1
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Wiberg RAW, Viktorin G, Schärer L. Mating strategy predicts gene presence/absence patterns in a genus of simultaneously hermaphroditic flatworms. Evolution 2022; 76:3054-3066. [PMID: 36199200 PMCID: PMC10092323 DOI: 10.1111/evo.14635] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Accepted: 09/28/2022] [Indexed: 01/22/2023]
Abstract
Gene repertoire turnover is a characteristic of genome evolution. However, we lack well-replicated analyses of presence/absence patterns associated with different selection contexts. Here, we study ∼100 transcriptome assemblies across Macrostomum, a genus of simultaneously hermaphroditic flatworms exhibiting multiple convergent shifts in mating strategy and associated reproductive morphologies. Many species mate reciprocally, with partners donating and receiving sperm at the same time. Other species convergently evolved to mate by hypodermic injection of sperm into the partner. We find that for orthologous transcripts annotated as expressed in the body region containing the testes, sequences from hypodermically inseminating species diverge more rapidly from the model species, Macrostomum lignano, and have a lower probability of being observed in other species. For other annotation categories, simpler models with a constant rate of similarity decay with increasing genetic distance from M. lignano match the observed patterns well. Thus, faster rates of sequence evolution for hypodermically inseminating species in testis-region genes result in higher rates of homology detection failure, yielding a signal of rapid evolution in sequence presence/absence patterns. Our results highlight the utility of considering appropriate null models for unobserved genes, as well as associating patterns of gene presence/absence with replicated evolutionary events in a phylogenetic context.
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Affiliation(s)
- R Axel W Wiberg
- Zoological Institute, Department of Environmental Sciences, University of Basel, Basel, CH-4051, Switzerland.,Evolutionary Biology, Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Uppsala, SE-75236, Sweden
| | - Gudrun Viktorin
- Zoological Institute, Department of Environmental Sciences, University of Basel, Basel, CH-4051, Switzerland
| | - Lukas Schärer
- Zoological Institute, Department of Environmental Sciences, University of Basel, Basel, CH-4051, Switzerland
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2
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Singh P, Schärer L. Evolution of sex allocation plasticity in a hermaphroditic flatworm genus. J Evol Biol 2022; 35:817-830. [PMID: 35583959 PMCID: PMC9321609 DOI: 10.1111/jeb.14020] [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: 11/26/2021] [Revised: 04/14/2022] [Accepted: 04/25/2022] [Indexed: 11/28/2022]
Abstract
Sex allocation theory in simultaneous hermaphrodites predicts that optimal sex allocation is influenced by local sperm competition, which occurs when related sperm compete to fertilize a given set of eggs. Different factors, including the mating strategy and the ability to self‐fertilize, are predicted to affect local sperm competition and hence the optimal SA. Moreover, since the local sperm competition experienced by an individual can vary temporally and spatially, this can favour the evolution of sex allocation plasticity. Here, using seven species of the free‐living flatworm genus Macrostomum, we document interspecific variation in sex allocation, but neither their mating strategy nor their ability to self‐fertilize significantly predicted sex allocation among these species. Since we also found interspecific variation in sex allocation plasticity, we further estimated standardized effect sizes for plasticity in response to (i) the presence of mating partners (i.e. in isolation vs. with partners) and (ii) the strength of local sperm competition (i.e. in small vs. large groups). We found that self‐fertilization predicted sex allocation plasticity with respect to the presence of mating partners, with plasticity being lower for self‐fertilizing species. Finally, we showed that interspecific variation in sex allocation is higher than intraspecific variation due to sex allocation plasticity. Our study suggests that both sex allocation and sex allocation plasticity are evolutionarily labile, with self‐fertilization predicting the latter in Macrostomum.
