Final answer:
It is difficult to confidently conclude whether the extinct Irish elk's large antlers evolved through intrasexual or intersexual selection without concrete evidence. Theories suggest antlers could have been used for male competition or female preference, or both, and similar selection pressures might be observed in living relatives like moose.
Step-by-step explanation:
The debate on whether the large antlers of the extinct Irish elk evolved through intrasexual selection or intersexual selection is based on different theories within evolutionary biology. Intrasexual selection refers to the competition within one sex, usually males, for the opportunity to mate, which often leads to the development of large or exaggerated traits such as antlers. Intersexual selection, on the other hand, involves choice by one sex, typically females, favoring males with certain traits, which could be antlers in the case of the Irish elk.
Both theories could explain the evolution of the Irish elk's large antlers. Large antlers could have served as a display in male-male competitions to gain access to females, supporting intrasexual selection. Alternatively, they may have evolved because females preferred mating with males that had larger antlers, suggesting intersexual selection. Without definitive behavioral observations or genetic studies from the extinct Irish elk, it is challenging to draw a concrete conclusion. However, understanding the role of antlers in living related species might offer some insights into this issue.