Problem:

"Two species that reduce one another's fitness on microevolutionary (short-term) timescales can increase each other's macroevolutionary (long-term) fitness"

Opinions?

Intuitive Examples:

Body Size - Predator-prey relationships or interference relationships (fighting, e.g. for territory) are often documented to put seletion pressures to grow in body size, often a positive feedback loop. In the short term the presence of the natural enemy in this case often leads to decreased population fitness (probability of being eaten/probability of fatal conflict over territory). But in the long term such large body sizes acts as an advantage over potential future enemies of the same kind. This is particularly relevant to marine ecosystems - where the size of fish often determine where in the food chain that fish is.

Speed/agility - Predators and prey that rely on speed/agility to
capture (predator) or escape (prey) undergo an evolutionary arms race leading to positive feedback of speed/agility boosting morphologies. In the short-term the natural enemy of the prey acts as a burden to
population fitness (probability of being eaten) but in deep time the prey has acquired morphological advantages over potential future
natural enemies such as competitors for resources.

Required:

Question: Venomousness -Why do venomous animals live in warm climates?

Does anybody know any source of this kind?