Editing Ecology (section)

==== Pressure ====

Climatic and [[osmotic pressure]] places [[physiological]] constraints on organisms, especially those that fly and respire at high altitudes, or dive to deep ocean depths.<ref name="Neri" /> These constraints influence vertical limits of ecosystems in the biosphere, as organisms are physiologically sensitive and adapted to atmospheric and osmotic water pressure differences.<ref name="Allee49"/> For example, oxygen levels decrease with decreasing pressure and are a limiting factor for life at higher altitudes.<ref name="Jacobsen08"/> 

[[Xylem|Water transportation]] by plants is another important [[ecophysiology|ecophysiological]] process affected by osmotic pressure gradients.<ref name="Strook08"/><ref name="Pockman95"/><ref name="Zimmermann02"/> [[Fluid pressure|Water pressure]] in the depths of oceans requires that organisms adapt to these conditions. For example, diving animals such as [[whale]]s, [[dolphin]]s, and [[seal (animal)|seals]] are specially adapted to deal with changes in sound due to water pressure differences.<ref name="Kastak98"/> Differences between [[hagfish]] species provide another example of adaptation to deep-sea pressure through specialized protein adaptations.<ref name="Nishiguchi10"/>