Macroevolutionary patterns of male reproductive investment in a clade of parasitic hermaphrodites
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Updated: Oct 20, 2026

Effect of Male Accessory Gland Products on Egg Laying in Gastropod Molluscs
Published on: June 22, 2014
D Zamparo1, D A McLennan, D R Brooks
1Centre for Comparative Biology and Biodiversity, Department of Zoology, University of Toronto, Ontario, Canada.
Abstract:
The Eucestoda is particularly relevant for questions concerning reproductive investment in male gametes because no other parasitic group displays such diversity in testis size and number within and among species. This diversity has long been used as a valuable taxonomic character, but few researchers have ever investigated its evolutionary significance. In this paper we investigate the evolution of testis number and size within Rhinebothroides (Platyhelminthes: Eucestoda). Our comparative, phylogenetic analysis revealed that overall allocation to male functions, as measured by relative testicular area, does not change within the clade, even though the packaging of that investment in numerous testes is highly variable within, and diverse among, members of the group.
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