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Affiliation(s)
- Pragya Singh
- Department of Environmental Sciences, Zoological Institute, University of Basel, Basel, Switzerland
| | - Lukas Schärer
- Department of Environmental Sciences, Zoological Institute, University of Basel, Basel, Switzerland
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3
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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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4
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Teves ME, Roldan ERS. Sperm bauplan and function and underlying processes of sperm formation and selection. Physiol Rev 2022; 102:7-60. [PMID: 33880962 PMCID: PMC8812575 DOI: 10.1152/physrev.00009.2020] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Revised: 04/14/2021] [Accepted: 04/19/2021] [Indexed: 01/03/2023] Open
Abstract
The spermatozoon is a highly differentiated and polarized cell, with two main structures: the head, containing a haploid nucleus and the acrosomal exocytotic granule, and the flagellum, which generates energy and propels the cell; both structures are connected by the neck. The sperm's main aim is to participate in fertilization, thus activating development. Despite this common bauplan and function, there is an enormous diversity in structure and performance of sperm cells. For example, mammalian spermatozoa may exhibit several head patterns and overall sperm lengths ranging from ∼30 to 350 µm. Mechanisms of transport in the female tract, preparation for fertilization, and recognition of and interaction with the oocyte also show considerable variation. There has been much interest in understanding the origin of this diversity, both in evolutionary terms and in relation to mechanisms underlying sperm differentiation in the testis. Here, relationships between sperm bauplan and function are examined at two levels: first, by analyzing the selective forces that drive changes in sperm structure and physiology to understand the adaptive values of this variation and impact on male reproductive success and second, by examining cellular and molecular mechanisms of sperm formation in the testis that may explain how differentiation can give rise to such a wide array of sperm forms and functions.
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Affiliation(s)
- Maria Eugenia Teves
- Department of Obstetrics and Gynecology, Virginia Commonwealth University, Richmond, Virginia
| | - Eduardo R S Roldan
- Department of Biodiversity and Evolutionary Biology, Museo Nacional de Ciencias Naturales (CSIC), Madrid, Spain
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5
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Wiberg RAW, Brand JN, Schärer L. Faster Rates of Molecular Sequence Evolution in Reproduction-Related Genes and in Species with Hypodermic Sperm Morphologies. Mol Biol Evol 2021; 38:5685-5703. [PMID: 34534329 PMCID: PMC8662610 DOI: 10.1093/molbev/msab276] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Sexual selection drives the evolution of many striking behaviors and morphologies and should leave signatures of selection at loci underlying these phenotypes. However, although loci thought to be under sexual selection often evolve rapidly, few studies have contrasted rates of molecular sequence evolution at such loci across lineages with different sexual selection contexts. Furthermore, work has focused on separate sexed animals, neglecting alternative sexual systems. We investigate rates of molecular sequence evolution in hermaphroditic flatworms of the genus Macrostomum. Specifically, we compare species that exhibit contrasting sperm morphologies, strongly associated with multiple convergent shifts in the mating strategy, reflecting different sexual selection contexts. Species donating and receiving sperm in every mating have sperm with bristles, likely to prevent sperm removal. Meanwhile, species that hypodermically inject sperm lack bristles, potentially as an adaptation to the environment experienced by hypodermic sperm. Combining functional annotations from the model, Macrostomum lignano, with transcriptomes from 93 congeners, we find genus-wide faster sequence evolution in reproduction-related versus ubiquitously expressed genes, consistent with stronger sexual selection on the former. Additionally, species with hypodermic sperm morphologies had elevated molecular sequence evolution, regardless of a gene's functional annotation. These genome-wide patterns suggest reduced selection efficiency following shifts to hypodermic mating, possibly due to higher selfing rates in these species. Moreover, we find little evidence for convergent amino acid changes across species. Our work not only shows that reproduction-related genes evolve rapidly also in hermaphroditic animals, but also that well-replicated contrasts of different sexual selection contexts can reveal underappreciated genome-wide effects.
