The Academy's Evolution Site

The concept of biological evolution is a fundamental concept in biology. The Academies have been for a long time involved in helping people who are interested in science understand the theory of evolution and how it affects all areas of scientific exploration.

This site offers a variety of sources for teachers, students and 무료 에볼루션 general readers of 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, represents the interconnectedness of all life. It appears in many spiritual traditions and cultures as an emblem of unity and love. It also has practical applications, like providing a framework for understanding the evolution of species and how they respond to changes in environmental conditions.

Early attempts to represent the world of biology were founded on categorizing organisms on their physical and metabolic characteristics. These methods, 에볼루션 바카라 based on the sampling of different parts of living organisms, or sequences of short DNA fragments, significantly expanded the diversity that could be included in a tree of life2. These trees are mostly populated by eukaryotes, and bacterial diversity is vastly underrepresented3,4.

In avoiding the necessity of direct observation and experimentation, genetic techniques have allowed us to depict the Tree of Life in a more precise way. We can create trees by using molecular methods like the small-subunit ribosomal gene.

Despite the massive growth of the Tree of Life through genome sequencing, much biodiversity still is waiting to be discovered. This is particularly true of microorganisms, which can be difficult to cultivate and are usually only represented in a single specimen5. A recent analysis of all genomes that are known has created a rough draft of the Tree of Life, including numerous bacteria and 에볼루션 바카라 archaea that have not been isolated, and whose diversity is poorly understood6.

This expanded Tree of Life can be used to determine the diversity of a specific area and determine if certain habitats need special protection. This information can be utilized in a variety of ways, including identifying new drugs, combating diseases and enhancing crops. The information is also incredibly useful for conservation efforts. It helps biologists discover areas that are likely to be home to cryptic species, which could have important metabolic functions and are susceptible to human-induced change. While funds to protect biodiversity are important, the best way to conserve the world's biodiversity is to equip more people in developing nations with the necessary knowledge to take action locally and encourage conservation.

Phylogeny

A phylogeny (also called an evolutionary tree) depicts the relationships between species. Scientists can build a phylogenetic chart that shows the evolutionary relationships between taxonomic groups based on molecular data and morphological similarities or differences. The phylogeny of a tree plays an important role in understanding the relationship between genetics, biodiversity and evolution.

A basic phylogenetic Tree (see Figure PageIndex 10 Identifies the relationships between organisms that have similar traits and have evolved from an ancestor that shared traits. These shared traits can be either analogous or homologous. Homologous traits share their evolutionary roots and analogous traits appear similar but do not have the same origins. Scientists arrange similar traits into a grouping known as a clade. All organisms in a group have a common trait, such as amniotic egg production. They all came from an ancestor with these eggs. A phylogenetic tree is then constructed by connecting the clades to determine the organisms which are the closest to each other.

Scientists use DNA or RNA molecular information to build a phylogenetic chart which is more precise and detailed. This information is more precise and provides evidence of the evolution of an organism. Molecular data allows researchers to determine the number of organisms that have the same ancestor and estimate their evolutionary age.

The phylogenetic relationships of a species can be affected by a variety of factors such as the phenomenon of phenotypicplasticity. This is a type behavior that alters as a result of unique 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 homologous and analogous features in the tree.

In addition, phylogenetics can aid in predicting the duration and rate of speciation. This information can help conservation biologists make decisions about the species they should safeguard from extinction. In the end, it is the preservation of phylogenetic diversity which will create an ecosystem that is balanced and complete.

Evolutionary Theory

The fundamental concept in evolution is that organisms alter over time because of their interactions with their environment. Many theories of evolution have been proposed by a variety of scientists including the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who proposed that a living organism develop gradually according to its requirements and needs, the Swedish botanist Carolus Linnaeus (1707-1778) who conceived the modern hierarchical taxonomy Jean-Baptiste Lamarck (1744-1829) who suggested that the use or misuse of traits cause changes that could be passed onto offspring.

In the 1930s and 1940s, ideas from a variety of fields -- including genetics, natural selection and particulate inheritance -- came together to form the modern evolutionary theory which explains how evolution happens through the variation of genes within a population, and how these variants change in time due to natural selection. This model, which is known as genetic drift, mutation, gene flow and sexual selection, is the foundation of current evolutionary biology, and can be mathematically described.

Recent discoveries in the field of evolutionary developmental biology have shown that variation can be introduced into a species through mutation, genetic drift and reshuffling of genes in sexual reproduction, as well as by migration between populations. These processes, along with others like directional selection and genetic erosion (changes in the frequency of the genotype over time), can lead to evolution that is defined as changes in the genome of the species over time, and also the change in phenotype as time passes (the expression of that genotype in the individual).

Students can gain a better understanding of the concept of phylogeny by using evolutionary thinking into all aspects of biology. In a study by Grunspan and colleagues., it was shown that teaching students about the evidence for evolution boosted their acceptance of evolution during 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 에볼루션 바카라 Thinking Evolutionarily: A Framework for Infusing Evolution in Life Sciences Education.

Evolution in Action

Traditionally scientists have studied evolution by studying fossils, 에볼루션 바카라 무료 comparing species and studying living organisms. However, evolution isn't something that occurred in the past. It's an ongoing process that is happening right now. Bacteria mutate and resist antibiotics, viruses evolve and elude new medications and animals change their behavior to the changing climate. The changes that result are often visible.

It wasn't until the 1980s that biologists began to realize that natural selection was at work. The reason is that different characteristics result in different rates of survival and reproduction (differential fitness), and can be transferred from one generation to the next.

In the past, if a certain allele - the genetic sequence that determines colour - was present in a population of organisms that interbred, it could become more common than any other allele. As time passes, that could mean the number of black moths in 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 a species, such as bacteria, has a high generation turnover. Since 1988 biologist Richard Lenski has been tracking twelve populations of E. coli that descended from a single strain; samples of each are taken every day and over 500.000 generations have passed.

Lenski's research has shown that mutations can drastically alter the rate at which a population reproduces--and so, the rate at which it changes. It also proves that evolution is slow-moving, a fact that many find difficult to accept.

Another example of microevolution is the way mosquito genes for resistance to pesticides show up more often in areas where insecticides are employed. Pesticides create an enticement that favors those with resistant genotypes.

The rapidity of evolution has led to an increasing appreciation of its importance, especially in a world shaped largely by human activity. This includes pollution, climate change, and habitat loss that hinders many species from adapting. Understanding the evolution process will help you make better decisions about the future of our planet and its inhabitants.