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Upadhyay VR, Ramesh V, Kumar H, Somagond YM, Priyadarsini S, Kuniyal A, Prakash V, Sahoo A. Phenomics in Livestock Research: Bottlenecks and Promises of Digital Phenotyping and Other Quantification Techniques on a Global Scale. OMICS : A JOURNAL OF INTEGRATIVE BIOLOGY 2024; 28:380-393. [PMID: 39012961 DOI: 10.1089/omi.2024.0109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/18/2024]
Abstract
Bottlenecks in moving genomics to real-life applications also include phenomics. This is true not only for genomics medicine and public health genomics but also in ecology and livestock phenomics. This expert narrative review explores the intricate relationship between genetic makeup and observable phenotypic traits across various biological levels in the context of livestock research. We unpack and emphasize the significance of precise phenotypic data in selective breeding outcomes and examine the multifaceted applications of phenomics, ranging from improvement to assessing welfare, reproductive traits, and environmental adaptation in livestock. As phenotypic traits exhibit strong correlations, their measurement alongside specific biological outcomes provides insights into performance, overall health, and clinical endpoints like morbidity and disease. In addition, automated assessment of livestock holds potential for monitoring the dynamic phenotypic traits across various species, facilitating a deeper comprehension of how they adapt to their environment and attendant stressors. A key challenge in genetic improvement in livestock is predicting individuals with optimal fitness without direct measurement. Temporal predictions from unmanned aerial systems can surpass genomic predictions, offering in-depth data on livestock. In the near future, digital phenotyping and digital biomarkers may further unravel the genetic intricacies of stress tolerance, adaptation and welfare aspects of animals enabling the selection of climate-resilient and productive livestock. This expert review thus delves into challenges associated with phenotyping and discusses technological advancements shaping the future of biological research concerning livestock.
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Affiliation(s)
| | - Vikram Ramesh
- ICAR-National Research Centre on Mithun, Medziphema, Nagaland, India
| | - Harshit Kumar
- ICAR-National Research Centre on Mithun, Medziphema, Nagaland, India
| | - Y M Somagond
- ICAR-National Research Centre on Mithun, Medziphema, Nagaland, India
| | | | - Aruna Kuniyal
- ICAR-National Research Centre on Camel, Bikaner, Rajasthan, India
| | - Ved Prakash
- ICAR-National Research Centre on Camel, Bikaner, Rajasthan, India
| | - Artabandhu Sahoo
- ICAR-National Research Centre on Camel, Bikaner, Rajasthan, India
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Dupont L, Audusseau H, Porco D, Butt KR. Mitonuclear discordance and patterns of reproductive isolation in a complex of simultaneously hermaphroditic species, the Allolobophora chlorotica case study. J Evol Biol 2022; 35:831-843. [PMID: 35567785 PMCID: PMC9322523 DOI: 10.1111/jeb.14017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 04/04/2022] [Accepted: 04/12/2022] [Indexed: 12/01/2022]
Abstract
Historical events of population fragmentation, expansion and admixture over geological time may result in complex patterns of reproductive isolation and may explain why, for some taxa, the study of mitochondrial (mt) and nuclear (nu) genetic data results in discordant evolutionary patterns. Complex patterns of taxonomic diversity were recently revealed in earthworms for which distribution is largely the result of paleogeographical events. Here, we investigated reproductive isolation patterns in a complex of cryptic species of earthworms in which discordant patterns between mt and nu genetic lineages were previously revealed, the Allolobophora chlorotica aggregate. Using four nu microsatellite markers and a fragment of the cytochrome c oxidase subunit I mt gene, we carried out a parentage analysis to investigate the mating patterns (i) between individuals belonging to two divergent mt lineages that cannot be distinguished with nu markers and (ii) between individuals belonging to lineages that are differentiated both at the mt and nu levels. Amongst the 157 field-collected individuals, 66 adults were used in cross-breeding experiments to form 22 trios based on their assignment to a mt lineage, and 453 obtained juveniles were genotyped. We showed that adults that mated with both their potential mates in the trio produced significantly more juveniles. In crosses between lineages that diverged exclusively at the mt level, a sex-specific pattern of reproduction characteristic to each lineage was observed, suggesting a possible conflict of interest concerning the use of male/female function between mating partners. In crosses between lineages that diverged both at the mt and nu levels, a high production of cocoons was counterbalanced by a low hatching rate, suggesting a post-zygotic reproductive isolation. Different degrees of reproductive isolation, from differential sex allocation to post-zygotic isolation, were thus revealed. Lineages appear to be at different stages in the speciation process, which likely explain the observed opposite patterns of mitonuclear congruence.
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Affiliation(s)
- Lise Dupont
- University of Paris-Est Creteil, CNRS, INRAE, IRD, IEES-Paris, Creteil, France.,Sorbonne Université, IEES-Paris, Paris, France.,Université de Paris, IEES-Paris, Paris, France
| | - Hélène Audusseau
- ECOBIO [(Ecosystèmes, Biodiversité, Evolution)]-UMR 6553, University of Rennes, CNRS, Rennes, France
| | - David Porco
- Musée National d'histoire Naturelle, Luxembourg, Luxembourg
| | - Kevin R Butt
- School of Natural Sciences, University of Central Lancashire, Preston, UK
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Brand JN, Harmon LJ, Schärer L. Frequent origins of traumatic insemination involve convergent shifts in sperm and genital morphology. Evol Lett 2022; 6:63-82. [PMID: 35127138 PMCID: PMC8802240 DOI: 10.1002/evl3.268] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 11/30/2021] [Accepted: 12/02/2021] [Indexed: 12/18/2022] Open
Abstract
Traumatic insemination is a mating behavior during which the (sperm) donor uses a traumatic intromittent organ to inject an ejaculate through the epidermis of the (sperm) recipient, thereby frequently circumventing the female genitalia. Traumatic insemination occurs widely across animals, but the frequency of its evolution, the intermediate stages via which it originates, and the morphological changes that such shifts involve remain poorly understood. Based on observations in 145 species of the free-living flatworm genus Macrostomum, we identify at least nine independent evolutionary origins of traumatic insemination from reciprocal copulation, but no clear indication of reversals. These origins involve convergent shifts in multivariate morphospace of male and female reproductive traits, suggesting that traumatic insemination has a canalizing effect on morphology. We also observed sperm in both the sperm receiving organ and within the body tissue of two species. These species had intermediate trait values indicating that traumatic insemination evolves through initial internal wounding during copulation. Finally, signatures of male-female coevolution of genitalia across the genus indicate that sexual selection and sexual conflict drive the evolution of traumatic insemination, because it allows donors to bypass postcopulatory control mechanisms of recipients.
