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Malmberg J, Martin SH, Gordon IJ, Sihvonen P, Duplouy A. Morphological changes in female reproductive organs in the African monarch butterfly, host to a male-killing Spiroplasma. PeerJ 2023; 11:e15853. [PMID: 37601261 PMCID: PMC10437039 DOI: 10.7717/peerj.15853] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Accepted: 07/16/2023] [Indexed: 08/22/2023] Open
Abstract
Background Sexual selection and conflicts within and between sexes promote morphological diversity of reproductive traits within species. Variation in the morphology of diagnostic reproductive characters within species offer an excellent opportunity to study these evolutionary processes as drivers of species diversification. The African monarch, Danaus chrysippus (Linnaeus, 1758), is widespread across Africa. The species is polytypic, with the respective geographical ranges of the four colour morphs only overlapping in East Africa. Furthermore, some of the populations host an endosymbiotic bacterium, Spiroplasma, which induces son-killing and distorts the local host population sex-ratio, creating sexual conflicts between the females seeking to optimize their fecundity and the limited mating capacity of the rare males. Methods We dissected females from Kenya, Rwanda and South Africa, where Spiroplasma vary in presence and prevalence (high, variable and absent, respectively), and conducted microscopy imaging of their reproductive organs. We then characterized the effect of population, female body size, and female mating status, on the size and shape of different genitalia characters of the D. chrysippus female butterflies. Results We showed that although the general morphology of the organs is conserved in D. chrysippus, female genitalia vary in size and shape between and within populations. The virgin females have smaller organs, while the same organs were expanded in mated females. Females from highly female-biased populations, where the male-killing Spiroplasma is prevalent, also have a larger area of their corpus bursae covered with signa structures. However, this pattern occurs because a larger proportion of the females remains virgin in the female-biased populations rather than because of male depletion due to the symbiont, as males from sex-ratio distorted populations did not produce significantly smaller nutritious spermatophores.
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Affiliation(s)
- Jenny Malmberg
- Organismal and Evolutionary Biology Research Programme, University of Helsinki, Helsinki, Finland
| | - Simon H. Martin
- Institute of Evolutionary Biology, The University of Edinburg, Ashworth Laboratories, Edinburg, UK
| | - Ian J. Gordon
- Centre of Excellence in Biodiversity and Natural Resource Management, Huye Campus, Huye, Rwanda
| | - Pasi Sihvonen
- Organismal and Evolutionary Biology Research Programme, University of Helsinki, Helsinki, Finland
- Finnish Museum of Natural History ‘Luomus’, University of Helsinki, Helsinki, Finland
| | - Anne Duplouy
- Organismal and Evolutionary Biology Research Programme, University of Helsinki, Helsinki, Finland
- Research Center for Ecological Change, University of Helsinki, Helsinki, Finland
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Rutagarama VP, Ireri PM, Sibomana C, Omufwoko KS, Martin SH, ffrench‐Constant RH, Eckardt W, Kaplin BK, Smith DAS, Gordon I. African Queens find mates when males are rare. Ecol Evol 2023; 13:e9956. [PMID: 37021082 PMCID: PMC10067808 DOI: 10.1002/ece3.9956] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 03/06/2023] [Accepted: 03/14/2023] [Indexed: 04/05/2023] Open
Abstract
In butterflies and moths, male-killing endosymbionts are transmitted from infected females via their eggs, and the male progeny then perish. This means that successful transmission of the parasite relies on the successful mating of the host. Paradoxically, at the population level, parasite transmission also reduces the number of adult males present in the final population for infected females to mate with. Here we investigate if successful female mating when males are rare is indeed a likely rate-limiting step in the transmission of male-killing Spiroplasma in the African Monarch, Danaus chrysippus. In Lepidoptera, successful pairings are hallmarked by the transfer of a sperm-containing spermatophore from the male to the female during copulation. Conveniently, this spermatophore remains detectable within the female upon dissection, and thus, spermatophore counts can be used to assess the frequency of successful mating in the field. We used such spermatophore counts to examine if altered sex ratios in the D. chrysippus do indeed affect female mating success. We examined two different field sites in East Africa where males were often rare. Surprisingly, mated females carried an average of 1.5 spermatophores each, regardless of male frequency, and importantly, only 10-20% remained unmated. This suggests that infected females will still be able to mate in the face of either Spiroplasma-mediated male killing and/or fluctuations in adult sex ratio over the wet-dry season cycle. These observations may begin to explain how the male-killing mollicute can still be successfully transmitted in a population where males are rare.
