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Dougherty LR, Skirrow MJA, Jennions MD, Simmons LW. Male alternative reproductive tactics and sperm competition: a meta-analysis. Biol Rev Camb Philos Soc 2022; 97:1365-1388. [PMID: 35229450 PMCID: PMC9541908 DOI: 10.1111/brv.12846] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 02/15/2022] [Accepted: 02/16/2022] [Indexed: 01/16/2023]
Abstract
In many animal species, males may exhibit one of several discrete, alternative ways of obtaining fertilisations, known as alternative reproductive tactics (ARTs). Males exhibiting ARTs typically differ in the extent to which they invest in traits that improve their mating success, or the extent to which they face sperm competition. This has led to the widespread prediction that males exhibiting ARTs associated with a high sperm competition risk, or lower investment into traits that improve their competitiveness before mating, should invest more heavily into traits that improve their competitiveness after mating, such as large ejaculates and high-quality sperm. However, despite many studies investigating this question since the 1990s, evidence for differences in sperm and ejaculate investment between male ARTs is mixed, and there has been no quantitative summary of this field. Following a systematic review of the literature, we performed a meta-analysis examining how testes size, sperm number and sperm traits differ between males exhibiting ARTs that face either a high or low sperm competition risk, or high or low investment in traits that increase mating success. We obtained data from 92 studies and 67 species from across the animal kingdom. Our analyses showed that male fish exhibiting ARTs facing a high sperm competition risk had significantly larger testes (after controlling for body size) than those exhibiting tactics facing a low sperm competition risk. However, this effect appears to be due to the inappropriate use of the gonadosomatic index as a body-size corrected measure of testes investment, which overestimates the difference in testes investment between male tactics in most cases. We found no significant difference in sperm number between males exhibiting different ARTs, regardless of whether sperm were measured from the male sperm stores or following ejaculation. We also found no significant difference in sperm traits between males exhibiting different ARTs, with the exception of sperm adenosine triphosphate (ATP) content in fish. Finally, the difference in post-mating investment between male ARTs was not influenced by the extent to which tactics were flexible, or by the frequency of sneakers in the population. Overall, our results suggest that, despite clear theoretical predictions, there is little evidence that male ARTs differ substantially in investment into sperm and ejaculates across species. The incongruence between theoretical and empirical results could be explained if (i) theoretical models fail to account for differences in overall resource levels between males exhibiting different ARTs or fundamental trade-offs between investment into different ejaculate and sperm traits, and (ii) studies often use sperm or ejaculate traits that do not reflect overall post-mating investment accurately or affect fertilisation success.
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Affiliation(s)
- Liam R Dougherty
- Department of Evolution, Ecology and Behaviour, University of Liverpool, Crown Street, Liverpool, L69 7RB, U.K
| | - Michael J A Skirrow
- Division of Ecology & Evolution, Research School of Biology, The Australian National University, 46 Sullivans Creek Road, Canberra, ACT, 2600, Australia
| | - Michael D Jennions
- Division of Ecology & Evolution, Research School of Biology, The Australian National University, 46 Sullivans Creek Road, Canberra, ACT, 2600, Australia
| | - Leigh W Simmons
- Centre for Evolutionary Biology, School of Biological Sciences, The University of Western Australia, Crawley, WA, 6009, Australia
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Schmoll T, Rudolfsen G, Schielzeth H, Kleven O. Sperm velocity in a promiscuous bird across experimental media of different viscosities. Proc Biol Sci 2020; 287:20201031. [PMID: 32673555 DOI: 10.1098/rspb.2020.1031] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
In species with internal fertilization, the female genital tract appears challenging to sperm, possibly resulting from selection on for example ovarian fluid to control sperm behaviour and, ultimately, fertilization. Few studies, however, have examined the effects of swimming media viscosities on sperm performance. We quantified effects of media viscosities on sperm velocity in promiscuous willow warblers Phylloscopus trochilus. We used both a reaction norm and a character-state approach to model phenotypic plasticity of sperm behaviour across three experimental media of different viscosities. Compared with a standard medium (Dulbecco's Modified Eagle Medium, DMEM), media enriched with 1% or 2% w/v methyl cellulose decreased sperm velocity by up to about 50%. Spermatozoa from experimental ejaculates of different males responded similarly to different viscosities, and a lack of covariance between elevations and slopes of individual velocity-by-viscosity reaction norms indicated that spermatozoa from high- and low-velocity ejaculates were slowed down by a similar degree when confronted with high-viscosity environments. Positive cross-environment (1% versus 2% cellulose) covariances of sperm velocity under the character-state approach suggested that sperm performance represents a transitive trait, with rank order of individual ejaculates maintained when expressed against different environmental backgrounds. Importantly, however, a lack of significant covariances in sperm velocity involving a cellulose concentration of 0% indicated that pure DMEM represented a qualitatively different environment, questioning the validity of this widely used standard medium for assaying sperm performance. Enriching sperm environments along ecologically relevant gradients prior to assessing sperm performance will strengthen explanatory power of in vitro studies of sperm behaviour.