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Affiliation(s)
- Jeremias N. Brand
- Department of Environmental Sciences, Zoological InstituteUniversity of BaselBaselCH‐4051Switzerland
- Department of Tissue Dynamics and RegenerationMax Planck Institute for Biophysical ChemistryGöttingenDE‐37077Germany
| | - Luke J. Harmon
- Department of Biological SciencesUniversity of IdahoMoscowIdaho83843
| | - Lukas Schärer
- Department of Environmental Sciences, Zoological InstituteUniversity of BaselBaselCH‐4051Switzerland
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Daupagne L, Koene JM. Disentangling female postmating responses induced by semen transfer components in a simultaneous hermaphrodite. Anim Behav 2020. [DOI: 10.1016/j.anbehav.2020.06.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Patlar B, Weber M, Temizyürek T, Ramm SA. Seminal Fluid-Mediated Manipulation of Post-mating Behavior in a Simultaneous Hermaphrodite. Curr Biol 2020; 30:143-149.e4. [DOI: 10.1016/j.cub.2019.11.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 09/25/2019] [Accepted: 11/05/2019] [Indexed: 10/25/2022]
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Norton CG, Wright MK. Strong first sperm precedence in the freshwater hermaphroditic snail Planorbella trivolvis. INVERTEBR REPROD DEV 2019. [DOI: 10.1080/07924259.2019.1630019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Hamada T, Kuriwada T. Boldness to predator is not significantly correlated with mating behaviour in a simultaneously hermaphroditic snail. ETHOL ECOL EVOL 2019. [DOI: 10.1080/03949370.2019.1625953] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Takatoshi Hamada
- Faculty of Education, Laboratory of Zoology, Kagoshima University, Korimoto 1-20-6, Kagoshima 890-0065, Japan
| | - Takashi Kuriwada
- Faculty of Education, Laboratory of Zoology, Kagoshima University, Korimoto 1-20-6, Kagoshima 890-0065, Japan
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Detwiler JT, Criscione CD. Role of parasite transmission in promoting inbreeding: II. Pedigree reconstruction reveals sib-transmission and consequent kin-mating. Mol Ecol 2017. [PMID: 28626973 DOI: 10.1111/mec.14210] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Even though parasitic flatworms are one of the most species-rich groups of hermaphroditic organisms, we know virtually nothing of their mating systems (selfing or kin-mating rates) in nature. Hence, we lack an understanding of the role of inbreeding in parasite evolution. The natural mating systems of parasitic flatworms have remained elusive due to the inherent difficulty in generating progeny-array data in many parasite systems. New developments in pedigree reconstruction allow direct inference of realized selfing rates in nature by simply using a sample of genotyped individuals. We built upon this advancement by utilizing the closed mating systems, that is, individual hosts, of endoparasites. In particular, we created a novel means to use pedigree reconstruction data to estimate potential kin-mating rates. With data from natural populations of a tapeworm, we demonstrated how our newly developed methods can be used to test for cosibling transmission and inbreeding depression. We then showed how independent estimates of the two mating system components, selfing and kin-mating rates, account for the observed levels of inbreeding in the populations. Thus, our results suggest that these natural parasite populations are in inbreeding equilibrium. Pedigree reconstruction analyses along with the new companion methods we developed will be broadly applicable across a myriad of parasite species. As such, we foresee that a new frontier will emerge wherein the diverse life histories of flatworm parasites could be utilized in comparative evolutionary studies to broadly address ecological factors or life history traits that drive mating systems and hence inbreeding in natural populations.
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Affiliation(s)
- Jillian T Detwiler
- Department of Biological Sciences, University of Manitoba, Winnipeg, MB, Canada
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Detwiler JT, Caballero IC, Criscione CD. Role of parasite transmission in promoting inbreeding: I. Infection intensities drive individual parasite selfing rates. Mol Ecol 2017. [DOI: 10.1111/mec.14211] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Koene JM. Sex determination and gender expression: Reproductive investment in snails. Mol Reprod Dev 2017; 84:132-143. [PMID: 27245260 PMCID: PMC6220956 DOI: 10.1002/mrd.22662] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Accepted: 05/22/2016] [Indexed: 02/01/2023]
Abstract
Sex determination is generally seen as an issue of importance for separate-sexed organisms; however, when considering other sexual systems, such as hermaphroditism, sex allocation is a less-binary form of sex determination. As illustrated here, with examples from molluscs, this different vantage point can offer important evolutionary insights. After all, males and females produce only one type of gamete, whereas hermaphrodites produce both. In addition, sperm and accessory gland products are donated bidirectionally. For reciprocal mating, this is obvious since sperm are exchanged within one mating interaction; but even unilaterally mating species end up mating in both sexual roles, albeit not simultaneously. With this in mind, I highlight two factors that play an important role in how reproductive investment is divided in snails: First, the individual's motivation to preferentially donate rather than receive sperm (or vice versa) leads to flexible behavioral performance, and thereby investment, of either sex. Second, due to the presence of both sexual roles within the same individual, partners are potentially able to influence investment in both sexual functions of their partner to their own benefit. The latter has already led to novel insights into how accessory gland products may evolve. Moreover, the current evidence points towards different ways in which allocation to reproduction can be changed in simultaneous hermaphrodites. These often differ from the separate-sexed situation, highlighting that comparison across different sexual systems may help identify commonalities and differences in physiological, and molecular mechanisms as well as evolutionary patterns. Mol. Reprod. Dev. 84: 132-143, 2017. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Joris M. Koene
- Faculty of Earth and Life SciencesDepartment of Ecological ScienceVrije UniversiteitAmsterdamThe Netherlands
- Terrestrial ZoologyNaturalis Biodiversity CentreLeidenThe Netherlands
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David KT, Tanabe P, Fieber LA. Resource Availability Drives Mating Role Selection in a Simultaneous Hermaphrodite Aplysia californica. THE BIOLOGICAL BULLETIN 2016; 231:199-206. [PMID: 28048961 PMCID: PMC5365073 DOI: 10.1086/691067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
In simultaneous hermaphrodites, a clear conflict exists between sperm donor and sperm recipient roles, and how such conflict is mediated remains up for debate. This study observed and recorded mating role selection as a function of resource availability in the simultaneous hermaphrodite Aplysia californica. When food was plentiful, animals assumed both sperm donor and recipient roles at relatively even frequency. However, when half of the mating pairs were placed on restricted diets, food-limited animals assumed the sperm donor role at significantly (P < 0.05) greater frequency than their ad libitum partners; nevertheless, the frequency of successful mating events remained the same. The mass and frequency of eggs laid were also significantly (P > 0.05) correlated with parental food intake. These results demonstrate how mating strategies can change within a mating season, as a result of shifting environmental conditions, and call for a diverse framework to address these issues in simultaneous hermaphroditic mating systems.
