DOCSLIB.ORG

The Influence of Developmental Temperature on Sperm Form and Function in Callosobruchus Maculatus

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Influence of Developmental Temperature on Sperm Form and Function in Callosobruchus Maculatus THE INFLUENCE OF DEVELOPMENTAL TEMPERATURE ON SPERM FORM AND FUNCTION IN CALLOSOBRUCHUS MACULATUS Ramakrishnan Vasudeva A thesis submitted in partial fulfilment of the requirements of the University of Lincoln for the degree of Doctor of Philosophy MARCH 2014 ii I dedicate this work to my Mother, Maya, Paul & Charles iii Acknowledgements First and foremost, I sincerely thank both my supervisors Dr. Paul Eady and Dr. Charles Deeming for their support and encouragement during the past three years, without which I could never have been able to write this. In 2006, I came to Lincoln to embark on a research project to study sexual conflict coevolution in the Bruchid beetle Callosobruchus maculatus. Thus, with the completion of my first research project the scene was set for a PhD in January 2010. I am forever in admiration of my insect populations as they provided me with a means for the past six years to learn about their Biology and apply it to study the processes of evolution. In that spirit I am truly indebted to my beetles (and to all those hundreds of beetles which I dissected). Paul and I have worked together for over six years now and throughout he has been an ace mentor and a great inspiration. He played a significant role in welding together the multifarious branches of knowledge. He also went to great troubles in making me understand the importance of maintaining consistency in all my work (lab assays, data management, statistical analysis and writing). Regular meetings turned out to be the lynchpin of my understandings and the primary source to clarify doubts and avail research ideas. He taught me to maintain a balance and focus on the facts: a way to replace my inconsistencies. I shall remain indebted to him forever for being a superb guide and I am fortunate to be able to call Paul a colleague and friend. Special thanks go to Dr. Charles Deeming for guiding me during the past three years. I shall remain forever grateful to him for providing support and insightful discussions on thermal switch experiments, ectothermic development and scientific writing. Similarly, I thank Dr. Daniel Pincheira- iv Donoso; his advice on various aspects of the PhD were extremely helpful. He made valuable suggestions on acquiring key references in thermal biology and evolutionary biology. Thanks are due to Prof. Geoff Parker for being patient with my requests for papers on several occasions. I also thank the departmental regulars at 'Cake Fridays' and lunchtime conversations; they brightened me up. I will remain grateful to Dr. William Hayes for being an excellent advisor on all aspects of scientific investigation. Throughout my time doctoral research, Bill has offered wonderful tutelage and sharing a work space with him was indeed great fun. I will miss him and our conversations over coffee and lunch breaks. In the same breath, I thank Mrs. Amanda Mylett for her help which made life easier. I thank my family and friends who have unconditionally supported me to pursue my dreams. In this regard, my sincere thanks are due to my mother, Mrs. Gomathy Ramaswamy, Kenny & Alison Bell, who I think were my parents in England. Ken and Ali always looked after me like one of their own. I am forever grateful to my friends Dr. Kandasamy Bharathi and Dr. Needhirajan for their support. Thanks also go to Miss. Jacqueline Mayer who has been extremely supportive and many-a-time the driving force. Thanks are due to my Uncle Mr. R. Perumalswamy, whose unhindered financial support helped me focus just on my PhD. I also thank Gopal and Mahua for being there and supporting me always. Thanks are due to my wife Maya Kumar, her parents (Mr. K. S. Kumar and Mrs. Radha Kumar) and sister (Miss. Nidhi Kumar) for their support (in a myriad ways) during the writing up stages, which let me complete what I had started. Maya has been an excellent support in every way. I admire her steadfastness and those uplifting moments v whenever I lost focus. Now, I can spend more time with her and we look forward to our future together. In conclusion, I gratefully acknowledge the funding I received towards my PhD from the University of Lincoln. I remain forever grateful to numerous researchers worldwide for their valuable contributions and my thanks are due to the Miss. Denise Bateman and the Library acquisitions team at the University of Lincoln for their support. vi Abstract This thesis examines the effects of the thermal rearing environment on larval development and its influence on the expression of primary reproductive traits in Callosobruchus maculatus. Chapter 1 provided basic outline to the thesis, starting with a general introduction to sexual selection and specifically its role in the evolution of genitalia and primary reproductive traits. These traits appear to exhibit a level of phenotypic plasticity and thus the opening chapter introduces this concept and its role in