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Affiliation(s)
- Vincent P. Rutagarama
- Department of Biology, College of Science and TechnologyUniversity of RwandaKigaliRwanda
| | - Piera M. Ireri
- International Centre for Insect Physiology and EcologyNairobiKenya
| | - Constantin Sibomana
- Department of Biology, College of Science and TechnologyUniversity of RwandaKigaliRwanda
| | - Kennedy S. Omufwoko
- Department of Ecology and Evolutionary BiologyPrinceton UniversityPrincetonNew JerseyUSA
| | - Simon H. Martin
- Institute of Ecology and Evolution, School of Biological SciencesUniversity of EdinburghEdinburghUK
| | | | | | - Beth K. Kaplin
- Department of Biology, College of Science and TechnologyUniversity of RwandaKigaliRwanda
- Center of Excellence in Biodiversity & Natural Resource ManagementUniversity of RwandaButareRwanda
| | | | - Ian Gordon
- Department of Biology, College of Science and TechnologyUniversity of RwandaKigaliRwanda
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Xochipiltecatl D, Cordero C, Baixeras J. The Functional Morphology of the Bursa Copulatrix of a Butterfly That Does Not Digest Spermatophores ( Leptophobiaaripa, Pieridae). INSECTS 2022; 13:714. [PMID: 36005339 PMCID: PMC9409082 DOI: 10.3390/insects13080714] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 07/07/2022] [Accepted: 07/09/2022] [Indexed: 06/15/2023]
Abstract
The bursa copulatrix of female Lepidoptera is a complex organ where crucial male-female reproductive interactions occur during and after copulation. The bursa copulatrix receives, stores, and digests the spermatophore and other substances transferred by the male during copulation, and is involved in changes in female receptivity, ovogenesis, and oviposition. Although females of the butterfly Leptophobia aripa do not digest the spermatophore, they possess a prominent signum. Since, in general, the function of the signum is considered to be the piercing or tearing of the spermatophore to initiate its digestion, its presence in L. aripa poses a conundrum. We undertook a microscopic study of the different components of the bursa copulatrix (ductus bursae and corpus bursae) and found structural differences that we interpreted in functional terms. We provide a detailed description of the signum and present experimental data regarding its effect on the spermatophore. Our observations led us to propose a novel hypothesis regarding the function of the signum.
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Affiliation(s)
- David Xochipiltecatl
- Posgrado en Ciencias Biológicas, Instituto de Ecología, Universidad Nacional Autónoma de México, Ciudad de Mexico 04510, Mexico
| | - Carlos Cordero
- Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, Ciudad de Mexico 04510, Mexico
| | - Joaquín Baixeras
- Institut Cavanilles de Biodiversitat i Biologia Evolutiva, Universitat de Valencia, Paterna, 6980 Valencia, Spain
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Xochipiltecatl D, Baixeras J, Cordero CR. Atypical functioning of female genitalia explains monandry in a butterfly. PeerJ 2021; 9:e12499. [PMID: 34900425 PMCID: PMC8614189 DOI: 10.7717/peerj.12499] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Accepted: 10/26/2021] [Indexed: 11/20/2022] Open
Abstract
Monandrous species are rare in nature, especially in animals where males transfer nutrients to females in the ejaculate. The proximate mechanisms responsible for monandry are poorly studied. In butterflies and moths, the male transfers a nutritious spermatophore into the corpus bursae (CB) of the female. The CB is a multifunctional organ that digests the spermatophore and has partial control of the post-mating sexual receptivity of the female. The spermatophore distends the CB and the post-mating sexual receptivity of the female is inversely proportional to the degree of distension. The CB of many butterfly species has a muscular sheath whose contractions mechanically contribute to digest the spermatophore. As the contents of the CB are absorbed, the degree of distension decreases and the female recovers receptivity. We studied the monandrous butterfly Leptophobia aripa (Boisduval, 1836) (Pieridae) and found that females do not digest the spermatophores. We investigated the structure of the CB and found that a muscular sheath is absent, indicating that in this butterfly females lack the necessary "apparatus" for the mechanical digestion of the spermatophore. We propose that female monandry in this species is result of its incapability to mechanically digest the spermatophore, which results in a constant degree of CB distension after mating and, thus, in the maintenance of the sexually unreceptive state of females. Hypotheses on the evolution of this mechanism are discussed.