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Graham S, Chapuis E, Meconcelli S, Bonel N, Sartori K, Christophe A, Alda P, David P, Janicke T. Size-assortative mating in simultaneous hermaphrodites: an experimental test and a meta-analysis. Behav Ecol Sociobiol 2015. [DOI: 10.1007/s00265-015-1999-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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13
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Henshaw JM, Kokko H, Jennions MD. Direct reciprocity stabilizes simultaneous hermaphroditism at high mating rates: A model of sex allocation with egg trading. Evolution 2015; 69:2129-39. [PMID: 26150086 DOI: 10.1111/evo.12717] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Revised: 06/17/2015] [Accepted: 06/19/2015] [Indexed: 01/14/2023]
Abstract
Simultaneous hermaphroditism is predicted to be unstable at high mating rates given an associated increase in sperm competition. The existence of reciprocal egg trading, which requires both hermaphroditism and high mating rates to evolve, is consequently hard to explain. We show using mathematical models that the presence of a trading economy creates an additional fitness benefit to egg production, which selects for traders to bias their sex allocation toward the female function. This female-biased sex allocation prevents pure females from invading a trading population, thereby allowing simultaneous hermaphroditism to persist stably at much higher levels of sperm competition than would otherwise be expected. More generally, our model highlights that simultaneous hermaphroditism can persist stably when mating opportunities are abundant, as long as sperm competition remains low. It also predicts that reciprocity will select for heavier investment in the traded resource.
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Affiliation(s)
- Jonathan M Henshaw
- Research School of Biology, The Australian National University, Australia.
| | - Hanna Kokko
- Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Switzerland
| | - Michael D Jennions
- Research School of Biology, The Australian National University, Australia
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14
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Understanding hermaphrodite species through game theory. J Math Biol 2015; 71:1505-24. [PMID: 25749650 DOI: 10.1007/s00285-015-0866-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Revised: 01/15/2015] [Indexed: 10/23/2022]
Abstract
We investigate the existence and stability of sexual strategies (sequential hermaphrodite, successive hermaphrodite or gonochore) at a proximate level. To accomplish this, we constructed and analyzed a general dynamical game model structured by size and sex. Our main objective is to study how costs of changing sex and of sexual competition should shape the sexual behavior of a hermaphrodite. We prove that, at the proximate level, size alone is insufficient to explain the tendency for a pair of prospective copulants to elect the male sexual role by virtue of the disparity in the energetic costs of eggs and sperm. In fact, we show that the stability of sequential vs. simultaneous hermaphrodite depends on sex change costs, while the stability of protandrous vs. protogynous strategies depends on competition cost.
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15
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Nakadera Y, Swart EM, Maas JPA, Montagne-Wajer K, Ter Maat A, Koene JM. Effects of age, size, and mating history on sex role decision of a simultaneous hermaphrodite. ACTA ACUST UNITED AC 2014; 26:232-241. [PMID: 25713474 PMCID: PMC4309981 DOI: 10.1093/beheco/aru184] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Revised: 09/12/2014] [Accepted: 09/16/2014] [Indexed: 11/13/2022]
Abstract
Quite a few animals are male and female at the same time, so they can choose to mate either as male or female on copulation. The decision to perform either sex role was known to be highly flexible depending on various, but often confounding, factors. For the pond snail, we report that young and small snails tend to mate as males first, though old and large snails do not seem to be better females. Contrasting with separate-sexed animals, simultaneous hermaphrodites display unique reproductive strategies as they are male and female at the same time. Simultaneous hermaphrodites that copulate unilaterally, for instance, make a decision to mate as a male or female. Previous studies have demonstrated that sex role preference in hermaphrodites is flexible and is controlled by several, often confounding, factors. We examined the relationship between sex role decisions and 3 life-history traits (age, size, and mating history) in the great pond snail, Lymnaea stagnalis. Based on our field observations, which indicate that adult individuals show overlapping generations and large variation in body size during the breeding season, we performed a sex role choice experiment in the laboratory. We found that young and small snails mate as males first. Both age and size significantly affected sex role decision, with age having a stronger effect. Furthermore, we tested whether L. stagnalis becomes reluctant to inseminate a mate after being inseminated because it is known that after insemination, male investment substantially reduces. Contrary to expectations, our results indicate that the receipt of seminal fluid does not seem to reduce male motivation. In sum, sex role decisions in L. stagnalis are largely determined by age and size but not by having received seminal fluid. This mating pattern, however, does not fully support the size-advantage model because large or old individuals did not perform better as females in our experiment. These results imply a conflicting mating interest, rather than harmonious agreement, between age- and size-different hermaphrodites.
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Affiliation(s)
- Yumi Nakadera
- Section Animal Ecology, Department of Ecological Science, Faculty of Earth and Life Sciences, VU University Amsterdam , De Boelelaan 1085, 1081HV Amsterdam , The Netherlands
| | - Elferra M Swart
- Section Animal Ecology, Department of Ecological Science, Faculty of Earth and Life Sciences, VU University Amsterdam , De Boelelaan 1085, 1081HV Amsterdam , The Netherlands
| | - Jeroen P A Maas
- Section Animal Ecology, Department of Ecological Science, Faculty of Earth and Life Sciences, VU University Amsterdam , De Boelelaan 1085, 1081HV Amsterdam , The Netherlands , ; Applied Biology, HAS University of Applied Sciences , Onderwijsboulevard 221, 5223DE 's-Hertogenbosch , The Netherlands , and
| | - Kora Montagne-Wajer
- Section Animal Ecology, Department of Ecological Science, Faculty of Earth and Life Sciences, VU University Amsterdam , De Boelelaan 1085, 1081HV Amsterdam , The Netherlands
| | - Andries Ter Maat
- Behavioural Neurobiology, Max Planck Institute for Ornithology , Eberhard-Gwinner-Strasse, 82319 Seewiesen , Germany
| | - Joris M Koene
- Section Animal Ecology, Department of Ecological Science, Faculty of Earth and Life Sciences, VU University Amsterdam , De Boelelaan 1085, 1081HV Amsterdam , The Netherlands
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Copulation order, density cues and variance in fertilization success in a cestode. Parasitology 2014; 141:934-9. [PMID: 24560286 DOI: 10.1017/s0031182014000043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Simultaneous hermaphrodites maximize their fitness by optimizing their investment into male or female functions. Allocation of resources to male function (tissues, traits, and/or behaviours increasing paternity) is predicted to increase as density, and the associated level of sperm competition, increases. We tested whether the simultaneous hermaphroditic cestode Schistocephalus solidus uses cues of potential partner densities in its fish intermediate host to improve its male reproductive success in the final host. We had two worms, one originating from a multiple infection in the fish intermediate host and one from a single infection, sequentially compete to fertilize the eggs of a third worm. The fertilization rates of the two competitors nearly always differed from the 50-50 null expectation, sometimes considerably, implying there was a 'winner' in each experimental competition. However, we did not find a significant effect of density in the fish host (single vs multiple) or mating order on paternity. Additional work will be needed to identify the traits and environmental conditions that explain the high variance in male reproductive success observed in this experiment.
