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Gordon K, Gonzales P, Lee C, Marcin J, Takashima Y, Lazzaro B, Wolfner M. Drosophila Arc1 is not required for male fertility or sperm competition success. MICROPUBLICATION BIOLOGY 2023; 2023:10.17912/micropub.biology.001053. [PMID: 38089935 PMCID: PMC10714220 DOI: 10.17912/micropub.biology.001053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Figures] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Revised: 11/27/2023] [Accepted: 11/27/2023] [Indexed: 02/01/2024]
Abstract
Activity-regulated cytoskeleton associated protein (Arc1), which is required for synaptic plasticity and metabolism in Drosophila , self-assembles into capsid-like structures that transport mRNAs in extracellular vesicles. In addition to expression in the brain and nervous system, Arc1 is expressed in the male accessory glands, an endothelial tissue that produces male seminal proteins and exosomes that impact male fertility. We thus hypothesized that Arc1 might impact male fertility. We measured the fertility, mating latency, mating duration, and sperm competition performance of Arc1 males relative to controls and found no evidence that Arc1 is required for any of these measures of male fertility.
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Affiliation(s)
- Kathleen Gordon
- Department of Entomology, Cornell University, Ithaca, New York, United States
| | - Patrick Gonzales
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, United States
| | - Caroline Lee
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, United States
| | - Jeremy Marcin
- Department of Entomology, Cornell University, Ithaca, New York, United States
| | - Yoko Takashima
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, United States
| | - Brian Lazzaro
- Department of Entomology, Cornell University, Ithaca, New York, United States
| | - Mariana Wolfner
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, United States
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2
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Chen DS, Clark AG, Wolfner MF. Octopaminergic/tyraminergic Tdc2 neurons regulate biased sperm usage in female Drosophila melanogaster. Genetics 2022; 221:6637517. [PMID: 35809068 PMCID: PMC9339280 DOI: 10.1093/genetics/iyac096] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Accepted: 06/07/2022] [Indexed: 02/07/2023] Open
Abstract
In polyandrous internally fertilizing species, a multiply-mated female can use stored sperm from different males in a biased manner to fertilize her eggs. The female's ability to assess sperm quality and compatibility is essential for her reproductive success, and represents an important aspect of postcopulatory sexual selection. In Drosophila melanogaster, previous studies demonstrated that the female nervous system plays an active role in influencing progeny paternity proportion, and suggested a role for octopaminergic/tyraminergic Tdc2 neurons in this process. Here, we report that inhibiting Tdc2 neuronal activity causes females to produce a higher-than-normal proportion of first-male progeny. This difference is not due to differences in sperm storage or release, but instead is attributable to the suppression of second-male sperm usage bias that normally occurs in control females. We further show that a subset of Tdc2 neurons innervating the female reproductive tract is largely responsible for the progeny proportion phenotype that is observed when Tdc2 neurons are inhibited globally. On the contrary, overactivation of Tdc2 neurons does not further affect sperm storage, release or progeny proportion. These results suggest that octopaminergic/tyraminergic signaling allows a multiply-mated female to bias sperm usage, and identify a new role for the female nervous system in postcopulatory sexual selection.
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Affiliation(s)
- Dawn S Chen
- Department of Molecular Biology and Genetics, Cornell University, Ithaca NY 14853, USA
| | - Andrew G Clark
- Department of Molecular Biology and Genetics, Cornell University, Ithaca NY 14853, USA
| | - Mariana F Wolfner
- Department of Molecular Biology and Genetics, Cornell University, Ithaca NY 14853, USA
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3
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Patlar B, Civetta A. Seminal fluid gene expression and reproductive fitness in Drosophila melanogaster. BMC Ecol Evol 2022; 22:20. [PMID: 35196983 PMCID: PMC8867848 DOI: 10.1186/s12862-022-01975-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Accepted: 02/15/2022] [Indexed: 11/24/2022] Open
Abstract
Background The rapid evolution of seminal fluid proteins (SFPs) has been suggested to be driven by adaptations to postcopulatory sexual selection (e.g. sperm competition). However, we have recently shown that most SFPs evolve rapidly under relaxed selective pressures. Given the role of SFPs in competition for fertilization phenotypes, like the ability to transfer and store sperm and the modulation of female receptivity and ovulation, the prevalence of selectively relaxed SFPs appears as a conundrum. One possible explanation is that selection on SFPs might be relaxed in terms of protein amino acid content, but adjustments of expression are essential for post-mating function. Interestingly, there is a general lack of systematic implementation of gene expression perturbation assays to monitor their effect on phenotypes related to sperm competition. Results We successfully manipulated the expression of 16 SFP encoding genes using tissue-specific knockdowns (KDs) and determined the effect of these genes’ perturbation on three important post-mating phenotypes: female refractoriness to remating, defensive (P1), and offensive (P2) sperm competitive abilities in Drosophila melanogaster. Our analyses show that KDs of tested SFP genes do not affect female refractoriness to remating and P2, however, most gene KDs significantly decreased P1. Moreover, KDs of SFP genes that are selectively constrained in terms of protein-coding sequence evolution have lower P1 than KDs of genes evolving under relaxed selection. Conclusions Our results suggest a more predominant role, than previously acknowledged, of variation in gene expression than coding sequence changes on sperm competitive ability in D. melanogaster. Supplementary Information The online version contains supplementary material available at 10.1186/s12862-022-01975-1.
