Seasonal changes in reproductive traits and paternity in the Japanese pygmy squid Idiosepius paradoxus

Sato, Noriyosi

doi:10.3354/meps12338

Cited by 4 publications

(4 citation statements)

References 48 publications

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“…A similar pattern of investment of male reproductive traits is found also in other decabrachians species (e.g. as shown for Ommastrephes bartramii by Brunetti et al ., 2006; and for Idiosepius paradoxus by Sato, 2017).…”

Section: Discussionmentioning

confidence: 97%

Reproductive biology and sperm storage characters in two bobtail squid species (Cephalopoda: Sepiolidae)

Sato,

Tanabe,

Uezu

et al. 2024

J. Mar. Biol. Ass.

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Bobtail squids (Family Sepiolidae) have a variety of sperm storage patterns, but their reproductive biology has not been studied in many species, especially those in Japanese waters. Two species, Austrorossia bipapillata (Subfamily Rossiinae) and Sepiolina nipponensis (Subfamily Heteroteuthinae) inhabit Suruga Bay in Japan. These were sampled approximately bimonthly by trawling at around 500 m between the end of September, 2020 and May, 2022. They were measured for body size (dorsal mantle length) and weighed for gonadosomatic index (GSI) calculation, and their sperm storage mechanism was investigated. The reproductive season occurs from May to October in A. bipapillata and from December to February in S. nipponensis. In both species, spermatangia were deposited inside the mantle cavity as implanted spermatangia. In A. bipapillata, 5.7 ± 6.5 spermatangia were deeply implanted in the opening of the oviduct, and in S. nipponensis 62.7 ± 61.5 spermatangia were attached to the left gill and surface of the connective-tissue capsule enclosing the digestive gland. The GSI was lower and there were fewer spermatophores stored in the spermatophoric sac of A. bipapillata males compared to S. nipponensis, leading us to suggest that it is exposed to weaker sperm competition than S. nipponensis, irrespective of similar sperm storage mechanism in the two species.

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Section: Discussionmentioning

confidence: 97%

Reproductive biology and sperm storage characters in two bobtail squid species (Cephalopoda: Sepiolidae)

Sato,

Tanabe,

Uezu

et al. 2024

J. Mar. Biol. Ass.

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“…In our results, we do not know the cost for females or why females remove more spermatangia, but females may avoid sperm storage bias for a certain male as genetic "bet-hedging". The egg batch of Japanese pygmy squid collected in the field was sired by many males and the fertilisation success was not skewed (Sato 2017). Genetic bet-hedging is an important factor to secure genetic diversity and offspring compatibility (Jennions and Petrie 2000;Garcia-Gonzalez et al 2015).…”

Section: Discussionmentioning

confidence: 99%

“…Spermatozoa are then released from the tip of the spermatangium and are activated on contact with seawater, transferred to the seminal receptacle by swimming actively and stored there (Sato et al 2010(Sato et al , 2014a. Paternity analysis of egg masses collected in the field revealed each studied female to have copulated with about 10 males, indicating a highly promiscuous mating system (Sato 2017). The sperm ejaculated by each male form a mixture in the seminal receptacle and the relative sperm volume remaining in the female's body is correlated with fertilisation success (Sato et al 2017).…”

Section: Introductionmentioning

confidence: 99%

“…Females elongate their mouth (buccal mass) and choose successful mates cryptically postcopulation by picking up and removing spermatangia before completing sperm transfer (Sato et al 2013b(Sato et al , 2014b. The volume of removed spermatangia is dependent on not only buccal mass elongation but also copulation duration and body size, and females prefer smaller males, but their preferences for long or short copulation duration vary from year to year (Sato et al 2014b and2017).…”

Section: Introductionmentioning

confidence: 99%

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The effect of predation risk on post-copulatory sexual selection in the Japanese pygmy squid

Sato

Uchida

Takegaki

2018

Behav Ecol Sociobiol

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Conspicuous male sexual traits (e.g. weapons for male-male competition and displays for courting females) may attract predators. Under conditions of high predation risk females typically become less choosy with respect to mates to reduce the time spent on mate selection. However, post-copulatory sexual traits, such as sperm ejaculation for sperm competition and sperm removal for cryptic female choice (CFC), may increase with predation risk because they are more inconspicuous to predators. To examine this hypothesis, we observed the reproductive behaviour in the Japanese pygmy squid, Idiosepius paradoxus, in which the male attaches ejaculated spermatangia to the female's body and the female removes the spermatangia after copulation. Squid from two populations (Ohmura and Oki), with low and high predation levels respectively, were copulated in tanks under controlled presence/absence of predator conditions. Among the Ohmura individuals spermatangia removal was suppressed in the presence of a predator. Females may not be able to remove spermatangia effectively when facing a predator because they feel threatened by the predator; as a result, more spermatangia were retained during trials in which they were exposed to predators. In contrast for squid from the Oki (high predation) population, which is exposed to a higher predation risk, were not strongly affected by the predator presence. While the males ejaculated more spermatangia, the females removed more of them. The effect of sexual conflict may be greater than that of the predation risk in the pygmy squid. This suggests adaptive differences in post-copulatory sexual selection traits linked to predation.

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A review of sperm storage methods and post-copulatory sexual selection in the Cephalopoda

Sato

2021

Biological Journal of the Linnean Society

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In many animal phyla, females have a unique sperm storage organ (SSO). Post-copulatory sexual selection is a powerful driving force of SSO evolution. SSOs are generally considered to have evolved through sexual antagonistic coevolution between male genitalia and the SSO and/or cryptic female choice (CFC). In cephalopods, sperm transfer and fertilization are conducted through complex processes, and sperm storage methods show inter-species variation. In some species, males implant spermatangia superficially under the female skin, and then sperm released from the spermatangia are transferred into a seminal receptacle (SR). Deep-sea cephalopods, which lack a SR, have instead evolved a deep-implanting method by which the spermatangium is embedded deep in the musculature of the mantle wall of the female. In some species, the female stores whole spermatangia within a spermatangium pocket. Because the males of most species do not insert an intromittent organ into the female when transferring sperm, SSO evolution may have been influenced by CFC alone. This review summarizes the sperm storage methods and the mechanisms of post-copulatory sexual selection in cephalopods and it is proposed that these diverse methods evolved as adaptive mechanisms through post-copulatory sexual selection.

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Seasonal changes in reproductive traits and paternity in the Japanese pygmy squid Idiosepius paradoxus

Cited by 4 publications

References 48 publications

Reproductive biology and sperm storage characters in two bobtail squid species (Cephalopoda: Sepiolidae)

Reproductive biology and sperm storage characters in two bobtail squid species (Cephalopoda: Sepiolidae)

The effect of predation risk on post-copulatory sexual selection in the Japanese pygmy squid

A review of sperm storage methods and post-copulatory sexual selection in the Cephalopoda

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