The Academy's Evolution Site

Biology is one of the most fundamental concepts in biology. The Academies are committed to helping those interested in the sciences understand evolution theory and how it is permeated in all areas of scientific research.

This site provides a wide range of sources for students, teachers as well as general readers about evolution. It contains the most important video clips from NOVA and 에볼루션 바카라 사이트 WGBH-produced science programs on DVD.

Tree of Life

The Tree of Life is an ancient symbol that symbolizes the interconnectedness of life. It is seen in a variety of religions and cultures as a symbol of unity and love. It can be used in many practical ways in addition to providing a framework to understand the evolution of species and how they respond to changing environmental conditions.

The earliest attempts to depict the world of biology focused on categorizing species into distinct categories that were distinguished by their physical and 에볼루션카지노사이트 metabolic characteristics1. These methods, based on the sampling of different parts of living organisms or sequences of short DNA fragments, significantly increased the variety that could be included in a tree of life2. These trees are largely composed by eukaryotes, and 에볼루션 바카라 사이트 the diversity of bacterial species is greatly underrepresented3,4.

Genetic techniques have significantly expanded our ability to depict the Tree of Life by circumventing the need for direct observation and experimentation. Particularly, molecular methods enable us to create trees using sequenced markers, such as the small subunit ribosomal RNA gene.

Despite the dramatic 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 which are usually only present in a single sample5. A recent analysis of all known genomes has produced a rough draft version of the Tree of Life, including a large number of archaea and bacteria that have not been isolated, and their diversity is not fully understood6.

The expanded Tree of Life is particularly beneficial in assessing the biodiversity of an area, which can help to determine if specific habitats require protection. The information can be used in a range of ways, from identifying the most effective remedies to fight diseases to enhancing crops. The information is also useful for conservation efforts. It can aid biologists in identifying the areas that are most likely to contain cryptic species that could have significant metabolic functions that could be at risk from anthropogenic change. While funding to protect biodiversity are essential, the best method to preserve the world's biodiversity is to empower more people in developing countries with the knowledge they need to act locally and support conservation.

Phylogeny

A phylogeny, also known as an evolutionary tree, reveals the connections between groups of organisms. Utilizing 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 groups. Phylogeny is crucial in understanding biodiversity, evolution and genetics.

A basic phylogenetic Tree (see Figure PageIndex 10 ) identifies the relationships between organisms that share similar traits that evolved from common ancestors. These shared traits can be either homologous or analogous. Homologous traits are the same in their evolutionary path. Analogous traits could appear like they are but they don't have the same ancestry. Scientists put similar traits into a grouping known as a clade. For 에볼루션 바카라 무료체험 instance, all the species in a clade have the characteristic of having amniotic eggs. They evolved from a common ancestor which had eggs. A phylogenetic tree is constructed by connecting the clades to identify the organisms that are most closely related to one another.

For a more detailed and accurate phylogenetic tree, scientists make use of molecular data from DNA or RNA to establish the relationships among organisms. This information is more precise than the morphological data and provides evidence of the evolution history of an organism or group. Molecular data allows researchers to identify the number of organisms that share an ancestor common to them and estimate their evolutionary age.

The phylogenetic relationships between species can be influenced by several factors, including phenotypic plasticity a kind of behavior that alters in response to unique environmental conditions. This can cause a characteristic to appear more resembling to one species than to another which can obscure the phylogenetic signal. This issue can be cured by using cladistics. This is a method that incorporates a combination of homologous and 에볼루션 바카라 사이트 analogous features in the tree.

Additionally, phylogenetics can help predict the length and speed of speciation. This information can aid conservation biologists to decide which species to protect from the threat of extinction. It is ultimately the preservation of phylogenetic diversity that will lead to a complete and balanced ecosystem.

Evolutionary Theory

The main idea behind evolution is that organisms acquire distinct characteristics over time based on their interactions with their environment. Many scientists have come up with theories of evolution, including the Islamic naturalist Nasir al-Din al-Tusi (1201-274), 에볼루션카지노사이트 (Evolutionsite89160.blogs100.com) who believed that a living thing would evolve according to its own needs, the Swedish taxonomist Carolus Linnaeus (1707-1778) who conceived the modern hierarchical system of taxonomy and Jean-Baptiste Lamarck (1844-1829), who suggested that the use or absence of traits can lead to changes that are passed on to the next generation.

In the 1930s and 1940s, theories from various fields, including natural selection, genetics & particulate inheritance, came together to create a modern evolutionary theory. This defines how evolution occurs by the variations in genes within the population, and how these variations alter over time due to natural selection. This model, known as genetic drift, mutation, gene flow, and sexual selection, is a key element of modern evolutionary biology and is mathematically described.

Recent advances in the field of evolutionary developmental biology have demonstrated how variations can be introduced to a species via mutations, genetic drift or reshuffling of genes in sexual reproduction, and even migration between populations. These processes, in conjunction with other ones like directionally-selected selection and erosion of genes (changes to the frequency of genotypes over time) can result in evolution. Evolution is defined by changes in the genome over time, as well as changes in phenotype (the expression of genotypes in individuals).

Incorporating evolutionary thinking into all areas of biology education could increase student understanding of the concepts of phylogeny as well as evolution. A recent study conducted by Grunspan and colleagues, for example, showed that teaching about the evidence for evolution helped students accept the concept of evolution in a college-level biology course. For more information on how to teach about evolution, please see The Evolutionary Potential in 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 looking back--analyzing fossils, comparing species and observing living organisms. Evolution is not a past event, but an ongoing process that continues to be observed today. The virus reinvents itself to avoid new antibiotics and bacteria transform to resist antibiotics. Animals alter their behavior as a result of a changing environment. The changes that result are often visible.

But it wasn't until the late 1980s that biologists understood that natural selection can be observed in action as well. The key is the fact that different traits confer an individual rate of survival and reproduction, 에볼루션 바카라사이트 and can be passed down from generation to generation.

In the past when one particular allele - the genetic sequence that defines color in a population of interbreeding organisms, it might quickly become more prevalent than all other alleles. Over time, this would mean that the number of moths sporting black pigmentation in a group may increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.

Observing evolutionary change in action is much easier when a species has a fast generation turnover such as bacteria. Since 1988, Richard Lenski, a biologist, has tracked twelve populations of E.coli that are descended from a single strain. Samples from each population have been taken frequently and more than 500.000 generations of E.coli have passed.

Lenski's research has shown that a mutation can profoundly alter the speed at which a population reproduces and, consequently, the rate at which it alters. It also shows evolution takes time, something that is difficult for some to accept.

Another example of microevolution is the way mosquito genes that confer resistance to pesticides show up more often in areas where insecticides are used. This is because the use of pesticides creates a selective pressure that favors individuals with resistant genotypes.

The rapidity of evolution has led to an increasing appreciation of its importance particularly 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 evolution can help us make better decisions regarding the future of our planet as well as the life of its inhabitants.