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Affiliation(s)
- Bahar Patlar
- Department of Biology, University of Winnipeg, Winnipeg, MB, R3B 2E9, Canada
| | - Alberto Civetta
- Department of Biology, University of Winnipeg, Winnipeg, MB, R3B 2E9, Canada.
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4
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Moyle LC, Wu M, Gibson MJS. Reproductive Proteins Evolve Faster Than Non-reproductive Proteins Among Solanum Species. FRONTIERS IN PLANT SCIENCE 2021; 12:635990. [PMID: 33912206 PMCID: PMC8072272 DOI: 10.3389/fpls.2021.635990] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 03/01/2021] [Indexed: 05/13/2023]
Abstract
Elevated rates of evolution in reproductive proteins are commonly observed in animal species, and are thought to be driven by the action of sexual selection and sexual conflict acting specifically on reproductive traits. Whether similar patterns are broadly observed in other biological groups is equivocal. Here, we examine patterns of protein divergence among wild tomato species (Solanum section Lycopersicon), to understand forces shaping the evolution of reproductive genes in this diverse, rapidly evolving plant clade. By comparing rates of molecular evolution among loci expressed in reproductive and non-reproductive tissues, our aims were to test if: (a) reproductive-specific loci evolve more rapidly, on average, than non-reproductive loci; (b) 'male'-specific loci evolve at different rates than 'female'-specific loci; (c) genes expressed exclusively in gametophytic (haploid) tissue evolve differently from genes expressed in sporophytic (diploid) tissue or in both tissue types; and (d) mating system variation (a potential proxy for the expected strength of sexual selection and/or sexual conflict) affects patterns of protein evolution. We observed elevated evolutionary rates in reproductive proteins. However, this pattern was most evident for female- rather than male-specific loci, both broadly and for individual loci inferred to be positively selected. These elevated rates might be facilitated by greater tissue-specificity of reproductive proteins, as faster rates were also associated with more narrow expression domains. In contrast, we found little evidence that evolutionary rates are consistently different in loci experiencing haploid selection (gametophytic-exclusive loci), or in lineages with quantitatively different mating systems. Overall while reproductive protein evolution is generally elevated in this diverse plant group, some specific patterns of evolution are more complex than those reported in other (largely animal) systems, and include a more prominent role for female-specific loci among adaptively evolving genes.
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5
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Wigby S, Brown NC, Allen SE, Misra S, Sitnik JL, Sepil I, Clark AG, Wolfner MF. The Drosophila seminal proteome and its role in postcopulatory sexual selection. Philos Trans R Soc Lond B Biol Sci 2020; 375:20200072. [PMID: 33070726 DOI: 10.1098/rstb.2020.0072] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Postcopulatory sexual selection (PCSS), comprised of sperm competition and cryptic female choice, has emerged as a widespread evolutionary force among polyandrous animals. There is abundant evidence that PCSS can shape the evolution of sperm. However, sperm are not the whole story: they are accompanied by seminal fluid substances that play many roles, including influencing PCSS. Foremost among seminal fluid models is Drosophila melanogaster, which displays ubiquitous polyandry, and exhibits intraspecific variation in a number of seminal fluid proteins (Sfps) that appear to modulate paternity share. Here, we first consolidate current information on the identities of D. melanogaster Sfps. Comparing between D. melanogaster and human seminal proteomes, we find evidence of similarities between many protein classes and individual proteins, including some D. melanogaster Sfp genes linked to PCSS, suggesting evolutionary conservation of broad-scale functions. We then review experimental evidence for the functions of D. melanogaster Sfps in PCSS and sexual conflict. We identify gaps in our current knowledge and areas for future research, including an enhanced identification of PCSS-related Sfps, their interactions with rival sperm and with females, the role of qualitative changes in Sfps and mechanisms of ejaculate tailoring. This article is part of the theme issue 'Fifty years of sperm competition'.
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Affiliation(s)
- Stuart Wigby
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool L69 7ZB, UK.,Faculty Biology, Applied Zoology, Technische Universität Dresden, 01069 Dresden, Germany
| | - Nora C Brown
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA
| | - Sarah E Allen
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA
| | - Snigdha Misra
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA
| | - Jessica L Sitnik
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA
| | - Irem Sepil
- Department of Zoology, University of Oxford, Oxford OX1 3PS, UK
| | - Andrew G Clark
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA
| | - Mariana F Wolfner
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA
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6
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Abstract
It has long been acknowledged that changes in the regulation of gene expression may account for major organismal differences. However, we still do not fully understand how changes in gene expression evolve and how do such changes influence organisms' differences. We are even less aware of the impact such changes might have in restricting gene flow between species. Here, we focus on studies of gene expression and speciation in the Drosophila model. We review studies that have identified gene interactions in post-mating reproductive isolation and speciation, particularly those that modulate male gene expression. We also address studies that have experimentally manipulated changes in gene expression to test their effect in post-mating reproductive isolation. We highlight the need for a more in-depth analysis of the role of selection causing disrupted gene expression of such candidate genes in sterile/inviable hybrids. Moreover, we discuss the relevance to incorporate more routinely assays that simultaneously evaluate the potential effects of environmental factors and genetic background in modulating plastic responses in male genes and their potential role in speciation.