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Affiliation(s)
- David Xochipiltecatl
- Posgrado en Ciencias Biológicas, Instituto de Ecología, Universidad Nacional Autónoma de México, Mexico City, México
| | - Joaquín Baixeras
- Institut Cavanilles de Biodiversitat i Biologia Evolutiva, Universitat de València, Paterna, Valencia, Spain
| | - Carlos R Cordero
- Departamento de Ecología Evolutiva, Universidad Nacional Autónoma de México, Mexico City, México
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Plakke MS, Walker JL, Lombardo JB, Goetz BJ, Pacella GN, Durrant JD, Clark NL, Morehouse NI. Characterization of Female Reproductive Proteases in a Butterfly from Functional and Evolutionary Perspectives. Physiol Biochem Zool 2019; 92:579-590. [DOI: 10.1086/705722] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Sloan NS, Simmons LW. The evolution of female genitalia. J Evol Biol 2019; 32:882-899. [PMID: 31267594 DOI: 10.1111/jeb.13503] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 06/14/2019] [Accepted: 06/21/2019] [Indexed: 02/07/2023]
Abstract
Female genitalia have been largely neglected in studies of genital evolution, perhaps due to the long-standing belief that they are relatively invariable and therefore taxonomically and evolutionarily uninformative in comparison with male genitalia. Contemporary studies of genital evolution have begun to dispute this view, and to demonstrate that female genitalia can be highly diverse and covary with the genitalia of males. Here, we examine evidence for three mechanisms of genital evolution in females: species isolating 'lock-and-key' evolution, cryptic female choice and sexual conflict. Lock-and-key genital evolution has been thought to be relatively unimportant; however, we present cases that show how species isolation may well play a role in the evolution of female genitalia. Much support for female genital evolution via sexual conflict comes from studies of both invertebrate and vertebrate species; however, the effects of sexual conflict can be difficult to distinguish from models of cryptic female choice that focus on putative benefits of choice for females. We offer potential solutions to alleviate this issue. Finally, we offer directions for future studies in order to expand and refine our knowledge surrounding female genital evolution.
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Affiliation(s)
- Nadia S Sloan
- Centre for Evolutionary Biology, School of Biological Sciences (M092), The University of Western Australia, Crawley, Western Australia, Australia
| | - Leigh W Simmons
- Centre for Evolutionary Biology, School of Biological Sciences (M092), The University of Western Australia, Crawley, Western Australia, Australia
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McNamara KB, Dougherty LR, Wedell N, Simmons LW. Experimental evolution reveals divergence in female genital teeth morphology in response to sexual conflict intensity in a moth. J Evol Biol 2019; 32:519-524. [DOI: 10.1111/jeb.13428] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Revised: 01/31/2019] [Accepted: 02/11/2019] [Indexed: 01/01/2023]
Affiliation(s)
- Kathryn B. McNamara
- Centre for Evolutionary Biology School of Biological Sciences (M092) the University of Western Australia Crawley Australia
| | - Liam R. Dougherty
- Institute of Integrative Biology University of Liverpool Liverpool UK
| | - Nina Wedell
- Centre for Ecology and Conservation University of Exeter Penryn UK
| | - Leigh W. Simmons
- Centre for Evolutionary Biology School of Biological Sciences (M092) the University of Western Australia Crawley Australia
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Meslin C, Cherwin TS, Plakke MS, Hill J, Small BS, Goetz BJ, Wheat CW, Morehouse NI, Clark NL. Structural complexity and molecular heterogeneity of a butterfly ejaculate reflect a complex history of selection. Proc Natl Acad Sci U S A 2017; 114:E5406-E5413. [PMID: 28630352 PMCID: PMC5502654 DOI: 10.1073/pnas.1707680114] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Male ejaculates are often structurally complex, and this complexity is likely to influence key reproductive interactions between males and females. However, despite its potential evolutionary significance, the molecular underpinnings of ejaculate structural complexity have received little empirical attention. To address this knowledge gap, we sought to understand the biochemical and functional properties of the structurally complex ejaculates of Pieris rapae butterflies. Males in this species produce large ejaculates called spermatophores composed of an outer envelope, an inner matrix, and a bolus of sperm. Females are thought to benefit from the nutrition contained in the soluble inner matrix through increases in longevity and fecundity. However, the indigestible outer envelope of the spermatophore delays female remating, allowing males to monopolize paternity for longer. Here, we show that these two nonsperm-containing spermatophore regions, the inner matrix and the outer envelope, differ in their protein composition and functional properties. We also reveal how these divergent protein mixtures are separately stored in the male reproductive tract and sequentially transferred to the female reproductive tract during spermatophore assembly. Intriguingly, we discovered large quantities of female-derived proteases in both spermatophore regions shortly after mating, which may contribute to spermatophore digestion and hence, female control over remating rate. Finally, we report evidence of past selection on these spermatophore proteins and female proteases, indicating a complex evolutionary history. Our findings illustrate how structural complexity of ejaculates may allow functionally and/or spatially associated suites of proteins to respond rapidly to divergent selective pressures, such as sexual conflict or reproductive cooperation.