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Kimura K, Chiba S. Strategic ejaculation in simultaneously hermaphroditic land snails: more sperm into virgin mates. BMC Evol Biol 2013; 13:264. [PMID: 24304518 PMCID: PMC4235035 DOI: 10.1186/1471-2148-13-264] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2013] [Accepted: 11/27/2013] [Indexed: 11/15/2022] Open
Abstract
Background It has been theorised that sperm competition promotes the strategic usage of costly sperm. Although sperm competition is thought to be an important driving force of reproductive traits in simultaneous hermaphrodites as well as in species with separate sexes, empirical studies on strategic ejaculation in simultaneous hermaphrodites are scarce. Results In the present study, we tested whether the simultaneously hermaphroditic land snail Euhadra quaesita adjusts the number of sperm donated according to the condition of the mate and whether the pattern of strategic ejaculation is in line with previously suggested theories. We found that individuals donated much more sperm when they copulated with a virgin mate than when they copulated with a non-virgin. Conclusion The virgin-biased pattern of ejaculation matches the theoretical prediction and suggests that sperm competition significantly influence the reproductive traits of simultaneously hermaphroditic land snails.
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Affiliation(s)
- Kazuki Kimura
- Department of Environmental Life Sciences, Graduate School of Life Sciences, Tohoku University, Kawauchi 41, Aoba-ku, Sendai 980-8576, Japan.
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Nakadera Y, Koene JM. Reproductive strategies in hermaphroditic gastropods: conceptual and empirical approaches. CAN J ZOOL 2013. [DOI: 10.1139/cjz-2012-0272] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
An individual optimizes its reproductive success by adopting a particular reproductive strategy. Studying the details of a reproductive strategy leads to an understanding of how sexual selection acts, as the former is the process via which the individual reproduces successfully. Hermaphroditic gastropods display a bewildering diversity of reproductive strategies, which may be due to their mode of gender expression, when compared with well-studied separate-sexed species. Extensive theoretical, observational, and experimental research has been conducted on this topic. However, despite our knowledge about the reproductive system of hermaphroditic gastropods, we still need to fill the gap between pre- and post-copulatory processes and reproductive success. Here, we review and propose conceptual and empirical approaches aimed at understanding reproductive strategies of hermaphroditic gastropods. In sum, our suggestions are (i) to focus on sex-biased traits, (ii) to take biologically reliable measurements at both the pre- and post-copulatory level that relate to reproductive success, and (iii) to examine the fitness consequences of biased sex allocation.
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Affiliation(s)
- Yumi Nakadera
- Section Animal Ecology, Department of Ecological Science, Faculty of Earth and Life Sciences, VU University Amsterdam, De Boelelaan 1085, 1081HV, Amsterdam, the Netherlands
| | - Joris M. Koene
- Section Animal Ecology, Department of Ecological Science, Faculty of Earth and Life Sciences, VU University Amsterdam, De Boelelaan 1085, 1081HV, Amsterdam, the Netherlands
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Lange R, Werminghausen J, Anthes N. Does traumatic secretion transfer manipulate mating roles or reproductive output in a hermaphroditic sea slug? Behav Ecol Sociobiol 2013. [DOI: 10.1007/s00265-013-1551-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Werminghausen J, Lange R, Anthes N. Seeking a Sex-Specific Coolidge Effect in a Simultaneous Hermaphrodite. Ethology 2013. [DOI: 10.1111/eth.12093] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Johanna Werminghausen
- Animal Evolutionary Ecology Group; Institute of Evolution and Ecology; Eberhard Karls Universität Tübingen; Tübingen; Germany
| | - Rolanda Lange
- Animal Evolutionary Ecology Group; Institute of Evolution and Ecology; Eberhard Karls Universität Tübingen; Tübingen; Germany
| | - Nils Anthes
- Animal Evolutionary Ecology Group; Institute of Evolution and Ecology; Eberhard Karls Universität Tübingen; Tübingen; Germany
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Schärer L, Pen I. Sex allocation and investment into pre- and post-copulatory traits in simultaneous hermaphrodites: the role of polyandry and local sperm competition. Philos Trans R Soc Lond B Biol Sci 2013; 368:20120052. [PMID: 23339243 PMCID: PMC3576586 DOI: 10.1098/rstb.2012.0052] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Sex allocation theory predicts the optimal allocation to male and female reproduction in sexual organisms. In animals, most work on sex allocation has focused on species with separate sexes and our understanding of simultaneous hermaphrodites is patchier. Recent theory predicts that sex allocation in simultaneous hermaphrodites should strongly be affected by post-copulatory sexual selection, while the role of pre-copulatory sexual selection is much less clear. Here, we review sex allocation and sexual selection theory for simultaneous hermaphrodites, and identify several strong and potentially unwarranted assumptions. We then present a model that treats allocation to sexually selected traits as components of sex allocation and explore patterns of allocation when some of these assumptions are relaxed. For example, when investment into a male sexually selected trait leads to skews in sperm competition, causing local sperm competition, this is expected to lead to a reduced allocation to sperm production. We conclude that understanding the evolution of sex allocation in simultaneous hermaphrodites requires detailed knowledge of the different sexual selection processes and their relative importance. However, little is currently known quantitatively about sexual selection in simultaneous hermaphrodites, about what the underlying traits are, and about what drives and constrains their evolution. Future work should therefore aim at quantifying sexual selection and identifying the underlying traits along the pre- to post-copulatory axis.
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Affiliation(s)
- Lukas Schärer
- Evolutionary Biology, Zoological Institute, University of Basel, Vesalgasse 1, 4051 Basel, Switzerland.