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Affiliation(s)
- Bahar Patlar
- Department of Biology, University of Winnipeg, Winnipeg, MB R3B 2E9, Canada.,Department of Biology, University of Winnipeg, Winnipeg, MB R3B 2E9, Canada
| | - Alberto Civetta
- Department of Biology, University of Winnipeg, Winnipeg, MB R3B 2E9, Canada
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7
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Davis H, Sosulski N, Civetta A. Reproductive isolation caused by azoospermia in sterile male hybrids of Drosophila. Ecol Evol 2020; 10:5922-5931. [PMID: 32607201 PMCID: PMC7319132 DOI: 10.1002/ece3.6329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 03/16/2020] [Accepted: 04/14/2020] [Indexed: 11/12/2022] Open
Abstract
Recently diverged populations in the early stages of speciation offer an opportunity to understand mechanisms of isolation and their relative contributions. Drosophila willistoni is a tropical species with broad distribution from Argentina to the southern United States, including the Caribbean islands. A postzygotic barrier between northern populations (North America, Central America, and the northern Caribbean islands) and southern populations (South American and the southern Caribbean islands) has been recently documented and used to propose the existence of two different subspecies. Here, we identify premating isolation between populations regardless of their subspecies status. We find no evidence of postmating prezygotic isolation and proceeded to characterize hybrid male sterility between the subspecies. Sterile male hybrids transfer an ejaculate that is devoid of sperm but causes elongation and expansion of the female uterus. In sterile male hybrids, bulging of the seminal vesicle appears to impede the movement of the sperm toward the sperm pump, where sperm normally mixes with accessory gland products. Our results highlight a unique form of hybrid male sterility in Drosophila that is driven by a mechanical impediment to transfer sperm rather than by an abnormality of the sperm itself. Interestingly, this form of sterility is reminiscent of a form of infertility (azoospermia) that is caused by lack of sperm in the semen due to blockages that impede the sperm from reaching the ejaculate.
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Affiliation(s)
- Hunter Davis
- Department of BiologyUniversity of WinnipegWinnipegMBCanada
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8
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McGeary MK, Findlay GD. Molecular evolution of the sex peptide network in Drosophila. J Evol Biol 2020; 33:629-641. [PMID: 31991034 DOI: 10.1111/jeb.13597] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2019] [Revised: 01/07/2020] [Accepted: 01/20/2020] [Indexed: 12/18/2022]
Abstract
Successful reproduction depends on interactions between numerous proteins beyond those involved directly in gamete fusion. Although such reproductive proteins evolve in response to sexual selection pressures, how networks of interacting proteins arise and evolve as reproductive phenotypes change remains an open question. Here, we investigated the molecular evolution of the 'sex peptide network' of Drosophila melanogaster, a functionally well-characterized reproductive protein network. In this species, the peptide hormone sex peptide (SP) and its interacting proteins cause major changes in female physiology and behaviour after mating. In contrast, females of more distantly related Drosophila species do not respond to SP. In spite of these phenotypic differences, we detected orthologs of all network proteins across 22 diverse Drosophila species and found evidence that most orthologs likely function in reproduction throughout the genus. Within SP-responsive species, we detected the recurrent, adaptive evolution of several network proteins, consistent with sexual selection acting to continually refine network function. We also found some evidence for adaptive evolution of several proteins along two specific phylogenetic lineages that correspond with increased expression of the SP receptor in female reproductive tracts or increased sperm length, respectively. Finally, we used gene expression profiling to examine the likely degree of functional conservation of the paralogs of an SP network protein that arose via gene duplication. Our results suggest a dynamic history for the SP network in which network members arose before the onset of robust SP-mediated responses and then were shaped by both purifying and positive selection.
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Affiliation(s)
- Meaghan K McGeary
- Department of Biology, College of the Holy Cross, Worcester, Massachusetts.,Department of Pathology, Yale School of Medicine, New Haven, Connecticut
| | - Geoffrey D Findlay
- Department of Biology, College of the Holy Cross, Worcester, Massachusetts
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9
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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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10
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Chen DS, Delbare SYN, White SL, Sitnik J, Chatterjee M, DoBell E, Weiss O, Clark AG, Wolfner MF. Female Genetic Contributions to Sperm Competition in Drosophila melanogaster. Genetics 2019; 212:789-800. [PMID: 31101677 PMCID: PMC6614900 DOI: 10.1534/genetics.119.302284] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Accepted: 05/11/2019] [Indexed: 11/18/2022] Open
Abstract
In many species, sperm can remain viable in the reproductive tract of a female well beyond the typical interval to remating. This creates an opportunity for sperm from different males to compete for oocyte fertilization inside the female's reproductive tract. In Drosophila melanogaster, sperm characteristics and seminal fluid content affect male success in sperm competition. On the other hand, although genome-wide association studies (GWAS) have demonstrated that female genotype plays a role in sperm competition outcome as well, the biochemical, sensory, and physiological processes by which females detect and selectively use sperm from different males remain elusive. Here, we functionally tested 26 candidate genes implicated via a GWAS for their contribution to the female's role in sperm competition, measured as changes in the relative success of the first male to mate (P1). Of these 26 candidates, we identified eight genes that affect P1 when knocked down in females, and showed that five of them do so when knocked down in the female nervous system. In particular, Rim knockdown in sensory pickpocket (ppk)+ neurons lowered P1, confirming previously published results, and a novel candidate, caup, lowered P1 when knocked down in octopaminergic Tdc2+ neurons. These results demonstrate that specific neurons in the female's nervous system play a functional role in sperm competition and expand our understanding of the genetic, neuronal, and mechanistic basis of female responses to multiple matings. We propose that these neurons in females are used to sense, and integrate, signals from courtship or ejaculates, to modulate sperm competition outcome accordingly.
