The Academy's Evolution Site

The concept of biological evolution is among the most important concepts in biology. The Academies have been for a long time involved in helping those interested in science comprehend the concept of evolution and how it permeates all areas of scientific exploration.

This site provides students, teachers and general readers with a range of educational 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 an emblem of love and unity in many cultures. It also has many practical applications, such as providing a framework for understanding the history of species and how they react to changes in the environment.

The first attempts at depicting the biological world focused on separating organisms into distinct categories which had been distinguished by physical and metabolic characteristics1. These methods, based on the sampling of different parts of living organisms, or sequences of small fragments of their DNA, significantly increased the variety that could be represented in the tree of life2. However these trees are mainly comprised of eukaryotes, and bacterial diversity is still largely unrepresented3,4.

Genetic techniques have greatly broadened our ability to visualize the Tree of Life by circumventing the need for direct observation and experimentation. Particularly, molecular methods enable us to create trees by using sequenced markers like the small subunit of ribosomal RNA gene.

Despite the dramatic expansion of the Tree of Life through genome sequencing, a lot of biodiversity is waiting to be discovered. This is especially relevant to microorganisms that are difficult to cultivate and are typically present in a single sample5. A recent study of all known genomes has produced a rough draft of the Tree of Life, including numerous archaea and bacteria that are not isolated and their diversity is not fully understood6.

This expanded Tree of Life can be used to assess the biodiversity of a particular area and determine if certain habitats require special protection. This information can be utilized in a range of ways, from identifying new treatments to fight disease to enhancing the quality of crop yields. This information is also useful to 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 vulnerable to anthropogenic change. While conservation funds are important, the most effective way to conserve the biodiversity of the world is to equip more people in developing countries with the information they require to act locally and promote conservation.

Phylogeny

A phylogeny, also known as an evolutionary tree, 에볼루션 슬롯게임 reveals the relationships between different groups of organisms. Utilizing molecular data, morphological similarities and differences or ontogeny (the course of development of an organism) scientists can create an phylogenetic tree that demonstrates the evolution of taxonomic categories. Phylogeny plays a crucial role in understanding biodiversity, genetics and evolution.

A basic phylogenetic tree (see Figure PageIndex 10 Finds the connections between organisms with 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 their evolutionary path. Analogous traits could appear like they are, but they do not have the same ancestry. Scientists organize similar traits into a grouping known as a clade. All organisms in a group have a common characteristic, for example, amniotic egg production. They all came from an ancestor who had these eggs. The clades then join to form a phylogenetic branch to identify organisms that have the closest relationship.

For a more detailed and accurate phylogenetic tree, scientists rely on molecular information from DNA or RNA to establish the connections between organisms. This data is more precise than morphological data and provides evidence of the evolutionary history of an individual or group. The use of molecular data lets researchers identify the number of species that share an ancestor common to them and estimate their evolutionary age.

The phylogenetic relationship can be affected by a variety of factors such as the phenomenon of phenotypicplasticity. This is a type behavior that alters in response to particular environmental conditions. This can cause a characteristic to appear more similar in one species than another, 에볼루션 무료 바카라 obscuring the phylogenetic signal. However, this issue can be cured by the use of techniques like cladistics, which include a mix of homologous and analogous features into the tree.

In addition, phylogenetics can aid in predicting the length and speed of speciation. This information can aid conservation biologists to decide which species to protect from the threat of extinction. Ultimately, it is the preservation of phylogenetic diversity that will create a complete and balanced ecosystem.

Evolutionary Theory

The central theme in evolution is that organisms change over time due to their interactions with their environment. Many theories of evolution have been proposed by a variety of scientists such as the Islamic naturalist Nasir al-Din al-Tusi (1201-1274) who proposed that a living organism develop slowly according to its requirements and needs, the Swedish botanist Carolus Linnaeus (1707-1778) who conceived the modern hierarchical taxonomy, as well as Jean-Baptiste Lamarck (1744-1829) who suggested that use or disuse of traits can cause changes that can be passed on to the offspring.

In the 1930s and 1940s, theories from various fields, such as genetics, natural selection, and particulate inheritance, merged to create a modern theorizing of evolution. This defines how evolution happens through the variation of genes in the population, and how these variations change with time due to natural selection. This model, called genetic drift or mutation, gene flow, and sexual selection, is the foundation of the current evolutionary biology and is mathematically described.

Recent discoveries in evolutionary developmental biology have revealed how variation can be introduced to a species through genetic drift, mutations and reshuffling of genes during sexual reproduction and migration between populations. These processes, along with others such as directional selection and gene erosion (changes in the frequency of genotypes over time) can lead to evolution. Evolution is defined as changes in the genome over time, as well as changes in the phenotype (the expression of genotypes in individuals).

Students can better understand the concept of phylogeny by using evolutionary thinking throughout all areas of biology. A recent study by Grunspan and colleagues, for instance, showed that teaching about the evidence supporting evolution increased students' acceptance of evolution in a college-level biology class. For more information on how to teach evolution look up The Evolutionary Potential in All Areas of Biology or Thinking Evolutionarily as a Framework for Integrating Evolution into Life Sciences Education.

Evolution in Action

Scientists have traditionally studied evolution through looking back in the past, analyzing fossils and 에볼루션 무료 바카라 comparing species. They also observe living organisms. However, evolution isn't something that happened in the past. It's an ongoing process, taking place in the present. Viruses evolve to stay away from new medications and bacteria mutate to resist antibiotics. Animals alter their behavior in the wake of a changing world. The changes that occur are often visible.

However, it wasn't until late 1980s that biologists understood that natural selection can be observed in action as well. The key is that various traits confer different rates of survival and reproduction (differential fitness) and can be passed from one generation to the next.

In the past, if an allele - the genetic sequence that determines color - appeared in a population of organisms that interbred, it might become more common than other allele. As time passes, this could mean that the number of moths sporting black pigmentation may increase. The same is true for many other characteristics--including morphology and behavior--that vary among populations of organisms.

The ability to observe evolutionary change is much easier when a species has a rapid generation turnover, as with bacteria. Since 1988, 에볼루션 바카라 체험 게이밍; fatahal.Com, Richard Lenski, a biologist, has been tracking twelve populations of E.coli that descend from one strain. Samples of each population have been taken regularly and more than 500.000 generations of E.coli have passed.

Lenski's research has shown that a mutation can dramatically alter the efficiency with which a population reproduces--and so the rate at which it evolves. It also shows evolution takes time, 무료 에볼루션 which is hard for some to accept.

Microevolution can also be seen in the fact that mosquito genes for resistance to pesticides are more common in populations where insecticides are used. Pesticides create an exclusive pressure that favors individuals who have resistant genotypes.

The rapidity of evolution has led to an increasing awareness of its significance particularly in a world that is largely shaped by human activity. This includes climate change, pollution, and habitat loss that hinders many species from adapting. Understanding the evolution process can help you make better decisions regarding the future of the planet and its inhabitants.