On the evolution of the mammalian baculum: vaginal friction, prolonged intromission or induced ovulation?

Authors: Larivière, S.¹; Ferguson, S. H.²

Source: Mammal Review, Volume 32, Number 4, December 2002 , pp. 283-294(12)

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Abstract:

The function of the mammalian baculum is a puzzling enigma in mammalian morphology. Three hypotheses for the evolution and persistence of the mammalian baculum have been proposed: the vaginal friction hypothesis; the prolonged intromission hypothesis; and the induced ovulation hypothesis. We tested these three hypotheses using phylogenetically corrected methods and data on North American carnivores. Baculum length was independent of sexual dimorphism and duration of copulation, thus refuting the vaginal friction and prolonged intromission hypotheses, respectively. Also, baculum length did not differ between induced ovulators and simultaneous ovulators, thus also refuting the induced ovulation hypothesis. We suggest that other aspects of carnivore life history, such as mating systems, may help explain the evolution of the mammalian baculum.

Keywords: baculum; comparative method; copulation duration; evolution; life history; North American carnivores; sexual dimorphism

Document Type: Research article

DOI: http://dx.doi.org/10.1046/j.1365-2907.2002.00112.x

Affiliations: 1: Delta Waterfowl Foundation, R.R. No. 1, Box 1, Portage La Prairie, Manitoba, Canada, R1N 3A1; 2: Faculty of Forestry and the Forest Environment, Lakehead University, 955 Oliver Road, Thunder Bay, Ontario, Canada, P7B 5E1

Publication date: 2002-12-01