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Affiliation(s)
- Dawn S Chen
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853-2703
| | - Sofie Y N Delbare
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853-2703
| | - Simone L White
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853-2703
| | - Jessica Sitnik
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853-2703
| | - Martik Chatterjee
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853-2703
| | - Elizabeth DoBell
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853-2703
| | - Orli Weiss
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853-2703
| | - Andrew G Clark
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853-2703
| | - Mariana F Wolfner
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853-2703
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11
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Poikela N, Kinnunen J, Wurdack M, Kauranen H, Schmitt T, Kankare M, Snook RR, Hoikkala A. Strength of sexual and postmating prezygotic barriers varies between sympatric populations with different histories and species abundances. Evolution 2019; 73:1182-1199. [PMID: 30957216 DOI: 10.1111/evo.13732] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Accepted: 03/14/2019] [Indexed: 12/23/2022]
Abstract
The impact of different reproductive barriers on species or population isolation may vary in different stages of speciation depending on evolutionary forces acting within species and through species' interactions. Genetic incompatibilities between interacting species are expected to reinforce prezygotic barriers in sympatric populations and lead to cascade reinforcement between conspecific populations living within and outside the areas of sympatry. We tested these predictions and studied whether and how the strength and target of reinforcement between Drosophila montana and Drosophila flavomontana vary between sympatric populations with different histories and species abundances. All barriers between D. montana females and D. flavomontana males were nearly complete, while in the reciprocal cross strong postzygotic isolation was accompanied by prezygotic barriers whose strength varied according to population composition. Sexual isolation between D. flavomontana females and D. montana males was increased in long-established sympatric populations, where D. flavomontana is abundant, while postmating prezygotic (PMPZ) barriers were stronger in populations where this species is a new invader and still rare and where female discrimination against heterospecific males was lower. Strengthening of sexual and PMPZ barriers in this cross also induced cascade reinforcement of respective barriers between D. flavomontana populations, which is a classic signature of reinforcement process.
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Affiliation(s)
- Noora Poikela
- Department of Biological and Environmental Science, University of Jyväskylä, Jyväskylä, Finland.,Department of Animal Ecology and Tropical Biology, University of Würzburg, Würzburg, Germany
| | - Johanna Kinnunen
- Department of Biological and Environmental Science, University of Jyväskylä, Jyväskylä, Finland
| | - Mareike Wurdack
- Department of Animal Ecology and Tropical Biology, University of Würzburg, Würzburg, Germany
| | - Hannele Kauranen
- Department of Biological and Environmental Science, University of Jyväskylä, Jyväskylä, Finland
| | - Thomas Schmitt
- Department of Animal Ecology and Tropical Biology, University of Würzburg, Würzburg, Germany
| | - Maaria Kankare
- Department of Biological and Environmental Science, University of Jyväskylä, Jyväskylä, Finland
| | - Rhonda R Snook
- Department of Zoology, Stockholm University, Stockholm, Sweden
| | - Anneli Hoikkala
- Department of Biological and Environmental Science, University of Jyväskylä, Jyväskylä, Finland
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12
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Castillo DM, Moyle LC. Conspecific sperm precedence is reinforced, but postcopulatory sexual selection weakened, in sympatric populations of Drosophila. Proc Biol Sci 2019; 286:20182535. [PMID: 30900533 PMCID: PMC6452082 DOI: 10.1098/rspb.2018.2535] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Accepted: 03/06/2019] [Indexed: 12/21/2022] Open
Abstract
Sexual selection can accelerate speciation by driving the evolution of reproductive isolation, but forces driving speciation could also reciprocally feedback on sexual selection. This might be particularly important in the context of 'reinforcement', where selection acts directly to increase prezygotic barriers to reduce the cost of heterospecific matings. Using assays of sperm competition within and between two sister species, we show a signature of reinforcement where these species interact: populations of Drosophila pseudoobscura that co-occur with sister species D. persimilis have an elevated ability to outcompete heterospecific sperm, consistent with selection for increased postcopulatory isolation. We also find these D. pseudoobscura populations have decreased sperm competitive ability against conspecifics, reducing the opportunity for sexual selection within these populations. Our findings demonstrate that direct selection to increase reproductive isolation against other species can compromise the efficacy of sexual selection within species, a collateral effect of reproductive traits responding to heterospecific interactions.
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Affiliation(s)
- Dean M. Castillo
- Department of Biology, Indiana University, 1001 East Third Street, Bloomington, IN 47405, USA
- Department of Molecular Biology and Genetics, Cornell University, 526 Campus Road, Ithaca, NY 14853, USA
| | - Leonie C. Moyle
- Department of Biology, Indiana University, 1001 East Third Street, Bloomington, IN 47405, USA
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13
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Singh A, Buehner NA, Lin H, Baranowski KJ, Findlay GD, Wolfner MF. Long-term interaction between Drosophila sperm and sex peptide is mediated by other seminal proteins that bind only transiently to sperm. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2018; 102:43-51. [PMID: 30217614 PMCID: PMC6249070 DOI: 10.1016/j.ibmb.2018.09.004] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Revised: 08/28/2018] [Accepted: 09/10/2018] [Indexed: 05/23/2023]
Abstract
Seminal fluid proteins elicit several post-mating physiological changes in mated Drosophila melanogaster females. Some of these changes persist for over a week after mating because the seminal protein that causes these changes, the Sex Peptide (SP), binds to sperm that are stored in the female reproductive tract. SP's sperm binding is mediated by a network of at least eight seminal proteins. We show here that some of these network proteins (CG1656, CG1652, CG9997 and Antares) bind to sperm within 2 h of mating, like SP. However, while SP remains bound to sperm at 4 days post-mating, none of the other network proteins are detectable at this time. We also observed that the same network proteins are detectable at 2 h post-mating in seminal receptacle tissue from which sperm have been removed, but are no longer detectable there by 4 days post-mating, suggesting short-term retention of these proteins in this female sperm storage organ. Our results suggest that these network proteins act transiently to facilitate the conditions for SP's binding to sperm, perhaps by modifying SP or the sperm surface, but are not part of a long-acting complex that stably attaches SP to sperm.