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Affiliation(s)
- R Axel W Wiberg
- Department of Environmental Sciences, Zoological Institute, University of Basel, Basel, Switzerland
| | - Jeremias N Brand
- Department of Environmental Sciences, Zoological Institute, University of Basel, Basel, Switzerland
| | - Lukas Schärer
- Department of Environmental Sciences, Zoological Institute, University of Basel, Basel, Switzerland
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6
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Strategic adjustment of ejaculate quality in response to variation of the socio-sexual environment. Behav Ecol Sociobiol 2021. [DOI: 10.1007/s00265-021-03032-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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7
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Meyer V, Klose M, Lerchl A. Spermatogenesis in the Roborovski hamster (Phodopus roborovskii) and the Chinese hamster (Cricetulus griseus). Andrology 2021; 9:1617-1630. [PMID: 33987974 DOI: 10.1111/andr.13035] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Revised: 05/04/2021] [Accepted: 05/06/2021] [Indexed: 11/29/2022]
Abstract
BACKGROUND Spermatogenesis is an elaborately organized and tightly regulated differentiation process. The spermatogenesis duration is stable within a certain species but highly variable between species of the same family. OBJECTIVES In this study, the spermatogenesis duration of the Roborovski hamster was measured for the first time, and the spermatogenesis duration of the Chinese hamster was re-assessed. MATERIALS AND METHODS Stage classification and cycle length measurement were carried out by labeling the dividing cells with bromodeoxyuridine and an antibody-based chromogen as well as with the periodic acid-Schiff/hematoxylin stain. Analysis was conducted using reference calculation and linear regression. Morphological measurements completed our set of methods. RESULTS The mean duration of one seminiferous epithelium cycle was 8.58 ± 0.34 days (mean ± SEM; Phodopus roborovskii) and 16.59 ± 0.47 days (Cricetulus griseus) based on the reference calculation. Slightly higher results were obtained using linear regression analysis: 9.72 ± 0.41 days for P. roborovskii and 17.64 ± 0.61 days for C. griseus. Additionally, a newly developed exemplary flowchart was proposed for the Roborovski hamster to facilitate spermatogenesis stage classification also in other species. The Chinese hamster presented an unexpectedly high paired epididymides weight of 1.701 ± 0.046 g (mean ± SEM) although having a body weight of only 40.5 ± 0.7 g. However, no significant correlation between the relative epididymis weight and spermatogenesis duration in mammals (Spearman rank correlation: r = -0.119, p = 0.607, n = 21) or rodents could be found (r = 0.045, p = 0.903, n = 11). CONCLUSION Our data emphasize the stability of the spermatogenesis duration within species and its remarkable variability between species. Further research is needed to identify the principal mechanisms and selection drivers that are responsible for such stability within species and the variability between species.
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Affiliation(s)
- Vivian Meyer
- Department of Life Sciences and Chemistry, Jacobs University, Bremen, Germany
| | - Melanie Klose
- Department of Life Sciences and Chemistry, Jacobs University, Bremen, Germany
| | - Alexander Lerchl
- Department of Life Sciences and Chemistry, Jacobs University, Bremen, Germany
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8
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Churchill ER, Bridle JR, Thom MD. Spatially clustered resources increase male aggregation and mating duration in Drosophila melanogaster. Anim Behav 2020. [DOI: 10.1016/j.anbehav.2020.09.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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9
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Ramm SA. Seminal fluid and accessory male investment in sperm competition. Philos Trans R Soc Lond B Biol Sci 2020; 375:20200068. [PMID: 33070740 DOI: 10.1098/rstb.2020.0068] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Sperm production and allocation strategies have been a central concern of sperm competition research for the past 50 years. But during the 'sexual cascade' there may be strong selection for alternative routes to maximizing male fitness. Especially with the evolution of internal fertilization, a common and by now well-studied example is the accessory ejaculate investment represented by seminal fluid, the complex mixture of proteins, peptides and other components transferred to females together with sperm. How seminal fluid investment should covary with sperm investment probably depends on the mechanism of seminal fluid action. If seminal fluid components boost male paternity success by directly enhancing sperm function or use, we might often expect a positive correlation between the two forms of male investment, whereas trade-offs seem more likely if seminal fluid acts independently of sperm. This is largely borne out by a broad taxonomic survey to establish the prevailing patterns of seminal fluid production and allocation during animal evolution, in light of which I discuss the gaps that remain in our understanding of this key ejaculate component and its relationship to sperm investment, before outlining promising approaches for examining seminal fluid-mediated sperm competitiveness in the post-genomic era. This article is part of the theme issue 'Fifty years of sperm competition'.
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Affiliation(s)
- Steven A Ramm
- Evolutionary Biology, Bielefeld University, Konsequenz 45, 33615 Bielefeld, Germany
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10
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Lemaître JF, Gaillard JM, Ramm SA. The hidden ageing costs of sperm competition. Ecol Lett 2020; 23:1573-1588. [PMID: 32906225 DOI: 10.1111/ele.13593] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 06/30/2020] [Accepted: 07/22/2020] [Indexed: 12/16/2022]
Abstract
Ageing and sexual selection are intimately linked. There is by now compelling evidence from studies performed across diverse organisms that males allocating resources to mating competition incur substantial physiological costs, ultimately increasing ageing. However, although insightful, we argue here that to date these studies cover only part of the relationship linking sexual selection and ageing. Crucially, allocation to traits important in post-copulatory sexual selection, that is sperm competition, has been largely ignored. As we demonstrate, such allocation could potentially explain much diversity in male and female ageing patterns observed both within and among species. We first review how allocation to sperm competition traits such as sperm and seminal fluid production depends on the quality of resources available to males and can be associated with a wide range of deleterious effects affecting both somatic tissues and the germline, and thus modulate ageing in both survival and reproductive terms. We further hypothesise that common biological features such as plasticity, prudent sperm allocation and seasonality of ejaculate traits might have evolved as counter-adaptations to limit the ageing costs of sperm competition. Finally, we discuss the implications of these emerging ageing costs of sperm competition for current research on the evolutionary ecology of ageing.