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Effects of mating status on copulatory and postcopulatory behaviour in a simultaneous hermaphrodite. Anim Behav 2013. [DOI: 10.1016/j.anbehav.2012.12.007] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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Hart MK, Shenoy K, Crowley PH. Sexual conflicts along gradients of density and predation risk: insights from an egg-trading fish. Evol Ecol 2011. [DOI: 10.1007/s10682-010-9459-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Anthes N, David P, Auld JR, Hoffer JNA, Jarne P, Koene JM, Kokko H, Lorenzi MC, Pélissié B, Sprenger D, Staikou A, Schärer L. Bateman gradients in hermaphrodites: an extended approach to quantify sexual selection. Am Nat 2010; 176:249-63. [PMID: 20636132 DOI: 10.1086/655218] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Sexual selection is often quantified using Bateman gradients, which represent sex-specific regression slopes of reproductive success on mating success and thus describe the expected fitness returns from mating more often. Although the analytical framework for Bateman gradients aimed at covering all sexual systems, empirical studies are biased toward separate-sex organisms, probably because important characteristics of other systems remain incompletely treated. Our synthesis complements the existing Bateman gradient approach with three essential reproductive features of simultaneous hermaphrodites. First, mating in one sex may affect fitness via the opposite sex, for example, through energetic trade-offs. We integrate cross-sex selection effects and show how they help characterizing sexually mutualistic versus antagonistic selection. Second, male and female mating successes may be correlated, complicating the interpretation of Bateman gradients. We show how to quantify the impact of this correlation on sexual selection and propose a principal component analysis on male and female mating success to facilitate interpretation. Third, self-fertilization is accounted for by adding selfed progeny as a separate category of reproductive success to analyses of Bateman gradients. Finally, using a worked example from the snail Biomphalaria glabrata, we illustrate how the extended analytical framework can enhance our understanding of sexual selection in hermaphroditic animals and plants.
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Affiliation(s)
- Nils Anthes
- Institute for Evolution and Ecology, University of Tübingen, Germany.
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Abbott JK. Intra-locus sexual conflict and sexually antagonistic genetic variation in hermaphroditic animals. Proc Biol Sci 2010; 278:161-9. [PMID: 20719776 DOI: 10.1098/rspb.2010.1401] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Intra-locus sexual conflict results when sex-specific selection pressures for a given trait act against the intra-sexual genetic correlation for that trait. It has been found in a wide variety of taxa in both laboratory and natural populations, but the importance of intra-locus sexual conflict and sexually antagonistic genetic variation in hermaphroditic organisms has rarely been considered. This is not so surprising given the conceptual and theoretical association of intra-locus sexual conflict with sexual dimorphism, but there is no a priori reason why intra-locus sexual conflict cannot occur in hermaphroditic organisms as well. Here, I discuss the potential for intra-locus sexual conflict in hermaphroditic animals and review the available evidence for such conflict, and for the existence of sexually antagonistic genetic variation in hermaphrodites. I argue that mutations with asymmetric effects are particularly likely to be important in mediating sexual antagonism in hermaphroditic organisms. Moreover, sexually antagonistic genetic variation is likely to play an important role in inter-individual variation in sex allocation and in transitions to and from gonochorism (separate sexes) in simultaneous hermaphrodites. I also describe how sequential hermaphrodites may experience a unique form of intra-locus sexual conflict via antagonistic pleiotropy. Finally, I conclude with some suggestions for further research.
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Affiliation(s)
- Jessica K Abbott
- Evolutionary Biology Centre (EBC), Department of Ecology and Genetics, Uppsala University, , Norbyvägen 18D, Uppsala 752 36, Sweden.
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Effects of body size on courtship role, mating frequency and sperm transfer in the land snail Succinea putris. Anim Behav 2010. [DOI: 10.1016/j.anbehav.2010.02.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Kebir A, Ben Miled S, Hbid ML, Bravo de la Parra R. Effects of density dependent sex allocation on the dynamics of a simultaneous hermaphroditic population: modelling and analysis. J Theor Biol 2010; 263:521-9. [PMID: 20026338 DOI: 10.1016/j.jtbi.2009.12.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2009] [Revised: 12/05/2009] [Accepted: 12/14/2009] [Indexed: 11/19/2022]
Abstract
In this work we present a mathematical model describing the dynamics of a population where sex allocation remains flexible throughout adult life and so can be adjusted to current environmental conditions. We consider that the fractions of immature individuals acquiring male and female sexual roles are density dependent through nonlinear functions of a weighted total population size. The main goal of this work is to understand the role of life-history parameters on the stabilization or destabilization of the population dynamics. The model turns out to be a nonlinear discrete model which is analysed by studying the existence of fixed points as well as their stability conditions in terms of model parameters. The existence of more complex asymptotic behaviours of system solutions is shown by means of numerical simulations. Females have larger fertility rate than males. On the other hand, increasing population density favours immature individuals adopting the male role. A positive equilibrium of the system exists whenever fertility and survival rates of one of the sexual roles, if shared by all adults, allow population growing while the opposite happens with the other sexual role. In terms of the female inherent net reproductive number, eta(F), it is shown that the positive equilibria are stable when eta(F) is larger and closed to 1 while for larger values of eta(F) a certain asymptotic assumption on the investment rate in the female function implies that the population density is permanent. Depending on the other parameters values, the asymptotic behaviour of solutions becomes more complex, even chaotic. In this setting the stabilization/destabilization effects of the abruptness rate in density dependence, of the survival rates and of the competition coefficients are analysed.
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Affiliation(s)
- A Kebir
- ENIT-LAMSIN, Tunis el Manar University, BP 37, 1002 Tunis Belvédère, Tunisia.
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KUPFERNAGEL SANDRA, RUSTERHOLZ HANSPETER, BAUR BRUNO. Variation in multiple paternity and sperm utilization patterns in natural populations of a simultaneous hermaphrodite land snail. Biol J Linn Soc Lond 2010. [DOI: 10.1111/j.1095-8312.2009.01361.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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VIZOSO DITAB, RIEGER GUNDE, SCHÄRER LUKAS. Goings-on inside a worm: functional hypotheses derived from sexual conflict thinking. Biol J Linn Soc Lond 2010. [DOI: 10.1111/j.1095-8312.2009.01363.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Chase R, Darbyson E, Horn KE, Samarova E. A mechanism aiding simultaneously reciprocal mating in snails. CAN J ZOOL 2010. [DOI: 10.1139/z09-121] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The majority of hermaphroditic animals mate on a given occasion as either male or female, but terrestrial snails and slugs generally mate reciprocally with each partner participating in both sexual roles. This manner of mating requires that the genitalia be exactly opposed prior to copulation attempts, a task made difficult in snails and slugs by the absence of hearing and very limited vision. In the brown garden snail, Cornu aspersum (Müller, 1774), we found that a small protruding structure associated with the genital atrium plays an important role in positioning the snails prior to copulation. Lesions of the penial lobe reduced mating success rates, delayed mating, increased the number of attempted intromissions, and increased the number of unilateral intromissions. The sensory capacity of the penial lobe is demonstrated by histological and electrophysiological evidence, and behavioral data suggest that the lobe is also a stimulus for the partner snail. A literature review suggests that structures functionally equivalent to the penial lobe may be present in many gastropod molluscs that mate simultaneously and reciprocally, but in none that mate in other ways.
