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Gómez RA, Maddison DR. Novelty and emergent patterns in sperm: Morphological diversity and evolution of spermatozoa and sperm conjugation in ground beetles (Coleoptera: Carabidae). J Morphol 2020; 281:862-892. [PMID: 32557896 DOI: 10.1002/jmor.21144] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 04/30/2020] [Accepted: 05/03/2020] [Indexed: 12/15/2022]
Abstract
The beetle family Carabidae, with about 40,000 species, exhibits enough diversity in sperm structure and behavior to be an excellent model system for studying patterns and processes of evolution. We explore their potential, documenting sperm form in 177 species of ground beetles using light microscopy and collecting data on one qualitative and seven quantitative phenotypic traits. Our sampling captures 61% of the tribal-level diversity of ground beetles. These data highlight the notable morphological diversity of sperm in ground beetles and suggest that sperm in the group have dynamic evolutionary histories with much morphological innovation and convergence. Sperm vary among species in total length (48-3,400 μm), head length (0.5-270 μm), and head width (0.2-6.3 μm). Most ground beetles make sperm with heads that are indistinct from the flagella at the gross morphological level. However, some or all Omophron, Trachypachus, and Dyschiriini make broad-headed sperm that show morphological differences between species. Most ground beetles package their sperm into groups of sperm, termed conjugates, and ground beetles show variation in conjugate form and in the number and arrangement of sperm in a conjugate. Most ground beetles make sperm conjugates by embedding their sperm in a hyaline rod or spermatostyle. The spermatostyle is remarkably variable among species and varies in length from 17 to 41,000 μm. Several unrelated groups of ground beetles make only singleton sperm, including Nebriinae, Cicindelinae, many Trechinae, and the tribe Paussini. In order to study patterns in sperm evolution, we combine these data with a low-resolution phylogeny of ground beetles. Results from modern comparative analyses suggest the following: (a) sperm differ from conjugates in some aspect of their underlying evolutionary process, (b) sperm have influenced conjugate evolution and vice versa, and (c) conjugation with a spermatostyle likely evolved early within the history of Carabidae and it has been lost independently at least three times.
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Affiliation(s)
- R Antonio Gómez
- Department of Integrative Biology, Oregon State University, Corvallis, Oregon, USA
| | - David R Maddison
- Department of Integrative Biology, Oregon State University, Corvallis, Oregon, USA
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Mateos M, Martinez Montoya H, Lanzavecchia SB, Conte C, Guillén K, Morán-Aceves BM, Toledo J, Liedo P, Asimakis ED, Doudoumis V, Kyritsis GA, Papadopoulos NT, Augustinos AA, Segura DF, Tsiamis G. Wolbachia pipientis Associated With Tephritid Fruit Fly Pests: From Basic Research to Applications. Front Microbiol 2020; 11:1080. [PMID: 32582067 PMCID: PMC7283806 DOI: 10.3389/fmicb.2020.01080] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Accepted: 04/30/2020] [Indexed: 12/19/2022] Open
Abstract
Members of the true fruit flies (family Tephritidae) are among the most serious agricultural pests worldwide, whose control and management demands large and costly international efforts. The need for cost-effective and environmentally friendly integrated pest management (IPM) has led to the development and implementation of autocidal control strategies. These approaches include the widely used sterile insect technique and the incompatible insect technique (IIT). IIT relies on maternally transmitted bacteria (namely Wolbachia) to cause a conditional sterility in crosses between released mass-reared Wolbachia-infected males and wild females, which are either uninfected or infected with a different Wolbachia strain (i.e., cytoplasmic incompatibility; CI). Herein, we review the current state of knowledge on Wolbachia-tephritid interactions including infection prevalence in wild populations, phenotypic consequences, and their impact on life history traits. Numerous pest tephritid species are reported to harbor Wolbachia infections, with a subset exhibiting high prevalence. The phenotypic effects of Wolbachia have been assessed in very few tephritid species, due in part to the difficulty of manipulating Wolbachia infection (removal or transinfection). Based on recent methodological advances (high-throughput DNA sequencing) and breakthroughs concerning the mechanistic basis of CI, we suggest research avenues that could accelerate generation of necessary knowledge for the potential use of Wolbachia-based IIT in area-wide integrated pest management (AW-IPM) strategies for the population control of tephritid pests.
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Affiliation(s)
- Mariana Mateos
- Departments of Ecology and Conservation Biology, and Wildlife and Fisheries Sciences, Texas A&M University, College Station, TX, United States
| | - Humberto Martinez Montoya
- Laboratorio de Genética y Genómica Comparativa, Unidad Académica Multidisciplinaria Reynosa Aztlan, Universidad Autónoma de Tamaulipas, Ciudad Victoria, Mexico
| | - Silvia B Lanzavecchia
- Instituto de Genética 'Ewald A. Favret' - GV IABIMO (INTA-CONICET) Hurlingham, Buenos Aires, Argentina
| | - Claudia Conte
- Instituto de Genética 'Ewald A. Favret' - GV IABIMO (INTA-CONICET) Hurlingham, Buenos Aires, Argentina
| | | | | | - Jorge Toledo
- El Colegio de la Frontera Sur, Tapachula, Mexico
| | - Pablo Liedo
- El Colegio de la Frontera Sur, Tapachula, Mexico
| | - Elias D Asimakis
- Department of Environmental Engineering, University of Patras, Agrinio, Greece
| | - Vangelis Doudoumis
- Department of Environmental Engineering, University of Patras, Agrinio, Greece
| | - Georgios A Kyritsis
- Laboratory of Entomology and Agricultural Zoology, Department of Agriculture Crop Production and Rural Environment, University of Thessaly, Larissa, Greece
| | - Nikos T Papadopoulos
- Laboratory of Entomology and Agricultural Zoology, Department of Agriculture Crop Production and Rural Environment, University of Thessaly, Larissa, Greece
| | - Antonios A Augustinos
- Department of Plant Protection, Institute of Industrial and Forage Crops, Hellenic Agricultural Organization - DEMETER, Patras, Greece
| | - Diego F Segura
- Instituto de Genética 'Ewald A. Favret' - GV IABIMO (INTA-CONICET) Hurlingham, Buenos Aires, Argentina
| | - George Tsiamis
- Department of Environmental Engineering, University of Patras, Agrinio, Greece
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Omotoriogun TC, Albrecht T, Gohli J, Hořák D, Johannessen LE, Johnsen A, Kreisinger J, Marki PZ, Ottosson U, Rowe M, Sedláček O, Lifjeld JT. Sperm length variation among Afrotropical songbirds reflects phylogeny rather than adaptations to the tropical environment. ZOOLOGY 2020; 140:125770. [DOI: 10.1016/j.zool.2020.125770] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2019] [Revised: 03/07/2020] [Accepted: 03/09/2020] [Indexed: 10/24/2022]
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54
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Hook KA, Fisher HS. Methodological considerations for examining the relationship between sperm morphology and motility. Mol Reprod Dev 2020; 87:633-649. [PMID: 32415812 PMCID: PMC7329573 DOI: 10.1002/mrd.23346] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2020] [Revised: 04/10/2020] [Accepted: 04/21/2020] [Indexed: 12/12/2022]
Abstract
Sperm cells of all taxa share a common goal to reach and fertilize an ovum, yet sperm are one of the most diverse cell types in nature. While the structural diversity of these cells is well recognized, the functional significance of variation in sperm design remains elusive. An important function of spermatozoa is a need to migrate toward the ova, often over long distances in a foreign environment, which may include a complex and hostile female reproductive tract. Several comparative and experimental studies have attempted to address the link between sperm morphology and motility, yet the conclusions drawn from these studies are often inconsistent, even within the same taxa. Much of what we know about the functional significance of sperm design in internally fertilizing species has been gleaned from in vitro studies, for which experimental parameters often vary among studies. We propose that discordant results from these studies are in part due to a lack of consistency of methods, conditions that do not replicate those of the female reproductive tract, and the overuse of simple linear measures of sperm shape. Within this review, we provide a toolkit for imaging, quantifying, and analyzing sperm morphology and movement patterns for in vitro studies and discuss emerging approaches. Results from studies linking morphology to motility enhance our understanding of the evolution of adaptive sperm traits and the mechanisms that regulate fertility, thus offering new insights into methods used in assisted reproductive technologies in animal science, conservation and public health.
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Affiliation(s)
- Kristin A. Hook
- Department of Biology, University of Maryland, College Park, U.S.A
| | - Heidi S. Fisher
- Department of Biology, University of Maryland, College Park, U.S.A
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55
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Friedman DA, Johnson BR, Linksvayer TA. Distributed physiology and the molecular basis of social life in eusocial insects. Horm Behav 2020; 122:104757. [PMID: 32305342 DOI: 10.1016/j.yhbeh.2020.104757] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 03/30/2020] [Accepted: 04/06/2020] [Indexed: 12/24/2022]
Abstract
The traditional focus of physiological and functional genomic research is on molecular processes that play out within a single multicellular organism. In the colonial (eusocial) insects such as ants, bees, and termites, molecular and behavioral responses of interacting nestmates are tightly linked, and key physiological processes are regulated at the scale of the colony. Such colony-level physiological processes regulate nestmate physiology in a distributed fashion, through various social communication mechanisms. As a result of physiological decentralization over evolutionary time, organismal mechanisms, for example related to pheromone detection, hormone signaling, and neural signaling pathways, are deployed in novel contexts to influence nestmate and colony traits. Here we explore how functional genomic, physiological, and behavioral studies can benefit from considering the traits of eusocial insects in this light. We highlight functional genomic work exploring how nestmate-level and colony-level traits arise and are influenced by interactions among physiologically-specialized nestmates of various developmental stages. We also consider similarities and differences between nestmate-level (organismal) and colony-level (superorganismal) physiological processes, and make specific hypotheses regarding the physiology of eusocial taxa. Integrating theoretical models of distributed systems with empirical functional genomics approaches will be useful in addressing fundamental questions related to the evolution of eusociality and collective behavior in natural systems.
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Affiliation(s)
- D A Friedman
- University of California, Davis, Department of Entomology, Davis, CA 95616, United States of America.
| | - B R Johnson
- University of California, Davis, Department of Entomology, Davis, CA 95616, United States of America
| | - T A Linksvayer
- University of Pennsylvania, Department of Biology, Pennsylvania, PA 19104, United States of America
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56
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Paoli F, Mercati D, Marianelli L, Roversi PF, Lupetti P, Dallai R. Sperm ultrastructure and spermatogenesis in the Japanese beetle Popillia japonica (Coleoptera, Scarabaeidae). Micron 2020; 135:102879. [PMID: 32416441 DOI: 10.1016/j.micron.2020.102879] [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: 03/06/2020] [Revised: 04/27/2020] [Accepted: 04/27/2020] [Indexed: 10/24/2022]
Abstract
Popillia japonica is an invasive scarab beetle native to Japan that in 1916 invaded New Jersey in USA. From that moment onwards, the insect has spread invading several US states, Canada, the Azores, Italy and, recently, Switzerland. It is a severe agricultural pest included in the EU priority pest list being able to feed on more than 300 plant species and having an important biotic potential. The general morphology of the reproductive apparatus shows paired testes, each of them having six testicular lobes grouped in threes. From the ventral part of each testicular lobe, each containing about 20 follicles, an efferent vessel originates that fuses with the other efferent vessels to form the deferent duct. A pair of long tubular accessory glands is present. The deferent ducts and accessory glands fuse together into an ejaculatory duct before entering the aedeagus. The sperm is a typical pterygote sperm, 110 μm long, composed of a head and a tail. In the head a three-layered acrosome of about 6 μm in length and a nucleus of about 18 μm long are present. During sperm maturation two C-shaped structures appear in the cytoplasm from the opposite sides of the nucleus that then disappear in late spermatids. In the tail a typical 9 + 9 + 2 flagellar axoneme and two mitochondrial derivatives are present. Moreover, in the head-tail transition region the centriolar adjunct forms a sheath from which three elongated accessory bodies originate. Two of these accessory bodies are placed alongside the axoneme, whilst the third one is placed beneath the mitochondrial derivatives. Mature sperm are grouped in cysts containing about 256 sperm cells. A morphological comparison with related species is provided.