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Affiliation(s)
- Jean-François Lemaître
- Université de Lyon, Université Lyon 1, CNRS, Laboratoire de Biométrie et Biologie Evolutive UMR5558, Villeurbanne, F-69622, France
| | - Jean-Michel Gaillard
- Université de Lyon, Université Lyon 1, CNRS, Laboratoire de Biométrie et Biologie Evolutive UMR5558, Villeurbanne, F-69622, France
| | - Steven A Ramm
- Evolutionary Biology, Bielefeld University, Konsequenz 45, Bielefeld, 33615, Germany
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11
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Teves ME, Roldan ERS, Krapf D, Strauss III JF, Bhagat V, Sapao P. Sperm Differentiation: The Role of Trafficking of Proteins. Int J Mol Sci 2020; 21:E3702. [PMID: 32456358 PMCID: PMC7279445 DOI: 10.3390/ijms21103702] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 05/10/2020] [Accepted: 05/20/2020] [Indexed: 12/15/2022] Open
Abstract
Sperm differentiation encompasses a complex sequence of morphological changes that takes place in the seminiferous epithelium. In this process, haploid round spermatids undergo substantial structural and functional alterations, resulting in highly polarized sperm. Hallmark changes during the differentiation process include the formation of new organelles, chromatin condensation and nuclear shaping, elimination of residual cytoplasm, and assembly of the sperm flagella. To achieve these transformations, spermatids have unique mechanisms for protein trafficking that operate in a coordinated fashion. Microtubules and filaments of actin are the main tracks used to facilitate the transport mechanisms, assisted by motor and non-motor proteins, for delivery of vesicular and non-vesicular cargos to specific sites. This review integrates recent findings regarding the role of protein trafficking in sperm differentiation. Although a complete characterization of the interactome of proteins involved in these temporal and spatial processes is not yet known, we propose a model based on the current literature as a framework for future investigations.
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Affiliation(s)
- Maria E. Teves
- Department of Obstetrics and Gynecology, Virginia Commonwealth University, Richmond VA 23298, USA;
| | - Eduardo R. S. Roldan
- Department of Biodiversity and Evolutionary Biology, Museo Nacional de Ciencias Naturales (CSIC), 28006-Madrid, Spain
| | - Diego Krapf
- Department of Electrical and Computer Engineering, Colorado State University, Fort Collins, CO 80523, USA;
| | - Jerome F. Strauss III
- Department of Obstetrics and Gynecology, Virginia Commonwealth University, Richmond VA 23298, USA;
| | - Virali Bhagat
- Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond VA 23298, USA;
| | - Paulene Sapao
- Department of Chemistry, Virginia Commonwealth University, Richmond VA, 23298, USA;
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12
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Giannakara A, Ramm SA. Evidence for inter-population variation in waiting times in a self-fertilizing flatworm. INVERTEBR REPROD DEV 2020. [DOI: 10.1080/07924259.2020.1732485] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Affiliation(s)
| | - Steven A. Ramm
- Evolutionary Biology, Bielefeld University, Bielefeld, Germany
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13
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Singh P, Vellnow N, Schärer L. Variation in sex allocation plasticity in three closely related flatworm species. Ecol Evol 2020; 10:26-37. [PMID: 31988714 PMCID: PMC6972800 DOI: 10.1002/ece3.5566] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 07/15/2019] [Accepted: 07/28/2019] [Indexed: 01/15/2023] Open
Abstract
Sex allocation (SA) theory for simultaneous hermaphrodites predicts an influence of group size on SA. Since group size can vary within an individual's lifetime, this can favor the evolution of phenotypically plastic SA. In an emerging comparative context, we here report on SA plasticity in three closely related Macrostomum flatworm species, namely Macrostomum janickei, Macrostomum cliftonensis, and Macrostomum mirumnovem. For each species, we experimentally raised worms in three group sizes (isolated, pairs, and octets) and two enclosure sizes (small and large) in all factorial combinations and studied the effects of these factors on different estimates of SA. In addition, we also evaluated whether isolated worms engage in self-fertilization. We found that all species have plastic SA, with M. cliftonensis being more plastic than the other two species, as assessed by comparing standardized effect sizes of (a) the presence/absence of mating partners and (b) the strength of sexual competition. Moreover, we found that sperm production rate-but not sperm morphology-is plastic in M. cliftonensis, and that only M. mirumnovem self-fertilized during our observation period. Our study suggests that both SA and SA plasticity can diverge even between closely related species.