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Affiliation(s)
- Tim Schmoll
- Evolutionary Biology, Bielefeld University, Konsequenz 45, D-33615 Bielefeld, Germany
| | - Geir Rudolfsen
- The Arctic University Museum of Norway, The Arctic University of Norway, NO-9037 Tromsø, Norway
| | - Holger Schielzeth
- Evolutionary Biology, Bielefeld University, Konsequenz 45, D-33615 Bielefeld, Germany.,Institute of Ecology and Evolution, Friedrich Schiller University Jena, Dornburger Str. 159, D-07743 Jena, Germany
| | - Oddmund Kleven
- Norwegian Institute for Nature Research (NINA), P.O. Box 5685 Torgarden, NO-7485 Trondheim, Norway
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3
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Pitnick S, Wolfner MF, Dorus S. Post-ejaculatory modifications to sperm (PEMS). Biol Rev Camb Philos Soc 2020; 95:365-392. [PMID: 31737992 PMCID: PMC7643048 DOI: 10.1111/brv.12569] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2019] [Revised: 10/12/2019] [Accepted: 10/16/2019] [Indexed: 12/15/2022]
Abstract
Mammalian sperm must spend a minimum period of time within a female reproductive tract to achieve the capacity to fertilize oocytes. This phenomenon, termed sperm 'capacitation', was discovered nearly seven decades ago and opened a window into the complexities of sperm-female interaction. Capacitation is most commonly used to refer to a specific combination of processes that are believed to be widespread in mammals and includes modifications to the sperm plasma membrane, elevation of intracellular cyclic AMP levels, induction of protein tyrosine phosphorylation, increased intracellular Ca2+ levels, hyperactivation of motility, and, eventually, the acrosome reaction. Capacitation is only one example of post-ejaculatory modifications to sperm (PEMS) that are widespread throughout the animal kingdom. Although PEMS are less well studied in non-mammalian taxa, they likely represent the rule rather than the exception in species with internal fertilization. These PEMS are diverse in form and collectively represent the outcome of selection fashioning complex maturational trajectories of sperm that include multiple, sequential phenotypes that are specialized for stage-specific functionality within the female. In many cases, PEMS are critical for sperm to migrate successfully through the female reproductive tract, survive a protracted period of storage, reach the site of fertilization and/or achieve the capacity to fertilize eggs. We predict that PEMS will exhibit widespread phenotypic plasticity mediated by sperm-female interactions. The successful execution of PEMS thus has important implications for variation in fitness and the operation of post-copulatory sexual selection. Furthermore, it may provide a widespread mechanism of reproductive isolation and the maintenance of species boundaries. Despite their possible ubiquity and importance, the investigation of PEMS has been largely descriptive, lacking any phylogenetic consideration with regard to divergence, and there have been no theoretical or empirical investigations of their evolutionary significance. Here, we (i) clarify PEMS-related nomenclature; (ii) address the evolutionary origin, maintenance and divergence in PEMS in the context of the protracted life history of sperm and the complex, selective environment of the female reproductive tract; (iii) describe taxonomically widespread types of PEMS: sperm activation, chemotaxis and the dissociation of sperm conjugates; (iv) review the occurence of PEMS throughout the animal kingdom; (v) consider alternative hypotheses for the adaptive value of PEMS; (vi) speculate on the evolutionary implications of PEMS for genomic architecture, sexual selection, and reproductive isolation; and (vii) suggest fruitful directions for future functional and evolutionary analyses of PEMS.
