Variability
Variability is simply the conception that items within a collection differ in some way from one another. Variability is crucial in biology, at many scales. Species differ in the roles that they play in ecosystems. Individuals within a species differ in multiple ways: phenotypically, genetically, and developmentally.
The easiest way to illustrate variability is using the techniques and tools of probability theory. One such tool is the distribution of a collection. One might go out and sample seed production of every plant in some local population in a year. The figure at right shows the distribution of seed production for a hypothetical population of plants. One thing to take from this figure is that most individuals failed to reproduce, but of those that did, some produced far more seeds than others. We can quantify variability in general through the variance, but the fact that there are few individuals that produce a lot of seeds is quantified by the skew. Skewed distributions are very common in biology, and play an important role in life history evolution and species coexistence. Indeed, skewed fitness distributions can be found in studies of bet-hedging in fluctuating environments and species coexistence in fluctuating environments. |