Maddy's Evolution Blog

While natural selection is a mechanism of evolution but that doesn't mean that natural selection will always lead to evolution. For example, if you are studying a population and notice that the smaller organisms in that population are able to hide from predators more easily, you would expect that natural selection would lead to the population evolving to be smaller over time. However, as you continue to study the population over many generations, you notice that the offspring grow into adults of varying sizes regardless of parent size. This is because size isn't heritability for this particular population. It won't matter if you study the population for 4 generations or 50, the offspring will continue to range from small to large in size with natural selection leading to the larger organisms being consumed by predators. The only way for natural selection to lead to evolution is if the trait that nature is selecting for is able to be inherited from parent to offspring.  Ther...

When you think of fitness you probably think of someone lifting weights or running x number of miles every day and while the idea of a cat lifting weights is adorable, that's not the kind of fitness we are talking about. In the case of animals (or any living thing) fitness is an individual's ability to pass on their traits to the next generation. But fitness isn't just about reproduction, it's also about how long an organism can survive. The longer an organism can survive, the more offspring they are going to produce and the higher the chances of some of those offspring surviving to maturity and reproducing.   How do you measure fitness? It seems like a simple question but the answer is actually complex. I know what your thinking, what do you mean it's complicated, you just said that fitness is just an organism's ability to survive long enough to produce offspring so all you need to measure is how many offspring a given organism produces and your done. Let's...