Step 1: Understand global warming impacts.
Global warming is expected to cause shifts in species distributions due to changes in temperature and habitat suitability. Generally, species are expected to move towards higher latitudes or elevations as temperatures rise.
Step 2: Evaluate each option.
Option (A): Birds are expected to shift to higher elevations as temperatures increase.
Option (B): Fish are likely to move to deeper waters as surface waters warm.
Option (C): Lizards, being ectothermic, are more likely to move towards higher latitudes or elevations, not the equator, as the equator is already at high temperatures.
Option (D): Mammals are expected to shift towards higher latitudes as temperatures rise.
Hence, the correct answer is (C).