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Affiliation(s)
- Scott Pitnick
- Department of Biology, Center for Reproductive Evolution, Syacuse University, Syracuse, NY 13244, USA
| | - Mariana F. Wolfner
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
| | - Steve Dorus
- Department of Biology, Center for Reproductive Evolution, Syacuse University, Syracuse, NY 13244, USA
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4
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Langen K, Thünken T, Klemm J, Sandmann S, Bakker TCM. Sperm size is negatively related to relative testis size in West African riverine cichlid fishes. Naturwissenschaften 2019; 106:30. [PMID: 31147792 DOI: 10.1007/s00114-019-1622-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Revised: 05/02/2019] [Accepted: 05/06/2019] [Indexed: 10/26/2022]
Abstract
Fishes show a great diversity of mating systems and fertilization mechanisms. This diversity creates an enormous potential for sperm competition. Typically, monogamous species face a low risk of sperm competition and invest less into sperm, and thus show smaller relative testis mass compared to polygamous species with high sperm competition. In cichlids, sperm competition risk is very variable. In lacustrine East African cichlids, large sperm are interpreted as an adaptation to sperm competition, as in those species sperm length correlates with sperm swimming speed. The aim of the present study was to examine variation in sperm and testis traits of substrate breeding cichlids from West African river systems and its relationship to sperm competition. Therefore, sperm traits (total sperm size, flagellum-, midpiece-, and head size) and sperm number were related to the gonadosomatic index (GSI), an indicator of sperm competition, in eight species of two large informal tribes, the chromidotilapiines and the haplotilapiines. We found significant differences between species in all examined sperm traits, sperm number, and GSI with pronounced differences between chromidotilapiines and haplotilapiines. We used a generalized least-squares approach to control for non-independence of data. GSI was positively correlated with sperm number but negatively correlated with total sperm size (also negatively with the flagellum and head size but not significantly with midpiece size). Sperm number and sperm size were negatively correlated suggesting a trade-off between sperm size and quality. Our results suggest that large sperm can evolve in species with relatively low sperm expenditure and probably in absence of high sperm competition between males.
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Affiliation(s)
- Kathrin Langen
- Institute for Evolutionary Biology and Ecology, University of Bonn, An der Immenburg 1, 53121, Bonn, Germany. .,Zoological Research Museum Alexander Koenig, Leibniz Institute for Animal Biodiversity, Adenauerallee 160/162, 53113, Bonn, Germany.
| | - Timo Thünken
- Institute for Evolutionary Biology and Ecology, University of Bonn, An der Immenburg 1, 53121, Bonn, Germany
| | - Janine Klemm
- Institute for Evolutionary Biology and Ecology, University of Bonn, An der Immenburg 1, 53121, Bonn, Germany
| | - Sarah Sandmann
- Institute for Evolutionary Biology and Ecology, University of Bonn, An der Immenburg 1, 53121, Bonn, Germany
| | - Theo C M Bakker
- Institute for Evolutionary Biology and Ecology, University of Bonn, An der Immenburg 1, 53121, Bonn, Germany
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5
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Vitt S, Mehlis-Rick M, Bakker TCM, Rick IP. Enhanced ambient UVB radiation affects post-mating, but not pre-mating sexual traits in a fish. Oecologia 2019; 190:355-366. [PMID: 31134331 DOI: 10.1007/s00442-019-04422-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Accepted: 05/19/2019] [Indexed: 12/11/2022]
Abstract
Organisms inhabiting shallow aquatic habitats currently experience increasing levels of solar ultraviolet B radiation (UVB). UVB causes damage on cellular and molecular levels and can affect associated life-history traits either through direct exposure or indirectly through oxidative stress generation. We examined UVB effects on pre- and post-mating sexual traits in three-spined stickleback fish (Gasterosteus aculeatus). Adult, reproductively non-active males were assigned to two exposure treatments under semi-natural conditions in an outdoor experiment; one group received natural radiation (UVBnormal) whilst the other group received additional UVB (UVBenhanced). After two months, colour metrics were used to quantify male breeding colouration as pre-mating trait. At the post-mating stage, sperm morphology, number and movement as well as testes mass were determined. Males did not significantly differ in sexual ornamentation between treatments, but UVBenhanced fish had smaller testes as well as fewer and shorter sperm than UVBnormal fish. Sperm movement was not significantly different between treatments. However, in UVBenhanced males, linear and progressive movement of sperm was positively correlated with sperm morphology (head-to-tail length ratio), whereas in UVBnormal males this relationship was negative (but not significant). Additionally, there was a significant treatment by body condition interaction concerning head-to-tail length ratio, i.e. head-to-tail length ratio increased with condition in UVBnormal males whereas there was no relationship in UVBenhanced fish. Our findings reveal that increased UVB levels influence post-mating fitness-relevant traits in males whilst having no significant impact on pre-mating sexual traits, suggesting selective UVB-effects at the gamete level with consequences for reproductive performance.