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Affiliation(s)
- Pragya Singh
- Evolutionary BiologyZoological InstituteUniversity of BaselBaselSwitzerland
| | - Nikolas Vellnow
- Evolutionary BiologyZoological InstituteUniversity of BaselBaselSwitzerland
- Evolutionary Biology DepartmentBielefeld UniversityBielefeldGermany
| | - Lukas Schärer
- Evolutionary BiologyZoological InstituteUniversity of BaselBaselSwitzerland
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14
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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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15
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Greenway EVG, Cirino LA, Wilner D, Somjee U, Anagnostou ME, Hepple RT, Miller CW. Extreme variation in testes size in an insect is linked to recent mating activity. J Evol Biol 2019; 33:142-150. [PMID: 31765505 DOI: 10.1111/jeb.13574] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Revised: 11/08/2019] [Accepted: 11/14/2019] [Indexed: 12/23/2022]
Abstract
Ample sperm production is essential for successful male reproduction in many species. The amount of sperm a male can produce is typically constrained by the size of his testes, which can be energetically expensive to grow and maintain. Although the economics of ejaculate allocation has been the focus of much theoretical and empirical literature, relatively little attention has been paid to individual adult variation and plasticity at the source of sperm production, the testes themselves. We experimentally address this issue using the insect Narnia femorata Stål (Hemiptera: Coreidae). We established the metabolic cost of testicular tissue and then quantified variation in individual testes mass in response to multiple mate quality and quantity treatments. We uncovered extreme variation across individuals and considerable short-term effects of mating activity on testes dry mass. Importantly, the observed variation in testes mass was associated with notable fitness consequences; females paired with males with larger testes had greater hatching success. Overall, pairing with a female resulted in a 11% reduction in dry testes mass. Despite this apparent considerable mating investment, we found no evidence of strategic allocation to higher quality females or longer-term changes in testes mass. The dynamic nature of testes mass and its metabolic cost is vital to consider in the context of re-mating rates, polyandry benefits and general mating system dynamics both in this species and more broadly.
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Affiliation(s)
- E V Ginny Greenway
- Entomology and Nematology Department, University of Florida, Gainesville, Florida
| | - Lauren A Cirino
- Entomology and Nematology Department, University of Florida, Gainesville, Florida
| | - Daniela Wilner
- Entomology and Nematology Department, University of Florida, Gainesville, Florida
| | - Ummat Somjee
- Entomology and Nematology Department, University of Florida, Gainesville, Florida.,Smithsonian Tropical Research Institute, Balboa, Ancon, Panama
| | | | - Russell T Hepple
- Department of Physical Therapy, University of Florida, Gainesville, Florida
| | - Christine W Miller
- Entomology and Nematology Department, University of Florida, Gainesville, Florida
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16
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Patlar B, Ramm SA. Genotype‐by‐environment interactions for seminal fluid expression and sperm competitive ability. J Evol Biol 2019; 33:225-236. [DOI: 10.1111/jeb.13568] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 10/25/2019] [Accepted: 11/06/2019] [Indexed: 12/01/2022]
Affiliation(s)
- Bahar Patlar
- Evolutionary Biology Bielefeld University Bielefeld Germany
| | - Steven A. Ramm
- Evolutionary Biology Bielefeld University Bielefeld Germany
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17
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Kustra MC, Kahrl AF, Reedy AM, Warner DA, Cox RM. Sperm morphology and count vary with fine-scale changes in local density in a wild lizard population. Oecologia 2019; 191:555-564. [PMID: 31624957 PMCID: PMC6825022 DOI: 10.1007/s00442-019-04511-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Accepted: 09/10/2019] [Indexed: 10/30/2022]
Abstract
Given that sperm production can be costly, theory predicts that males should optimally adjust the quantity and/or quality of their sperm in response to their social environment to maximize their paternity success. Although experiments demonstrate that males can alter their ejaculates in response to manipulations of the social environment and studies show that ejaculate traits covary with social environment across populations, it is unknown whether individual variation in sperm traits corresponds to natural variation found within wild populations. Using an island population of brown anole lizards (Anolis sagrei), we tested the prediction that sperm traits (sperm count, sperm morphology, sperm velocity) respond to natural variation in the risk of sperm competition, as inferred from the local density and operational sex ratio (OSR) of conspecifics. We found that males living in high-density areas of the island produced relatively larger sperm midpieces, smaller sperm heads, and lower sperm counts. Sperm traits were unrelated to OSR after accounting for the covariance between OSR and density. Our findings broaden the implications of sperm competition theory to intrapopulation social environment variation by showing that sperm count and sperm morphology vary with fine-scale differences in density within a single wild population.