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Affiliation(s)
- F Paoli
- CREA Research Centre for Plant Protection and Certification, via di Lanciola 12/a, 50125 Firenze, Italy.
| | - D Mercati
- Department of Life Sciences, University of Siena, via Aldo Moro 2, 53100 Siena, Italy.
| | - L Marianelli
- CREA Research Centre for Plant Protection and Certification, via di Lanciola 12/a, 50125 Firenze, Italy.
| | - P F Roversi
- CREA Research Centre for Plant Protection and Certification, via di Lanciola 12/a, 50125 Firenze, Italy.
| | - P Lupetti
- Department of Life Sciences, University of Siena, via Aldo Moro 2, 53100 Siena, Italy.
| | - R Dallai
- Department of Life Sciences, University of Siena, via Aldo Moro 2, 53100 Siena, Italy.
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57
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Pitnick S, Wolfner MF, Dorus S. Post-ejaculatory modifications to sperm (PEMS). Biol Rev Camb Philos Soc 2020; 95:365-392. [PMID: 31737992 PMCID: PMC7643048 DOI: 10.1111/brv.12569] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2019] [Revised: 10/12/2019] [Accepted: 10/16/2019] [Indexed: 12/15/2022]
Abstract
Mammalian sperm must spend a minimum period of time within a female reproductive tract to achieve the capacity to fertilize oocytes. This phenomenon, termed sperm 'capacitation', was discovered nearly seven decades ago and opened a window into the complexities of sperm-female interaction. Capacitation is most commonly used to refer to a specific combination of processes that are believed to be widespread in mammals and includes modifications to the sperm plasma membrane, elevation of intracellular cyclic AMP levels, induction of protein tyrosine phosphorylation, increased intracellular Ca2+ levels, hyperactivation of motility, and, eventually, the acrosome reaction. Capacitation is only one example of post-ejaculatory modifications to sperm (PEMS) that are widespread throughout the animal kingdom. Although PEMS are less well studied in non-mammalian taxa, they likely represent the rule rather than the exception in species with internal fertilization. These PEMS are diverse in form and collectively represent the outcome of selection fashioning complex maturational trajectories of sperm that include multiple, sequential phenotypes that are specialized for stage-specific functionality within the female. In many cases, PEMS are critical for sperm to migrate successfully through the female reproductive tract, survive a protracted period of storage, reach the site of fertilization and/or achieve the capacity to fertilize eggs. We predict that PEMS will exhibit widespread phenotypic plasticity mediated by sperm-female interactions. The successful execution of PEMS thus has important implications for variation in fitness and the operation of post-copulatory sexual selection. Furthermore, it may provide a widespread mechanism of reproductive isolation and the maintenance of species boundaries. Despite their possible ubiquity and importance, the investigation of PEMS has been largely descriptive, lacking any phylogenetic consideration with regard to divergence, and there have been no theoretical or empirical investigations of their evolutionary significance. Here, we (i) clarify PEMS-related nomenclature; (ii) address the evolutionary origin, maintenance and divergence in PEMS in the context of the protracted life history of sperm and the complex, selective environment of the female reproductive tract; (iii) describe taxonomically widespread types of PEMS: sperm activation, chemotaxis and the dissociation of sperm conjugates; (iv) review the occurence of PEMS throughout the animal kingdom; (v) consider alternative hypotheses for the adaptive value of PEMS; (vi) speculate on the evolutionary implications of PEMS for genomic architecture, sexual selection, and reproductive isolation; and (vii) suggest fruitful directions for future functional and evolutionary analyses of PEMS.
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Affiliation(s)
- Scott Pitnick
- Department of Biology, Center for Reproductive Evolution, Syacuse University, Syracuse, NY 13244, USA
| | - Mariana F. Wolfner
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
| | - Steve Dorus
- Department of Biology, Center for Reproductive Evolution, Syacuse University, Syracuse, NY 13244, USA
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58
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Hadlow JH, Evans JP, Lymbery RA. Egg-induced changes to sperm phenotypes shape patterns of multivariate selection on ejaculates. J Evol Biol 2020; 33:797-807. [PMID: 32125748 DOI: 10.1111/jeb.13611] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 02/17/2020] [Accepted: 02/24/2020] [Indexed: 12/22/2022]
Abstract
Sperm cells exhibit extraordinary phenotypic diversity and rapid rates of evolution, yet the adaptive value of most sperm traits remains equivocal. Recent findings suggest that to understand how selection targets ejaculates, we must recognize that female-imposed physiological conditions often alter sperm phenotypes. These phenotypic changes may influence the relationships among sperm traits and their association with fitness. Here, we show that chemical substances released by eggs (known to modify sperm physiology and behaviour) alter patterns of selection on a suite of sperm traits in the mussel Mytilus galloprovincialis. We use multivariate selection analyses to characterize linear and nonlinear selection acting on sperm traits in (a) seawater alone and (b) seawater containing egg-derived chemicals (egg water). Our analyses revealed that nonlinear selection on canonical axes of multiple traits (notably sperm velocity, sperm linearity and percentage of motile sperm) was the most important form of selection overall, but importantly these patterns were only evident when sperm phenotypes were measured in egg water. These findings reveal the subtle way that females can alter patterns of selection, with the implication that overlooking environmentally moderated changes to sperm, may result in erroneous interpretations of how selection targets phenotypic (co)variation in sperm traits.
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Affiliation(s)
- Jessica H Hadlow
- Centre for Evolutionary Biology, School of Biological Sciences, University of Western Australia, Crawley, WA, Australia
| | - Jonathan P Evans
- Centre for Evolutionary Biology, School of Biological Sciences, University of Western Australia, Crawley, WA, Australia
| | - Rowan A Lymbery
- Centre for Evolutionary Biology, School of Biological Sciences, University of Western Australia, Crawley, WA, Australia
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59
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Tomáška Ľ, Nosek J. Co-evolution in the Jungle: From Leafcutter Ant Colonies to Chromosomal Ends. J Mol Evol 2020; 88:293-318. [PMID: 32157325 DOI: 10.1007/s00239-020-09935-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 02/25/2020] [Indexed: 02/06/2023]
Abstract
Biological entities are multicomponent systems where each part is directly or indirectly dependent on the others. In effect, a change in a single component might have a consequence on the functioning of its partners, thus affecting the fitness of the entire system. In this article, we provide a few examples of such complex biological systems, ranging from ant colonies to a population of amino acids within a single-polypeptide chain. Based on these examples, we discuss one of the central and still challenging questions in biology: how do such multicomponent consortia co-evolve? More specifically, we ask how telomeres, nucleo-protein complexes protecting the integrity of linear DNA chromosomes, originated from the ancestral organisms having circular genomes and thus not dealing with end-replication and end-protection problems. Using the examples of rapidly evolving topologies of mitochondrial genomes in eukaryotic microorganisms, we show what means of co-evolution were employed to accommodate various types of telomere-maintenance mechanisms in mitochondria. We also describe an unprecedented runaway evolution of telomeric repeats in nuclei of ascomycetous yeasts accompanied by co-evolution of telomere-associated proteins. We propose several scenarios derived from research on telomeres and supported by other studies from various fields of biology, while emphasizing that the relevant answers are still not in sight. It is this uncertainty and a lack of a detailed roadmap that makes the journey through the jungle of biological systems still exciting and worth undertaking.
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Affiliation(s)
- Ľubomír Tomáška
- Department of Genetics, Faculty of Natural Sciences, Comenius University in Bratislava, Ilkovičova 6, 842 15, Bratislava, Slovakia.
| | - Jozef Nosek
- Department of Biochemistry, Faculty of Natural Sciences, Comenius University in Bratislava, Ilkovičova 6, 842 15, Bratislava, Slovakia
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60
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Hopkins BR, Sepil I, Wigby S. Structural variation in Drosophila melanogaster spermathecal ducts and its association with sperm competition dynamics. ROYAL SOCIETY OPEN SCIENCE 2020; 7:200130. [PMID: 32269825 PMCID: PMC7137968 DOI: 10.1098/rsos.200130] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Accepted: 02/27/2020] [Indexed: 06/11/2023]
Abstract
The ability of female insects to retain and use sperm for days, months, or even years after mating requires specialized storage organs in the reproductive tract. In most orders, these organs include a pair of sclerotized capsules known as spermathecae. Here, we report that some Drosophila melanogaster females exhibit previously uncharacterized structures within the distal portion of the muscular duct that links a spermatheca to the uterus. We find that these 'spermathecal duct presences' (SDPs) may form in either or both ducts and can extend from the duct into the sperm-storing capsule itself. We further find that the incidence of SDPs varies significantly between genotypes, but does not change significantly with the age or mating status of females, the latter indicating that SDPs are not composed of or stimulated by sperm or male seminal proteins. We show that SDPs affect neither the number of first male sperm held in a spermatheca nor the number of offspring produced after a single mating. However, we find evidence that SDPs are associated with a lack of second male sperm in the spermathecae after females remate. This raises the possibility that SDPs provide a mechanism for variation in sperm competition outcome among females.
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Affiliation(s)
- Ben R. Hopkins
- Department of Zoology, University of Oxford, Oxford OX1 3SZ, UK
- Department of Evolution and Ecology, University of California – Davis, One Shields Ave., Davis, CA 95616, USA
| | - Irem Sepil
- Department of Zoology, University of Oxford, Oxford OX1 3SZ, UK
| | - Stuart Wigby
- Department of Zoology, University of Oxford, Oxford OX1 3SZ, UK
- Faculty Biology, Applied Zoology, Technische Universität Dresden, 01069 Dresden, Germany
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61
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Horn M, Mitesser O, Hovestadt T, Yoshii T, Rieger D, Helfrich-Förster C. The Circadian Clock Improves Fitness in the Fruit Fly, Drosophila melanogaster. Front Physiol 2019; 10:1374. [PMID: 31736790 PMCID: PMC6838225 DOI: 10.3389/fphys.2019.01374] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2019] [Accepted: 10/17/2019] [Indexed: 12/17/2022] Open
Abstract
It is assumed that a properly timed circadian clock enhances fitness, but only few studies have truly demonstrated this in animals. We raised each of the three classical Drosophila period mutants for >50 generations in the laboratory in competition with wildtype flies. The populations were either kept under a conventional 24-h day or under cycles that matched the mutant’s natural cycle, i.e., a 19-h day in the case of pers mutants and a 29-h day for perl mutants. The arrhythmic per0 mutants were grown together with wildtype flies under constant light that renders wildtype flies similar arrhythmic as the mutants. In addition, the mutants had to compete with wildtype flies for two summers in two consecutive years under outdoor conditions. We found that wildtype flies quickly outcompeted the mutant flies under the 24-h laboratory day and under outdoor conditions, but perl mutants persisted and even outnumbered the wildtype flies under the 29-h day in the laboratory. In contrast, pers and per0 mutants did not win against wildtype flies under the 19-h day and constant light, respectively. Our results demonstrate that wildtype flies have a clear fitness advantage in terms of fertility and offspring survival over the period mutants and – as revealed for perl mutants – this advantage appears maximal when the endogenous period resonates with the period of the environment. However, the experiments indicate that perl and pers persist at low frequencies in the population even under the 24-h day. This may be a consequence of a certain mating preference of wildtype and heterozygous females for mutant males and time differences in activity patterns between wildtype and mutants.
