Paternal devotion reduces testicle size in glass frogs
Published: Thursday, Feb 22nd 2024, 13:10
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Caring glass frog fathers have smaller testicles than those who run away after mating. This has to do with the different reproductive strategies of different glass frog species, as a study involving the University of Bern shows.
In frogs from the glass frog family, fertilization takes place outside the body: The females lay unfertilized eggs on leaves and the males spread their sperm over them. In some species of glass frogs, the males guard and care for their offspring, while others do not, as the University of Bern reported on Thursday.
In a study published in the journal "Proceedings of the Royal Society B", the researchers have now shown that there is a correlation between this brood care and testicle size. "We were surprised at how clearly these correlations are evident in glass frogs," said co-author Eva Ringler, Professor of Behavioral Ecology at the University of Bern, in the press release. In total, the research team studied 37 different species of glass frogs native to the tropical rainforests of Central and South America. In eleven of these species, the males take care of the offspring, in the others they do not.
Protection against "spawn piracy"
The researchers suspect that the reason for this lies in evolution. "If a male guards his own clutch, it reduces the risk of fertilization by other males," explained Ringler. This is because external fertilization carries the risk of "spawn piracy". This means that other male frogs manage to spread their own sperm on a fresh clutch of eggs and thus fertilize those eggs that have not yet been fertilized by the sperm of the original mating male.
Guarding and caring for the eggs reduces the selection pressure for greater sperm production and therefore larger testicles, explained the researcher. This is because the smaller the testicles, the lower the potential for the formation of gametes.
©Keystone/SDA
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