Blog Post Module 3

 For me, fitness is the ability of an organism to thrive in its environment given its physiological characteristics. This "thriving" can be the ability of an organism to have the largest proportion of the food or have success in terms of reproduction. In a natural population, I would define fitness as an organism's ability to survive and reproduce compared to other members of that same population. If the death rate of a population is already very high, an individual who has high fitness in that organization may still have high chance of dying, but not as high as other members in the population. For example, a cheetah with shorter than average legs may have reduced fitness due to the length of stride they are capable of producing. This phenotype could slow them down when they are trying to catch prey. On the other hand, a cheetah with longer, more muscular legs may have the ability to run faster and longer, assuring that they can catch their prey and survive. Due to the higher rate of survival among cheetahs with longer, more muscular legs, they are able to reproduce more often and therefore, have a higher level of fitness. Of course, scientists cannot simply assume that cheetahs with longer, more muscular legs are better at catching prey than those with shorter legs. They have to perform experiments and data analysis. One way of doing this would be to measure the leg length of a number of cheetahs in a population and monitor the number of prey they catch. In addition, the study must also be longitudinal, showing that cheetahs with longer legs tend to have higher rates of survival than those with shorter legs. By combining the survival rates and number of prey caught by different cheetahs in a population over time with longer versus shorter legs, scientists might be able to discover a positive correlation between longer leg length and survival. By controlling for confounding variables (factors that affect cheetah survival rates other than leg length), scientists may then be able to conclude that cheetahs with longer legs survive more often than cheetahs with shorter legs; hence, increasing fitness.