evolution and diversification. Phenotypic plasticity in the primary reproductive traits of insects and the evolutionary consequences of this plasticity are discussed. Chapter 2 examined the effect of larval rearing temperature on larval development and offspring size. Larvae go through 4 larval instars prior to pupation. Unsurprisingly larvae reared at 17°C took approximately four times longer to develop than those larvae reared at 33°C but those beetles that completed their development at the coolest temperature were the largest, in agreement with Bergmann’s rule. This chapter paved way for the experiments carried out in subsequent chapters. Chapter 3 investigated the effect of developmental temperature on the expression of primary reproductive traits (e.g. sperm length and egg size) and life-history traits (e.g. adult longevity and fecundity). Sperm length exhibited phenotypic plasticity, being shortest when larvae developed at the temperature vii extremes (17°C & 33°C). Beetles raised at 17°C inseminated the fewest sperm despite the fact that these males had the largest absolute testes size. Developmental temperature affected female fecundity; females that underwent larval development at 17°C laid the fewest eggs. These females along with those reared at 33°C also laid the largest eggs. In general egg size tended to increase with decreasing developmental temperature (in agreement with Bergmann’s rule) although sperm size gives a more mixed response being largest at an intermediate temperature. This is in agreement with the effect of developmental temperature on sperm size in dung flies, but in guppies and a species of snail sperm size increased with decreasing temperature. Chapter 4 used thermal switch experiments to identify when, during larval development, the expression of sperm length was sensitive to temperature. Thermal switching involves an abrupt shift in the thermal environment experienced by the developing larvae, such that development starts at one environment and is completed at either a higher or lower thermal rearing environment. There appeared to be two thermal sensitive periods (TSP) for the expression of sperm length: one during the very stages of ontogeny and one around the time of instar III to instar IV. This is the first demonstration of a TSP in relation to the phenotypic expression of the sperm. The findings of this chapter are discussed in relation to previous shift-once or shift-twice experiments on reptilian embryos and a handful of insects. Chapter 5 studied the consequences of thermal environment during larval development and as adults on copula duration. Both larval rearing temperature viii and post-eclosion temperature affected copula duration; males reared at the lowest temperature taking longer to complete copulation. This is the first demonstration that larval rearing temperature affects copulatory behaviour. It is argued that because thermal heterogeneity is likely to be common in nature, this under-examined component of male behaviour could account for much variation in copulatory behaviour in nature. Chapter 6 examined the effect of larval rearing temperature on the outcome of sperm competition. Males reared at 17°C were less successful at sperm defence and sperm offence, whilst males reared at 33°C were less successful at sperm offence in comparison to males reared at 27°C. This is the first study to report an effect of developmental temperature on the outcome of postcopulatory sexual selection. The results are discussed in light of the physiological consequences of developmental temperature on male ejaculatory characteristics. Chapter 7 discusses the possible mechanisms and consequences of phenotypic plasticity in reproductive traits as a result of experiencing heterogeneous environments during development, and how these processes might interact with postcopulatory sexual selection. Further work on understanding the role of phenotypic plasticity in the evolution of primary reproductive traits is required. ix Contents Acknowledgements iii Abstract vi CHAPTER 1. GENERAL INTRODUCTION 1.1 Sexual selection 1 1.2 Postcopulatory sexual selection 5 1.3 Thermal biology, phenotypic plasticity and the temperature-size rule 12 1.4 Adaptive plasticity or pathological effects? 18 1.5 Ecological consequences of phenotypic plasticity 20 1.6 Phenotypic plasticity in primary reproductive traits 26 1.7 Thesis aims & objectives 31 CHAPTER 2. THE EFFECT OF TEMPERATURE ON LARVAL GROWTH AND DEVELOPMENT 2.1 Introduction 32 2.2 Materials and Methods 37 2.2.1 Model system and experimental design 37 2.3 Results 39 2.4 Discussion 45 CHAPTER 3. THE EFFECT OF THERMAL ENVIRONMENT ON THE EXPRESSION OF SPERM LENGTH 3.1 Introduction 53 3.2 Materials and Methods 58 3.2.1 The effect of larval rearing temperature on the adult phenotype 58 3.2.2 The effect of post-eclosion temperature on primary reproductive traits 60 3.3 Results 61 3.4 Discussion 68 x CHAPTER 4. THERMAL SWITCH EXPERIMENTS REVEAL WHEN DURING DEVELOPMENT, SPERM LENGTH IS TEMPERATURE SENSITIVE 4.1 Introduction 76 4.2 Materials and Methods 83 4.2.1 Measurements 85 4.3 Results 85 4.4 Discussion 90 CHAPTER 5.