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Affiliation(s)
- Simon Vitt
- Institute for Evolutionary Biology and Ecology, University of Bonn, An der Immenburg 1, 53121, Bonn, Germany.
| | - Marion Mehlis-Rick
- Institute for Evolutionary Biology and Ecology, University of Bonn, An der Immenburg 1, 53121, Bonn, Germany
| | - Theo C M Bakker
- Institute for Evolutionary Biology and Ecology, University of Bonn, An der Immenburg 1, 53121, Bonn, Germany
| | - Ingolf P Rick
- Institute for Evolutionary Biology and Ecology, University of Bonn, An der Immenburg 1, 53121, Bonn, Germany
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6
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Morita M, Ugwu SI, Kohda M. Variations in the breeding behavior of cichlids and the evolution of the multi-functional seminal plasma protein, seminal plasma glycoprotein 120. BMC Evol Biol 2018; 18:197. [PMID: 30572831 PMCID: PMC6302530 DOI: 10.1186/s12862-018-1292-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Accepted: 11/09/2018] [Indexed: 11/27/2022] Open
Abstract
Background Seminal plasma proteins are associated with successful fertilization. However, their evolutionary correlation with fertilization mechanisms remains unclear. Cichlids from Lake Tanganyika show a variety-rich spawning behavior that is associated with the transfer of the sperm to the egg for fertilization. One of these behaviors, called “oral fertilization,” emerged during their speciation. In oral fertilization, females nuzzle the milt from male genitalia and pick up the released eggs in their mouths, which are then fertilized inside the oral cavity. Thus, the success of the fertilization is dependent on the retention of sperm in the oral cavity during spawning. Sperm aggregation and immobilization in viscous seminal plasma may help retain the sperm inside the oral cavity, which ultimately determines the success of the fertilization. Seminal plasma glycoprotein 120 (SPP120) is one of the major seminal plasma proteins present in cichlids. SPP120 has been implicated to immobilize sperm and increase the milt viscosity. However, the functional linkage between oral fertilization and seminal plasma proteins has not been investigated. Results During trials of simulated oral fertilization, it was observed that milt viscosity contributed to fertilization success by facilitating longer retention of the milt inside the mouth during spawning. Glycosylation of SPP120 was associated with high milt viscosity. Its glycosylation was specifically present in the milt of cichlid species exhibiting oral fertilization. Moreover, recombinant SPP120 from several the oral fertilization species strongly immobilized/aggregated sperm. Therefore, the functions of SPP120 (immobilization/aggregation and its glycosylation) may contribute to success of oral fertilization, and these functions of SPP120 are more prominent in oral fertilization species. In addition, comparative phylogenetic analyses showed a positive evolutionary correlation between SPP120 function and oral fertilization. Hence, these evolutions may have occurred to keep up with the transition in the mode of fertilization. In addition, rapid evolution in the molecular sequence might be associated with functional modifications of SPP120. Conclusion These results suggest that SPP120 might be associated with oral fertilization. In other words, reproductive traits that define the interaction between sperms and eggs could be the evolutionary selective force that cause the rapid functional modification of the fertilization-related reproductive protein, SPP120. Electronic supplementary material The online version of this article (10.1186/s12862-018-1292-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Masaya Morita
- Sesoko Station, Tropical Biosphere Research Center, University of the Ryukyus, Sesoko, Motobu, Okinawa, 905-0227, Japan.
