Mira's Science Blogs

File:Homology vertebrates-en.svg  by  Волков Владислав Петрович Evolution is a change in heritable traits in a population over various generations. But how do we know that evolution has taken place? Comparative Anatomy, Embryology and Development, Fossil Record, DNA comparisons, and Morphology are all ways that we can use evidence to see whether evolution has taken place. Comparative Anatomy includes the various similarities and differences between living things. For example, we can compare the bone structure of a human, vs, the bone structure of a whale. Next, Embryology and Development is how species can develop before, and after birth. For example, humans are very similar to many other species before birth, however, after birth, you can spot many differences. Fossil Record includes much various observation of organisms that have lived in the past. By looking at fossil records of dinosaurs, we can find species that are closely related to them. Next, DNA comparisons are when

File:Lichte en zwarte versie berkenspanner crop.jpg  by  Chiswick Chap Summary: Natural selection occurs when a species with the fittest trait survive to pass on the gene to their offspring. In other words, natural selection is when a species with a specific trait survives long enough to reproduce. This means that if there are two of the same species, however, they have a different trait, the population of the species with the fittest trait will increase because that trait helps it survive. A good example of natural selection is the peppered moth. Before the 19th century, the air was cleaner, and the bark on trees was light in color. This meant that the peppered moths could easily blend in with the trees, and avoid predators. However, during the 19th century, many industries used coal, meaning that it polluted the air and changed the trees a darker shade of brown. This meant the peppered moths were not camouflaged with the trees, exposing them to their predators. This meant tha

File: Mutation and selection diagram by Elembis Summary Evolution is a change in the hereditable traits within a population, over generations. There are five mechanisms for evolution. The mechanisms include genetic drift, mating with specific traits, mutations, movement or gene flow, and adaptation or natural selection.  Genetic drift is a slow change of specific genes in a population. There are two effects that can cause genetic drift, called the founder effect and bottlenecking. The founder effect is when a small sample with a specific trait moves to a different place and only procreates within itself. The next effect is bottlenecking, which is when a disaster wipes out most of a population. Only the surviving traits can be passed on. A mutation is a change in the DNA. Mutations are always random and can be defined as an error in the DNA code. Some mutations can have a small effect and do not matter to evolution. However, some mutations, such as long ears in cats, can

Despite what many people think, we are not in a sixth mass extinction. A mass extinction is when many species become extinct over a short period of time, which is not what is currently happening in the world. Many people face the misconception that we are in a sixth mass extinction because numbers in various animals have dropped. However, numbers in animals have not dropped much in the past fifty years. We are also not in a sixth mass extinction because when climate change affects many species, most animals can move or adapt to the new climate, and do not become extinct. Finally, we are not in a sixth mass extinction because we are not seeing any similarities in nature than those that have happened in the past five mass extinctions. Many scientists believe that we are in a sixth mass extinction because numbers in various animals have dropped. However, numbers in animals have not dropped much in the past fifty years. By comparing the rate of extinction during the past five mass extinc