The Academy's Evolution Site

Biology is one of the most central concepts in biology. The Academies have been active for a long time in helping people who are interested in science understand the concept of evolution and how it affects all areas of scientific research.

This site provides a wide range of resources for 에볼루션 게이밍 teachers, students and 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 is an ancient symbol of the interconnectedness of all life. It is seen in a variety of religions and cultures as symbolizing unity and love. It can be used in many practical ways in addition to providing a framework to understand the evolution of species and 에볼루션사이트 how they respond to changes in environmental conditions.

The first attempts to depict the world of biology were based on categorizing organisms based on their metabolic and physical characteristics. These methods, which rely on the collection of various parts of organisms or short fragments of DNA, have significantly increased the diversity of a Tree of Life2. However these trees are mainly comprised of eukaryotes, and bacterial diversity remains vastly underrepresented3,4.

Genetic techniques have significantly expanded our ability to depict the Tree of Life by circumventing the requirement for direct observation and experimentation. In particular, molecular methods allow us to build trees using sequenced markers like the small subunit of ribosomal RNA gene.

Despite the massive expansion of the Tree of Life through genome sequencing, 에볼루션 무료체험 a large amount of biodiversity is waiting to be discovered. This is particularly true of microorganisms, which can be difficult to cultivate and are typically only found in a single specimen5. A recent analysis of all genomes known to date has produced a rough draft version of the Tree of Life, including many bacteria and archaea that are not isolated and their diversity is not fully understood6.

This expanded Tree of Life can be used to evaluate the biodiversity of a specific area and determine if certain habitats need special protection. The information is useful in a variety of ways, such as identifying new drugs, combating diseases and improving crops. The information is also incredibly valuable to conservation efforts. It can help biologists identify areas that are likely to be home to species that are cryptic, which could perform important metabolic functions and be vulnerable to human-induced change. While funds to protect biodiversity are essential but the most effective way to ensure the preservation of biodiversity around the world is for more people in developing countries to be equipped with the knowledge to act locally in order to promote conservation from within.

Phylogeny

A phylogeny, also called an evolutionary tree, shows the relationships between different groups of organisms. Using molecular data similarities and differences in morphology, or ontogeny (the course of development of an organism) scientists can construct an phylogenetic tree that demonstrates the evolutionary relationships between taxonomic categories. The phylogeny of a tree plays an important role in understanding biodiversity, genetics and evolution.

A basic phylogenetic Tree (see Figure PageIndex 10 Finds the connections between organisms that have similar characteristics and have evolved from an ancestor that shared traits. These shared traits may be analogous or homologous. Homologous traits are the same in terms of their evolutionary journey. Analogous traits may look like they are but they don't share the same origins. Scientists organize similar traits into a grouping known as a clade. For example, all of the species in a clade share the characteristic of having amniotic eggs and 에볼루션 바카라 evolved from a common ancestor that had eggs. The clades then join to form a phylogenetic branch that can determine which organisms have the closest connection to each other.

Scientists utilize DNA or RNA molecular information to construct a phylogenetic graph that is more accurate and detailed. This information is more precise and gives evidence of the evolutionary history of an organism. Researchers can use Molecular Data to determine the evolutionary age of organisms and identify how many organisms share a common ancestor.

The phylogenetic relationships of organisms are influenced by many factors including phenotypic plasticity, an aspect of behavior that changes in response to specific environmental conditions. This can cause a trait to appear more similar to one species than another, 에볼루션 무료체험 obscuring the phylogenetic signal. This problem can be addressed by using cladistics, which incorporates an amalgamation of homologous and analogous traits in the tree.

Additionally, phylogenetics can help predict the duration and rate at which speciation occurs. This information can aid conservation biologists to make decisions about the species they should safeguard from the threat of extinction. In the end, it is the preservation of phylogenetic diversity that will lead to an ecosystem that is balanced and complete.

Evolutionary Theory

The fundamental concept in evolution is that organisms change over time due to their interactions with their environment. Many theories of evolution have been developed by a wide range 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 needs and needs, the Swedish botanist Carolus Linnaeus (1707-1778) who developed the modern hierarchical taxonomy Jean-Baptiste Lamarck (1744-1829) who suggested that the use or misuse of traits can cause changes that could be passed onto offspring.

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

Recent discoveries in the field of evolutionary developmental biology have revealed how variation can be introduced to a species by mutations, genetic drift and reshuffling of genes during sexual reproduction, and even 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 lead to evolution that is defined as changes in the genome of the species over time, 에볼루션 바카라 무료체험 and also by changes in phenotype as time passes (the expression of that genotype in the individual).

Students can gain a better understanding of phylogeny by incorporating evolutionary thinking throughout all areas of biology. A recent study conducted by Grunspan and colleagues, for instance revealed that teaching students about the evidence that supports evolution increased students' understanding of evolution in a college-level biology class. 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 into Life Sciences Education.

Evolution in Action

Traditionally scientists have studied evolution through studying fossils, comparing species and studying living organisms. Evolution is not a past event; it is a process that continues today. Bacteria mutate and resist antibiotics, viruses re-invent themselves and escape new drugs and animals change their behavior in response to a changing planet. The results are often evident.

But it wasn't until the late 1980s that biologists realized that natural selection could be seen in action, as well. The reason is that different traits confer different rates of survival and reproduction (differential fitness) and are passed down from one generation to the next.

In the past when one particular allele--the genetic sequence that controls coloration - was present in a population of interbreeding organisms, it might quickly become more common than all other alleles. 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.

Monitoring evolutionary changes in action is easier when a particular species has a fast generation turnover like bacteria. Since 1988 the 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 over 50,000 generations have now passed.

Lenski's work has shown that mutations can alter the rate of change and the rate 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 that confer resistance to pesticides are more prevalent in populations where insecticides are used. This is because the use of pesticides creates a pressure that favors individuals with resistant genotypes.

The rapidity of evolution has led to a growing appreciation of its importance particularly 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 regarding the future of the planet and its inhabitants.