| | - Stanley Ifeanyi Ugwu
- Sesoko Station, Tropical Biosphere Research Center, University of the Ryukyus, Sesoko, Motobu, Okinawa, 905-0227, Japan
| | - Masanori Kohda
- Laboratory of Animal Sociology, Department of Biology and Geosciences, Graduate School of Sciences, Osaka City University, Sumiyoshi, Osaka, 558-8585, Japan
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7
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Taborsky M, Schütz D, Goffinet O, van Doorn GS. Alternative male morphs solve sperm performance/longevity trade-off in opposite directions. SCIENCE ADVANCES 2018; 4:eaap8563. [PMID: 29806019 PMCID: PMC5966226 DOI: 10.1126/sciadv.aap8563] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2017] [Accepted: 04/17/2018] [Indexed: 05/31/2023]
Abstract
Males pursuing alternative reproductive tactics have been predicted to face a trade-off between maximizing either swimming performance or endurance of their sperm. However, empirical evidence for this trade-off is equivocal, which may be due to simplistic assumptions. In the shell-brooding cichlid fish Lamprologus callipterus, two Mendelian male morphs compete for fertilization by divergent means: Bourgeois nest males ejaculate sperm, on average, about six times farther from the unfertilized ova than do parasitic dwarf males. This asymmetry is opposite to the usual situation, in which bourgeois males typically benefit from superior fertilization opportunities, suggesting that nest males' sperm should persist longer than dwarf male sperm. The assumed trade-off between sperm swimming performance and longevity predicts that, in turn, sperm of dwarf males should outperform that of nest males in swimming efficiency. Measurement of sperm performance and endurance reveals that dwarf male spermatozoa swim straighter initially than those of nest males, but their motility declines earlier and their velocity slows down more abruptly. Nest male sperm survives longer, which relates to a larger sperm head plus midpiece, implying more mitochondria. Thus, the trade-off between sperm performance and endurance is optimized in opposite directions by alternative male morphs. We argue that the relative success of alternative sperm performance strategies can be influenced strongly by environmental factors such as the time window between gamete release and fertilization, and the position of gamete release. This is an important yet little understood aspect of gametic adaptations to sperm competition.
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Affiliation(s)
- Michael Taborsky
- Department of Behavioural Ecology, Institute of Ecology and Evolution, University of Bern, Wohlenstrasse 50a, CH-3032 Hinterkappelen, Switzerland
| | - Dolores Schütz
- Department of Behavioural Ecology, Institute of Ecology and Evolution, University of Bern, Wohlenstrasse 50a, CH-3032 Hinterkappelen, Switzerland
| | - Olivier Goffinet
- Department of Behavioural Ecology, Institute of Ecology and Evolution, University of Bern, Wohlenstrasse 50a, CH-3032 Hinterkappelen, Switzerland
| | - G. Sander van Doorn
- Department of Behavioural Ecology, Institute of Ecology and Evolution, University of Bern, Wohlenstrasse 50a, CH-3032 Hinterkappelen, Switzerland
- Centre for Ecological and Evolutionary Studies, University of Groningen, P.O. Box 11103, 9700 CC Groningen, Netherlands
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SCHREMPF A, MOSER A, DELABIE J, HEINZE J. Sperm traits differ between winged and wingless males of the antCardiocondyla obscurior. Integr Zool 2016; 11:427-432. [DOI: 10.1111/1749-4877.12191] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Alexandra SCHREMPF
- Zoology/Evolutionary Biology; University of Regensburg; Regensburg Germany
| | - Astrid MOSER
- Zoology/Evolutionary Biology; University of Regensburg; Regensburg Germany
| | - Jacques DELABIE
- Myrmecological Laboratory; Cocoa Research Center CEPLAC; Itabuna Brazil
