Male Internal Fertilization and Introsperm-like Sperm of the Seaweed Pipefish (Syngnathus schlegeli)

Watanabe, Satoshi; Hara, Masako; Watanabe, Yoshirô

doi:10.2108/zsj.17.759

Cited by 39 publications

(42 citation statements)

References 14 publications

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“…Given these results, it could be argued that cases of apparently discordant sex roles, as in S. schlegeli (reversed according to Watanabe et al 2000 under a female-biased sex ratio, and conventional according to Kornienko 2001 under an even sex ratio), might just reflect a behavioural plasticity, similar to that described for S. abaster.…”

Section: Discussionmentioning

confidence: 74%

Reversing sex role reversal: compete only when you must

Silva¹,

Vieira²,

Almada³

et al. 2010

Animal Behaviour

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Keywords:black striped pipefish competition female-female-interaction mating tactics operational sex ratio (OSR) sex role reversal Syngnathidae Syngnathus abasterThe operational sex ratio (OSR) is thought to be a major factor influencing the intensity of mating competition and sexual selection. Even though many studies on species with conventional sex roles have shown that alterations in the OSR can either intensify male-male competition or promote female-female competitive interactions, sometimes resulting in a reversal of sex roles, it is not known how, and how quickly, individuals with reversed sex roles respond to fluctuations in this ratio. We tested for a direct influence of adult sex ratios (as a direct estimation of the OSR) on the reproductive behaviour of the sex role-reversed black striped pipefish, Syngnathus abaster. Although imbalances in the OSR effectively modulated the expression of sex roles, with males and females varying in the degree of choosiness and competitive displays, alterations in the sex ratios did not promote a similar response pattern in both sexes. A surplus of males resulted in a reversion to conventional sex roles observed when both sexes coexist in similar numbers, with males competing intensely and exhibiting a conspicuous ornament towards other males. An excess of females, in contrast, did not result in an overall increase in female competitive interactions. Only small, less attractive, females were more prone to compete as the proportion of males decreased. Large females, however, seemed to rely on their greater mating prospects, thereby avoiding the hypothetical costs of intrasexual competition. Ó

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Section: Discussionmentioning

confidence: 74%

Reversing sex role reversal: compete only when you must

Silva¹,

Vieira²,

Almada³

et al. 2010

Animal Behaviour

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“…On the contrary, the various morphs reported in S. abaster by Dzyuba et al (2008) each sperm class difficult, thus assessing their respective function and potential adaptive significance problematical. 2 As mentioned in the introduction, the spermatozoa of acquasperm type, reported in the seminal fluid of Syngnathus schlegeli and Hippocampus kuda (Watanabe et al 2000;Van Look et al 2007) could be either parasperm or, more likely, developing spermatids. The semicystic spermatogenetic process causes a precocious release from the spermatocysts of germ cells, which complete their development within the lumen of testis (Carcupino et al 1999;.…”

Section: Discussionmentioning

confidence: 99%

“…This sperm type is a mono-flagellate cell with an elongated nucleus, and it is typical of internal fertilizing fishes (Jamieson 1991). In the testis lumen of Syngnathus schlegeli and Hippocampus kuda (Watanabe et al 2000;Van Look et al 2007), eusperm are seen to be free together with another kind of sperm, similar to those categorized as 'aquasperm' type. The acquasperm are characterized by a spherical head and are typical of external fertilizing fish (Jamieson 1991).…”

Section: Introductionmentioning

confidence: 92%

“…The functional spermatozoa of all syngnathids examined up to now (Carcupino et al 1999;Watanabe et al 2000;AhKing et al 2006;Van Look et al 2007;Biagi et al 2008Biagi et al , 2014Dzyuba et al 2008) may be considered belonging to the 'introsperm type' (according to the classification of Jamieson (1991). This sperm type is a mono-flagellate cell with an elongated nucleus, and it is typical of internal fertilizing fishes (Jamieson 1991).…”

Section: Introductionmentioning

confidence: 99%

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Intra‐ and intermale variability of mature sperm traits analysed in two brackish water populations of the pipefish Syngnathus abaster (Syngnathidae)

et al. 2015

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Piras, F., Biagi, F., Floris, A., Farina, V., Zedda, M., Franzoi, P., Carcupino, M. 2016. Intra-and intermale variability of mature sperm traits analysed in two brackish water populations of the pipefish Syngnathus abaster (Syngnathidae).-Acta Zool ogica (Stockholm) 97: 177-186.Sperm cells are highly diversified in animals, and considerable research effort has focused on variation in sperm morphology among species. Surprisingly, little is known about intraspecific variation in sperm morphology. We analysed withinand between-male variation in mature sperm traits in two brackish water populations of the pipefish Syngnathus abaster. Four morphometric parameters, such as the width and length of the head (including nucleus, and midpiece), length of flagellum and total sperm length were taken into account. The differences in all morphometric parameters analysed between populations were not statistically significant. Moreover, the multidimensional scaling analysis shows that (i) the two populations seem to be indistinguishable based on their spermatozoa and (ii) there is not polymorphism, being sperm not distinguishable into discrete classes both within a single male and between males of each populations. The latter datum does not seem to support the presence of polymorphic sperm in syngnathids. Both populations, however, exhibit a high variation in all sperm traits, both among individual sperm within an ejaculate and among males within each population. The relationship between sperm traits variability and the low selection pressure determined by the absence of postcopulatory sexual selection (i.e. absence of sperm competition) is discussed.

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“…It would be interesting to study whether CW occurs in these species as well, which include pipefish (Watanabe et al 2000), planarians (Ullyot and Beauchamp 1931), but also insects (Jolivet 2008). Some of the latter species have normal sex roles and may be useful to separate whether wounding benefits males or the wound inflictor.…”

Section: Cw and Sex-role Reversalmentioning

confidence: 99%

Copulatory Wounding and Traumatic Insemination

Reinhardt

Anthes

Lange

2015

Cold Spring Harb Perspect Biol

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Copulatory wounding (CW) is widespread in the animal kingdom, but likely underreported because of its cryptic nature. We use four case studies (Drosophila flies, Siphopteron slugs, Cimex bugs, and Callosobruchus beetles) to show that CW entails physiological and lifehistory costs, but can evolve into a routine mating strategy that, in some species, involves insemination through the wound. Although interspecific variation in CW is documented, few data exist on intraspecific and none on individual differences. Although defensive mechanisms evolve in the wound recipient, our review also indicates that mating costs in species with CW are slightly higher than in other species. Whether such costs are dose-or frequencydependent, and whether defense occurs as resistance or tolerance, decisively affects the evolutionary outcome. In addition to sexual conflict, CW may also become a model system for reproductive isolation. In this context, we put forward a number of predictions, including (1) occasional CW is more costly than routine CW, (2) CW is more costly in between-than within-population matings, and (3) in the presence of CW, selection may favor the transmission of sexually transmitted diseases if they induce resource allocation. Finally, we outline, and briefly discuss, several medical implications of CW in humans.

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Male Internal Fertilization and Introsperm-like Sperm of the Seaweed Pipefish (Syngnathus schlegeli)

Abstract: BioOne Complete (complete.BioOne.org) is a full-text database of 200 subscribed and open-access titles in the biological, ecological, and environmental sciences published by nonprofit societies, associations, museums, institutions, and presses.

Cited by 39 publications

References 14 publications

Reversing sex role reversal: compete only when you must

Reversing sex role reversal: compete only when you must

Intra‐ and intermale variability of mature sperm traits analysed in two brackish water populations of the pipefish Syngnathus abaster (Syngnathidae)

Copulatory Wounding and Traumatic Insemination

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