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Affiliation(s)
- Melanie Horn
- Neurobiology and Genetics, Theodor-Boveri Institute, Biocenter, Julius-Maximilians University Würzburg, Würzburg, Germany
| | - Oliver Mitesser
- Theoretical Evolutionary Ecology Group, Biocenter, Department of Animal Ecology and Tropical Biology, Julius-Maximilians University Würzburg, Würzburg, Germany
| | - Thomas Hovestadt
- Theoretical Evolutionary Ecology Group, Biocenter, Department of Animal Ecology and Tropical Biology, Julius-Maximilians University Würzburg, Würzburg, Germany
| | - Taishi Yoshii
- Graduate School of Natural Science and Technology, Okayama University, Okayama, Japan
| | - Dirk Rieger
- Neurobiology and Genetics, Theodor-Boveri Institute, Biocenter, Julius-Maximilians University Würzburg, Würzburg, Germany
| | - Charlotte Helfrich-Förster
- Neurobiology and Genetics, Theodor-Boveri Institute, Biocenter, Julius-Maximilians University Würzburg, Würzburg, Germany
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62
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Zajitschek S, Zajitschek F, Josway S, Al Shabeeb R, Weiner H, Manier MK. Costs and benefits of giant sperm and sperm storage organs in
Drosophila melanogaster. J Evol Biol 2019; 32:1300-1309. [DOI: 10.1111/jeb.13529] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Revised: 08/06/2019] [Accepted: 08/22/2019] [Indexed: 11/28/2022]
Affiliation(s)
- Susanne Zajitschek
- Department of Biological Sciences George Washington University Washington DC USA
- School of Biological, Earth and Environmental Sciences University of New South Wales Sydney NSW Australia
| | - Felix Zajitschek
- Department of Biological Sciences George Washington University Washington DC USA
- School of Biological, Earth and Environmental Sciences University of New South Wales Sydney NSW Australia
| | - Sarah Josway
- Department of Biological Sciences George Washington University Washington DC USA
| | - Reem Al Shabeeb
- Department of Biological Sciences George Washington University Washington DC USA
| | - Halli Weiner
- Department of Biological Sciences George Washington University Washington DC USA
| | - Mollie K. Manier
- Department of Biological Sciences George Washington University Washington DC USA
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63
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Civetta A, Ranz JM. Genetic Factors Influencing Sperm Competition. Front Genet 2019; 10:820. [PMID: 31572439 PMCID: PMC6753916 DOI: 10.3389/fgene.2019.00820] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Accepted: 08/08/2019] [Indexed: 12/26/2022] Open
Abstract
Females of many different species often mate with multiple males, creating opportunities for competition among their sperm. Although originally unappreciated, sperm competition is now considered a central form of post-copulatory male–male competition that biases fertilization. Assays of differences in sperm competitive ability between males, and interactions between females and males, have made it possible to infer some of the main mechanisms of sperm competition. Nevertheless, classical genetic approaches have encountered difficulties in identifying loci influencing sperm competitiveness while functional and comparative genomic methodologies, as well as genetic variant association studies, have uncovered some interesting candidate genes. We highlight how the systematic implementation of approaches that incorporate gene perturbation assays in experimental competitive settings, together with the monitoring of progeny output or sperm features and behavior, has allowed the identification of genes unambiguously linked to sperm competitiveness. The emerging portrait from 45 genes (33 from fruit flies, 8 from rodents, 2 from nematodes, and 2 from ants) is their remarkable breadth of biological roles exerted through males and females, the non-preponderance of sperm genes, and their overall pleiotropic nature.
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Affiliation(s)
- Alberto Civetta
- Department of Biology, University of Winnipeg, Winnipeg, MB, Canada
| | - José M Ranz
- Department of Ecology and Evolutionary Biology, University of California, Irvine, CA, United States
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64
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Rowley A, Locatello L, Kahrl A, Rego M, Boussard A, Garza-Gisholt E, Kempster RM, Collin SP, Giacomello E, Follesa MC, Porcu C, Evans JP, Hazin F, Garcia-Gonzalez F, Daly-Engel T, Mazzoldi C, Fitzpatrick JL. Sexual selection and the evolution of sperm morphology in sharks. J Evol Biol 2019; 32:1027-1035. [PMID: 31250483 DOI: 10.1111/jeb.13501] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 06/16/2019] [Accepted: 06/22/2019] [Indexed: 01/18/2023]
Abstract
Post-copulatory sexual selection, and sperm competition in particular, is a powerful selective force shaping the evolution of sperm morphology. Although mounting evidence suggests that post-copulatory sexual selection influences the evolution of sperm morphology among species, recent evidence also suggests that sperm competition influences variation in sperm morphology at the intraspecific level. However, contradictory empirical results and limited taxonomic scope have led to difficulty in assessing the generality of sperm morphological responses to variation in the strength of sperm competition. Here, we use phylogenetically controlled analyses to explore the effects of sperm competition on sperm morphology and variance in sharks, a basal vertebrate group characterized by wide variation in rates of multiple mating by females, and consequently sperm competition risk. Our analyses reveal that shark species experiencing greater levels of sperm competition produce sperm with longer flagella and that sperm flagellum length is less variable in species under higher sperm competition risk. In contrast, neither the length of the sperm head and midpiece nor variation in sperm head and midpiece length was associated with sperm competition risk. Our findings demonstrate that selection influences both the inter- and intraspecific variation in sperm morphology and suggest that the flagellum is an important target of sexual selection in sharks. These findings provide important insight into patterns of selection on the ejaculate in a basal vertebrate lineage.
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Affiliation(s)
- Amy Rowley
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK.,Department of Zoology, Stockholm University, Stockholm, Sweden
| | - Lisa Locatello
- Department of Biology, University of Padova, Padua, Italy
| | - Ariel Kahrl
- Department of Zoology, Stockholm University, Stockholm, Sweden
| | - Mariana Rego
- Laboratório de Histologia Animal, Departamento de Morfologia e Fisiologia Animal, Universidade Federal Rural de Pernambuco, Recife, Brazil
| | - Annika Boussard
- Department of Zoology, Stockholm University, Stockholm, Sweden
| | - Eduardo Garza-Gisholt
- Oceans Graduate School, The University of Western Australia, Crawley, Western Australia, Australia.,The UWA Oceans Institute, The University of Western Australia, Crawley, Western Australia, Australia
| | - Ryan M Kempster
- Oceans Graduate School, The University of Western Australia, Crawley, Western Australia, Australia.,The UWA Oceans Institute, The University of Western Australia, Crawley, Western Australia, Australia
| | - Shaun P Collin
- Oceans Graduate School, The University of Western Australia, Crawley, Western Australia, Australia.,The UWA Oceans Institute, The University of Western Australia, Crawley, Western Australia, Australia.,School of Life Sciences, La Trobe University, Bundoora, Victoria, Australia
| | - Eva Giacomello
- MARE - Marine and Environmental Sciences Centre, IMAR- Institute of the Sea, OKEANOS Centre- University of the Azores, Horta, Portugal
| | - Maria C Follesa
- Department of Life and Environmental Sciences, University of Cagliari, Cagliari, Italy
| | - Cristina Porcu
- Department of Life and Environmental Sciences, University of Cagliari, Cagliari, Italy
| | - Jonathan P Evans
- Centre for Evolutionary Biology, School of Biological Sciences, University of Western Australia, Crawley, Western Australia, Australia
| | - Fabio Hazin
- Laboratório de Histologia Animal, Departamento de Morfologia e Fisiologia Animal, Universidade Federal Rural de Pernambuco, Recife, Brazil
| | - Francisco Garcia-Gonzalez
- Centre for Evolutionary Biology, School of Biological Sciences, University of Western Australia, Crawley, Western Australia, Australia.,Estacion Biologica de Doñana-CSIC, Sevilla, Spain
| | - Toby Daly-Engel
- Department of Ocean Engineering and Marine Sciences, Florida Institute of Technology, Melbourne, FL, USA
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65
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Turani B, Aliko V, Shkembi E. Characterization of Albanian water frog, Pelophylax shqipericus, sperm traits and morphology, by using phase contrast microscopy. Microsc Res Tech 2019; 82:1802-1809. [PMID: 31313452 DOI: 10.1002/jemt.23346] [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: 03/25/2019] [Revised: 05/28/2019] [Accepted: 06/13/2019] [Indexed: 11/10/2022]
Abstract
Mature spermatozoa traits and morphology of endangered Albanian water frog, Pelophylax shqipericus, have been characterized for the first time through phase contrast microscopy, as part of successful implementation of in vitro fertilization technique for this species. The basic morphology of P. shqipericus spermatozoa consists of an elongated, thick, smooth-edged, and solid-staining head, continuing with a thin and long tail which usually extends 2.48 times the head length. The acrosome was not clearly discernible so the measurements were done on the head as a whole, while the middle section was better visible. Average length of head, including the acrosome and midsection was estimated to be 11.78 μm ± 0.32, while the tail length resulted 29.24 ± 1.75 μm. The average thickness of the head was shown to be 3.45 μm. The total sperm length resulted to be 41.02 ± 1.83 μm. The average sperm concentration was estimated of 25.5 × 106 /ml. Sperm amount, survival rate and motility were also measured. The sperm survival rate was maximal immediately after preparation of the suspension and tended to decrease over time of storage, reaching 50% after 72 hr. Decreased sperm motility seemed to follow the same trend as sperm viability. Sperm traits resulted to be very similar both in size and in shape with those of "Lessonae" frog group, one of the lineages of Western Palearctic species complex, suggesting a strong phylogenetic relationship among these species.
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Affiliation(s)
- Blerta Turani
- University of Tirana, Faculty of Natural Sciences, Tirana, Albania
| | - Valbona Aliko
- University of Tirana, Faculty of Natural Sciences, Tirana, Albania
| | - Entela Shkembi
- Semiology Laboratory, Medical Center, Dani Andrology, Tirana, Albania
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66
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Fernandes Martins MJ. Adult sex-ratio in ostracods and its implications for sexual selection. INVERTEBR REPROD DEV 2019. [DOI: 10.1080/07924259.2019.1592789] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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67
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Støstad HN, Rowe M, Johnsen A, Lifjeld JT. Sperm head abnormalities are more frequent in songbirds with more helical sperm: A possible trade-off in sperm evolution. J Evol Biol 2019; 32:666-674. [PMID: 30945783 DOI: 10.1111/jeb.13446] [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: 10/11/2018] [Revised: 02/25/2019] [Accepted: 03/17/2019] [Indexed: 11/28/2022]
Abstract
Sperm morphology varies enormously across the animal kingdom. Whilst knowledge of the factors that drive the evolution of interspecific variation in sperm morphology is accumulating, we currently have little understanding of factors that may constrain evolutionary change in sperm traits. We investigated whether susceptibility to sperm abnormalities could represent such a constraint in songbirds, a group characterized by a distinctive helical sperm head shape. Specifically, using 36 songbird species and data from light and scanning electron microscopy, we examined among-species correlations between the occurrence of sperm head abnormalities and sperm morphology, as well as the correlation between sperm head abnormalities and two indicators of sperm competition. We found that species with more helically shaped sperm heads (i.e., a wider helical membrane and more pronounced cell waveform) had a higher percentage of abnormal sperm heads than species with less helical sperm (i.e., relatively straight sperm) and that sperm head traits were better predictors of head abnormalities than total sperm length. In contrast, there was no correlation between sperm abnormalities and the level of sperm competition. Given that songbird species with more pronounced helical sperm have higher average sperm swimming speed, our results suggest an evolutionary trade-off between sperm performance and the structural integrity of the sperm head. As such, susceptibility to morphological abnormalities may constrain the evolution of helical sperm morphology in songbirds.