| | - Jürgen HEINZE
- Zoology/Evolutionary Biology; University of Regensburg; Regensburg Germany
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9
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10
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Ota K, Awata S, Morita M, Yokoyama R, Kohda M. Territorial males can sire more offspring in nests with smaller doors in the cichlid Lamprologus lemairii. J Hered 2014; 105:416-22. [PMID: 24574486 DOI: 10.1093/jhered/esu009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
To examine how territorial males counter reproductive parasites, we examined the paternity of broods guarded by territorial males using 5 microsatellite loci and factors that determine siring success in a wild population of the Lake Tanganyika cichlid Lamprologus lemairii. Females enter rock holes (nests) and spawn inside, and territorial males release milt over the nest openings. Sneakers attempt to dart into the nests, but territorial males often interrupt the attempt. The body size of territorial males (territorial defense ability) and the size of nest opening (the ability to prevent sneakers from nest intrusions) are predicted to be factors that affect paternity at the premating stage, whereas milt quality traits are factors that affect paternity at the postmating stage. Parentage analyses of 477 offspring revealed that most clutches have few or no cuckolders, and territorial males sired >80% of eggs in 7 of the 10 analyzed clutches. Larger territorial males that spawned in nests with narrower openings had greater siring success. In contrast, none of the milt traits affected the siring success. These suggest that territorial male L. lemairii adopt premating strategies whereby they effectively prevent reproductive parasitism.
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Affiliation(s)
- Kazutaka Ota
- the Department of Biology and Geosciences, Osaka City University, 3-3-138 Sumiyoshi, Osaka 558-8585, Japan
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11
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Evans JP, Sherman CDH. Sexual selection and the evolution of egg-sperm interactions in broadcast-spawning invertebrates. THE BIOLOGICAL BULLETIN 2013; 224:166-183. [PMID: 23995741 DOI: 10.1086/bblv224n3p166] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Many marine invertebrate taxa are broadcast spawners, where multiple individuals release their gametes into the water for external fertilization, often in the presence of gametes from heterospecifics. Consequently, sperm encounter the considerable challenges of locating and fertilizing eggs from conspecific females. To overcome these challenges, many taxa exhibit species-specific attraction of sperm toward eggs through chemical signals released from eggs (sperm chemotaxis) and species-specific gamete recognition proteins (GRPs) that mediate compatibility of gametes at fertilization. In this prospective review, we highlight these selective forces, but also emphasize the role that sexual selection, manifested through sperm competition, cryptic female choice, and evolutionary conflicts of interest between the sexes (sexual conflict), can also play in mediating the action of egg chemoattractants and GRPs, and thus individual reproductive fitness. Furthermore, we explore patterns of selection at the level of gametes (sperm phenotype, gamete plasticity, and egg traits) to identify putative traits targeted by sexual selection in these species. We conclude by emphasizing the excellent, but relatively untapped, potential of broadcast-spawning marine invertebrates as model systems to illuminate several areas of research in post-mating sexual selection.
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Affiliation(s)
- Jonathan P Evans
- Centre for Evolutionary Biology, School of Animal Biology, University of Western Australia, Crawley, Australia.
