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Testes weight, body weight and mating systems in marsupials and monotremes


Rose, RW and Nevison, CM and Dixson, AF, Testes weight, body weight and mating systems in marsupials and monotremes, Journal of Zoology, 243 pp. 523-531. ISSN 0952-8369 (1997) [Refereed Article]

DOI: doi:10.1111/j.1469-7998.1997.tb02798.x


Relationships between testes weight, body weight and mating systems were examined in 40 marsupial species and in the extant monotremes. Relationships between relative testes weight and mating systems in marsupials resemble those previously described for primates. Thus relative testes weights are greatest in those marsupials where females mate with multiple males during the fertile period, i.e. polyandrous species (e.g. Antechinus flavipes, Isoodon obesulus, Perameles nasuta, Potorous tridactylus, Macropus eugenii and M. agilis) and smallest in monandrous forms (e.g. Petauroides volans and Petaurus breviceps) where females usually mate with a single male. These findings are consistent with effects of sperm competition upon the evolution of relative testes sizes in marsupials. Where field studies on marsupial mating systems are lacking, we make predictions based upon examination of their relative testes weights. Tarsipes rostratus, Acrobates pygmaeus, Macropus rufogriseus and Sarcophilus harrisii are predicted to engage in multiple matings and sperm competition. Conversely, Lasiorhinus latifrons, Cercatetus concinnus and Pseudoantechinus macdonnellensis are predicted to be monandrous in their mating behaviour. The monotremes (Ornithorhynchus anatinus, Tachyglossus aculeatus and Zaglossus bruijnii) are characterized by possession of very large testes; monotremes are shown to have significantly greater relative testes weights than marsupials, primates or arian species. This taxonomic difference is unlikely to be related to the occurrence of oviparity or to the abdominal position of the testes in the Monotremata. Their mating systems are not known in detail, but some evidence for multiple matings (and hence for sperm competition) exists for Tachyglossus aculeatus so that their large testes may be adaptive in this context.

Item Details

Item Type:Refereed Article
Research Division:Biological Sciences
Research Group:Evolutionary biology
Research Field:Evolutionary biology not elsewhere classified
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the environmental sciences
UTAS Author:Rose, RW (Associate Professor Randy Rose)
ID Code:11651
Year Published:1997
Web of Science® Times Cited:34
Deposited By:Zoology
Deposited On:1997-08-01
Last Modified:2011-08-12

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