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Hosono S, Masuda Y, Tokioka S, Kawamura T, Iwata Y. Squid male alternative reproductive tactics are determined by birth date. Proc Biol Sci 2024; 291:20240156. [PMID: 38654644 PMCID: PMC11040241 DOI: 10.1098/rspb.2024.0156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Accepted: 03/13/2024] [Indexed: 04/26/2024] Open
Abstract
Alternative reproductive tactics (ARTs) are discontinuous phenotypes associated with reproduction, observed in males of many species. Typically, large males adopt a tactic of competing with rivals for mating, while small males adopt a tactic of stealing fertilization opportunities from the large males. The 'birth date hypothesis', proposing that the date of birth influences the determination of each male's reproductive tactic, has been tested only in teleost fish to date. Here, the birth date hypothesis was tested in ARTs of Japanese spear squid Heterololigo bleekeri (consort/sneaker) by analysing statolith growth increments. The birth date significantly differed between consorts (early-hatched) and sneakers (late-hatched). However, no differences were detected in growth history up to 100 days from hatching. Most immature males caught during the reproductive season were larger than sneakers, and their hatch date was similar to that of consorts, suggesting that these immature males had already been following a life-history pathway as a consort. These results indicate that ARTs of H. bleekeri are determined based on their hatch date in early life. This study firstly suggests that the birth date hypothesis applies to aquatic invertebrates, suggesting that the mechanism by which birth date determines the individual phenotype is a phenomenon more common than previously believed.
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Affiliation(s)
- Shota Hosono
- Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Chiba 277-0882, Japan
| | - Yoshio Masuda
- Miyagi Prefecture Fisheries Technology Institute, Ishinomaki, Miyagi, Japan
| | - Shun Tokioka
- Shiogama Field Station, Fisheries Resources Institute, Japan Fisheries Research and Education Agency, Shiogama, Miyagi, Japan
| | - Tomohiko Kawamura
- Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Chiba 277-0882, Japan
| | - Yoko Iwata
- Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Chiba 277-0882, Japan
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Young JAM, Balshine S, Earn DJD. Modelling the impacts of male alternative reproductive tactics on population dynamics. J R Soc Interface 2023; 20:20230359. [PMID: 37876276 PMCID: PMC10598431 DOI: 10.1098/rsif.2023.0359] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2023] [Accepted: 08/30/2023] [Indexed: 10/26/2023] Open
Abstract
Observations of male alternative reproductive tactics (ARTs) in a variety of species have stimulated the development of mathematical models that can account for the evolution and stable coexistence of multiple male phenotypes. However, little attention has been given to the population dynamic consequences of ARTs. We present a population model that takes account of the existence of two male ARTs (guarders and sneakers), assuming that tactic frequencies are environmentally determined and tactic reproductive success depends on the densities of both types. The presence of sneakers typically increases overall population density. However, if sneakers comprise a sufficiently large proportion of the population-or, equivalently, if guarders are sufficiently rare-then it is possible for the total population to crash to extinction (in this extreme regime, there is also an Allee effect, i.e. a threshold density below which the population will go extinct). We apply the model to the example of the invasive round goby (Neogobius melanostomus). We argue that ARTs can dramatically influence population dynamics and suggest that considering such phenotypic plasticity in population models is potentially important, especially for species of conservation or commercial importance.