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Affiliation(s)
- Akanksha Singh
- Dept. of Molecular Biology & Genetics, Cornell University, Ithaca, NY, 14853, USA
| | - Norene A Buehner
- Dept. of Molecular Biology & Genetics, Cornell University, Ithaca, NY, 14853, USA
| | - He Lin
- Dept. of Molecular Biology & Genetics, Cornell University, Ithaca, NY, 14853, USA; East China Normal University, Shanghai, China
| | | | - Geoffrey D Findlay
- Dept. of Molecular Biology & Genetics, Cornell University, Ithaca, NY, 14853, USA; Dept. of Biology, College of the Holy Cross, Worcester, MA, 01610, USA
| | - Mariana F Wolfner
- Dept. of Molecular Biology & Genetics, Cornell University, Ithaca, NY, 14853, USA.
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14
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Garlovsky MD, Snook RR. Persistent postmating, prezygotic reproductive isolation between populations. Ecol Evol 2018; 8:9062-9073. [PMID: 30271566 PMCID: PMC6157668 DOI: 10.1002/ece3.4441] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 06/23/2018] [Accepted: 07/09/2018] [Indexed: 12/23/2022] Open
Abstract
Studying reproductive barriers between populations of the same species is critical to understand how speciation may proceed. Growing evidence suggests postmating, prezygotic (PMPZ) reproductive barriers play an important role in the evolution of early taxonomic divergence. However, the contribution of PMPZ isolation to speciation is typically studied between species in which barriers that maintain isolation may not be those that contributed to reduced gene flow between populations. Moreover, in internally fertilizing animals, PMPZ isolation is related to male ejaculate-female reproductive tract incompatibilities but few studies have examined how mating history of the sexes can affect the strength of PMPZ isolation and the extent to which PMPZ isolation is repeatable or restricted to particular interacting genotypes. We addressed these outstanding questions using multiple populations of Drosophila montana. We show a recurrent pattern of PMPZ isolation, with flies from one population exhibiting reproductive incompatibility in crosses with all three other populations, while those three populations were fully fertile with each other. Reproductive incompatibility is due to lack of fertilization and is asymmetrical, affecting female fitness more than males. There was no effect of male or female mating history on reproductive incompatibility, indicating that PMPZ isolation persists between populations. We found no evidence of variability in fertilization outcomes attributable to different female × male genotype interactions, and in combination with our other results, suggests that PMPZ isolation is not driven by idiosyncratic genotype × genotype interactions. Our results show PMPZ isolation as a strong, consistent barrier to gene flow early during speciation and suggest several targets of selection known to affect ejaculate-female reproductive tract interactions within species that may cause this PMPZ isolation.
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Affiliation(s)
| | - Rhonda R. Snook
- Department of Animal and Plant SciencesUniversity of SheffieldSheffieldUK
- Department of ZoologyStockholm UniversityStockholmSweden
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15
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Lobov AA, Maltseva AL, Starunov VV, Babkina IY, Ivanov VA, Mikhailova NA, Granovitch AI. LOSP: A putative marker of parasperm lineage in male reproductive system of the prosobranch mollusk Littorina obtusata. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2018; 330:193-201. [PMID: 29750393 DOI: 10.1002/jez.b.22803] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Revised: 03/20/2018] [Accepted: 04/11/2018] [Indexed: 12/15/2022]
Abstract
Reproductive isolation is the key attribute of biological species and establishment of the reproductive barriers is an essential event for speciation. Among the mechanisms of reproductive isolation, gamete incompatibility due to the variability of gamete interaction proteins may drive fast divergence even in sympatry. However, the number of available models to study this phenomenon is limited. In case of internally fertilized invertebrates, models to study gamete incompatibility and sperm competition mechanisms are restricted to a single taxon: insects. Here, we propose a group of closely related Littorina species as a new model for such studies. Particularly since periwinkles are already thoroughly studied in terms of morphology, physiology, ecology, phylogeny, and ecological speciation. Earlier, we have identified the first species-specific Littorina sperm protein (LOSP) with no known conservative domains or homologies. LOSP is relatively abundant component of sperm extracts and might be involved in gamete incompatibility. Here, we characterize its definitive localization and mRNA expression pattern in the male reproductive system by immunocytochemistry and RNA in situ hybridization. We demonstrate that LOSP distribution is limited to the parasperm cells. Losp gene expression occurs only at the early stages of parasperm development. The protein is stored within granules of mature parasperm and, most likely, is released after ejaculation inside female reproductive system. Thus, LOSP is the only described molluscan paraspermal protein to date, and there is a possibility for LOSP to be involved in gamete incompatibility since heterospermy is a common phenomenon among Littorina.