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Affiliation(s)
| | - Melissah Rowe
- Natural History Museum, University of Oslo, Oslo, Norway.,Department of Biosciences, Centre for Ecological and Evolutionary Synthesis, University of Oslo, Oslo, Norway
| | - Arild Johnsen
- Natural History Museum, University of Oslo, Oslo, Norway
| | - Jan T Lifjeld
- Natural History Museum, University of Oslo, Oslo, Norway
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68
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Kahrl AF, Johnson MA, Cox RM. Rapid evolution of testis size relative to sperm morphology suggests that post-copulatory selection targets sperm number in Anolis lizards. J Evol Biol 2019; 32:302-309. [PMID: 30659673 DOI: 10.1111/jeb.13414] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Revised: 12/14/2018] [Accepted: 01/14/2019] [Indexed: 11/28/2022]
Abstract
Post-copulatory sexual selection is thought to be responsible for much of the extraordinary diversity in sperm morphology across metazoans. However, the extent to which post-copulatory selection targets sperm morphology versus sperm production is generally unknown. To address this issue, we simultaneously characterized the evolution of sperm morphology (length of the sperm head, midpiece and flagellum) and testis size (a proxy for sperm production) across 26 species of Anolis lizards, a group in which sperm competition is likely. We found that the length of the sperm midpiece has evolved 2-3 times faster than that of the sperm head or flagellum, suggesting that midpiece size may be the most important aspect of sperm morphology with respect to post-copulatory sexual selection. However, testis size has evolved faster than any aspect of sperm morphology or body size, supporting the hypothesis that post-copulatory sexual selection acts more strongly upon sperm production than upon sperm morphology. Likewise, evolutionary increases in testis size, which typically indicate increased sperm competition, are not associated with predictable changes in sperm morphology, suggesting that any effects of post-copulatory selection on sperm morphology are either weak or variable in direction across anoles. Collectively, our results suggest that sperm production is the primary target of post-copulatory sexual selection in this lineage.
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Affiliation(s)
- Ariel F Kahrl
- Zoologiska institutionen: Etologi, Stockholm University, Stockholm, Sweden.,Department of Biology, University of Virginia, Charlottesville, Virginia
| | | | - Robert M Cox
- Department of Biology, University of Virginia, Charlottesville, Virginia
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69
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Bilton DT, Ribera I, Short AEZ. Water Beetles as Models in Ecology and Evolution. ANNUAL REVIEW OF ENTOMOLOGY 2019; 64:359-377. [PMID: 30629892 DOI: 10.1146/annurev-ento-011118-111829] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Beetles have colonized water many times during their history, with some of these events involving extensive evolutionary radiations and multiple transitions between land and water. With over 13,000 described species, they are one of the most diverse macroinvertebrate groups in most nonmarine aquatic habitats and occur on all continents except Antarctica. A combination of wide geographical and ecological range and relatively accessible taxonomy makes these insects an excellent model system for addressing a variety of questions in ecology and evolution. Work on water beetles has recently made important contributions to fields as diverse as DNA taxonomy, macroecology, historical biogeography, sexual selection, and conservation biology, as well as predicting organismal responses to global change. Aquatic beetles have some of the best resolved phylogenies of any comparably diverse insect group, and this, coupled with recent advances in taxonomic and ecological knowledge, is likely to drive an expansion of studies in the future.
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Affiliation(s)
- David T Bilton
- Marine Biology and Ecology Research Centre, School of Biological and Marine Sciences, University of Plymouth, Plymouth PL4 8AA, United Kingdom;
| | - Ignacio Ribera
- Institute of Evolutionary Biology (CSIC-Pompeu Fabra University), 08003 Barcelona, Spain;
| | - Andrew Edward Z Short
- Department of Ecology and Evolutionary Biology; and Division of Entomology, Biodiversity Institute, University of Kansas, Lawrence, Kansas 66045, USA;
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70
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Hooper DM, Griffith SC, Price TD. Sex chromosome inversions enforce reproductive isolation across an avian hybrid zone. Mol Ecol 2018; 28:1246-1262. [PMID: 30230092 DOI: 10.1111/mec.14874] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Revised: 08/23/2018] [Accepted: 08/27/2018] [Indexed: 12/11/2022]
Abstract
Across hybrid zones, the sex chromosomes are often more strongly differentiated than the autosomes. This is regularly attributed to the greater frequency of reproductive incompatibilities accumulating on sex chromosomes and their exposure in the heterogametic sex. Working within an avian hybrid zone, we explore the possibility that chromosome inversions differentially accumulate on the Z chromosome compared to the autosomes and thereby contribute to Z chromosome differentiation. We analyse the northern Australian hybrid zone between two subspecies of the long-tailed finch (Poephila acuticauda), first described based on differences in bill colour, using reduced-representation genomic sequencing for 293 individuals over a 1,530-km transect. Autosomal differentiation between subspecies is minimal. In contrast, 75% of the Z chromosome is highly differentiated and shows a steep genomic cline, which is displaced 350 km to the west of the cline in bill colour. Differentiation is associated with two or more putative chromosomal inversions, each predominating in one subspecies. If inversions reduce recombination between hybrid incompatibilities, they are selectively favoured and should therefore accumulate in hybrid zones. We argue that this predisposes inversions to differentially accumulate on the Z chromosome. One genomic region affecting bill colour is on the Z, but the main candidates are on chromosome 8. This and the displacement of the bill colour and Z chromosome cline centres suggest that bill colour has not strongly contributed to inversion accumulation. Based on cline width, however, the Z chromosome and bill colour both contribute to reproductive isolation established between this pair of subspecies.
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Affiliation(s)
- Daniel M Hooper
- Cornell Lab of Ornithology, Cornell University, Ithaca, New York.,Committe on Evolutionary Biology, University of Chicago, Chicago, Illinois
| | - Simon C Griffith
- Department of Biological Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Trevor D Price
- Department of Ecology and Evolution, University of Chicago, Chicago, Illinois
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71
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Rojas Mora A, Meniri M, Ciprietti S, Helfenstein F. Is sperm morphology functionally related to sperm swimming ability? A case study in a wild passerine bird with male hierarchies. BMC Evol Biol 2018; 18:142. [PMID: 30231935 PMCID: PMC6146611 DOI: 10.1186/s12862-018-1260-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Accepted: 09/11/2018] [Indexed: 11/21/2022] Open
Abstract
Background Sexual selection continues after copulation via either sperm competition or cryptic female choice, and favors sperm traits that maximize sperm competitiveness. Both sperm swimming velocity and longevity are important determinants of the outcome of sperm competition. Theoretically, sperm morphology can influence sperm velocity at least in three different non-exclusive ways: (i) longer sperm may generate more propelling thrust, (ii) bigger midpieces may produce more energy, and/or (iii) larger flagella or mid-pieces relative to the head size may compensate for the drag forces around the head. A growing number of studies have investigated the relationship of sperm morphology with sperm performance, which remains equivocal at both the inter- and intra-specific levels. Here, we used House Sparrows to test the functional relationship between sperm morphology with sperm velocity and longevity. Based on a previous study showing that sperm swimming ability covaries with social rank, we predicted that —if a functional relationship exists—1) sperm morphology should differ across social ranks, and 2) correlations between sperm morphology and sperm velocity and/or sperm longevity should be constant across social ranks. Results We found no differences in sperm morphology across social ranks. Moreover, we found that sperm morphology may be correlated with sperm velocity, but such relationship varied across social ranks. This result contradicts the hypothesis of a functional relationship between sperm morphology and sperm performance. Finally, after experimentally manipulating social ranks, we observed that relationships between sperm morphology and sperm velocity and/or sperm longevity disappeared or changed direction. Conclusions We suggest that in species with internal fertilization, while sperm morphology is likely constrained by the morphology of the female sperm storage organs, selection may act upon physiological traits that enhance sperm performance. Hence, these two selection forces could decouple sperm performance from sperm morphology. Electronic supplementary material The online version of this article (10.1186/s12862-018-1260-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Alfonso Rojas Mora
- Laboratory of Evolutionary Ecophysiology, Institute of Biology, Faculty of Sciences, University of Neuchatel, Neuchatel, Switzerland. .,Present Address: Laboratory of Ecology and Epidemiology of Parasites, Institute of Biology, Faculty of Sciences, University of Neuchatel, Rue Emile-Argand 11, 2000, Neuchatel, Switzerland.
| | - Magali Meniri
- Laboratory of Evolutionary Ecophysiology, Institute of Biology, Faculty of Sciences, University of Neuchatel, Neuchatel, Switzerland
| | - Sabrina Ciprietti
- Laboratory of Evolutionary Ecophysiology, Institute of Biology, Faculty of Sciences, University of Neuchatel, Neuchatel, Switzerland
| | - Fabrice Helfenstein
- Laboratory of Evolutionary Ecophysiology, Institute of Biology, Faculty of Sciences, University of Neuchatel, Neuchatel, Switzerland
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72
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Lu GA, Zhao Y, Yang H, Lan A, Shi S, Liufu Z, Huang Y, Tang T, Xu J, Shen X, Wu CI. Death of new microRNA genes in Drosophila via gradual loss of fitness advantages. Genome Res 2018; 28:1309-1318. [PMID: 30049791 PMCID: PMC6120634 DOI: 10.1101/gr.233809.117] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Accepted: 07/20/2018] [Indexed: 01/23/2023]
Abstract
The prevalence of de novo coding genes is controversial due to length and coding constraints. Noncoding genes, especially small ones, are freer to evolve de novo by comparison. The best examples are microRNAs (miRNAs), a large class of regulatory molecules ∼22 nt in length. Here, we study six de novo miRNAs in Drosophila, which, like most new genes, are testis-specific. We ask how and why de novo genes die because gene death must be sufficiently frequent to balance the many new births. By knocking out each miRNA gene, we analyzed their contributions to the nine components of male fitness (sperm production, length, and competitiveness, among others). To our surprise, the knockout mutants often perform better than the wild type in some components, and slightly worse in others. When two of the younger miRNAs are assayed in long-term laboratory populations, their total fitness contributions are found to be essentially zero. These results collectively suggest that adaptive de novo genes die regularly, not due to the loss of functionality, but due to the canceling out of positive and negative fitness effects, which may be characterized as "quasi-neutrality." Since de novo genes often emerge adaptively and become lost later, they reveal ongoing period-specific adaptations, reminiscent of the "Red-Queen" metaphor for long-term evolution.