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Affiliation(s)
- Camille Meslin
- Institut National de la Recherche Agronomique (INRA), Institute of Ecology and Environmental Sciences of Paris (IEES-Paris), 78026 Versailles Cedex, France
| | - Tamara S Cherwin
- Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, PA 15260
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260
| | - Melissa S Plakke
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260
| | | | - Brandon S Small
- Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, PA 15260
| | - Breanna J Goetz
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260
| | | | - Nathan I Morehouse
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260;
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH 45221
| | - Nathan L Clark
- Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, PA 15260;
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260
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Plakke MS, Deutsch AB, Meslin C, Clark NL, Morehouse NI. Dynamic digestive physiology of a female reproductive organ in a polyandrous butterfly. ACTA ACUST UNITED AC 2016; 218:1548-55. [PMID: 25994634 DOI: 10.1242/jeb.118323] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Reproductive traits experience high levels of selection because of their direct ties to fitness, often resulting in rapid adaptive evolution. Much of the work in this area has focused on male reproductive traits. However, a more comprehensive understanding of female reproductive adaptations and their relationship to male characters is crucial to uncover the relative roles of sexual cooperation and conflict in driving co-evolutionary dynamics between the sexes. We focus on the physiology of a complex female reproductive adaptation in butterflies and moths: a stomach-like organ in the female reproductive tract called the bursa copulatrix that digests the male ejaculate (spermatophore). Little is known about how the bursa digests the spermatophore. We characterized bursa proteolytic capacity in relation to female state in the polyandrous butterfly Pieris rapae. We found that the virgin bursa exhibits extremely high levels of proteolytic activity. Furthermore, in virgin females, bursal proteolytic capacity increases with time since eclosion and ambient temperature, but is not sensitive to the pre-mating social environment. Post copulation, bursal proteolytic activity decreases rapidly before rebounding toward the end of a mating cycle, suggesting active female regulation of proteolysis and/or potential quenching of proteolysis by male ejaculate constituents. Using transcriptomic and proteomic approaches, we report identities for nine proteases actively transcribed by bursal tissue and/or expressed in the bursal lumen that may contribute to observed bursal proteolysis. We discuss how these dynamic physiological characteristics may function as female adaptations resulting from sexual conflict over female remating rate in this polyandrous butterfly.
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Affiliation(s)
- Melissa S Plakke
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Aaron B Deutsch
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Camille Meslin
- Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Nathan L Clark
- Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Nathan I Morehouse
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
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Cordero-Rivera A. Sperm removal during copulation confirmed in the oldest extant damselfly, Hemiphlebia mirabilis. PeerJ 2016; 4:e2077. [PMID: 27257552 PMCID: PMC4888289 DOI: 10.7717/peerj.2077] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Accepted: 05/03/2016] [Indexed: 11/29/2022] Open
Abstract
Postcopulatory sexual selection may favour mechanisms to reduce sperm competition, like physical sperm removal by males. To investigate the origin of sperm removal, I studied the reproductive behaviour and mechanisms of sperm competition in the only living member of the oldest damselfly family, Hemiphlebia mirabilis, one species that was considered extinct in the 1980s. This species displays scramble competition behaviour. Males search for females with short flights and both sexes exhibit a conspicuous “abdominal flicking”. This behaviour is used by males during an elaborate precopulatory courtship, unique among Odonata. Females use a similar display to reject male attempts to form tandem, but eventually signal receptivity by a particular body position. Males immobilise females during courtship using their legs, which, contrarily to other damselflies, never autotomise. Copulation is short (range 4.1–18.7 min), and occurs in two sequential stages. In the first stage, males remove part of the stored sperm, and inseminate during the second stage, at the end of mating. The male genital ligula matches the size and form of female genitalia, and ends by two horns covered by back-oriented spines. The volume of sperm in females before copulation was 2.7 times larger than the volume stored in females whose copulation was interrupted at the end of stage I, indicative of a significant sperm removal. These results point out that sperm removal is an old character in the evolution of odonates, possibly dating back to the Permian.