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Affiliation(s)
- Jennifer A. M. Young
- Department of Mathematics and Statistics, McMaster University, Hamilton, Ontario, Canada L8S 4K1
| | - Sigal Balshine
- Department of Psychology, Neuroscience and Behaviour, McMaster University, Hamilton, Ontario, Canada L8S 4K1
| | - David J. D. Earn
- Department of Mathematics and Statistics, McMaster University, Hamilton, Ontario, Canada L8S 4K1
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Marian JEAR, Apostólico LH, Chiao CC, Hanlon RT, Hirohashi N, Iwata Y, Mather J, Sato N, Shaw PW. Male Alternative Reproductive Tactics and Associated Evolution of Anatomical Characteristics in Loliginid Squid. Front Physiol 2019; 10:1281. [PMID: 31680998 PMCID: PMC6803530 DOI: 10.3389/fphys.2019.01281] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Accepted: 09/24/2019] [Indexed: 01/27/2023] Open
Abstract
Loliginid squids provide a unique model system to explore male alternative reproductive tactics (ARTs) and their linkage to size, behavioral decision making, and possibly age. Large individuals fight one another and the winners form temporary consortships with females, while smaller individuals do not engage in male-male agonistic bouts but use various sneaker tactics to obtain matings, each with varying mating and fertilization success. There is substantial behavioral flexibility in most species, as smaller males can facultatively switch to the alternative consort behaviors as the behavioral context changes. These forms of ARTs can involve different: mating posture; site of spermatophore deposition; fertilization success; and sperm traits. Most of the traits of male dimorphism (both anatomical and behavioral) are consistent with traditional sexual selection theory, while others have unique features that may have evolved in response to the fertilization environment faced by each temporary or permanent male morph.
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Affiliation(s)
- José E A R Marian
- Department of Zoology, Institute of Biosciences, University of São Paulo, São Paulo, Brazil
| | - Lígia H Apostólico
- Department of Zoology, Institute of Biosciences, University of São Paulo, São Paulo, Brazil
| | - Chuan-Chin Chiao
- Department of Life Sciences, National Tsing Hua University, Hsinchu, Taiwan
| | - Roger T Hanlon
- Marine Biological Laboratory, Woods Hole, MA, United States
| | | | - Yoko Iwata
- Atmosphere and Ocean Research Institute, University of Tokyo, Kashiwa, Japan, Japan
| | - Jennifer Mather
- Department of Psychology, University of Lethbridge, Lethbridge, AB, Canada
| | - Noriyosi Sato
- Department of Fisheries, School of Marine Science and Technology, Tokai University, Shizuoka, Japan
| | - Paul W Shaw
- Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Aberystwyth, United Kingdom.,Department of Ichthyology & Fisheries Science, Rhodes University, Grahamstown, South Africa
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Apostólico LH, Marian JEAR. Behavior of "Intermediate" Males of the Dimorphic Squid Doryteuthis pleii Supports an Ontogenetic Expression of Alternative Phenotypes. Front Physiol 2019; 10:1180. [PMID: 31572225 PMCID: PMC6753871 DOI: 10.3389/fphys.2019.01180] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Accepted: 09/02/2019] [Indexed: 11/13/2022] Open
Abstract
The expression of alternative reproductive tactics (ARTs) by different-sized males of loliginid squids has been extensively investigated. In loliginids, alternative phenotypes are characterized by discontinuous differences in behavior, body size, sperm deposition site, and morphology and functioning of ejaculates. Large consort males guard females, display agonistic behaviors toward rival consort males, and mate with females in the male-parallel (MP) position. Small sneaker males avoid fighting contests and instead adopt furtive behaviors to access females guarded by consort males, mating with females in the head-to-head (HH) posture. Recently, the reappraisal of preserved material from the loliginid squid Doryteuthis pleii showed that intermediate-sized males (so-called “intermediate” males) had both sneaker- and consort-like ejaculates, leading to the hypothesis of them being a transitional stage between both phenotypes. Here, we describe observations made in captivity showing that intermediate males can display agonistic behaviors toward consort males and mate with females in both mating positions, depending on the male’s current reproductive context, i.e., generally in HH, but switching to MP when the female is laying eggs. Such unusual findings of intermediate males simultaneously displaying behaviors of both sneaker and consort males comprise additional evidence corroborating the ontogenetic hypothesis for phenotypic expression of ARTs in this species. Taken together, our results indicate that (1) instead of competing with large consort males for female access and monopolization, small/young males adopt sneaker tactics to obtain mating opportunities, and (2) as they continue to grow, they gradually modify the morphology of their ejaculates and their mating behavior, going through an “intermediate” stage, before becoming large consort males.