Load more

Recommended publications
  • Experimental Evolutionary Biology of Learning in Drosophila Melanogaster
    CORE Metadata, citation and similar papers at core.ac.uk Provided by RERO DOC Digital Library Département de Biologie, Unité d’Ecologie et d’Evolution Université de Fribourg (Suisse) EXPERIMENTAL EVOLUTIONARY BIOLOGY OF LEARNING IN DROSOPHILA MELANOGASTER THESE Présentée à la Faculté des Sciences de l’Université de Fribourg (Suisse) Pour l’obtention du grade de Doctor rerum naturalium Frederic MERY de Montpellier (France) These N° 1403 Imprimerie Copyphot SA (Fribourg) Acceptée par la Faculté des Sciences de l’Université de Fribourg (Suisse) sur la proposition de Tadeusz Kawecki, Victoria Braithwaite, Dieter Ebert et Dietrich Meyer (President du jury) Fribourg le 19 Fevrier 2003 Le Directeur de thèse le Doyen Tadeusz J. Kawecki Dionys Baeriswyl Table of contents Abstract ..............................................................................................................................................................3 Résumé ..............................................................................................................................................................4 Introduction.........................................................................................................................................................5 CHAPTER 1: Experimental Evolution of Learning Ability in Fruit Flies............................................................15 CHAPTER 2: A fitness cost of learning ability in Drosophila melanogaster ....................................................27 CHAPTER 3: An induced fitness
    [Show full text]
  • The Role of Mating Systems in Sexual Selection in Parasitoid Wasps
    Biol. Rev. (2014), pp. 000–000. 1 doi: 10.1111/brv.12126 Beyond sex allocation: the role of mating systems in sexual selection in parasitoid wasps Rebecca A. Boulton∗, Laura A. Collins and David M. Shuker Centre for Biological Diversity, School of Biology, University of St Andrews, Dyers Brae, Greenside place, Fife KY16 9TH, U.K. ABSTRACT Despite the diverse array of mating systems and life histories which characterise the parasitic Hymenoptera, sexual selection and sexual conflict in this taxon have been somewhat overlooked. For instance, parasitoid mating systems have typically been studied in terms of how mating structure affects sex allocation. In the past decade, however, some studies have sought to address sexual selection in the parasitoid wasps more explicitly and found that, despite the lack of obvious secondary sexual traits, sexual selection has the potential to shape a range of aspects of parasitoid reproductive behaviour and ecology. Moreover, various characteristics fundamental to the parasitoid way of life may provide innovative new ways to investigate different processes of sexual selection. The overall aim of this review therefore is to re-examine parasitoid biology with sexual selection in mind, for both parasitoid biologists and also researchers interested in sexual selection and the evolution of mating systems more generally. We will consider aspects of particular relevance that have already been well studied including local mating structure, sex allocation and sperm depletion. We go on to review what we already know about sexual selection in the parasitoid wasps and highlight areas which may prove fruitful for further investigation. In particular, sperm depletion and the costs of inbreeding under chromosomal sex determination provide novel opportunities for testing the role of direct and indirect benefits for the evolution of mate choice.