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Affiliation(s)
- R. Chase
- Department of Biology, McGill University, 1205, avenue Docteur Penfield, Montréal, QC H3A 1B1, Canada
| | - E. Darbyson
- Department of Biology, McGill University, 1205, avenue Docteur Penfield, Montréal, QC H3A 1B1, Canada
| | - K. E. Horn
- Department of Biology, McGill University, 1205, avenue Docteur Penfield, Montréal, QC H3A 1B1, Canada
| | - E. Samarova
- Department of Biology, McGill University, 1205, avenue Docteur Penfield, Montréal, QC H3A 1B1, Canada
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Hermann PM, Genereux B, Wildering WC. Evidence for age-dependent mating strategies in the simultaneous hermaphrodite snail, Lymnaea stagnalis (L.). ACTA ACUST UNITED AC 2009; 212:3164-73. [PMID: 19749110 DOI: 10.1242/jeb.030031] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In many mating systems female reproductive capacity is a limiting resource over which males will compete. As a consequence, males and females have usually different fitness optimization strategies which may give rise to sexual conflict. Since simultaneous hermaphrodites have, in theory, the option to mate as male or as female at any time, conflict will occur if partners insist in taking the same role. Several lines of evidence exists that body size influences gender choice. However, growth in many invertebrates is indeterminate and therefore age is generally a covariant of size. We therefore investigated the effect of age on mating choices in the simultaneous hermaphrodite Lymnaea stagnalis. Using fully sexually mature animals sampled from three different age groups we show that copulation frequency declines with age. Specifically, in age-matched couples the frequency of primary and reciprocal copulations declines with age. Furthermore, the younger partner tends to mate as male with greater probability in couples of unequal age. Size was never a factor in the sex role preference of Lymnaea. Thus, young Lymnaea always attempt to copulate as male independent of the age of their partner, whereas senior snails act primarily as female. The sex role choices of middle-aged snails appear to depend on their partner's age. In addition, we demonstrate that the likelihood that an animal will copulate as male is not correlated with prostate gland size but correlates with the level of afferent electrical activity recorded in the nerve originating in the prostate gland. Together, our results indicate the existence of an age- and not size-dependent mating system in Lymnaea.
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Affiliation(s)
- Petra M Hermann
- Department of Biological Sciences, Faculty of Science, University of Calgary, Calgary, Alberta, T2N 1N4 Canada.
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Häderer IK, Werminghausen J, Michiels NK, Timmermeyer N, Anthes N. No effect of mate novelty on sexual motivation in the freshwater snail Biomphalaria glabrata. Front Zool 2009; 6:23. [PMID: 19818155 PMCID: PMC2766376 DOI: 10.1186/1742-9994-6-23] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2009] [Accepted: 10/12/2009] [Indexed: 11/24/2022] Open
Abstract
Background When mating effort (e.g. via ejaculates) is high, males are expected to strategically allocate their resources depending on the expected fitness gains from a given mating opportunity. One mechanism to achieve strategic mating is the Coolidge effect, where male sexual motivation declines across repeated encounters with a familiar partner, but resuscitates when encountering a novel female. Experimental tests of male mate choice via mechanisms such as the Coolidge effect, however, remain scarce. Moreover, it is untested to date whether the Coolidge effect occurs in a sex-specific manner in simultaneous hermaphrodites, where the motivation to mate with a familiar partner may vary with previous mating activity in the male or female role. Results We exposed focal hermaphroditic freshwater snails, Biomphalaria glabrata, repeatedly to either a familiar or a novel partner. None of our proxies of sexual motivation (remating likelihood, mating delay, copulation duration) varied between the novel and familiar partner treatments. Moreover, the mating role taken during the first copulation did not affect the subsequent choice of mating roles in the familiar partner treatment as would be expected if focals preferred to avoid mating twice in the same role with a familiar partner. This indicates the absence of sex-specific effects of partner novelty. Conclusion Our data indicate that mate novelty does affect neither overall sexual motivation nor the choice of mating roles in B. glabrata. Hence, male mate choice via a Coolidge effect appears inexistent in this invertebrate hermaphrodite. We discuss the possible roles of insufficient fitness gains for discriminatory behaviour in populations with frequent mate encounters as well as poor mate discrimination capacities. Our findings lend also no support to the novel prediction that sexual motivation in simultaneous hermaphrodites varies with the mating roles taken during previous copulations, calling for empirical investigation in further hermaphrodite systems.
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Affiliation(s)
- Ines K Häderer
- Animal Evolutionary Ecology, Institute for Evolution and Ecology, Eberhard Karls-Universität Tübingen, Auf der Morgenstelle 28, 72076 Tübingen, Germany
| | - Johanna Werminghausen
- Animal Evolutionary Ecology, Institute for Evolution and Ecology, Eberhard Karls-Universität Tübingen, Auf der Morgenstelle 28, 72076 Tübingen, Germany
| | - Nico K Michiels
- Animal Evolutionary Ecology, Institute for Evolution and Ecology, Eberhard Karls-Universität Tübingen, Auf der Morgenstelle 28, 72076 Tübingen, Germany
| | - Nadine Timmermeyer
- Animal Evolutionary Ecology, Institute for Evolution and Ecology, Eberhard Karls-Universität Tübingen, Auf der Morgenstelle 28, 72076 Tübingen, Germany
| | - Nils Anthes
- Animal Evolutionary Ecology, Institute for Evolution and Ecology, Eberhard Karls-Universität Tübingen, Auf der Morgenstelle 28, 72076 Tübingen, Germany
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Janicke T, Schärer L. Sex allocation predicts mating rate in a simultaneous hermaphrodite. Proc Biol Sci 2009; 276:4247-53. [PMID: 19740883 DOI: 10.1098/rspb.2009.1336] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Sexual selection theory for separate-sexed animals predicts that the sexes differ in the benefit they can obtain from multiple mating. Conventional sex roles assume that the relationship between the number of mates and the fitness of an individual is steeper in males compared with females. Under these conditions, males are expected to be more eager to mate, whereas females are expected to be choosier. Here we hypothesize that the sex allocation, i.e. the reproductive investment devoted to the male versus female function, can be an important predictor of the mating strategy in simultaneous hermaphrodites. We argue that within-species variation in sex allocation can cause differences in the proportional fitness gain derived through each sex function. Individuals should therefore adjust their mating strategy in a way that is more beneficial to the sex function that is relatively more pronounced. To test this, we experimentally manipulated the sex allocation in a simultaneously hermaphroditic flatworm and investigated whether this affects the mating behaviour. The results demonstrate that individuals with a more male-biased sex allocation (i.e. relatively large testes and small ovaries) are more eager to mate compared with individuals with a more female-biased sex allocation (i.e. relatively small testes and large ovaries). We argue that this pattern is comparable to conventional gender roles in separate-sexed organisms.
