Final answer:
Ultimate mechanisms are the evolutionary explanations for behaviors or traits, as opposed to proximate mechanisms. They play a role in understanding ecological sustainability, illustrating the need to look at long-term processes, although the complexity of such systems makes complete knowledge difficult to attain.
Step-by-step explanation:
In regards to the biologist Nikolaas Tinbergen, the term ultimate mechanisms refers to the evolutionary reasons behind certain behaviors or traits in animals. This concept contrasts with proximate mechanisms, which describe the immediate physiological or environmental triggers for a behavior.
While Tinbergen focused on ethology (the study of animal behavior), the concept of ultimate mechanisms can also apply to ecological sustainability. It suggests that to achieve sustainability, we need to understand not just the immediate causes of ecological issues, but also the underlying, long-term evolutionary processes that contribute to the stability and resilience of ecosystems. However, achieving complete knowledge of these complex systems can be incredibly challenging due to their inherent complexity.