Why thermal biology?
Temperature affects many biological processes. It dramatically affects things like the enzymatic rates of cells, the development of embryos, and the optimal functioning of muscles. The flow of heat into and out of organisms is a source of energy gain or loss, thus playing a vital role in energy budgets. All organisms have evolved adaptations around temperature.
Why is the environment important?
For such an important factor, temperature on the Earth changes a lot - there are daily and annual cycles, and weather patterns that introduce uncertainty. Organisms will lose heat energy in environments colder than themselves, and they will gain heat energy in warmer environments. A major focus of thermal biology is the study of how heat energy is exchanged between organisms and their environments. Things like color, insulation (fur and feathers), and behavior can greatly affect these exchanges.
What does temperature have to do with evolution?
Evolution selects for organisms that produce more offspring than other members of the same species - this is called biological fitness. Temperature can affect fitness in three major ways:
- The developmental environment. Temperatures that are too cold or too hot during development can have disastrous effects, but in general warmer temperatures speed up development so that offspring can hatch earlier and access resources.
- Performance. Muscles, digestion, and other metabolic process all have an optimal temperature. For example, cold muscles are typically slower than warmer muscles, which can affect how successfully an animal hunts.
- The energy budget. Reproduction costs energy, and taking energy from the environment in the form of heat can free up energy from food for reproduction.