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Affiliation(s)
- Tim Janicke
- Zoological Institute, University of Basel, Vesalgasse 1, Basel 4051, Switzerland.
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Smolensky N, Romero MR, Krug PJ. Evidence for costs of mating and self-fertilization in a simultaneous hermaphrodite with hypodermic insemination, the Opisthobranch Alderia willowi. THE BIOLOGICAL BULLETIN 2009; 216:188-199. [PMID: 19366929 DOI: 10.1086/bblv216n2p188] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Simultaneous hermaphrodites offer the chance to study antagonistic coevolution between the sexes when individuals function in both roles. Traumatic mating by hypodermic insemination has repeatedly evolved in hermaphroditic taxa, but evidence for the fitness costs of such male-advantage traits is lacking. When reared in isolation, specimens of the sea slug Alderia willowi (Opisthobranchia: Sacoglossa) initially laid clutches of unfertilized eggs but 4 days later began self-fertilizing; this is only the third report of selfing in an opisthobranch. Hypodermic insemination may allow selfing in Alderia if penetration of the body wall bypasses internal mechanisms that promote outcrossing. Selfing specimens and slugs reared in pairs had reduced fecundity compared to isolated slugs laying unfertilized clutches, suggesting that hypodermic insemination imposes a cost of mating. Egg production increased for field-caught slugs separated after mating compared to slugs held in pairs, a further indication that accessibility to mates imposes a fitness cost to the female function. Such antagonism can confer a competitive advantage to slugs mating in the male role but diminish reproduction in the female role among hermaphrodites capable of long-term sperm storage. Alderia willowi is also a rare case of poecilogony, with adults producing either planktotrophic or lecithotrophic larvae. Our rearing studies revealed that most slugs switched between expressed development modes at some point; such reproductive flexibility within individuals is unprecedented, even among poecilogonous species.
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Affiliation(s)
- Nicole Smolensky
- Department of Biological Sciences, California State University, Los Angeles, California 90032-8201, USA
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Sprenger D, Lange R, Michiels NK, Anthes N. The role of body size in early mating behavior in a simultaneous hermaphrodite, Chelidonura sandrana. Behav Ecol Sociobiol 2009. [DOI: 10.1007/s00265-009-0738-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Abstract
Sex allocation is a crucial life-history parameter in all sexual organisms. Over the last decades a body of evolutionary theory, sex allocation theory, was developed, which has yielded capital insight into the evolution of optimal sex allocation patterns and adaptive evolution in general. Most empirical work, however, has focused on species with separate sexes. Here I review sex allocation theory for simultaneous hermaphrodites and summarize over 50 empirical studies, which have aimed at evaluating this theory in a diversity of simultaneous hermaphrodites spanning nine animal phyla. These studies have yielded considerable qualitative support for several predictions of sex allocation theory, such as a female-biased sex allocation when the number of mates is limited, and a shift toward a more male-biased sex allocation with increasing numbers of mates. In contrast, many fundamental assumptions, such as the trade-off between male and female allocation, and numerous predictions, such as brooding limiting the returns from female allocation, are still poorly supported. Measuring sex allocation in simultaneously hermaphroditic animals remains experimentally demanding, which renders evaluation of more quantitative predictions a challenging task. I identify the main questions that need to be addressed and point to promising avenues for future research.
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Affiliation(s)
- Lukas Schärer
- University of Basel, Zoological Institute, Evolutionary Biology, Vesalgasse 1, 4051 Basel, Switzerland.
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JORDAENS KURT, DILLEN LOBKE, BACKELJAU THIERRY. Shell shape and mating behaviour in pulmonate gastropods (Mollusca). Biol J Linn Soc Lond 2009. [DOI: 10.1111/j.1095-8312.2008.01122.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Ludwig AN, Walsh PJ. Multiple mating, sperm storage, and mating preference in Aplysia californica. THE BIOLOGICAL BULLETIN 2008; 215:265-271. [PMID: 19098147 DOI: 10.2307/25470710] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Aplysia californica, a simultaneous hermaphrodite, has the ability to store and digest allosperm and frequently mates with multiple partners. Using controlled matings and behavioral observations, we characterized the mating behavior of multiply-mated A. californica. Regardless of their initial mating role, all animals mated a second time. Individuals acting as the initial sperm donor showed no preference for second mating role when paired with a "virgin" partner. However, individuals acting as the initial sperm recipient showed a highly significant preference for acting as the sperm donor in subsequent matings, when paired with a "virgin" partner. This preference disappeared when the initial sperm recipient spawned a fertilized egg mass prior to the second mating bout. On average, singly mated animals laid 2.85 +/- 0.39 (mean +/- SE, n = 13) egg masses before accepting sperm from a second donor. These results support the notion that depletion of stored allosperm plays a crucial role in the resolution of sexual conflict and the mating decisions of A. californica.