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Affiliation(s)
- Matthew C Kustra
- Department of Biology, University of Virginia, Charlottesville, VA, 22904, USA.,Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, CA, 95064, USA
| | - Ariel F Kahrl
- Department of Biology, University of Virginia, Charlottesville, VA, 22904, USA. .,Stockholm University, Zoologiska institutionen: Etologi, 106 91, Stockholm, Sweden.
| | - Aaron M Reedy
- Department of Biology, University of Virginia, Charlottesville, VA, 22904, USA.,Department of Biological Sciences, Auburn University, Auburn, AL, 36849, USA
| | - Daniel A Warner
- Department of Biological Sciences, Auburn University, Auburn, AL, 36849, USA
| | - Robert M Cox
- Department of Biology, University of Virginia, Charlottesville, VA, 22904, USA
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18
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Vasudeva R, Sutter A, Sales K, Dickinson ME, Lumley AJ, Gage MJG. Adaptive thermal plasticity enhances sperm and egg performance in a model insect. eLife 2019; 8:e49452. [PMID: 31570120 PMCID: PMC6773439 DOI: 10.7554/elife.49452] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Accepted: 09/13/2019] [Indexed: 12/16/2022] Open
Abstract
Rising and more variable global temperatures pose a challenge for biodiversity, with reproduction and fertility being especially sensitive to heat. Here, we assessed the potential for thermal adaptation in sperm and egg function using Tribolium flour beetles, a warm-temperate-tropical insect model. Following temperature increases through adult development, we found opposing gamete responses, with males producing shorter sperm and females laying larger eggs. Importantly, this gamete phenotypic plasticity was adaptive: thermal translocation experiments showed that both sperm and eggs produced in warmer conditions had superior reproductive performance in warmer environments, and vice versa for cooler production conditions and reproductive environments. In warmer environments, gamete plasticity enabled males to double their reproductive success, and females could increase offspring production by one-third. Our results reveal exciting potential for sensitive but vital traits within reproduction to handle increasing and more variable thermal regimes in the natural environment.
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Affiliation(s)
| | - Andreas Sutter
- School of Biological SciencesUniversity of East AngliaNorwichUnited Kingdom
| | - Kris Sales
- School of Biological SciencesUniversity of East AngliaNorwichUnited Kingdom
| | | | - Alyson J Lumley
- School of Biological SciencesUniversity of East AngliaNorwichUnited Kingdom
| | - Matthew JG Gage
- School of Biological SciencesUniversity of East AngliaNorwichUnited Kingdom
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Ramm SA, Lengerer B, Arbore R, Pjeta R, Wunderer J, Giannakara A, Berezikov E, Ladurner P, Schärer L. Sex allocation plasticity on a transcriptome scale: Socially sensitive gene expression in a simultaneous hermaphrodite. Mol Ecol 2019; 28:2321-2341. [PMID: 30891857 DOI: 10.1111/mec.15077] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Revised: 03/04/2019] [Accepted: 03/11/2019] [Indexed: 12/11/2022]
Abstract
Phenotypic plasticity can enable organisms to produce optimal phenotypes in multiple environments. A crucial life history trait that is often highly plastic is sex allocation, which in simultaneous hermaphrodites describes the relative investment into the male versus female sex functions. Theory predicts-and morphological evidence supports-that greater investment into the male function is favoured with increasing group size, due to the increasing importance of sperm competition for male reproductive success. Here, we performed a genome-wide gene expression assay to test for such sex allocation plasticity in a model simultaneous hermaphrodite, the free-living flatworm Macrostomum lignano. Based on RNA-Seq data from 16 biological replicates spanning four different group size treatments, we demonstrate that at least 10% of the >75,000 investigated transcripts in M. lignano are differentially expressed according to the social environment, rising to >30% of putative gonad-specific transcripts (spermatogenesis and oogenesis candidates) and tail-specific transcripts (seminal fluid candidates). This transcriptional response closely corresponds to the expected shift away from female and towards male reproductive investment with increasing sperm competition level. Using whole-mount in situ hybridization, we then confirm that many plastic transcripts exhibit the expected organ-specific expression, and RNA interference of selected testis- and ovary-specific candidates establishes that these indeed function in gametogenesis pathways. We conclude that a large proportion of sex-specific transcripts in M. lignano are differentially expressed according to the prevailing ecological conditions and that these are functionally relevant to key reproductive phenotypes. Our study thus begins to bridge organismal and molecular perspectives on sex allocation plasticity.