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Affiliation(s)
- Guang-An Lu
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, Guangdong, China
| | - Yixin Zhao
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, Guangdong, China
| | - Hao Yang
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, Guangdong, China
| | - Ao Lan
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, Guangdong, China
| | - Suhua Shi
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, Guangdong, China
| | - Zhongqi Liufu
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, Guangdong, China
| | - Yumei Huang
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, Guangdong, China
| | - Tian Tang
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, Guangdong, China
| | - Jin Xu
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, Guangdong, China
- Center for Personal Dynamic Regulomes, Stanford University, Stanford, California 94305, USA
| | - Xu Shen
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, Guangdong, China
| | - Chung-I Wu
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, Guangdong, China
- Department of Ecology and Evolution, University of Chicago, Chicago, Illinois 60637, USA
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73
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Lymbery RA, Kennington WJ, Evans JP. Multivariate Sexual Selection on Ejaculate Traits under Sperm Competition. Am Nat 2018; 192:94-104. [DOI: 10.1086/697447] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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74
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Weber M, Wunderer J, Lengerer B, Pjeta R, Rodrigues M, Schärer L, Ladurner P, Ramm SA. A targeted in situ hybridization screen identifies putative seminal fluid proteins in a simultaneously hermaphroditic flatworm. BMC Evol Biol 2018; 18:81. [PMID: 29848299 PMCID: PMC5977470 DOI: 10.1186/s12862-018-1187-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Accepted: 04/30/2018] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Along with sperm, in many taxa ejaculates also contain large numbers of seminal fluid proteins (SFPs). SFPs and sperm are transferred to the mating partner, where they are thought to play key roles in mediating post-mating sexual selection. They modulate the partner's behavior and physiology in ways that influence the reproductive success of both partners, thus potentially leading to sexual conflict. Despite the presumed general functional and evolutionary significance of SFPs, their identification and characterization has to date focused on just a few animal groups, predominantly insects and mammals. Moreover, until now seminal fluid profiling has mainly focused on species with separate sexes. Here we report a comprehensive screen for putative SFPs in the simultaneously hermaphroditic flatworm Macrostomum lignano. RESULTS Based on existing transcriptomic data, we selected 150 transcripts known to be (a) predominantly expressed in the tail region of the worms, where the seminal fluid-producing prostate gland cells are located, and (b) differentially expressed in social environments differing in sperm competition level, strongly implying that they represent a phenotypically plastic aspect of male reproductive allocation in this species. For these SFP candidates, we then performed whole-mount in situ hybridization (ISH) experiments to characterize tissue-specific expression. In total, we identified 98 transcripts that exhibited prostate-specific expression, 76 of which we found to be expressed exclusively in the prostate gland cells; additional sites of expression for the remaining 22 included the testis or other gland cells. Bioinformatics analyses of the prostate-limited candidates revealed that at least 64 are predicted to be secretory proteins, making these especially strong candidates to be SFPs that are transferred during copulation. CONCLUSIONS Our study represents a first comprehensive analysis using a combination of transcriptomic and ISH screen data to identify SFPs based on transcript expression in seminal fluid-producing tissues. We thereby extend the range of taxa for which seminal fluid has been characterized to a flatworm species with a sequenced genome and for which several methods such as antibody staining, transgenesis and RNA interference have been established. Our data provide a basis for testing the functional and evolutionary significance of SFPs.
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Affiliation(s)
- Michael Weber
- Evolutionary Biology, Bielefeld University, Konsequenz 45, 33615 Bielefeld, Germany
| | - Julia Wunderer
- Institute of Zoology and Center of Molecular Biosciences Innsbruck, University of Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - Birgit Lengerer
- Institute of Zoology and Center of Molecular Biosciences Innsbruck, University of Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - Robert Pjeta
- Institute of Zoology and Center of Molecular Biosciences Innsbruck, University of Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - Marcelo Rodrigues
- Institute of Zoology and Center of Molecular Biosciences Innsbruck, University of Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
- Current address: School of Natural and Environmental Sciences, Ridley Building, Newcastle University, Newcastle upon Tyne, England NE1 7RU UK
| | - Lukas Schärer
- Evolutionary Biology, Zoological Institute, University of Basel, Vesalgasse 1, 4051 Basel, Switzerland
| | - Peter Ladurner
- Institute of Zoology and Center of Molecular Biosciences Innsbruck, University of Innsbruck, Technikerstr. 25, A-6020 Innsbruck, Austria
| | - Steven A. Ramm
- Evolutionary Biology, Bielefeld University, Konsequenz 45, 33615 Bielefeld, Germany
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75
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Lüpold S, Pitnick S. Sperm form and function: what do we know about the role of sexual selection? Reproduction 2018; 155:R229-R243. [DOI: 10.1530/rep-17-0536] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Accepted: 02/19/2018] [Indexed: 12/20/2022]
Abstract
Sperm morphological variation has attracted considerable interest and generated a wealth of predominantly descriptive studies over the past three centuries. Yet, apart from biophysical studies linking sperm morphology to swimming velocity, surprisingly little is known about the adaptive significance of sperm form and the selective processes underlying its tremendous diversification throughout the animal kingdom. Here, we first discuss the challenges of examining sperm morphology in an evolutionary context and why our understanding of it is far from complete. Then, we review empirical evidence for how sexual selection theory applies to the evolution of sperm form and function, including putative secondary sexual traits borne by sperm.
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76
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Cocks OTM, Eady PE. Microsurgical manipulation reveals pre-copulatory function of key genital sclerites. ACTA ACUST UNITED AC 2018; 221:jeb.173427. [PMID: 29559546 DOI: 10.1242/jeb.173427] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Accepted: 03/13/2018] [Indexed: 11/20/2022]
Abstract
The copulatory organs of male insects are generally complex, species-specific arrangements of hardened sclerotized plates bound together by flexible, less sclerotized cuticle. Their extensive morphological diversification is a recurrent pattern in the evolutionary radiation of animals, yet a clear consensus as to what selection pressures drive this divergence is still to emerge. In part, this stems from the fact that the function of individual sclerites that integrate to form the aedeagus are poorly understood. In insects, the male copulatory organ is often bounded by two lateral parameres tipped with setae. In a number of species, these have been observed to brush against the terminal abdominal sclerites of the female, suggesting a role in pre- and/or post-copulatory female choice. However, in the absence of experimental manipulation, their function remains elusive. Here, we used microsurgery to reduce paramere length and show that males with one or both paramere tips removed were less likely to achieve genital coupling than sham-operated male control groups. Where treatment males did achieve copulation, surgical removal of the paramere tip(s) had no detectable effect on copulation duration or on the outcome of sperm competition. Surgical manipulation of the end-plate, a genital sclerite that covers the ostium of the median lobe (the non-intromittent section of the aedeagus), resulted in near-complete failure of males to achieve copulation. Our experimental manipulations show that the parameres and end-plate function during pre-copulatory sexual interactions and thus most likely evolved in response to sexual selection occurring prior to insemination.
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Affiliation(s)
- Oliver T M Cocks
- School of Life Sciences, University of Lincoln, Brayford Pool, Lincoln LN6 7TS, UK
| | - Paul E Eady
- School of Life Sciences, University of Lincoln, Brayford Pool, Lincoln LN6 7TS, UK
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77
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Turissini DA, McGirr JA, Patel SS, David JR, Matute DR. The Rate of Evolution of Postmating-Prezygotic Reproductive Isolation in Drosophila. Mol Biol Evol 2018; 35:312-334. [PMID: 29048573 PMCID: PMC5850467 DOI: 10.1093/molbev/msx271] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Reproductive isolation is an intrinsic aspect of species formation. For that reason, the identification of the precise isolating traits, and the rates at which they evolve, is crucial to understanding how species originate and persist. Previous work has measured the rates of evolution of prezygotic and postzygotic barriers to gene flow, yet no systematic analysis has studied the rates of evolution of postmating-prezygotic (PMPZ) barriers. We measured the magnitude of two barriers to gene flow that act after mating occurs but before fertilization. We also measured the magnitude of a premating barrier (female mating rate in nonchoice experiments) and two postzygotic barriers (hybrid inviability and hybrid sterility) for all pairwise crosses of all nine known extant species within the melanogaster subgroup. Our results indicate that PMPZ isolation evolves faster than hybrid inviability but slower than premating isolation. Next, we partition postzygotic isolation into different components and find that, as expected, hybrid sterility evolves faster than hybrid inviability. These results lend support for the hypothesis that, in Drosophila, reproductive isolation mechanisms (RIMs) that act early in reproduction (or in development) tend to evolve faster than those that act later in the reproductive cycle. Finally, we tested whether there was evidence for reinforcing selection at any RIM. We found no evidence for generalized evolution of reproductive isolation via reinforcement which indicates that there is no pervasive evidence of this evolutionary process. Our results indicate that PMPZ RIMs might have important evolutionary consequences in initiating speciation and in the persistence of new species.
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Affiliation(s)
- David A Turissini
- Department of Biology, University of North Carolina, Chapel Hill, NC
| | - Joseph A McGirr
- Department of Biology, University of North Carolina, Chapel Hill, NC
| | - Sonali S Patel
- Department of Biology, University of North Carolina, Chapel Hill, NC
| | - Jean R David
- Laboratoire Evolution, Génomes, Comportement, Ecologie (EGCE) CNRS, IRD, Univ. Paris-sud, Université Paris-Saclay, 91198 Gif sur Yvette, France
- Institut de Systématique, Evolution, Biodiversité, UMR 7205, CNRS, MNHN, UPMC, EPHE, Muséum National d’Histoire Naturelle, Sorbonne Universités, rue Buffon, 75005, Paris, France
| | - Daniel R Matute
- Department of Biology, University of North Carolina, Chapel Hill, NC
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78
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Degner EC, Harrington LC. A mosquito sperm's journey from male ejaculate to egg: Mechanisms, molecules, and methods for exploration. Mol Reprod Dev 2018; 83:897-911. [PMID: 27147424 PMCID: PMC5086422 DOI: 10.1002/mrd.22653] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2016] [Accepted: 04/22/2016] [Indexed: 12/12/2022]
Abstract
The fate of mosquito sperm in the female reproductive tract has been addressed sporadically and incompletely, resulting in significant gaps in our understanding of sperm-female interactions that ultimately lead to fertilization. As with other Diptera, mosquito sperm have a complex journey to their ultimate destination, the egg. After copulation, sperm spend a short time at the site of insemination where they are hyperactivated and quickly congregate near the entrance of the spermathecal ducts. Within minutes, they travel up the narrow ducts to the spermathecae, likely through the combined efforts of female transport and sperm locomotion. The female nourishes sperm and maintains them in these permanent storage organs for her entire life. When she is ready, the female coordinates the release of sperm with ovulation, and the descending egg is fertilized. Although this process has been well studied via microscopy, many questions remain regarding the molecular processes that coordinate sperm motility, movement through the reproductive tract, maintenance, and usage. In this review, we describe the current understanding of a mosquito sperm's journey to the egg, highlighting gaps in our knowledge of mosquito reproductive biology. Where insufficient information is available in mosquitoes, we describe analogous processes in other organisms, such as Drosophila melanogaster, as a basis for comparison, and we suggest future areas of research that will illuminate how sperm successfully traverse the female reproductive tract. Such studies may yield molecular targets that could be manipulated to control populations of vector species. Mol. Reprod. Dev. 83: 897-911, 2016 © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Ethan C Degner
- Department of Entomology, Cornell University, Ithaca, New York
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79
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Horváth B, Kalinka AT. The genetics of egg retention and fertilization success in Drosophila: One step closer to understanding the transition from facultative to obligate viviparity. Evolution 2018; 72:318-336. [PMID: 29265369 DOI: 10.1111/evo.13411] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Revised: 10/16/2017] [Accepted: 11/14/2017] [Indexed: 12/17/2022]
Abstract
Oviparous, facultative egg retention enables Drosophila females to withhold fertilized eggs in their reproductive tracts until circumstances favor oviposition. The propensity to retain fertilized eggs varies greatly between species, and is correlated with other reproductive traits, such as egg size and ovariole number. While previous studies have described the phenomenon, no study to date has characterized within-species variation or the genetic basis of the trait. Here, we develop a novel microscope-based method for measuring egg retention in Drosophila females and determine the range of phenotypic variation in mated female egg retention in a subset of 91 Drosophila Genetic Reference Panel (DGRP) lines. We inferred the genetic basis of egg retention using a genome-wide association study (GWAS). Further, the scoring of more than 95,000 stained, staged eggs enabled estimates of fertilization success for each line. We found evidence that ovary- and spermathecae-related genes as well as genes affecting olfactory behavior, male mating behavior, male-female attraction and sperm motility may play a crucial role in post-mating physiology. Based on our findings we also propose potential evolutionary routes toward obligate viviparity. In particular, we propose that the loss of fecundity incurred by viviparity could be offset by benefits arising from enhanced mate discrimination, resource specialization, or modified egg morphology.