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Affiliation(s)
- Arseniy A Lobov
- Department of Invertebrate Zoology, Faculty of Biology, St Petersburg State University, St. Petersburg, Russia
| | - Arina L Maltseva
- Department of Invertebrate Zoology, Faculty of Biology, St Petersburg State University, St. Petersburg, Russia
| | - Viktor V Starunov
- Department of Invertebrate Zoology, Faculty of Biology, St Petersburg State University, St. Petersburg, Russia.,Zoological Institute of RAS, St. Petersburg, Russia
| | - Irina Y Babkina
- Department of Invertebrate Zoology, Faculty of Biology, St Petersburg State University, St. Petersburg, Russia
| | - Vadim A Ivanov
- Laboratory of Tumor growth cytology, Institute of Cytology RAS, St. Petersburg, Russia
| | - Natalia A Mikhailova
- Department of Invertebrate Zoology, Faculty of Biology, St Petersburg State University, St. Petersburg, Russia.,Centre of Cell Technologies, Institute of Cytology RAS, St. Petersburg, Russia
| | - Andrey I Granovitch
- Department of Invertebrate Zoology, Faculty of Biology, St Petersburg State University, St. Petersburg, Russia
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16
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Moving Speciation Genetics Forward: Modern Techniques Build on Foundational Studies in Drosophila. Genetics 2018; 207:825-842. [PMID: 29097397 DOI: 10.1534/genetics.116.187120] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Accepted: 06/23/2017] [Indexed: 12/12/2022] Open
Abstract
The question of how new species evolve has been examined at every level, from macroevolutionary patterns of diversification to molecular population genetic analyses of specific genomic regions between species pairs. Drosophila has been at the center of many of these research efforts. Though our understanding of the speciation process has grown considerably over the past few decades, very few genes have been identified that contribute to barriers to reproduction. The development of advanced molecular genetic and genomic methods provides promising avenues for the rapid discovery of more genes that contribute to speciation, particularly those involving prezygotic isolation. The continued expansion of tools and resources, especially for species other than Drosophila melanogaster, will be most effective when coupled with comparative approaches that reveal the genetic basis of reproductive isolation across a range of divergence times. Future research programs in Drosophila have high potential to answer long-standing questions in speciation. These include identifying the selective forces that contribute to divergence between populations and the genetic basis of traits that cause reproductive isolation. The latter can be expanded upon to understand how the genetic basis of reproductive isolation changes over time and whether certain pathways and genes are more commonly involved.
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17
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Tinghitella RM, Lackey ACR, Martin M, Dijkstra PD, Drury JP, Heathcote R, Keagy J, Scordato ESC, Tyers AM. On the role of male competition in speciation: a review and research agenda. Behav Ecol 2017. [DOI: 10.1093/beheco/arx151] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Affiliation(s)
| | - Alycia C R Lackey
- Department of Biological Sciences, Watershed Studies Institute, Murray State University, Murray, KY, USA
| | - Michael Martin
- Department of Biology, Oxford College of Emory University, Oxford, GA, USA
| | - Peter D Dijkstra
- Department of Biology, Central Michigan University, Mount Pleasant, MI, USA
| | - Jonathan P Drury
- Department of Ecology & Evolutionary Biology, University of California, Los Angeles, Los Angeles, CA, USA
| | - Robert Heathcote
- Centre for Research in Animal Behaviour, College of Life and Environmental Sciences, University of Exeter, Exeter, UK
| | - Jason Keagy
- Department of Animal Biology, School of Integrative Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Elizabeth S C Scordato
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO, USA
| | - Alexandra M Tyers
- Molecular Ecology and Fisheries Genetics Laboratory, School of Biological Sciences, Bangor, Gwynedd,, Wales, UK
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18
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Cooper JC, Phadnis N. Parallel Evolution of Sperm Hyper-Activation Ca2+ Channels. Genome Biol Evol 2017; 9:1938-1949. [PMID: 28810709 PMCID: PMC5553355 DOI: 10.1093/gbe/evx131] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/09/2017] [Indexed: 01/06/2023] Open
Abstract
Sperm hyper-activation is a dramatic change in sperm behavior where mature sperm burst into a final sprint in the race to the egg. The mechanism of sperm hyper-activation in many metazoans, including humans, consists of a jolt of Ca2+ into the sperm flagellum via CatSper ion channels. Surprisingly, all nine CatSper genes have been independently lost in several animal lineages. In Drosophila, sperm hyper-activation is performed through the cooption of the polycystic kidney disease 2 (pkd2) Ca2+ channel. The parallels between CatSpers in primates and pkd2 in Drosophila provide a unique opportunity to examine the molecular evolution of the sperm hyper-activation machinery in two independent, nonhomologous calcium channels separated by > 500 million years of divergence. Here, we use a comprehensive phylogenomic approach to investigate the selective pressures on these sperm hyper-activation channels. First, we find that the entire CatSper complex evolves rapidly under recurrent positive selection in primates. Second, we find that pkd2 has parallel patterns of adaptive evolution in Drosophila. Third, we show that this adaptive evolution of pkd2 is driven by its role in sperm hyper-activation. These patterns of selection suggest that the evolution of the sperm hyper-activation machinery is driven by sexual conflict with antagonistic ligands that modulate channel activity. Together, our results add sperm hyper-activation channels to the class of fast evolving reproductive proteins and provide insights into the mechanisms used by the sexes to manipulate sperm behavior.
