Why small males have big sperm: dimorphic squid sperm linked to alternative mating behaviours
Author Information
Author(s): Iwata Yoko, Shaw Paul, Fujiwara Eiji, Shiba Kogiku, Kakiuchi Yasutaka, Hirohashi Noritaka
Primary Institution: Institute of Biological, Environmental and Rural Sciences (IBERS), Aberystwyth University
Hypothesis
Does sperm size vary between different male mating tactics in the squid Loligo bleekeri?
Conclusion
The study found that different sized males produce distinctly different sperm types, but this dimorphism is not driven by sperm competition.
Supporting Evidence
- Sneaker males produce larger sperm than consort males.
- Sperm from both male types were capable of fertilization.
- No significant difference in swimming speed was observed between consort and sneaker sperm.
- The size distribution of sperm stored in the seminal receptacle was not biased toward longer sperm.
Takeaway
In squids, smaller males have bigger sperm than larger males, but this isn't because of competition; it's about where the sperm is stored.
Methodology
The study measured sperm size and conducted in vitro fertilization assays using sperm from consort and sneaker males.
Limitations
The study does not explore the genetic factors influencing male morphology or mating tactics.
Participant Demographics
Males of the squid species Loligo bleekeri, categorized as consort or sneaker based on size.
Statistical Information
P-Value
P < 0.01
Statistical Significance
p<0.01
Digital Object Identifier (DOI)
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