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Affiliation(s)
- Barbara Horváth
- Institut für Populationsgenetik, Veterinärmedizinische Universität Wien, Veterinärplatz 1, Vienna A-1210, Austria.,Vienna Graduate School of Population Genetics, Veterinärmedizinische Universität Wien, Veterinärplatz 1, Vienna A-1210, Austria.,Current Address: Barbara Ellis, Institutionen för ekologi och genetik, Evolutionsbiologiskt Centrum (EBC), Norbyvägen 18D, 752 36 Uppsala, Sweden
| | - Alex T Kalinka
- Institut für Populationsgenetik, Veterinärmedizinische Universität Wien, Veterinärplatz 1, Vienna A-1210, Austria
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80
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Comeault AA, Venkat A, Matute DR. Correlated evolution of male and female reproductive traits drive a cascading effect of reinforcement in Drosophila yakuba. Proc Biol Sci 2017; 283:rspb.2016.0730. [PMID: 27440664 DOI: 10.1098/rspb.2016.0730] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Accepted: 06/23/2016] [Indexed: 11/12/2022] Open
Abstract
Selection against maladaptive hybridization can drive the evolution of reproductive isolation in a process called reinforcement. While the importance of reinforcement in evolution has been historically debated, many examples now exist. Despite these examples, we typically lack a detailed understanding of the mechanisms limiting the spread of reinforced phenotypes throughout a species' range. Here we address this issue in the fruit fly Drosophila yakuba, a species that hybridizes with its sister species D. santomea and is undergoing reinforcement in a well-defined hybrid zone on the island of São Tomé. Within this region, female D. yakuba show increased postmating-prezygotic (gametic) isolation towards D. santomea when compared with females from allopatric populations. We use a combination of natural collections, fertility assays, and experimental evolution to understand why reinforced gametic isolation in D. yakuba is confined to this hybrid zone. We show that, among other traits, D. yakuba males from sympatric populations sire fewer progeny than allopatric males when mated to allopatric D. yakuba females. Our results provide a novel example of reinforcement acting on a postmating-prezygotic trait in males, resulting in a cascade of reproductive isolation among conspecific populations.
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Affiliation(s)
- Aaron A Comeault
- Biology Department, University of North Carolina, 250 Bell Tower Drive, Chapel Hill, NC 27599, USA
| | - Aarti Venkat
- Department of Human Genetics, The University of Chicago, 920 East 58th Street, Chicago, IL 60637, USA
| | - Daniel R Matute
- Biology Department, University of North Carolina, 250 Bell Tower Drive, Chapel Hill, NC 27599, USA
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81
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Liao WB, Huang Y, Zeng Y, Zhong MJ, Luo Y, Lüpold S. Ejaculate evolution in external fertilizers: Influenced by sperm competition or sperm limitation? Evolution 2017; 72:4-17. [PMID: 28975611 DOI: 10.1111/evo.13372] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Revised: 09/22/2017] [Accepted: 09/26/2017] [Indexed: 12/19/2022]
Abstract
The evolution of sperm quality and quantity is shaped by various selective processes, with sperm competition generally considered the primary selective agent. Particularly in external fertilizers, however, sperm limitation through gamete dispersal can also influence gamete investments, but empirical data examining this effect are limited. Here, we studied the relative importance of sperm competition and the spawning conditions in explaining the macroevolutionary patterns of sperm size and number within two taxa with external fertilization but differences in their reproductive biology. In frogs, sperm swim slowly but for up to hours as they penetrate the gelatinous egg coating, whereas fish sperm typically swim fast, are very short-lived (seconds to minutes), and often face a relatively higher risk of being moved away from the ova by currents. Our phylogenetic models and path analyses revealed different trajectories of ejaculate evolution in these two taxa. Sperm size and number responded primarily to variation in sperm competition in the anurans, but more strongly to egg number and water turbulence in the fishes. Whereas the results across anurans align with the general expectation that sexual selection is the main driver of ejaculate evolution, our findings across the fishes suggest that sperm limitation has been underappreciated.
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Affiliation(s)
- Wen Bo Liao
- Key Laboratory of Southwest China Wildlife Resources Conservation (Ministry of Education), China West Normal University, Nanchong 637009, Sichuan, China
| | - Yan Huang
- Key Laboratory of Southwest China Wildlife Resources Conservation (Ministry of Education), China West Normal University, Nanchong 637009, Sichuan, China
| | - Yu Zeng
- Key Laboratory of Southwest China Wildlife Resources Conservation (Ministry of Education), China West Normal University, Nanchong 637009, Sichuan, China
| | - Mao Jun Zhong
- Key Laboratory of Southwest China Wildlife Resources Conservation (Ministry of Education), China West Normal University, Nanchong 637009, Sichuan, China
| | - Yi Luo
- Key Laboratory of Southwest China Wildlife Resources Conservation (Ministry of Education), China West Normal University, Nanchong 637009, Sichuan, China
| | - Stefan Lüpold
- Department of Evolutionary Biology and Environmental Studies, University of Zurich-Irchel, Winterthurerstrasse 190, 8057 Zurich, Switzerland
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82
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Wensing KU, Koppik M, Fricke C. Precopulatory but not postcopulatory male reproductive traits diverge in response to mating system manipulation in Drosophila melanogaster. Ecol Evol 2017; 7:10361-10378. [PMID: 29238561 PMCID: PMC5723610 DOI: 10.1002/ece3.3542] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 09/11/2017] [Accepted: 09/14/2017] [Indexed: 01/01/2023] Open
Abstract
Competition between males creates potential for pre‐ and postcopulatory sexual selection and conflict. Theory predicts that males facing risk of sperm competition should evolve traits to secure their reproductive success. If those traits are costly to females, the evolution of such traits may also increase conflict between the sexes. Conversely, under the absence of sperm competition, one expectation is for selection on male competitive traits to relax thereby also relaxing sexual conflict. Experimental evolution studies are a powerful tool to test this expectation. Studies in multiple insect species have yielded mixed and partially conflicting results. In this study, we evaluated male competitive traits and male effects on female costs of mating in Drosophila melanogaster after replicate lines evolved for more than 50 generations either under enforced monogamy or sustained polygamy, thus manipulating the extent of intrasexual competition between males. We found that in a setting where males competed directly with a rival male for access to a female and fertilization of her ova polygamous males had superior reproductive success compared to monogamous males. When comparing reproductive success solely in double mating standard sperm competition assays, however, we found no difference in male sperm defense competitiveness between the different selection regimes. Instead, we found monogamous males to be inferior in precopulatory competition, which indicates that in our system, enforced monogamy relaxed selection on traits important in precopulatory rather than postcopulatory competition. We discuss our findings in the context of findings from previous experimental evolution studies in Drosophila ssp. and other invertebrate species.
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Affiliation(s)
- Kristina U. Wensing
- Institute for Evolution and BiodiversityUniversity of MuensterMuensterGermany
- Muenster Graduate School of EvolutionUniversity of MuensterMuensterGermany
| | - Mareike Koppik
- Institute for Evolution and BiodiversityUniversity of MuensterMuensterGermany
| | - Claudia Fricke
- Institute for Evolution and BiodiversityUniversity of MuensterMuensterGermany
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83
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A sex-linked supergene controls sperm morphology and swimming speed in a songbird. Nat Ecol Evol 2017; 1:1168-1176. [DOI: 10.1038/s41559-017-0235-2] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Accepted: 06/06/2017] [Indexed: 01/08/2023]
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84
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Fernandes Martins MJ, Hunt G, Lockwood R, Swaddle JP, Horne DJ. Correlation between investment in sexual traits and valve sexual dimorphism in Cyprideis species (Ostracoda). PLoS One 2017; 12:e0177791. [PMID: 28678866 PMCID: PMC5497955 DOI: 10.1371/journal.pone.0177791] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Accepted: 05/03/2017] [Indexed: 11/19/2022] Open
Abstract
Assessing the long-term macroevolutionary consequences of sexual selection has been hampered by the difficulty of studying this process in the fossil record. Cytheroid ostracodes offer an excellent system to explore sexual selection in the fossil record because their readily fossilized carapaces are sexually dimorphic. Specifically, males are relatively more elongate than females in this superfamily. This sexual shape difference is thought to arise so that males carapaces can accommodate their very large copulatory apparatus, which can account for up to one-third of body volume. Here we test this widely held explanation for sexual dimorphism in cytheroid ostracodes by correlating investment in male genitalia, a trait in which sexual selection is seen as the main evolutionary driver, with sexual dimorphism of carapace in the genus Cyprideis. We analyzed specimens collected in the field (C. salebrosa, USA; C. torosa, UK) and from collections of the National Museum of Natural History, Washington, DC (C. mexicana). We digitized valve outlines in lateral view to obtain measures of size (valve area) and shape (elongation, measured as length to height ratio), and obtained several dimensions from two components of the hemipenis: the muscular basal capsule, which functions as a sperm pump, and the section that includes the intromittent organ (terminal extension). In addition to the assessment of this primary sexual trait, we also quantified two dimensions of the male secondary sexual trait—where the transformed right walking leg functions as a clasping organ during mating. We also measured linear dimensions from four limbs as indicators of overall (soft-part) body size, and assessed allometry of the soft anatomy. We observed significant correlations in males between valve size, but not elongation, and distinct structural parts of the hemipenis, even after accounting for their shared correlation with overall body size. We also found weak but significant positive correlation between valve elongation and the degree of sexual dimorphism of the walking leg, but only in C. torosa. The correlation between the hemipenis parts, especially basal capsule size and male valve size dimorphism suggests that sexual selection on sperm size, quantity, and/or efficiency of transfer may drive sexual size dimorphism in these species, although we cannot exclude other aspects of sexual and natural selection.
