Emily's Take on Evolution

 The Bubonic Plague (a.k.a. the Black Death): The Bubonic plague caused a tragic global epidemic that impacted much of Asia and Europe in the mid 1300s. This disease killed millions of people over a span of five years. It was thought to be spread through the trading ships traveling and docking at different ports. People had very little knowledge of pathogens and how they are spread at this point. We now know this disease is spread by Yersinia pestis bacteria. It travels through the air and via infection by pests like fleas and rats (bite). Previously, before we had some semblance of city organization/urbanization, people stayed with their own and there was no concentrated area of people. This limited spread of disease and contact between infected individuals. However, around mid 1300s, throughout the world people were eager to travel and colonize new places. The movement of people from one place to drastically different areas sped up the rate this disease was able to spread. The li...

 I think the speed of speciation is not a set in stone. I think it depends on many factors such as resource availability, geographical location, relationship to other organisms and populations, predation, genetic similarities and differences, etc. I do think the speed of speciation varies between different modes of speciation. Speciation is typically a gradual process but I believe this could be sped up by instances of strong selection in subgroups of a species. If one group is located in a certain area and then a natural disaster occurs isolating them from the rest of the population, the way they adapt and evolve is going to be different based on their specific gene pool and environment. Allopatric speciation involves physical geographical barriers whereas sympatric speciation does not. This impacts the degree of pre-mating isolation and can therefore impact how species diverge. Additionally, polyploidization for instance leads to instant isolation from the ancestral species so th...