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Affiliation(s)
- Steven A Ramm
- Evolutionary Biology, Bielefeld University, Bielefeld, Germany.,Evolutionary Biology, Zoological Institute, University of Basel, Basel, Switzerland
| | - Birgit Lengerer
- Institute of Zoology & CMBI, University of Innsbruck, Innsbruck, Austria
| | - Roberto Arbore
- Evolutionary Biology, Zoological Institute, University of Basel, Basel, Switzerland
| | - Robert Pjeta
- Institute of Zoology & CMBI, University of Innsbruck, Innsbruck, Austria
| | - Julia Wunderer
- Institute of Zoology & CMBI, University of Innsbruck, Innsbruck, Austria
| | | | - Eugene Berezikov
- ERIBA, University Medical Center Groningen, Groningen, The Netherlands
| | - Peter Ladurner
- Institute of Zoology & CMBI, University of Innsbruck, Innsbruck, Austria
| | - Lukas Schärer
- Evolutionary Biology, Bielefeld University, Bielefeld, Germany
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20
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Patlar B, Weber M, Ramm SA. Genetic and environmental variation in transcriptional expression of seminal fluid proteins. Heredity (Edinb) 2019; 122:595-611. [PMID: 30356222 PMCID: PMC6461930 DOI: 10.1038/s41437-018-0160-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Revised: 08/29/2018] [Accepted: 09/18/2018] [Indexed: 12/31/2022] Open
Abstract
Seminal fluid proteins (SFPs) are crucial mediators of sexual selection and sexual conflict. Recent studies have chiefly focused on environmentally induced plasticity as one source of variation in SFP expression, particularly in response to differing sperm competition levels. However, understanding the evolution of a trait in heterogenous environments requires estimates of both environmental and genetic sources of variation, as well as their interaction. Therefore, we investigated how environment (specifically mating group size, a good predictor of sperm competition intensity), genotype and genotype-by-environment interactions affect seminal fluid expression. To do so, we reared 12 inbred lines of a simultaneously hermaphroditic flatworm Macrostomum lignano in groups of either two or eight worms and measured the expression levels of 58 putative SFP transcripts. We then examined the source of variation in the expression of each transcript individually and for multivariate axes extracted from a principal component analysis. We found that mating group size did not affect expression levels according to the single transcript analyses, nor did it affect the first principal component (presumably representing overall investment in seminal fluid production). However, mating group size did affect the relative expression of different transcripts captured by the second principal component (presumably reflecting variation in seminal fluid composition). Most transcripts were genetically variable in their expression level and several exhibited genotype-by-environment interactions; relative composition also showed high genetic variation. Collectively, our results reveal the tightly integrated nature of the seminal fluid transcriptome and provide new insights into the quantitative genetic basis of seminal fluid investment and composition.
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Affiliation(s)
- Bahar Patlar
- Evolutionary Biology, Bielefeld University, Bielefeld, Germany.
| | - Michael Weber
- Evolutionary Biology, Bielefeld University, Bielefeld, Germany
| | - Steven A Ramm
- Evolutionary Biology, Bielefeld University, Bielefeld, Germany
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21
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Mouton S, Wudarski J, Grudniewska M, Berezikov E. The regenerative flatworm Macrostomum lignano, a model organism with high experimental potential. THE INTERNATIONAL JOURNAL OF DEVELOPMENTAL BIOLOGY 2019; 62:551-558. [PMID: 29938766 DOI: 10.1387/ijdb.180077eb] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Understanding the process of regeneration has been one of the longstanding scientific aims, from a fundamental biological perspective, as well as within the applied context of regenerative medicine. Because regeneration competence varies greatly between organisms, it is essential to investigate different experimental animals. The free-living marine flatworm Macrostomum lignano is a rising model organism for this type of research, and its power stems from a unique set of biological properties combined with amenability to experimental manipulation. The biological properties of interest include production of single-cell fertilized eggs, a transparent body, small size, short generation time, ease of culture, the presence of a pluripotent stem cell population, and a large regeneration competence. These features sparked the development of molecular tools and resources for this animal, including high-quality genome and transcriptome assemblies, gene knockdown, in situ hybridization, and transgenesis. Importantly, M. lignano is currently the only flatworm species for which transgenesis methods are established. This review summarizes biological features of M. lignano and recent technological advances towards experimentation with this animal. In addition, we discuss the experimental potential of this model organism for different research questions related to regeneration and stem cell biology.