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Affiliation(s)
- Maria João Fernandes Martins
- Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington DC, United States of America
- * E-mail:
| | - Gene Hunt
- Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington DC, United States of America
| | - Rowan Lockwood
- Department of Geology, College of William and Mary, Williamsburg, Virginia, United States of America
| | - John P. Swaddle
- Department of Biology, College of William and Mary, Williamsburg, Virginia, United States of America
| | - David J. Horne
- School of Geography, Queen Mary University of London, London, United Kingdom
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85
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Saari S, Andjelković A, Garcia GS, Jacobs HT, Oliveira MT. Expression of Ciona intestinalis AOX causes male reproductive defects in Drosophila melanogaster. BMC DEVELOPMENTAL BIOLOGY 2017; 17:9. [PMID: 28673232 PMCID: PMC5496232 DOI: 10.1186/s12861-017-0151-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/06/2017] [Accepted: 06/14/2017] [Indexed: 02/08/2023]
Abstract
Background Mitochondrial alternative respiratory-chain enzymes are phylogenetically widespread, and buffer stresses affecting oxidative phosphorylation in species that possess them. However, they have been lost in the evolutionary lineages leading to vertebrates and arthropods, raising the question as to what survival or reproductive disadvantages they confer. Recent interest in using them in therapy lends a biomedical dimension to this question. Methods Here, we examined the impact of the expression of Ciona intestinalis alternative oxidase, AOX, on the reproductive success of Drosophila melanogaster males. Sperm-competition assays were performed between flies carrying three copies of a ubiquitously expressed AOX construct, driven by the α-tubulin promoter, and wild-type males of the same genetic background. Results In sperm-competition assays, AOX conferred a substantial disadvantage, associated with decreased production of mature sperm. Sperm differentiation appeared to proceed until the last stages, but was spatially deranged, with spermatozoids retained in the testis instead of being released to the seminal vesicle. High AOX expression was detected in the outermost cell-layer of the testis sheath, which we hypothesize may disrupt a signal required for sperm maturation. Conclusions AOX expression in Drosophila thus has effects that are deleterious to male reproductive function. Our results imply that AOX therapy must be developed with caution. Electronic supplementary material The online version of this article (doi:10.1186/s12861-017-0151-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Sina Saari
- Institute of Biosciences and Medical Technology, Tampere University Hospital, University of Tampere, FI-33014, Tampere, Finland
| | - Ana Andjelković
- Institute of Biosciences and Medical Technology, Tampere University Hospital, University of Tampere, FI-33014, Tampere, Finland
| | - Geovana S Garcia
- Departamento de Tecnologia, Faculdade de Ciências Agrárias e Veterinárias, Universidade Estadual Paulista "Júlio de Mesquita Filho", Jaboticabal, SP, 14884-900, Brazil
| | - Howard T Jacobs
- Institute of Biosciences and Medical Technology, Tampere University Hospital, University of Tampere, FI-33014, Tampere, Finland. .,Institute of Biotechnology, University of Helsinki, FI-00014, Helsinki, Finland.
| | - Marcos T Oliveira
- Institute of Biosciences and Medical Technology, Tampere University Hospital, University of Tampere, FI-33014, Tampere, Finland.,Departamento de Tecnologia, Faculdade de Ciências Agrárias e Veterinárias, Universidade Estadual Paulista "Júlio de Mesquita Filho", Jaboticabal, SP, 14884-900, Brazil
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86
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Syed ZA, Chatterjee M, Samant MA, Prasad NG. Reproductive Isolation through Experimental Manipulation of Sexually Antagonistic Coevolution in Drosophila melanogaster. Sci Rep 2017; 7:3330. [PMID: 28611437 PMCID: PMC5469766 DOI: 10.1038/s41598-017-03182-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Accepted: 04/26/2017] [Indexed: 12/01/2022] Open
Abstract
Promiscuity can drive the evolution of sexual conflict before and after mating occurs. Post mating, the male ejaculate can selfishly manipulate female physiology, leading to a chemical arms race between the sexes. Theory suggests that drift and sexually antagonistic coevolution can cause allopatric populations to evolve different chemical interactions between the sexes, thereby leading to postmating reproductive barriers and speciation. There is, however, little empirical evidence supporting this form of speciation. We tested this theory by creating an experimental evolutionary model of Drosophila melanogaster populations undergoing different levels of interlocus sexual conflict. We found that allopatric populations under elevated sexual conflict show assortative mating, indicating premating reproductive isolation. Further, these allopatric populations also show reduced copulation duration and sperm defense ability when mating happens between individuals across populations compared to that within the same population, indicating postmating prezygotic isolation. Sexual conflict can cause reproductive isolation in allopatric populations through the coevolution of chemical (postmating prezygotic) as well as behavioural (premating) interactions between the sexes. Thus, to our knowledge, we provide the first comprehensive evidence of postmating (as well as premating) reproductive isolation due to sexual conflict.
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Affiliation(s)
- Zeeshan Ali Syed
- Indian Institute of Science Education and Research Mohali, Knowledge City, Sector 81, SAS Nagar, PO Manauli, Mohali, Punjab, 140306, India
| | - Martik Chatterjee
- Indian Institute of Science Education and Research Mohali, Knowledge City, Sector 81, SAS Nagar, PO Manauli, Mohali, Punjab, 140306, India
| | - Manas Arun Samant
- Indian Institute of Science Education and Research Mohali, Knowledge City, Sector 81, SAS Nagar, PO Manauli, Mohali, Punjab, 140306, India
| | - Nagaraj Guru Prasad
- Indian Institute of Science Education and Research Mohali, Knowledge City, Sector 81, SAS Nagar, PO Manauli, Mohali, Punjab, 140306, India.
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87
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Godwin JL, Vasudeva R, Michalczyk Ł, Martin OY, Lumley AJ, Chapman T, Gage MJG. Experimental evolution reveals that sperm competition intensity selects for longer, more costly sperm. Evol Lett 2017; 1:102-113. [PMID: 30283643 PMCID: PMC6089504 DOI: 10.1002/evl3.13] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Revised: 04/24/2017] [Accepted: 05/02/2017] [Indexed: 12/12/2022] Open
Abstract
It is the differences between sperm and eggs that fundamentally underpin the differences between the sexes within reproduction. For males, it is theorized that widespread sperm competition leads to selection for investment in sperm numbers, achieved by minimizing sperm size within limited resources for spermatogenesis in the testis. Here, we empirically examine how sperm competition shapes sperm size, after more than 77 generations of experimental selection of replicate lines under either high or low sperm competition intensities in the promiscuous flour beetle Tribolium castaneum. After this experimental evolution, populations had diverged significantly in their sperm competitiveness, with sperm in ejaculates from males evolving under high sperm competition intensities gaining 20% greater paternity than sperm in ejaculates from males that had evolved under low sperm competition intensity. Males did not change their relative investment into sperm production following this experimental evolution, showing no difference in testis sizes between high and low intensity regimes. However, the more competitive males from high sperm competition intensity regimes had evolved significantly longer sperm and, across six independently selected lines, there was a significant association between the degree of divergence in sperm length and average sperm competitiveness. To determine whether such sperm elongation is costly, we used dietary restriction experiments, and revealed that protein-restricted males produced significantly shorter sperm. Our findings therefore demonstrate that sperm competition intensity can exert positive directional selection on sperm size, despite this being a costly reproductive trait.
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Affiliation(s)
- Joanne L. Godwin
- School of Biological SciencesUniversity of East AngliaNorwich Research ParkNorwichNR4 7TJUnited Kingdom
| | - Ramakrishnan Vasudeva
- School of Biological SciencesUniversity of East AngliaNorwich Research ParkNorwichNR4 7TJUnited Kingdom
| | | | | | - Alyson J. Lumley
- School of Biological SciencesUniversity of East AngliaNorwich Research ParkNorwichNR4 7TJUnited Kingdom
| | - Tracey Chapman
- School of Biological SciencesUniversity of East AngliaNorwich Research ParkNorwichNR4 7TJUnited Kingdom
| | - Matthew J. G. Gage
- School of Biological SciencesUniversity of East AngliaNorwich Research ParkNorwichNR4 7TJUnited Kingdom
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88
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McDiarmid CS, Friesen CR, Ballen C, Olsson M. Sexual coloration and sperm performance in the Australian painted dragon lizard,
Ctenophorus pictus. J Evol Biol 2017; 30:1303-1312. [DOI: 10.1111/jeb.13092] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Accepted: 04/12/2017] [Indexed: 12/16/2022]
Affiliation(s)
- C. S. McDiarmid
- School of Life and Environmental Sciences University of Sydney Sydney NSW Australia
| | - C. R. Friesen
- School of Life and Environmental Sciences University of Sydney Sydney NSW Australia
| | - C. Ballen
- College of Biological Sciences University of Minnesota Minneapolis MN USA
| | - M. Olsson
- Department of Biological and Environmental Sciences Göteborg University Göteborg Sweden
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89
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Ultrastructural analysis of the mature spermatozoon in the copperhead, Agkistrodon contortrix (Linnaeus, 1766). ZOOMORPHOLOGY 2017. [DOI: 10.1007/s00435-017-0353-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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90
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Postmating Female Control: 20 Years of Cryptic Female Choice. Trends Ecol Evol 2017; 32:368-382. [PMID: 28318651 PMCID: PMC5511330 DOI: 10.1016/j.tree.2017.02.010] [Citation(s) in RCA: 196] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Revised: 02/08/2017] [Accepted: 02/09/2017] [Indexed: 12/22/2022]
Abstract
Cryptic female choice (CFC) represents postmating intersexual selection arising from female-driven mechanisms at or after mating that bias sperm use and impact male paternity share. Although biologists began to study CFC relatively late, largely spurred by Eberhard's book published 20 years ago, the field has grown rapidly since then. Here, we review empirical progress to show that numerous female processes offer potential for CFC, from mating through to fertilization, although seldom has CFC been clearly demonstrated. We then evaluate functional implications, and argue that, under some conditions, CFC might have repercussions for female fitness, sexual conflict, and intersexual coevolution, with ramifications for related evolutionary phenomena, such as speciation. We conclude by identifying directions for future research in this rapidly growing field.
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91
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Rode NO, Soroye P, Kassen R, Rundle HD. Air-borne genotype by genotype indirect genetic effects are substantial in the filamentous fungus Aspergillus nidulans. Heredity (Edinb) 2017; 119:1-7. [PMID: 28295032 DOI: 10.1038/hdy.2017.9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Revised: 01/16/2017] [Accepted: 01/17/2017] [Indexed: 01/01/2023] Open
Abstract
Genotype by genotype indirect genetic effects (G × G IGEs) occur when the phenotype of an individual is influenced by an interaction between its own genotype and those of neighbour individuals. Little is known regarding the relative importance of G × G IGEs compared with other forms of direct and indirect genetic effects. We quantified the relative importance of IGEs in the filamentous fungus Aspergillus nidulans, a species in which IGEs are likely to be important as air-borne social interactions are known to affect growth. We used a collection of distantly related wild isolates, lab strains and a set of closely related mutation accumulation lines to estimate the contribution of direct and indirect genetic effects on mycelium growth rate, a key fitness component. We found that indirect genetic effects were dominated by G × G IGEs that occurred primarily between a focal genotype and its immediate neighbour within a vertical stack, and these accounted for 11% of phenotypic variation. These results indicate that G × G IGEs may be substantial, at least in some systems, and that the evolutionary importance of these interactions may be underappreciated, especially in microbes. We advocate for a wider use of the IGE framework in both applied (for example, choice of varietal mixtures in plant breeding) and evolutionary genetics (kin selection/kin competition studies).
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Affiliation(s)
- N O Rode
- Department of Biology, University of Ottawa, Ottawa, ON, Canada
| | - P Soroye
- Department of Biology, University of Ottawa, Ottawa, ON, Canada
| | - R Kassen
- Department of Biology, University of Ottawa, Ottawa, ON, Canada
| | - H D Rundle
- Department of Biology, University of Ottawa, Ottawa, ON, Canada
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92
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Davis JS, Castillo DM, Moyle LC. Remating responses are consistent with male postcopulatory manipulation but not reinforcement in D. pseudoobscura. Ecol Evol 2017; 7:507-515. [PMID: 28116047 PMCID: PMC5243186 DOI: 10.1002/ece3.2628] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 10/21/2016] [Accepted: 10/25/2016] [Indexed: 11/05/2022] Open
Abstract
Reinforcement occurs when hybridization between closely related lineages produces low-fitness offspring, prompting selection for elevated reproductive isolation specifically in areas of sympatry. Both premating and postmating prezygotic behaviors have been shown to be the target of reinforcing selection, but it remains unclear whether remating behaviors experience reinforcement, although they can also influence offspring identity and limit formation of hybrids. Here, we evaluated evidence for reinforcing selection on remating behaviors in Drosophila pseudoobscura, by comparing remating traits in females from populations historically allopatric and sympatric with Drosophila persimilis. We found that the propensity to remate was not higher in sympatric females, compared to allopatric females, regardless of whether the first mated male was heterospecific or conspecific. Moreover, remating behavior did not contribute to interspecific reproductive isolation among any population; that is, females showed no higher propensity to remate following a heterospecific first mating than following a conspecific first mating. Instead, we found that females are less likely to remate after initial matings with unfamiliar males, regardless of species identity. This is consistent with one scenario of postmating sexual conflict in which females are poorly defended against postcopulatory manipulation by males with whom they have not coevolved. Our results are generally inconsistent with reinforcement on remating traits and suggest that this behavior might be more strongly shaped by the consequences of local antagonistic male-female interactions than interactions with heterospecifics.