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Affiliation(s)
- Lígia H Apostólico
- Department of Zoology, Institute of Biosciences, University of São Paulo, São Paulo, Brazil
| | - José E A R Marian
- Department of Zoology, Institute of Biosciences, University of São Paulo, São Paulo, Brazil
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Balmer A, Zinner B, Gorrell JC, Coltman DW, Raveh S, Dobson FS. Alternative reproductive tactics and lifetime reproductive success in a polygynandrous mammal. Behav Ecol 2018. [DOI: 10.1093/beheco/ary187] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Affiliation(s)
- Adele Balmer
- Integrative Life Sciences Program, Virginia Commonwealth University, Richmond, VA, USA
- Department of Biological Sciences, Auburn University, Auburn, AL, USA
| | - Bertram Zinner
- Department of Mathematics and Statistics, Auburn University, Auburn, AL, USA
| | | | - David W Coltman
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Shirley Raveh
- University of Glasgow, Institute of Biodiversity, Animal Health and Comparative Medicine, Glasgow, Scotland
- Université de Neuchâtel, Institut de Biologie, Eco-Ethologie, Neuchâtel, Switzerland
| | - F Stephen Dobson
- Department of Biological Sciences, Auburn University, Auburn, AL, USA
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Saad LO, Schwaha T, Handschuh S, Wanninger A, Marian JEAR. A mating plug in a squid? Sneaker spermatophores can block the female sperm-storage organ in Doryteuthis plei. ZOOLOGY 2018; 130:47-56. [PMID: 30502838 DOI: 10.1016/j.zool.2018.08.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Revised: 08/13/2018] [Accepted: 08/19/2018] [Indexed: 11/18/2022]
Abstract
Males from numerous animal taxa have evolved strategies for obstructing the female genitalia with copulatory plugs, reducing the risk of sperm competition and thus resulting in an advantage in sexual selection. Several lines of evidence suggest that sperm competition is a common feature in the complex squid mating systems, which include the evolution of alternative mating tactics (consort vs. sneaker). However, mating plugs have hitherto not been reported for the group. Investigating the female sperm-storage organ (i.e., seminal receptacle, SR) of the squid Doryteuthis plei, we found cases in which everted spermatophores (i.e., spermatangia) were implanted into the SR and blocking its opening. Here, we describe this finding of "plugged spermatangia" based on microscopy analyses (histology and microCT) of SRs of females from three experimental groups (before and after recent mating and after egg release). We show that sneaker male spermatophores may block the opening of the SR, possibly functioning as temporary copulatory plugs that physically obstruct the SR. Together with previous experimental data on spermatophore functioning, our results suggest that plug efficiency is high until at least 5 h after mating, when spermatangia are turgid and full of sperm, clogging the organ's opening. After that time, plugs gradually decrease their efficiency as they lose turgidity by releasing part of their sperm content. However, one experimental female still had a plugged spermatangium blocking a major portion of the opening even after 48 h without mating. Within the context of squid mating systems and sexual selection, we hypothesize that plugged spermatangia are a sneaker strategy associated with minimizing sperm competition between sneaker males.
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Affiliation(s)
- Luiza O Saad
- Department of Zoology, Institute of Biosciences, University of São Paulo, Rua do Matão, Travessa 14, n. 101, 05508-090, São Paulo, SP, Brazil.
| | - Thomas Schwaha
- Department of Integrative Zoology, Faculty of Life Sciences, University of Vienna, Althanstraße 14, 1090 Vienna, Austria.
| | - Stephan Handschuh
- VetImaging, VetCore Facility for Research, University of Veterinary Medicine, Veterinärplatz 1, 1210, Vienna, Austria.
| | - Andreas Wanninger
- Department of Integrative Zoology, Faculty of Life Sciences, University of Vienna, Althanstraße 14, 1090 Vienna, Austria.
| | - José E A R Marian
- Department of Zoology, Institute of Biosciences, University of São Paulo, Rua do Matão, Travessa 14, n. 101, 05508-090, São Paulo, SP, Brazil.
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