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12
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Johnson DW, Monro K, Marshall DJ. THE MAINTENANCE OF SPERM VARIABILITY: CONTEXT-DEPENDENT SELECTION ON SPERM MORPHOLOGY IN A BROADCAST SPAWNING INVERTEBRATE. Evolution 2012; 67:1383-95. [DOI: 10.1111/evo.12022] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2012] [Accepted: 11/01/2012] [Indexed: 01/15/2023]
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13
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Affiliation(s)
- Kazutaka Ota
- Department of Zoology, Graduate School of Sciences; Kyoto University; Kyoto; Japan
| | - Michio Hori
- Department of Zoology, Graduate School of Sciences; Kyoto University; Kyoto; Japan
| | - Masanori Kohda
- Department of Biology and Geosciences; Osaka City University; Osaka; Japan
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14
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Engqvist L. Evolutionary Modeling Predicts a Decrease in Postcopulatory Sperm Viability as a Response to Increasing Levels of Sperm Competition. Am Nat 2012; 179:667-77. [DOI: 10.1086/665000] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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15
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Changes in reproductive life-history strategies in response to nest density in a shell-brooding cichlid, Telmatochromis vittatus. Naturwissenschaften 2011; 99:23-31. [PMID: 22089034 DOI: 10.1007/s00114-011-0864-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2011] [Revised: 10/31/2011] [Accepted: 11/03/2011] [Indexed: 10/15/2022]
Abstract
To determine whether the appearance of a reproductively parasitic tactic varies, and how this variation affects territorial males of the Lake Tanganyika cichlid fish Telmatochromis vittatus, we examined the reproductive ecology of territorial males in Mtondwe and compared it with that of a neighboring Wonzye population, where nest density differs from that at Mtondwe. In Wonzye, with high nest density, male tactics change with their body size from a territorial to a non-territorial parasitic tactic called piracy in which they conquer several nests defended by territorial males and take over the nests while females are spawning. These "pirate" males could decrease the costs incurred by travelling among nests by exclusively targeting aggregations of nests in close proximity while avoiding separate nests. Territorial males in Wonzye sacrifice the potential higher attractiveness offered by large nests and instead compete for nests farther from neighbors on which pirates less frequently intrude. In contrast, the Mtondwe population had lower nest density and piracy was absent. Given that the success of piracy depends on the close proximity of nests, nest density is likely responsible for the observed variation in the occurrence of piracy between the two populations. Furthermore, in Mtondwe, territorial males competed for larger nests and were smaller than the territorial males in Wonzye. Thus, this lower nest density may free territorial males from the selection pressures for increased size caused by both defense against nest piracy and the need to develop into pirates as they grow.
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16
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Sefc KM. Mating and Parental Care in Lake Tanganyika's Cichlids. INTERNATIONAL JOURNAL OF EVOLUTIONARY BIOLOGY 2011; 2011:470875. [PMID: 21822482 PMCID: PMC3142683 DOI: 10.4061/2011/470875] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 12/30/2010] [Revised: 03/22/2011] [Accepted: 05/02/2011] [Indexed: 11/20/2022]
Abstract
Cichlid fishes of Lake Tanganyika display a variety of mating and parental care behaviors, including polygamous and monogamous mouthbrooding and substrate breeding, cooperative breeding, as well as various alternative reproductive tactics such as sneaking and piracy. Moreover, reproductive behaviors sometimes vary within species both in space and in time. Here, I survey reports on mating and parenting behaviors of Lake Tanganyika cichlid species and address the evolution of mating and parental care patterns and sexual dimorphism. Notes on measures of sexual selection intensity and the difficulties of defining mating systems and estimating selection intensities at species level conclude the essay.
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Affiliation(s)
- Kristina M. Sefc
- Department of Zoology, Karl-Franzens University Graz, Universitätsplatz 2, 8010 Graz, Austria
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17
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Ota K, Kohda M. Social status-dependent nest choice of territorial males under reproductive parasitism in a Lake Tanganyika cichlid Telmatochromis vittatus. JOURNAL OF FISH BIOLOGY 2011; 78:700-712. [PMID: 21366567 DOI: 10.1111/j.1095-8649.2010.02872.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Field and laboratory studies were conducted to examine how territorial males of a Lake Tanganyika cichlid Telmatochromis vittatus balance the conflicting demands on nest choice between occupying large nests with more females and avoiding reproductive parasitism (nest piracy, which is adopted by the largest males in the population). Pirates less frequently intruded the nests farther from neighbours, perhaps due to the costs associated with travelling between nests. The field experiment showed that territorial male T. vittatus sacrificed the fitness benefits that large nests offer and instead prioritized occupying the nests farther from neighbours on which fewer pirates intruded. The field observations suggested that they adopt different strategies for nest choice according to their relative competitive ability to pirates; the large territorial males, who are size-matched to pirates and can defend their nests against them, compete for larger nests among the more-isolated nests, whereas subordinate territorial males, which are smaller than pirates and thus inferior to them, compete for the more-isolated nests among the less-isolated nests. These findings suggest that the territorial male T. vittatus chooses the more-isolated nests to avoid pirate males at the expense of occupying large nests.
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Affiliation(s)
- K Ota
- Department of Biology and Geosciences, Osaka City University, Sumiyoshi, Osaka 558-8585, Japan.
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