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Bretman A, Rouse J, Westmancoat JD, Chapman T. The role of species-specific sensory cues in male responses to mating rivals in Drosophila melanogaster fruitflies. Ecol Evol 2017; 7:9247-9256. [PMID: 29187965 PMCID: PMC5696429 DOI: 10.1002/ece3.3455] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 08/14/2017] [Accepted: 08/15/2017] [Indexed: 12/02/2022] Open
Abstract
Complex sets of cues can be important in recognizing and responding to conspecific mating competitors and avoiding potentially costly heterospecific competitive interactions. Within Drosophila melanogaster, males can detect sensory inputs from conspecifics to assess the level of competition. They respond to rivals by significantly extending mating duration and gain significant fitness benefits from doing so. Here, we tested the idea that the multiple sensory cues used by D. melanogaster males to detect conspecifics also function to minimize “off‐target” responses to heterospecific males that they might encounter (Drosophila simulans, Drosophila yakuba, Drosophila pseudoobscura, or Drosophila virilis). Focal D. melanogaster males exposed to D. simulans or D. pseudoobscura subsequently increased mating duration, but to a lesser extent than following exposure to conspecific rivals. The magnitude of rivals’ responses expressed by D. melanogaster males did not align with genetic distance between species, and none of the sensory manipulations caused D. melanogaster to respond to males of all other species tested. However, when we removed or provided “false” sensory cues, D. melanogaster males became more likely to show increased mating duration responses to heterospecific males. We suggest that benefits of avoiding inaccurate assessment of the competitive environment may shape the evolution of recognition cues.
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Affiliation(s)
| | - James Rouse
- School of Biology University of Leeds Leeds UK
| | | | - Tracey Chapman
- School of Biological Sciences University of East Anglia Norwich UK
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20
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Two Loci Contribute Epistastically to Heterospecific Pollen Rejection, a Postmating Isolating Barrier Between Species. G3-GENES GENOMES GENETICS 2017; 7:2151-2159. [PMID: 28512086 PMCID: PMC5499124 DOI: 10.1534/g3.117.041673] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Recognition and rejection of heterospecific male gametes occurs in a broad range of taxa, although the complexity of mechanisms underlying these components of postmating cryptic female choice is poorly understood. In plants, the arena for postmating interactions is the female reproductive tract (pistil), within which heterospecific pollen tube growth can be arrested via active molecular recognition and rejection. Unilateral incompatibility (UI) is one such postmating barrier in which pollen arrest occurs in only one direction of an interspecific cross. We investigated the genetic basis of pistil-side UI between Solanum species, with the specific goal of understanding the role and magnitude of epistasis between UI QTL. Using heterospecific introgression lines (ILs) between Solanum pennellii and S. lycopersicum, we assessed the individual and pairwise effects of three chromosomal regions (ui1.1, ui3.1, and ui12.1) previously associated with interspecific UI among Solanum species. Specifically, we generated double introgression (‘pyramided’) genotypes that combined ui12.1 with each of ui1.1 and ui3.1, and assessed the strength of UI pollen rejection in the pyramided lines, compared to single introgression genotypes. We found that none of the three QTL individually showed UI rejection phenotypes, but lines combining ui3.1 and ui12.1 showed significant pistil-side pollen rejection. Furthermore, double ILs (DILs) that combined different chromosomal regions overlapping ui3.1 differed significantly in their rate of UI, consistent with at least two genetic factors on chromosome three contributing quantitatively to interspecific pollen rejection. Together, our data indicate that loci on both chromosomes 3 and 12 are jointly required for the expression of UI between S. pennellii and S. lycopersicum, suggesting that coordinated molecular interactions among a relatively few loci underlie the expression of this postmating prezygotic barrier. In addition, in conjunction with previous data, at least one of these loci appears to also contribute to conspecific self-incompatibility (SI), consistent with a partially shared genetic basis between inter- and intraspecific mechanisms of postmating prezygotic female choice.
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21
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Pease JB, Guerrero RF, Sherman NA, Hahn MW, Moyle LC. Molecular mechanisms of postmating prezygotic reproductive isolation uncovered by transcriptome analysis. Mol Ecol 2016; 25:2592-608. [DOI: 10.1111/mec.13679] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Revised: 04/25/2016] [Accepted: 04/27/2016] [Indexed: 12/22/2022]
Affiliation(s)
- James B. Pease
- Department of Biology Indiana University 1001 East Third Street Bloomington IN 47405 USA
| | - Rafael F. Guerrero
- Department of Biology Indiana University 1001 East Third Street Bloomington IN 47405 USA
| | - Natasha A. Sherman
- Department of Biology Indiana University 1001 East Third Street Bloomington IN 47405 USA
| | - Matthew W. Hahn
- Department of Biology Indiana University 1001 East Third Street Bloomington IN 47405 USA
- School of Informatics and Computing Indiana University 1001 East Third Street Bloomington IN 47405 USA
| | - Leonie C. Moyle
- Department of Biology Indiana University 1001 East Third Street Bloomington IN 47405 USA
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22
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Frazee SR, Masly JP. Multiple sexual selection pressures drive the rapid evolution of complex morphology in a male secondary genital structure. Ecol Evol 2015; 5:4437-50. [PMID: 26664690 PMCID: PMC4667835 DOI: 10.1002/ece3.1721] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Revised: 08/14/2015] [Accepted: 08/19/2015] [Indexed: 12/30/2022] Open
Abstract
The genitalia of internally fertilizing taxa represent a striking example of rapid morphological evolution. Although sexual selection can shape variation in genital morphology, it has been difficult to test whether multiple sexual selection pressures combine to drive the rapid evolution of individual genital structures. Here, we test the hypothesis that both pre‐ and postcopulatory sexual selection can act in concert to shape complex structural variation in secondary genital morphology. We genetically modified the size and shape of the posterior lobes of Drosophila melanogaster males and tested the consequences of morphological variation on several reproductive measures. We found that the posterior lobes are necessary for genital coupling and that they are also the targets of multiple postcopulatory processes that shape quantitative variation in morphology, even though these structures make no direct contact with the external female genitalia or internal reproductive organs during mating. We also found that males with smaller and less structurally complex posterior lobes suffer substantial fitness costs in competitive fertilization experiments. Our results show that sexual selection mechanisms can combine to shape the morphology of a single genital structure and that the posterior lobes of D. melanogaster are the targets of multiple postcopulatory selection pressures.
