All About Speciation

All About Speciation Evolution is most usually defined as a change in a population of a species over time through the accumulation of adaptations that are acted upon by natural selection. That may be a mouth full and nearly impossible to truly understand if there is not a full grasp on what a species actually is or how one changes over time. Sure, things change, but what makes them change? How does that affect other species? How long does it all take? Here we will shed some light on these questions and others like them about how evolution and speciation works. Definition of Species Perhaps the most important thing to be understood before truly grasping the idea of speciation and evolution is correctly defining the word species. Most books and reference materials will define the word species as a group of individual organisms that can interbreed in nature and produce viable offspring. While this definition is a good starting place, lets examine why it may not be quite  as accurate as it should be. First of all, there are many species out there that are asexual. This means there is no real interbreeding happening within those species. Any unicellular organism would be asexual. Some other types of fungi also produce their own spores for asexual reproduction. Some plants can also self-pollinate meaning they also do not interbreed. Do these species undergo speciation and ultimately evolution? The short answer to this question is yes, they do. However, while evolution is usually driven by natural selection, natural selection cannot work on a gene pool that does not have any variation. Offspring of an asexual organism are essentially clones and have no traits that are different within the entire population. However, some changes at the microevolutionary level may occur. Spontaneous DNA mutations are one way new genes can enter the picture and natural selection then has diversity to work on within that species. Eventually, those mutations and adaptations add up if they are favorable and the species changes. Another problem with the basic definition of a species is the existence of what are known as hybrids. Hybrids are offspring of two different species, like how mating a horse with a donkey gives a mule. Some hybrids are sterile, which is sort of taken care of with the viable offspring part of the original species definition. However, many other hybrids are capable of producing their own offspring. This is especially true in plants. Biologists do not agree on a single definition of the term species. Depending on the context, the word species may be defined in more than a dozen different ways. Scientists often choose a definition that fits their needs or combines several to take care of that problem. For the majority of evolution biologists, the general definition above usually suits their purposes, although alternate definitions may be used to explain various parts of the Theory of Evolution. Definition of Speciation Now that a basic definition of species has been decided, it is possible to define the term speciation. Much like a family tree, the tree of life has several branches that show where species change and become new species. The point on the tree where a species change is called speciation. Using the definition of species above, it is when the new organisms can no longer interbreed with the original organisms in nature and produce viable offspring. At that point, they are now a new species and speciation has occurred. On a phylogenetic tree, speciation is the point on the tree where the branches diverge from one another. The farther back on the tree the branches diverge, the less closely they are related to one another. Points, where the branches are closer together, means those species recently diverged from each other. How Does Speciation Occur? Most of the time, speciation occurs through divergent evolution. Divergent evolution is when a species becomes less similar and changes into new species. The original species that branches off is then known as the most recent common ancestor of the new species. That is the process that causes speciation, but what triggers divergent evolution? Charles Darwin described the mechanism of evolution which he called natural selection. The basic idea behind natural selection is that species undergo changes and accumulate adaptations that are favorable for their environments. After enough adaptations have built up, the species is no longer the same as it was and speciation has occurred. Where do these changes come from? Microevolution is the changing of the species on a molecular level like with DNA mutations. If they are significant mutations, they will cause adaptations that may or may not be favorable for their environment. Natural selection will work on these individuals and the ones with the most favorable adaptations survive to create the new species. Changes in species can also happen on a larger scale. Macroevolution examines those changes. One of the most common causes of speciation is called geographic isolation. This is when a population of a species is separated from the original population and over time, the two populations accumulate different adaptations and undergo speciation. If they were brought back together after the speciation has happened, they will no longer be able to interbreed and are therefore not the same species anymore. Sometimes speciation happens because of reproductive isolation. Unlike geographic isolation, the population is still together in the same area, but something causes some of the individuals to no longer be able to mate and produce offspring with the original species. This could be something along the lines of a change in mating season or a different mating ritual. In some cases, males and females of the species have special colors or distinct markings. If these mating indicators were to change, the original species may no longer recognize the new individuals as potential mates. There are four types of speciation. Allopatric speciation and peripatric speciation are caused by geographic isolation. Parapatric speciation and sympatic speciation are the other two types and are generally due to reproductive isolation. How Speciation Affects Other Species Speciation of one species can affect the evolution of other species if they have a close relationship in an ecosystem. When populations of different species come together to form a community, they often depend on each other in some way for survival or to make life easier. This is especially apparent in food webs and food chains and in particular predator and prey relationships. If one of these species were to change, other species may also need to change. An example of this coevolution or cospeciation could be the speed of a prey species. The prey may accumulate adaptations that create larger leg muscles to help them run faster. If the predator does not adapt, it may starve. Therefore, only faster predators, or perhaps stealthier predators, will survive to pass down their favorable adaptations to their offspring. That means since the prey evolved or became a new species, the predator had to also evolve or change.

Shakespeare essays

Shakespeare essays The first two years of Shakespeares education came from the most elementary level of schooling called petty school. You learned to read and write in English and math, but the main thing was to try and get you to grammar school. Most petty schools where run by a young wife. The main thing that is studied is Latin grammar, with Plautus, Terence and Seneca as classical sources. The reason for teaching Latin grammar was because it was what classes were taught in at universities. Also at this time Latin was the language of international affairs another important reason for learning it. The days in the life of a petty schoolboy were a lot different than todays times. If you were one of the children that went to a public school your school day looked something like this. The day began at 7:00 am in the winter and 6:00am in the summer. After everyone said there prayers they work till about 9:00, in which then they have breakfast. Then after breakfast they resume work until 11:00. Dinner (lunch) is from 11:00 to 1:00. The school day ends at 5:00 or 5:30pm. Now if you were lucky and went to a private school your day wasnt quite as rough. School began at 7:00am, and from 7:00 to 7:30 you did dancing. At 7:30 you were served breakfast. Then at 8:00 you had your French studies. Then from 9:00 to 10:00 you had Latin. 10:00 to 10:30 brought on Writing and Drawing. Then at 10:30 came your prayers, Recreation time, and Dinner (lunch). Cosmography, which is the study of space, came at 1:00 till 2:00. At 2:00 the study of Latin resumed again. Then from 3:00 to 4:00 they studied French again. When 4:00 came they did some more writing. Then from 4:30 to 5:30 it was Prayers, Recreation time, and Supper (dinner). Then they went home after 5:30. Some of the studies that Shakespeare did were probably done at the petty school. He would have learned literature from Ovid, Plautus, Cicero, and Quintilian, as well as some Latin history, philo...