European researchers at several institutions have found evidence that supports another one of Darwin's speculations: A male roe deer's antlers are representative of the individual's attributes, and thus play a central role in sexual selection.
Jean-Michel Gaillard comments, "Our results provide evidence that antler size of male roe deer mainly reflects their age and body mass, and is more resilient to variation in environmental conditions such as climate, food resources, and density."
"Body mass and age are both reliable descriptors of individual quality in most vertebrates and have been shown to affect the ability to fight and the dominance of males. Hence, by choosing their sexual partners on the basis of their large antlers, females may thus ensure that they mate with a high quality mate," says Cécile Vanpé.
Petter Kjellander adds, "Males may also use antler size of rival males as a cue to assess the possibility of winning a fight in order to control and monopolize more females for reproduction."
Mark Hewison concludes, "This leads to the key question of whether males with larger antlers do have greater access to females than other males." According to François Klein, Guy Van Laere, and Daniel Delorme, this study clearly indicates that antler size might be used as an indicator of individual quality on which management rules could be based.
(Yikes, awkward quotes with no narrative. Someone was in a hurry.)
I have visited two natural history museums in the past few months, the AMNH in New York and the NMNH in DC, both of which have nice specimens of one of my all time favorite animals, Megaloceros, or the "Irish elk" (an unfortunate name; the animal was actually a deer).
In antler and body mass, the gigantism of Megaloceros has long provided evolutionary biologists with an interesting conversation piece - what is the benefit of having antlers so big that the animal might have trouble navigating ancient forests? Gould thought it was merely a case of normal allometry, pointing out that comparable extant deer have exaggerated antlers with respect to body size as well.
This experiment gives a bit more credence to the sexual selection hypothesis - Megaloceros' antler gigantism was selected intra-population by breeding females as indicators of the males vigor and strength. As far as resilience to the environment, well, Megaloceros didn't have much of a chance. The last ice age decimated the vegetation it consumed for food.
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Ah, now I can explain why this was not a problem.
I spent my first 5 summers at a Department of Forestry research station in northern Ontario, Canada where my father was working. Upon questioning how a bull moose with large antlers could run away into the bush so fast, one of the researchers (and we're talking Actual Scientists here!) kindly explained to me that, "They take their antlers off and put them in their pockets."
I trust that this clears up the issue ...