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Affiliation(s)
- Adam N Ludwig
- Division of Marine Biology and Fisheries, NIH NCRR National Resource for Aplysia, Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600 Rickenbacker Causeway, Miami, Florida 33149, USA
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Chase R, Darbyson E. Differential survival of allosperm by location within the female storage organ of the snail Cornu aspersum. CAN J ZOOL 2008. [DOI: 10.1139/z08-109] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The sperm storage organ of terrestrial gastropod molluscs is implicated in sexual selection because it has a complex structure and it functions in a context of intense sperm competition. Received sperm are stored in spermathecal tubules. In our sample using the brown garden snail ( Cornu aspersum (Müller, 1774)) (n = 58), the mean number of tubules per animal was 16, with lengths ranging from ≤40 to 2480 μm. A hereditary influence on tubule number was indicated by clutch-dependent variations. From histological sections, we counted the spermatozoa that were present in the tubules of ex-virgin snails 1, 2, 4, and 8 weeks after mating (n = 40). Sperm were distributed, on average, across 75% of the tubules in individual snails, thus contradicting one proposed mechanism for cryptic female choice. The total number of sperm declined 66% over 8 weeks, with the largest losses incurred by sperm in the lumens of the tubules and sperm gathered in clusters. By contrast, in the same period, the numbers of sperm that were in contact with the walls of the tubules remained relatively stable. These data imply that sperm survive best when attached to the epithelial wall, either because they derive nutrition from the epithelium or because they use the epithelium as an anchor.
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Affiliation(s)
- Ronald Chase
- Department of Biology, McGill University, 1205 avenue Docteur Penfield, Montréal, QC H3A 1B1, Canada
| | - Emily Darbyson
- Department of Biology, McGill University, 1205 avenue Docteur Penfield, Montréal, QC H3A 1B1, Canada
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Anthes N, Michiels NK. Precopulatory stabbing, hypodermic injections and unilateral copulations in a hermaphroditic sea slug. Biol Lett 2008; 3:121-4. [PMID: 17251120 PMCID: PMC2375930 DOI: 10.1098/rsbl.2006.0596] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Reciprocity constitutes the prevalent mating mechanism among simultaneous hermaphrodites. Yet, when copulations in the female role confer fitness costs through male manipulation, it becomes advantageous sometimes to mate unilaterally in the male role only. In the sea slug Siphopteron quadrispinosum, acting males stab their partner with a bipartite penis, which not only hypodermically injects prostate fluids, but also apparently mechanically enforces unilateral male matings. Despite a pronounced male mating drive in both partners, unilaterality ensued when one slug stabbed more rapidly than its partner. The acting male may thus avoid the costs inflicted by traumatic injections and penial spines. While future studies need to elucidate the net fitness consequences of stabbing, our behavioural evidence is in line with the hypothesis that mating in S. quadrispinosum represents conflicting rather than complementary mating interests between mates.
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Affiliation(s)
- Nils Anthes
- Animal Evolutionary Ecology, Zoological Institute, University of Tübingen, Auf der Morgenstelle 28, 72076 Tübingen, Germany.
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45
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Norton CG, Johnson AF, Mueller RL. Relative size influences gender role in the freshwater hermaphroditic snail, Helisoma trivolvis. Behav Ecol 2008. [DOI: 10.1093/beheco/arn099] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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46
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Sex allocation in simultaneous hermaphrodites: Trade-offs between sex-specific costs and lifespan. THEOR ECOL-NETH 2008. [DOI: 10.1007/s12080-008-0020-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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47
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Effects of isolation and body size on the mating behaviour of the hermaphroditic land snail Succinea putris. Anim Behav 2008. [DOI: 10.1016/j.anbehav.2007.09.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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48
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Sprenger D, Faber J, Michiels NK, Anthes N. Natural female mating rate maximizes hatchling size in a marine invertebrate. J Anim Ecol 2008; 77:696-701. [PMID: 18298520 DOI: 10.1111/j.1365-2656.2008.01376.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
1. Males and females often differ in their optimal mating rates, resulting potentially in conflicts over remating. In species with separate sexes, females typically have a lower optimal mating rate than males, and can regulate contacts with males accordingly. The realized mating rate may therefore be closer to the female's optimum. In simultaneous hermaphrodites, however, it has been suggested that the intraindividual optimization between 'male' and 'female' interests generates more 'male'-driven mating rates. 2. In order to assess the consequences of variation in mating rate on 'female' reproductive output, we exposed the simultaneously hermaphroditic sea slug Chelidonura sandrana to four mating rate regimes and recorded the effects on a variety of fitness components. 3. In focal 'females', we found (i) a slight but significant linear decrease in fecundity with mating rate, whereas (ii) maternal investment in egg capsule volume peaked at an intermediate mating rate. 4. Combining the observed fecundity cost with the apparent benefits of larger offspring size suggests that total female fitness is maximized at an intermediate mating rate. With the latter being close to the natural mating rate of C. sandrana in the field, our findings challenge the assumption of 'male'-driven mating systems in simultaneous hermaphrodites. 5. Our study provides experimental evidence for various mathematical models in which female fitness is maximized at intermediate mating rates.
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Affiliation(s)
- D Sprenger
- Animal Evolutionary Ecology, University of Tübingen, Auf der Morgenstelle 28, 72076 Tübingen, Germany.
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Prior selfing and the selfing syndrome in animals: an experimental approach in the freshwater snailBiomphalaria pfeifferi. Genet Res (Camb) 2008; 90:61-72. [DOI: 10.1017/s0016672307008919] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
SummaryInbreeding species of hermaphroditic animals practising copulation have been characterized by few copulations, no waiting time (the time that an isolated individual waits for a partner before initiating reproduction compared with paired individuals) and limited inbreeding (self-fertilization) depression. This syndrome, which has never been fully studied before in any species, is analysed here in the highly selfing freshwater snailBiomphalaria pfeifferi. We conducted an experiment under laboratory conditions over two generations (G1and G2) using snails sampled from two populations (100 individuals per population). G1individuals were either isolated or paired once a week (potentially allowing for crosses), and monitored during 29 weeks for growth, fecundity and survival. Very few copulations were observed in paired snails, and there was a positive correlation in copulatory activity (e.g. number of copulations) between the male and female sexual roles. The waiting time was either null or negative, meaning that isolated individuals initiated reproduction before paired ones. G2offspring did not differ in hatching rate and survival (to 28 days) between treatments, but offspring from paired individuals grew faster than those from isolated individuals. On the whole, the self-fertilization depression was extremely low in both populations. Another important result is that paired G1individuals began laying (selfed) eggs several weeks prior to initiating copulation: this is the first characterization of prior selfing (selfing initiated prior to any outcrossing) in a hermaphroditic animal. A significant population effect was observed on most traits studied. Our results are discussed with regard to the maintenance of low outcrossing rates in highly inbreeding species.
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Anthes N, Schulenburg H, Michiels NK. EVOLUTIONARY LINKS BETWEEN REPRODUCTIVE MORPHOLOGY, ECOLOGY AND MATING BEHAVIOR IN OPISTHOBRANCH GASTROPODS. Evolution 2008; 62:900-16. [DOI: 10.1111/j.1558-5646.2008.00326.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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