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Affiliation(s)
- Adolfo Cordero-Rivera
- ECOEVO Lab, Departamento de Ecoloxía e Bioloxía Animal, Universidade de Vigo , Pontevedra, Galiza , Spain
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Brennan PLR, Prum RO. Mechanisms and Evidence of Genital Coevolution: The Roles of Natural Selection, Mate Choice, and Sexual Conflict. Cold Spring Harb Perspect Biol 2015; 7:a017749. [PMID: 26134314 DOI: 10.1101/cshperspect.a017749] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Genital coevolution between the sexes is expected to be common because of the direct interaction between male and female genitalia during copulation. Here we review the diverse mechanisms of genital coevolution that include natural selection, female mate choice, male-male competition, and how their interactions generate sexual conflict that can lead to sexually antagonistic coevolution. Natural selection on genital morphology will result in size coevolution to allow for copulation to be mechanically possible, even as other features of genitalia may reflect the action of other mechanisms of selection. Genital coevolution is explicitly predicted by at least three mechanisms of genital evolution: lock and key to prevent hybridization, female choice, and sexual conflict. Although some good examples exist in support of each of these mechanisms, more data on quantitative female genital variation and studies of functional morphology during copulation are needed to understand more general patterns. A combination of different approaches is required to continue to advance our understanding of genital coevolution. Knowledge of the ecology and behavior of the studied species combined with functional morphology, quantitative morphological tools, experimental manipulation, and experimental evolution have been provided in the best-studied species, all of which are invertebrates. Therefore, attention to vertebrates in any of these areas is badly needed.
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Affiliation(s)
- Patricia L R Brennan
- Departments of Psychology and Biology, University of Massachusetts, Amherst, MA 01003 Organismic and Evolutionary Biology Graduate Program, University of Massachusetts, Amherst, MA 01003
| | - Richard O Prum
- Department of Ecology and Evolutionary Biology and Peabody Museum of Natural History, Yale University, New Haven, CT 06520
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Meslin C, Plakke MS, Deutsch AB, Small BS, Morehouse NI, Clark NL. Digestive organ in the female reproductive tract borrows genes from multiple organ systems to adopt critical functions. Mol Biol Evol 2015; 32:1567-80. [PMID: 25725432 PMCID: PMC4572785 DOI: 10.1093/molbev/msv048] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Persistent adaptive challenges are often met with the evolution of novel physiological traits. Although there are specific examples of single genes providing new physiological functions, studies on the origin of complex organ functions are lacking. One such derived set of complex functions is found in the Lepidopteran bursa copulatrix, an organ within the female reproductive tract that digests nutrients from the male ejaculate or spermatophore. Here, we characterized bursa physiology and the evolutionary mechanisms by which it was equipped with digestive and absorptive functionality. By studying the transcriptome of the bursa and eight other tissues, we revealed a suite of highly expressed and secreted gene products providing the bursa with a combination of stomach-like traits for mechanical and enzymatic digestion of the male spermatophore. By subsequently placing these bursa genes in an evolutionary framework, we found that the vast majority of their novel digestive functions were co-opted by borrowing genes that continue to be expressed in nonreproductive tissues. However, a number of bursa-specific genes have also arisen, some of which represent unique gene families restricted to Lepidoptera and may provide novel bursa-specific functions. This pattern of promiscuous gene borrowing and relatively infrequent evolution of tissue-specific duplicates stands in contrast to studies of the evolution of novelty via single gene co-option. Our results suggest that the evolution of complex organ-level phenotypes may often be enabled (and subsequently constrained) by changes in tissue specificity that allow expression of existing genes in novel contexts, such as reproduction. The extent to which the selective pressures encountered in these novel roles require resolution via duplication and sub/neofunctionalization is likely to be determined by the need for specialized reproductive functionality. Thus, complex physiological phenotypes such as that found in the bursa offer important opportunities for understanding the relative role of pleiotropy and specialization in adaptive evolution.
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Affiliation(s)
- Camille Meslin
- Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh
| | - Melissa S Plakke
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh
| | - Aaron B Deutsch
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh
| | - Brandon S Small
- Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh
| | | | - Nathan L Clark
- Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh
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