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93
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Multiple Genes Cause Postmating Prezygotic Reproductive Isolation in the Drosophila virilis Group. G3-GENES GENOMES GENETICS 2016; 6:4067-4076. [PMID: 27729433 PMCID: PMC5144975 DOI: 10.1534/g3.116.033340] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Understanding the genetic basis of speciation is a central problem in evolutionary biology. Studies of reproductive isolation have provided several insights into the genetic causes of speciation, especially in taxa that lend themselves to detailed genetic scrutiny. Reproductive barriers have usually been divided into those that occur before zygote formation (prezygotic) and after (postzygotic), with the latter receiving a great deal of attention over several decades. Reproductive barriers that occur after mating but before zygote formation [postmating prezygotic (PMPZ)] are especially understudied at the genetic level. Here, I present a phenotypic and genetic analysis of a PMPZ reproductive barrier between two species of the Drosophila virilis group: D. americana and D. virilis This species pair shows strong PMPZ isolation, especially when D. americana males mate with D. virilis females: ∼99% of eggs laid after these heterospecific copulations are not fertilized. Previous work has shown that the paternal loci contributing to this incompatibility reside on two chromosomes, one of which (chromosome 5) likely carries multiple factors. The other (chromosome 2) is fixed for a paracentric inversion that encompasses nearly half the chromosome. Here, I present two results. First, I show that PMPZ in this species cross is largely due to defective sperm storage in heterospecific copulations. Second, using advanced intercross and backcross mapping approaches, I identify genomic regions that carry genes capable of rescuing heterospecific fertilization. I conclude that paternal incompatibility between D. americana males and D. virilis females is underlain by four or more genes on chromosomes 2 and 5.
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94
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Gracielle I, Tidon R, Báo S. Structure and ultrastructure of spermatozoon in six species of Drosophilidae (Diptera). Tissue Cell 2016; 48:596-604. [DOI: 10.1016/j.tice.2016.10.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Revised: 10/12/2016] [Accepted: 10/17/2016] [Indexed: 11/16/2022]
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95
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Smith RJ, Matzke-Karasz R, Kamiya T. Sperm length variations in five species of cypridoidean non-marine ostracods (Crustacea). Cell Tissue Res 2016; 366:483-497. [PMID: 27449928 DOI: 10.1007/s00441-016-2459-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Accepted: 06/17/2016] [Indexed: 11/25/2022]
Abstract
Spermatozoa of the ostracod superfamily Cypridoidea include some of the longest in the animal kingdom, but unlike other so-called giant spermatozoa, they are aflagellate, probably evolved only once, and represent an exceptionally old trait. Sperm length variations within cypridoidean species remain poorly known, a lack that hinders the development of hypotheses to explain their length and variation. For this study, the lengths of 500 spermatozoa from each of five species of freshwater cypridoidean ostracods, Candonopsis tenuis (Brady, 1886), Fabaeformiscandona subacuta (Yang, 1982), Heterocypris rotundata (Bronshtein, 1928), Ilyocypris japonica Okubo, 1990, and Notodromas trulla Smith and Kamiya, 2014, were measured, including the lengths of the posterior and anterior regions. No overall pattern in sperm variation was discernible. Length variations between species, between males of the same species, and within individual males varied from low (Candonopsis tenuis) to extraordinarily large (Notodromas trulla and Fabaeformiscandona subacuta). Sperm competition, cryptic female choice, sperm heteromorphism, and testis size are unlikely to explain all of the variations observed. Age structures of the populations sampled might play a role in explaining some intraspecific variation. The differing amounts of variation in sperm characters revealed in this study suggest that multiple evolutionary trends and pressures shape sperm lengths in this superfamily.
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Affiliation(s)
- Robin J Smith
- Lake Biwa Museum, Oroshimo 1091, Kusatsu, Shiga Prefecture, 525-0001, Japan.
| | - Renate Matzke-Karasz
- Department of Earth and Environmental Sciences, Palaeontology, Ludwig-Maximilians-Universität München and GeoBio-Center LMU, 80333, Munich, Germany.
| | - Takahiro Kamiya
- College of Science and Engineering, School of Natural System, University of Kanazawa, Kakuma, Kanazawa, 920-1192, Japan
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96
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Beekman M, Nieuwenhuis B, Ortiz-Barrientos D, Evans JP. Sexual selection in hermaphrodites, sperm and broadcast spawners, plants and fungi. Philos Trans R Soc Lond B Biol Sci 2016; 371:20150541. [PMID: 27619704 PMCID: PMC5031625 DOI: 10.1098/rstb.2015.0541] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/23/2016] [Indexed: 11/12/2022] Open
Abstract
Darwin was the first to recognize that sexual selection is a strong evolutionary force. Exaggerated traits allow same-sex individuals to compete over access to mates and provide a mechanism by which mates are selected. It is relatively easy to appreciate how inter- and intrasexual selection work in organisms with the sensory capabilities to perceive physical or behavioural traits that signal mate quality or mate compatibility, and to assess the relative quality of competitors. It is therefore not surprising that most studies of sexual selection have focused on animals with separate sexes and obvious adaptations that function in the context of reproductive competition. Yet, many sexual organisms are both male and female at the same time, often lack sexual dimorphism and never come into direct contact at mating. How does sexual selection act in such species, and what can we learn from them? Here, we address these questions by exploring the potential for sexual selection in simultaneous hermaphrodites, sperm- and broadcast spawners, plants and fungi. Our review reveals a range of mechanisms of sexual selection, operating primarily after gametes have been released, which are common in many of these groups and also quite possibly in more familiar (internally fertilizing and sexually dimorphic) organisms.This article is part of the themed issue 'Weird sex: the underappreciated diversity of sexual reproduction'.
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Affiliation(s)
- Madeleine Beekman
- School of Life and Environmental Sciences, University of Sydney, 2006 New South Wales, Australia
| | - Bart Nieuwenhuis
- Department of Ecology and Genetics, Uppsala University, Norbyvägen 18D, 75236 Uppsala, Sweden
| | | | - Jonathan P Evans
- Centre for Evolutionary Biology, School of Animal Biology, University of Western Australia, 6009 Western Australia, Australia
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97
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Droge-Young EM, Belote JM, Perez GS, Pitnick S. Resolving mechanisms of short-term competitive fertilization success in the red flour beetle. JOURNAL OF INSECT PHYSIOLOGY 2016; 93-94:1-10. [PMID: 27343847 DOI: 10.1016/j.jinsphys.2016.06.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Revised: 06/06/2016] [Accepted: 06/08/2016] [Indexed: 06/06/2023]
Abstract
Postcopulatory sexual selection occurs when sperm from multiple males occupy a female's reproductive tract at the same time and is expected to generate strong selection pressures on traits related to competitive fertilization success. However, knowledge of competitive fertilization success mechanisms and characters targeted by resulting selection is limited, partially due to the difficulty of discriminating among sperm from different males within the female reproductive tract. Here, we resolved mechanisms of competitive fertilization success in the promiscuous flour beetle Tribolium castaneum. Through creation of transgenic lines with fluorescent-tagged sperm heads, we followed the fate of focal male sperm in female reproductive tracts while tracking paternity across numerous rematings. Our results indicate that a given male's sperm persist and fertilize eggs through at least seven rematings. Additionally, the proportion of a male's sperm in the bursa (the site of spermatophore deposition), which is influenced by both timing of female's ejecting excess sperm and male size, significantly predicted paternity share in the 24h following a mating. Contrary to expectation, proportional representation of sperm within the female's specialized sperm-storage organ did not significantly predict paternity, though spermathecal sperm may play a role in fertilization when females do not have access to mates for longer time periods. We address the adaptive significance of the identified reproductive mechanisms in the context of T. castaneum's unique mating system and ecology.
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Affiliation(s)
| | - John M Belote
- Department of Biology, Syracuse University, Syracuse, NY 13244, USA
| | - Giselle S Perez
- Department of Biology, Syracuse University, Syracuse, NY 13244, USA
| | - Scott Pitnick
- Department of Biology, Syracuse University, Syracuse, NY 13244, USA
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98
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Lüpold S, Fitzpatrick JL. Sperm number trumps sperm size in mammalian ejaculate evolution. Proc Biol Sci 2016; 282:rspb.2015.2122. [PMID: 26582027 DOI: 10.1098/rspb.2015.2122] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Postcopulatory sexual selection is widely accepted to underlie the extraordinary diversification of sperm morphology. However, why does it favour longer sperm in some taxa but shorter in others? Two recent hypotheses addressing this discrepancy offered contradictory explanations. Under the sperm dilution hypothesis, selection via sperm density in the female reproductive tract favours more but smaller sperm in large, but the reverse in small, species. Conversely, the metabolic constraint hypothesis maintains that ejaculates respond positively to selection in small endothermic animals with high metabolic rates, whereas low metabolic rates constrain their evolution in large species. Here, we resolve this debate by capitalizing on the substantial variation in mammalian body size and reproductive physiology. Evolutionary responses shifted from sperm length to number with increasing mammalian body size, thus supporting the sperm dilution hypothesis. Our findings demonstrate that body-size-mediated trade-offs between sperm size and number can explain the extreme diversification in sperm phenotypes.
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Affiliation(s)
- Stefan Lüpold
- Computational and Evolutionary Biology, Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, UK
| | - John L Fitzpatrick
- Computational and Evolutionary Biology, Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, UK
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99
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Kotrba M. The female reproductive tract of Grallipeza sp. A (Diptera: Micropezidae)—large ventral receptacle substitutes for spermathecae convergently in small and widely separated dipteran clades. ORG DIVERS EVOL 2016. [DOI: 10.1007/s13127-016-0267-5] [Citation(s) in RCA: 3] [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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100
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Xiao S, Xia L. Quantity versus quality: the sperm war. Asian J Androl 2016; 18:900-901. [PMID: 27506335 PMCID: PMC5109884 DOI: 10.4103/1008-682x.185849] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
The evolution of sperm traits manifests itself prolifically across species, and postcopulatory sexual selection (PSS), as executed by the female, accompanies this process. The adaptive significance of some sperm traits (for example, the shape and number of sperms) is well understood. However, the evolution of germ size has not been fully exploited. The most recent study by Lüpold et al.1 reveals that the evolution of longer sperm is driven by the female seminal receptacle and mating frequency in Drosophila, which, in turn, increases the benefits to females. These findings provide a comprehensive interpretation regarding the evolution of sperm size.
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Affiliation(s)
- Shan Xiao
- Key Laboratory of Zebrafish Modeling and Drug Screening for Human Diseases of Guangdong Higher Education Institutes, Department of Cell Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China
| | - Laixin Xia
- Key Laboratory of Zebrafish Modeling and Drug Screening for Human Diseases of Guangdong Higher Education Institutes, Department of Cell Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China
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