Question

You hypothesize that antlers of male deer are costly signals of fighting ability that are directed toward other males. Give three testable predictions that stem from this hypothesis. How would you test each? (3 ways)

Answer 1

• Antlers are like the beards on guys at hunting camp – they are secondary sexual characteristics that separate females and males but don’t directly contribute to reproduction.

1. Antlers in whitetails most likely evolved to be used for fighting other bucks. Unlike bighorn sheep that “ram” heads or bears that stand and fight, whitetails lock heads and push each other around to establish dominance.
2. Antlers are the perfect structure to accommodate this style of fighting. Bucks can and do injure other bucks with their antlers while fighting, but I contend that’s not their main goal. If bucks were primarily trying to injure or kill other bucks, then they could do so at a much higher rate by attacking foes in the body rather than the head. Fights among bucks are typically well choreographed and proceed through an escalating series of vocalizations and body posturing before reaching the fighting stage that nearly always begins with the bucks locking antlers prior to pushing each other.
3. Bucks first lock antlers and then use their body size, strength, and attitude to exert their dominance. An antler’s structure even helps support this as they contain more collagen than long bones like femurs, and this permits more flexibility and allow antlers to yield more before breaking. Larger antlers can also signify good nutrition, suggesting the buck was able to locate high-quality food and was healthy enough to convert a portion of those nutrients to antler growth which make it dominant as in case of whitetail doe or red deer.The dominant buck may have recently won the right to breed by defeating other rival bucks, or he is simply the only buck in the area at the crucial time.