    [Show full text]
  • El Colegio De La Frontera Sur
    El Colegio de la Frontera Sur Factores que influyen en la dispersión espacio-temporal de broca del café Hypothenemus hampei (Coleoptera: Curculionidae) Tesis presentada como requisito parcial para optar al grado de Doctora en Ciencias en Ecología y Desarrollo Sustentable Con orientación en Ecología de Artrópodos y Manejo de plagas Por Ariana Karina Román Ruiz 2017 El Colegio de la Frontera Sur Tapachula, Chiapas a 16 de junio de 201 7 Las personas abajo firmantes. miembros del jurado examinador de: Ariana Karina Román Ruiz hacemos constar que hemos revisado y aprobado la tesis titulada: 'Factores que influyen en la dispersión espacio-temporal de broca del café hthenemus hampei (Coleoptera: Curculionidae)" Parii obtener el grado de Doctora en Ciencias en Ecologla y Desarrollo Sustentable Nombre Firma . Juan Francisco Barrera Oaytan U/ Dr. Bernard P. Dufour ridad Cruz L6per Juliia Cesar Rojas León I Dr. Jm5 Pablo Liedo Fernandez 1 Dr. Jorge Toledo Arreob 1 br. Jaime Wmez Ruiz Dra. Mane Liliane Jeanne Dor Roques Colegio de la Frontera Sur Tapachula, chispas a 16 de junio de 20 17 Las personas abajo firmantes, miembros del jurado examinador de: Ariana Karina Román Ruiz hacemos constar que hemos revisado y aprobado la tesis titulada: "Factores que influyen en la dispersión espacio-temporal de broca del caf6 Hypothenemus hampei (Coleoptera: Curculionidae)" Para obtener el grado de Doctora en Ciencias en Ecologla y Desarrollo Sustentable Nombre Firma Director Dr. Juan Francisco Barrera Gaytán Co-Director Dr. Bernard P. Dufour Asesor h. Leopoldo Caridad Cruz Lópn AsesorDr. Julio Cesar Rojas León Sinodal adicional Dr. José Pablo Liedo Fernhdez Sinodal adicional Dr.
    [Show full text]
  • A Drosophila Melanogaster Poszt-Meiotikus Spermatogenezisében Szerepet Játszó Gének Vizsgálata
    A Drosophila melanogaster poszt-meiotikus spermatogenezisében szerepet játszó gének vizsgálata Ph.D. értekezés Vedelek Viktor Témavezető: Dr. Sinka Rita Biológia Doktori Iskola Szegedi Tudományegyetem Természettudományi és Informatikai Kar Genetikai Tanszék Szeged 2016 Tartalomjegyzék Tartalomjegyzék ...................................................................................................................................... 2 Rövidítések jegyzéke ............................................................................................................................... 4 1. Bevezetés ............................................................................................................................................. 5 1.1 A Drosophila melanogaster alkalmazása, mint genetikai modellszervezet .................................. 5 1.2 A Drosophila spermatogenezise .................................................................................................... 6 1.2.1 A spermatogenezis korai szakasza ......................................................................................... 9 1.2.2 A meiotikus ciszták, kerek spermatidák ................................................................................. 9 1.2.3 A poszt-meiotikus fejlődés első szakasza, a megnyúlás ....................................................... 10 1.2.4 A poszt-meiotikus fejlődés későbbi szakasza, az individualizáció ........................................ 11 1.3 A mitokondriumok szerepe a spermatogenezis során ...............................................................
