developed by a wide variety 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, the Swedish botanist Carolus Linnaeus (1707-1778) who designed modern hierarchical taxonomy, and Jean-Baptiste Lamarck (1744-1829) who suggested that use or disuse of traits cause changes that can be passed onto offspring.

In the 1930s and 에볼루션 바카라사이트 1940s, ideas from a variety of fields--including natural selection, genetics, and particulate inheritance -- came together to form the modern evolutionary theory, which defines how evolution is triggered by the variation of genes within a population, and how those variations change over time as a result of natural selection. This model, which is known as genetic drift, mutation, gene flow and sexual selection, is the foundation of modern evolutionary biology and is mathematically described.

Recent discoveries in the field of evolutionary developmental biology have demonstrated that genetic variation can be introduced into a species via genetic drift, mutation, and reshuffling of genes during sexual reproduction, as well as by migration between populations. These processes, as well as other ones like directional selection and genetic erosion (changes in the frequency of an individual's genotype over time) can result in evolution, which is defined by change in the genome of the species over time, and the change in phenotype as time passes (the expression of that genotype in an individual).

Students can gain a better understanding of the concept of phylogeny by using evolutionary thinking into all aspects of biology. A recent study conducted by Grunspan and colleagues, for example revealed that teaching students about the evidence that supports evolution helped students accept the concept of evolution in a college biology class. For more information on how to teach about evolution, see The Evolutionary Potential in all Areas of Biology and Thinking Evolutionarily: A Framework for Infusing the Concept of Evolution into Life Sciences Education.

Evolution in Action

Traditionally, scientists have studied evolution by studying fossils, comparing species and studying living organisms. However, evolution isn't something that occurred in the past; it's an ongoing process happening right now. Viruses evolve to stay away from new antibiotics and bacteria transform to resist antibiotics. Animals adapt their behavior as a result of a changing environment. The changes that result are often evident.

It wasn't until the late 1980s that biologists began realize that natural selection was also at work. The key is the fact that different traits can confer the ability to survive at different rates and reproduction, and can be passed down from one generation to the next.

In the past, if one allele - the genetic sequence that determines colour was present in a population of organisms that interbred, it might become more common than any other allele. Over time, that would mean that the number of black moths within the 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 see evolutionary change when an organism, like bacteria, has a high generation turnover. Since 1988 biologist Richard Lenski has been tracking twelve populations of E. bacteria that descend from a single strain; samples of each population are taken every day and over fifty thousand generations have been observed.

Lenski's work has shown that mutations can alter the rate at which change occurs and the efficiency of a population's reproduction. It also shows evolution takes time, a fact that is difficult for some 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 the use of pesticides creates a selective pressure that favors people with resistant genotypes.

The rapid pace at which evolution takes place has led to an increasing appreciation of its importance in a world shaped by human activity--including climate change, 에볼루션바카라사이트 pollution, and the loss of habitats that hinder many species from adjusting. Understanding evolution can assist you in making better choices about the future of our planet and its inhabitants.