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Affiliation(s)
- Stephen R Frazee
- Department of Biology University of Oklahoma Norman Oklahoma 73019
| | - John P Masly
- Department of Biology University of Oklahoma Norman Oklahoma 73019
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23
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Bundus JD, Alaei R, Cutter AD. Gametic selection, developmental trajectories, and extrinsic heterogeneity in Haldane's rule. Evolution 2015; 69:2005-17. [PMID: 26102479 DOI: 10.1111/evo.12708] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Accepted: 06/01/2015] [Indexed: 12/31/2022]
Abstract
Deciphering the genetic and developmental causes of the disproportionate rarity, inviability, and sterility of hybrid males, Haldane's rule, is important for understanding the evolution of reproductive isolation between species. Moreover, extrinsic and prezygotic factors can contribute to the magnitude of intrinsic isolation experienced between species with partial reproductive compatibility. Here, we use the nematodes Caenorhabditis briggsae and C. nigoni to quantify the sensitivity of hybrid male viability to extrinsic temperature and developmental timing, and test for a role of mito-nuclear incompatibility as a genetic cause. We demonstrate that hybrid male inviability manifests almost entirely as embryonic, not larval, arrest and is maximal at the lowest rearing temperatures, indicating an intrinsic-by-extrinsic interaction to hybrid inviability. Crosses using mitochondrial substitution strains that have reciprocally introgressed mitochondrial and nuclear genomes show that mito-nuclear incompatibility is not a dominant contributor to postzygotic isolation and does not drive Haldane's rule in this system. Crosses also reveal that competitive superiority of X-bearing sperm provides a novel means by which postmating prezygotic factors exacerbate the rarity of hybrid males. These findings highlight the important roles of gametic, developmental, and extrinsic factors in modulating the manifestation of Haldane's rule.
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Affiliation(s)
- Joanna D Bundus
- Department of Ecology & Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada, M5S 3B2
| | - Ravin Alaei
- Department of Ecology & Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada, M5S 3B2
| | - Asher D Cutter
- Department of Ecology & Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada, M5S 3B2.
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Rodríguez-García MJ, Machado V, Galián J. Identification and characterisation of putative seminal fluid proteins from male reproductive tissue EST libraries in tiger beetles. BMC Genomics 2015; 16:391. [PMID: 25981911 PMCID: PMC4434525 DOI: 10.1186/s12864-015-1619-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2014] [Accepted: 05/05/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The study of proteins transferred through semen can provide important information for biological questions such as adaptive evolution, the origin of new species and species richness. The objective of this study was to identify seminal fluid proteins (SFPs) that may contribute to the study of the reproductive system of tiger beetles (cicindelids), a group of more than 2,500 species distributed worldwide that occupy a great diversity of habitats. RESULTS Two cDNA libraries were constructed from the male gonads of Calomera littoralis and Cephalota litorea. Expressed sequence tags (ESTs) were analysed by bioinformatics approaches and 14 unigenes were selected as candidate SFPs, which were submitted to Reverse Transcription Polymerase Chain Reaction (RT-PCR) to identify patterns of tissue-specific expression. We have identified four novel putative SFPs of cicindelids, of which similarity searches did not show homologues with known function. However, two of the protein classes (immune response and hormone) predicted by Protfun are similar to SFPs reported in other insects. Searches for homology in other cicindelids showed one lineage specific SFPs (rapidly evolving proteins), only present in the closely related species C. littoralis and Lophyra flexuosa and two conserved SFP present in other tiger beetles species tested. CONCLUSIONS This work represents the first characterisation of putative SFPs in Adephagan species of the order Coleoptera. The results will serve as a foundation for further studies aimed to understand gene (and protein) functions and their evolutionary implications in this group of ecologically relevant beetles.
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Affiliation(s)
- María Juliana Rodríguez-García
- Department of Zoology and Physical Anthropology, Faculty of Veterinary, University of Murcia, Campus Mare Nostrum, E-30100, Murcia, Spain.
| | - Vilmar Machado
- Department of Zoology and Physical Anthropology, Faculty of Veterinary, University of Murcia, Campus Mare Nostrum, E-30100, Murcia, Spain.
| | - José Galián
- Department of Zoology and Physical Anthropology, Faculty of Veterinary, University of Murcia, Campus Mare Nostrum, E-30100, Murcia, Spain.
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