The Academy's Evolution Site

The concept of biological evolution is among the most fundamental concepts in biology. The Academies are involved in helping those interested in science to understand evolution theory and how it can be applied across all areas of scientific research.

This site provides teachers, students 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, an ancient symbol, 에볼루션 블랙잭 symbolizes the interconnectedness of all life. It appears in many religions and cultures as symbolizing unity and love. It also has practical applications, like providing a framework for understanding the history of species and how they respond to changes in the environment.

Early attempts to represent the biological world were based on categorizing organisms based on their metabolic and physical characteristics. These methods, based on the sampling of various parts of living organisms or on sequences of small fragments of their DNA greatly increased the variety of organisms that could be represented in a tree of life2. However these trees are mainly composed of eukaryotes; bacterial diversity is not represented in a large way3,4.

By avoiding the need for direct experimentation and observation genetic techniques have allowed us to depict the Tree of Life in a more precise way. Trees can be constructed using molecular methods such as the small subunit ribosomal gene.

Despite the rapid growth of the Tree of Life through genome sequencing, a lot of biodiversity is waiting to be discovered. This is particularly true for microorganisms that are difficult to cultivate and are typically only present in a single sample5. A recent study of all known genomes has created a rough draft of the Tree of Life, including numerous archaea and bacteria that have not been isolated and their diversity is not fully understood6.

The expanded Tree of Life is particularly useful in assessing the diversity of an area, helping to determine whether specific habitats require protection. This information can be utilized in a range of ways, from identifying new medicines to combating disease to enhancing the quality of crops. The information is also valuable to conservation efforts. It helps biologists discover areas most likely to be home to cryptic species, which may have vital metabolic functions and are susceptible to human-induced change. While funds to protect biodiversity are important, the best method to protect the world's biodiversity is to empower the people of developing nations with the knowledge they need to take action locally and encourage conservation.

Phylogeny

A phylogeny (also called an evolutionary tree) illustrates the relationship between organisms. Utilizing molecular data 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 categories. The concept of phylogeny is fundamental to understanding the evolution of biodiversity, evolution and genetics.

A basic phylogenetic tree (see Figure PageIndex 10 ) determines the relationship between organisms with similar traits that have evolved from common ancestral. These shared traits are either analogous or homologous. Homologous traits are similar in their underlying evolutionary path while analogous traits appear similar, but do not share the same origins. Scientists group similar traits together into a grouping called a clade. All organisms in a group share a characteristic, for example, 무료 에볼루션 amniotic egg production. They all evolved from an ancestor who had these eggs. A phylogenetic tree can be constructed by connecting clades to determine the organisms who are the closest to each other.

Scientists use DNA or RNA molecular information to build a phylogenetic chart that is more accurate and detailed. This information is more precise than the morphological data and provides evidence of the evolution history of an individual or group. The use of molecular data lets researchers determine the number of species that share a common ancestor and to estimate their evolutionary age.

The phylogenetic relationships between organisms are influenced by many factors, including phenotypic flexibility, an aspect of behavior that alters in response to unique environmental conditions. This can cause a characteristic to appear more similar in one species than another, 에볼루션 clouding the phylogenetic signal. However, this problem can be solved through the use of methods such as cladistics that include a mix of similar and homologous traits into the tree.

Additionally, phylogenetics can help predict the duration and rate of speciation. This information can assist conservation biologists make decisions about which species to protect from extinction. In the end, it's the preservation of phylogenetic diversity that will lead to an ecosystem that is balanced and complete.

Evolutionary Theory

The central theme of evolution is that organisms acquire various characteristics over time based on 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 would develop according to its own requirements as well as the Swedish taxonomist Carolus Linnaeus (1707-1778) who conceived the modern taxonomy system that is hierarchical and Jean-Baptiste Lamarck (1844-1829), who believed that the use or non-use of traits can lead to changes that can be passed on to future generations.

In the 1930s and 1940s, theories from various fields, including genetics, natural selection, and particulate inheritance -- came together to form the modern evolutionary theory that explains how evolution is triggered by the variation of genes within a population and how those variations change in time as a result of natural selection. This model, which encompasses mutations, genetic drift in gene flow, and sexual selection can be mathematically described.

Recent discoveries in the field of evolutionary developmental biology have demonstrated the ways in which variation can be introduced to a species via mutations, genetic drift and reshuffling of genes during sexual reproduction and 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 lead to evolution which is defined by changes in the genome of the species over time, and the change in phenotype over time (the expression of that genotype in the individual).

Incorporating evolutionary thinking into all areas of biology education could increase students' understanding of phylogeny and evolution. In a study by Grunspan et al. It was demonstrated that teaching students about the evidence for evolution increased their understanding of evolution in a college-level course in biology. To find out more about how to teach about evolution, look up The Evolutionary Potential of All Areas of Biology and Thinking Evolutionarily: A Framework for Infusing Evolution into Life Sciences Education.

Evolution in Action

Traditionally, scientists have studied evolution by studying fossils, comparing species and studying living organisms. But evolution isn't just something that occurred in the past, it's an ongoing process taking place today. Bacteria evolve and resist antibiotics, viruses re-invent themselves and elude new medications, and animals adapt their behavior in response to the changing climate. The resulting changes are often easy to see.

It wasn't until the 1980s that biologists began realize that natural selection was in play. The main reason is that different traits confer a different rate of survival and reproduction, and can be passed on from one generation to the next.

In the past, if one particular allele--the genetic sequence that controls coloration - was present in a group of interbreeding species, it could rapidly become more common than other alleles. Over time, this would mean that the number of moths with black pigmentation could increase. The same is true for 바카라 에볼루션 many other characteristics--including morphology and behavior--that vary among populations of organisms.

Monitoring evolutionary changes in action is much easier when a species has a rapid turnover of its generation like bacteria. Since 1988, Richard Lenski, a biologist, has studied twelve populations of E.coli that descend from one strain. Samples of each population have been taken frequently 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 shows evolution takes time, a fact that is hard for 에볼루션 some to accept.

Microevolution can be observed in the fact that mosquito genes for resistance to pesticides are more prevalent in populations that have used insecticides. This is due to the fact that the use of pesticides causes a selective pressure that favors individuals with resistant genotypes.

The rapidity of evolution has led to an increasing awareness of its significance, especially in a world which is largely shaped by human activities. This includes pollution, climate change, and habitat loss that prevents many species from adapting. Understanding the evolution process will help us make better decisions regarding the future of our planet and the lives of its inhabitants.