    [Show full text]
  • 2012. Download
    Sydney College of the Arts The University of Sydney DOCTOR OF PHILOSOPHY 2012 THESIS THE AESTHETICS OF REPRODUCTIVE MORPHOLOGIES By Maria Fernanda Cardoso August 2012 Statement This volume is presented as a record of the work undertaken for the degree of Doctor of Philosophy at Sydney College of the Arts, University of Sydney. 2 Table of Contents Acknowledgements ............................................................................................. 4 List of Illustrations ............................................................................................... 6 Summary ........................................................................................................... 10 Introduction ...................................................................................................... 11 Chapter One ..................................................................................................... 16 Identifying Genitalic Extravagance and Imagining a Museum as a Means of Investigating and Communicating Strangeness in Animal Reproductive Morphology 16 Imagining a Museum .............................................................................................. 20 A Museum is Born —Press Release ........................................................................ 23 MoCO Timeline: an idea in time ............................................................................ 24 Chapter Two ...................................................................................................... 29 How to Make Your
    [Show full text]
  • Project Title
    Consequences of Plasticity: How do Individual Conditions Affect Physiology, Survival and Copulatory Behaviours in Drosophila? Emily Rose Churchill Master of Science by Research University of York Biology January 2016 Abstract Drosophila melanogaster are a polygamous species: males and females repeat copulation with multiple mates. When more than one male’s sperm have to compete to fertilise the same female’s eggs, sperm competition occurs. This has driven individuals to develop physiological and behavioural plastic responses to enable them to outcompete others and increase their chances of siring successful offspring. But what effect do variable environmental conditions have on these responses? Plasticity comes with a cost, often causing reproductive-survival trade-offs to occur. Previous experiments have failed to show how stress impacts reproductive terminal investment, and other plastic responses, so this study aims to contribute knowledge to this field. The experiments were completed using a combination of stresses to weaken Drosophila: a two-day starvation period and either age (three, 14 and 28 days) or varying sperm competition levels (solitary males, pairs, groups of eight and solitary males in the presence of pheromones). Evidence of trade-offs and plastic reproductive terminal investment was investigated by monitoring behavioural responses (courtship behaviours, rejection responses and copulatory durations), physiological responses (spermatogenesis, egg production and fat reserve levels), as well as activity and starvation resistance as a proxy for longevity. Aged and starved flies, and flies that were not placed under sperm competition, were less active and had a shorter lifespan. These weaker males also tended to exert less energy into courtship behaviours; however they also copulated for longer.
    [Show full text]
  • Drosophila Information Service
    DROSOPHILA INFORMATION SERVICE -" 80 July 1997 Material contributed by DROSOPHILA WORKERS and arranged by James N. Thompson jr. prepared at Department of Zoology University of Oklahoma Norman, Oklahoma 73019 ...................................................................................................................................................................................................................................................... DROSOPHILA INFORMATION SERVICE ..' ~. ..' ~ ::;;-.:., -~'X.::..~'J . -- /J ~"'i,,_#t - 4jY jf':: -:-:~~~=!ø:~ Number 80 July 1997 Prepared at the Department of Zoology University of Oklahoma Norman, Oklahoma 73019 U.S.A. ii DIS 80 (July 1997) Preface Drosophila Information Service was first printed in March, 1934. Material contributed by Drosophila workers was arranged by C.B. Bridges and M. Demerec. As noted in its preface, which is reprinted in DIS 75, Drosophila Information Service was undertaken because, "An appreciable share of credit for the fine accomplishments in Drosophila genetics is due to the broadmindedness of the original Drosophila workers who established the policy of a free exchange of material and information among all actively interested in Drosophila research. This policy has proved to be a great stimulus for the use of Drosophila material in genetic research and is directly responsible for many important contributions." During the more than 60 years following that first issue, DIS has continued to promote open communication. The production of DIS 80 could not have been completed without the generous efforts of many people. Diane Jackson and Stanton Gray helped prepare and proof manuscripts; Gloria Stephens, Diane Jackson, Shalia Newby, and Caroline Tawes maintained key records; and Coral McCallster advised on artwork and computer graphics. Two special issues of Drosophila Information Service have appeared since DIS 77, the 1996 regular issue. DIS 78 and 79 were edited by William Gelbart on behalf of the FlyBase Consortium.