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Affiliation(s)
- Stijn Mouton
- European Research Institute for the Biology of Ageing, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
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Firman RC, Garcia‐Gonzalez F, Simmons LW, André GI. A competitive environment influences sperm production, but not testes tissue composition, in house mice. J Evol Biol 2018; 31:1647-1654. [DOI: 10.1111/jeb.13360] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Revised: 07/26/2018] [Accepted: 07/28/2018] [Indexed: 12/30/2022]
Affiliation(s)
- Renée C. Firman
- Centre for Evolutionary Biology School of Biological Sciences (M092) The University of Western Australia Crawley WA Australia
| | - Francisco Garcia‐Gonzalez
- Centre for Evolutionary Biology School of Biological Sciences (M092) The University of Western Australia Crawley WA Australia
- Estacion Biológica de Doñana CSIC Sevilla Spain
| | - Leigh W. Simmons
- Centre for Evolutionary Biology School of Biological Sciences (M092) The University of Western Australia Crawley WA Australia
| | - Gonçalo I. André
- Centre for Evolutionary Biology School of Biological Sciences (M092) The University of Western Australia Crawley WA Australia
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23
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Vellnow N, Marie-Orleach L, Zadesenets KS, Schärer L. Bigger testes increase paternity in a simultaneous hermaphrodite, independently of the sperm competition level. J Evol Biol 2017; 31:180-196. [DOI: 10.1111/jeb.13212] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 10/31/2017] [Accepted: 11/14/2017] [Indexed: 12/12/2022]
Affiliation(s)
- N. Vellnow
- Zoological Institute, Evolutionary Biology; University of Basel; Basel Switzerland
| | | | | | - L. Schärer
- Zoological Institute, Evolutionary Biology; University of Basel; Basel Switzerland
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Giannakara A, Ramm SA. Self-fertilization, sex allocation and spermatogenesis kinetics in the hypodermically inseminating flatworm Macrostomum pusillum. ACTA ACUST UNITED AC 2017; 220:1568-1577. [PMID: 28183866 DOI: 10.1242/jeb.149682] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Accepted: 02/03/2017] [Indexed: 01/15/2023]
Abstract
The free-living flatworm genus Macrostomum is an emerging model system for studying the links between sex allocation, sexual selection and mating system evolution, as well as the underlying developmental and physiological mechanisms responsible for wide intra- and inter-specific variability in reproductive phenotypes. Despite compelling comparative morphological evidence of sexual diversity, detailed experimental work on reproductive behaviour and physiology in Macrostomum has so far been largely limited to just two species, M. lignano and M. hystrix, an obligate and a preferential outcrosser, respectively. In this study, we establish that a third species, M. pusillum, exhibits a combination of reproductive traits strikingly different from both of its congeners. Unlike M. lignano, we demonstrate that M. pusillum does not adjust sex allocation or the speed of spermatogenesis to the prevailing social group size. Macrostomumpusillum's relatively simple sperm morphology likely explains the short spermatogenesis duration we report, and is linked to a hypodermically inseminating mode of fertilization, which we show also means that these worms are capable of self-fertilization. Surprisingly, and unlike M. hystrix, selfing in isolated worms commences after only a short (if any) delay compared with the onset of reproduction in grouped individuals, with little evidence of differential inbreeding depression in 'isolated' progeny. These combined results suggest that, in nature, M. pusillum may be regularly selfing, in contrast to the congeners studied to date. Our findings highlight the rapid and correlated evolution of reproductive traits, and reinforce the utility of the genus Macrostomum for understanding the evolutionary and developmental mechanisms responsible for this diversity.
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Affiliation(s)
- Athina Giannakara
- Evolutionary Biology, Bielefeld University, Morgenbreede 45, Bielefeld 33615, Germany
| | - Steven A Ramm
- Evolutionary Biology, Bielefeld University, Morgenbreede 45, Bielefeld 33615, Germany
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