Individuals of some species change sex to maximize their reproductive success. Differences in parental investment lead to the sexes having different strategies to maximize reproductive success. Mate choice may be based on the traits of potential mates or by some other criterion, such as territory quality. Organisms allocate limited energy supplies to different needs, including the maintenance of homeostasis. In temperate and polar zones, day length is more reliable than weather as an indicator for seasonal cycles.
Natural selection favors traits that maximize reproductive success.
Most nitrogen conversions are performed only by prokaryotes. Phosphate has a limited local cycle and a long-term geological cycle. Organisms must maintain homeostasis despite environmental variability. Their ability to maintain homeostasis differs. Negative feedback systems maintain homeostasis.