    [Show full text]
  • The Relative Roles of Natural and Sexual Selection in the Evolution of Tardigrade Gamete Morphology
    Master’s Thesis The relative roles of natural and sexual selection in the evolution of tardigrade gamete morphology Serge Ryndov University of Jyväskylä Department of Biological and Environmental Science Ecology and Evolutionary Biology 16.05.2021 UNIVERSITY OF JYVÄSKYLÄ, Faculty of Mathematics and Science Department of Biological and Environmental Science Ecology and Evolutionary Biology Ryndov Serge: The relative roles of natural and sexual selection in the evolution of tardigrade sperm morphology MSc thesis: 53 p., 1 appendix Supervisors: Academy Research Fellow, Sara Calhim Postdoctoral Researcher, Matteo Vecchi May 2021 Keywords: gonad, fluorescent, Macrobiotidae, midpiece, sperm, spermatheca Spermatazoa are the most diverse cell type in the animal kingdom. In many animal taxa, sperm variation across and within species has been shown to be associated with the degree of postcopulatory sexual selection and fertilization conditions. For example, promiscuous species have reduced intraspecific sperm morphometric variation and internal fertilization is linked with more complex sperm designs. Tardigrades are micrometazoans best known for their cryptobiotic ability (i.e. a reversible dormant state when environmental conditions are unfavourable). Moreover, they have incredible yet unexplored variation in reproductive biology and gametes. I quantified the variation in tardigrade primary reproductive traits (e.g. relative gonad size, sperm and egg morphology) at intra- and inter-specific levels. I also investigated the relative roles of the evolutionary processes of natural (egg shell complexity) and sexual (presence of the spermatheca) selection on tardigrade sperm design. My comparative approach used data from 12 Macrobiotus species (order: Parachela). I found a large difference in the effect size of the relative midpiece length in the species with and without the spermatheca, indicating that the prolonged storage requires more energy that is generated in the midpiece.
    [Show full text]
  • SCOTT PITNICK Center for Reproductive Evolution
    CURRICULUM VITAE SCOTT PITNICK Center for Reproductive Evolution & Department of Biology Syracuse University, Syracuse, NY 13244 Office phone: (315) 443-5128 Lab phone: (315) 443-7248 Email: [email protected] Fax: (315) 443-2156 Webpage: http://asfaculty.syr.edu/pages/bio/Pitnick-Scott.html EDUCATION Cornell University B.S., Entomology 1986 Arizona State University Ph.D., Zoology 1992 POSITIONS HELD Institution Title Year Syracuse University Weeden Professor of Biology (endowed) 2014-present Professor of Biology 2009-present Associate Professor of Biology 2001-2009 Assistant Professor of Biology 1996-2001 Bowling Green St. Univ. NSF Postdoctoral Fellow 1994-1996 Arizona State University Postdoctoral Associate 1993-1994 Center for Insect Science Graduate Fellow 1990-1992 AWARDS AND RECOGNITION • Weeden Professorship in Biology (2014 – present) – I am the inaugural recipient of this endowed professorship in Syracuse University’s College of Arts and Sciences, made possible by a generous gift by Mike and Jane Weeden (5 year, renewable appointment). • Silver Sperm Award (2013) – A biennial award presented at the Biology of Spermatozoa Conference, UK (highest honor given by international group of my most immediate peers). • Faculty of 1000 Biology – six publications highlighted (27, 29, 34, 36, 41, 44). • Cover Art Competition (2013) for Reproduction, the journal of the Society for Reproduction and Fertility – Winner (http://www.reproduction- online.org/content/145/4.cover-expansion). • Nikon, Small World in Motion Competition (2012) – Second Place (http://www.nikonsmallworld.com/galleries/swim/2012-small-world-in-motion- competition). • Olympus Bioscapes International Digital Imaging Competition (2012) – Honorable Mention (http://www.olympusbioscapes.com/gallery/year/2012 -- our video of fluorescently-tagged sperm in vivo was included in a museum tour sponsored by Olympus America in cooperation with Scientific American, touring cities across the U.S.
    [Show full text]
  • Sexual Selection and the Evolution of Mating Systems in Flies
    Sexual selection and the evolution of mating systems in flies Gerald S. Wilkinson* and Philip M. Johns Department of Biology, University of Maryland *correspondence Department of Biology University of Maryland College Park, MD 20742 Phone: 301-405-6942 Fax: 301-314-9358 Email: [email protected] In: The Biology of the Diptera. (D.K. Yeates and B.M. Weigmann, eds.) pp. 312-339. Columbia University Press, New York Wilkinson and Johns Mating systems in flies I. Introduction Flies are a model group for the study of mating systems because of their extensive evolutionary diversification and ecological variation (see Yeates and Wiegmann, this volume). For example, adults of some species feed on nectar, pollen or other exudates, others suck blood from vertebrate hosts or are exclusively predaceous, and a few are even kleptoparasitic (Sivinski 1999). Larvae of many species are detritovores in semiaquatic or aquatic environments, but parasitic larval forms have also evolved repeatedly, as have plant-feeding forms. Based on classical mating system theory (Emlen & Oring 1977), one would expect that the ecological diversity exhibited by adult flies would influence the form of the mating system. As will become clear from this chapter, to a large extent this prediction is supported. Second, many species of flies in two families, Tephritidae and Drosophilidae, have received extensive study due to their economic importance and use as model organisms respectively (we reworded this, Drosophilidae have no medical or economic importance). The scope, detail and diversity of studies on these groups provide a fertile ground to identify patterns and establish causal mechanisms . Finally, due in part to the development of Drosophila melanogaster as a model system for the study of genetics, Mendelian markers have been available for many years and have been used to quantify parentage and sperm precedence.
    [Show full text]
  • Sperm Form and Function: What Do We Know About the Role of Sexual Selection?
    155 5 REPRODUCTIONREVIEW Sperm form and function: what do we know about the role of sexual selection? Stefan Lüpold1 and Scott Pitnick2 1Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland and 2Center for Reproductive Evolution, Department of Biology, Syracuse University, Syracuse, New York, USA Correspondence should be addressed to S Lüpold; Email: [email protected] 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. Reproduction (2018) 155 R229–R243 Introduction 2009a, Fig. 1). In 1679, Antonie van Leeuwenhoek noted that sperm varied between taxa, and some Sexual selection is widely regarded as the principal 150 years later, Rudolf Wagner illustrated the marked agent underlying the astonishing diversification of differences in the sperm morphology of mammals, sperm morphology. Consistent
    [Show full text]
  • How Sexual Selection Can Drive the Evolution of Costly Sperm Ornamentation Stefan Lüpold1,2*, Mollie K
    LETTER doi:10.1038/nature18005 How sexual selection can drive the evolution of costly sperm ornamentation Stefan Lüpold1,2*, Mollie K. Manier1,3, Nalini Puniamoorthy1,4, Christopher Schoff1, William T. Starmer1, Shannon H. Buckley Luepold1, John M. Belote1 & Scott Pitnick1* Post-copulatory sexual selection (PSS), fuelled by female promiscuity, sperm competition15 and cryptic female choice2. The best-known adap- is credited with the rapid evolution of sperm quality traits across tation to post-copulatory sexual selection (PSS) is the production of diverse taxa1. Yet, our understanding of the adaptive significance of copious sperm. More sperm should nearly always enhance competitive sperm ornaments and the cryptic female preferences driving their fertilization success, thus explaining the widespread positive correlation evolution is extremely limited1,2. Here we review the evolutionary between relative testis size and sperm competition risk15. Taxa with allometry of exaggerated sexual traits (for example, antlers, horns, this adaptation will tend to exhibit positive covariation between the tail feathers, mandibles and dewlaps), show that the giant sperm of strength of PSS and sexual disparity in reproductive potential, similar some Drosophila species are possibly the most extreme ornaments3,4 to the pattern for premating sexual selection. in all of nature and demonstrate how their existence challenges A theoretical conundrum arises, however, when considering that theories explaining the intensity of sexual selection, mating-system PSS also selects for longer sperm in Drosophila3,16–18 and numerous evolution and the fundamental nature of sex differences5–9. We also other taxa1. Because sperm length competes locally for resources with combine quantitative genetic analyses of interacting sex-specific sperm number owing to their spatial and temporal co-occurrence traits in D.
    [Show full text]