1
|
Sperm morphology and performance in relation to postmating prezygotic isolation in two recently diverged passerine species. Sci Rep 2022; 12:22275. [PMID: 36566302 PMCID: PMC9789955 DOI: 10.1038/s41598-022-26101-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Accepted: 12/09/2022] [Indexed: 12/25/2022] Open
Abstract
Divergence in sperm phenotype and female reproductive environment may be a common source of postmating prezygotic (PMPZ) isolation between species. However, compared to other reproductive barriers it has received much less attention. In this study, we examined sperm morphology and velocity in two hybridizing passerine species, the common nightingale (Luscinia megarhynchos) and thrush nightingale (L. luscinia). In addition, we for the first time characterized a passerine female reproductive tract fluid proteome. We demonstrate that spermatozoa of the common nightingale have significantly longer and wider midpiece (proximal part of the flagellum containing mitochondria) and longer tail compared to spermatozoa of thrush nightingale. On the other hand, they have significantly shorter and narrower acrosome. Importantly, these differences did not have any effect on sperm velocity. Furthermore, the fluid from the reproductive tract of common nightingale females did not differentially affect velocity of conspecific and heterospecific sperm. Our results indicate that the observed changes in the flagellum and acrosome size are unlikely to contribute to PMPZ isolation through differential sperm velocity of conspecific and heterospecific sperm in the female reproductive tract. However, they could affect other postcopulatory processes, which might be involved in PMPZ isolation, such as sperm storage, longevity or sperm-egg interaction.
Collapse
|
2
|
Yusuf LH, Tyukmaeva V, Hoikkala A, Ritchie MG. Divergence and introgression among the virilis group of Drosophila. Evol Lett 2022; 6:537-551. [PMID: 36579165 PMCID: PMC9783487 DOI: 10.1002/evl3.301] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 09/23/2022] [Accepted: 10/12/2022] [Indexed: 12/03/2022] Open
Abstract
Speciation with gene flow is now widely regarded as common. However, the frequency of introgression between recently diverged species and the evolutionary consequences of gene flow are still poorly understood. The virilis group of Drosophila contains 12 species that are geographically widespread and show varying levels of prezygotic and postzygotic isolation. Here, we use de novo genome assemblies and whole-genome sequencing data to resolve phylogenetic relationships and describe patterns of introgression and divergence across the group. We suggest that the virilis group consists of three, rather than the traditional two, subgroups. Some genes undergoing rapid sequence divergence across the group were involved in chemical communication and desiccation tolerance, and may be related to the evolution of sexual isolation and adaptation. We found evidence of pervasive phylogenetic discordance caused by ancient introgression events between distant lineages within the group, and more recent gene flow between closely related species. When assessing patterns of genome-wide divergence in species pairs across the group, we found no consistent genomic evidence of a disproportionate role for the X chromosome as has been found in other systems. Our results show how ancient and recent introgressions confuse phylogenetic reconstruction, but may play an important role during early radiation of a group.
Collapse
Affiliation(s)
- Leeban H. Yusuf
- Centre for Biological Diversity, School of BiologyUniversity of St AndrewsSt AndrewsKY16 9THUnited Kingdom
| | - Venera Tyukmaeva
- Centre for Biological Diversity, School of BiologyUniversity of St AndrewsSt AndrewsKY16 9THUnited Kingdom,Department of Evolution, Ecology and BehaviourUniversity of LiverpoolLiverpoolL69 7ZBUnited Kingdom
| | - Anneli Hoikkala
- Department of Biological and Environmental ScienceUniversity of JyväskyläJyväskylä40014Finland
| | - Michael G. Ritchie
- Centre for Biological Diversity, School of BiologyUniversity of St AndrewsSt AndrewsKY16 9THUnited Kingdom
| |
Collapse
|
3
|
Malec P, Weber J, Böhmer R, Fiebig M, Meinert D, Rein C, Reinisch R, Henrich M, Polyvas V, Pollmann M, von Berg L, König C, Steidle JLM. The emergence of ecotypes in a parasitoid wasp: a case of incipient sympatric speciation in Hymenoptera? BMC Ecol Evol 2021; 21:204. [PMID: 34781897 PMCID: PMC8591844 DOI: 10.1186/s12862-021-01938-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 11/08/2021] [Indexed: 11/24/2022] Open
Abstract
Background To understand which reproductive barriers initiate speciation is a major question in evolutionary research. Despite their high species numbers and specific biology, there are only few studies on speciation in Hymenoptera. This study aims to identify very early reproductive barriers in a local, sympatric population of Nasonia vitripennis (Walker 1836), a hymenopterous parasitoid of fly pupae. We studied ecological barriers, sexual barriers, and the reduction in F1-female offspring as a postmating barrier, as well as the population structure using microsatellites. Results We found considerable inbreeding within female strains and a population structure with either three or five subpopulation clusters defined by microsatellites. In addition, there are two ecotypes, one parasitizing fly pupae in bird nests and the other on carrion. The nest ecotype is mainly formed from one of the microsatellite clusters, the two or four remaining microsatellite clusters form the carrion ecotype. There was slight sexual isolation and a reduction in F1-female offspring between inbreeding strains from the same microsatellite clusters and the same ecotypes. Strains from different microsatellite clusters are separated by a reduction in F1-female offspring. Ecotypes are separated only by ecological barriers. Conclusions This is the first demonstration of very early reproductive barriers within a sympatric population of Hymenoptera. It demonstrates that sexual and premating barriers can precede ecological separation. This indicates the complexity of ecotype formation and highlights the general need for more studies within homogenous populations for the identification of the earliest barriers in the speciation process. Supplementary Information The online version contains supplementary material available at 10.1186/s12862-021-01938-y.
Collapse
Affiliation(s)
- Pawel Malec
- Naturpark Steigerwald E.V., 91443, Scheinfeld, Germany
| | - Justus Weber
- Dep. of Chemical Ecology 190T, Institute of Biology, University of Hohenheim, 70593, Stuttgart, Germany
| | - Robin Böhmer
- Natural History Museum Bern, 3005, Bern, Switzerland
| | - Marc Fiebig
- Untere Naturschutzbehörde, Landratsamt Kitzingen, 97318, Kitzingen, Germany
| | | | - Carolin Rein
- Apicultural State Institute, University of Hohenheim, 70593, Stuttgart, Germany
| | - Ronja Reinisch
- Dep. of Chemical Ecology 190T, Institute of Biology, University of Hohenheim, 70593, Stuttgart, Germany
| | - Maik Henrich
- Wildlife Ecology and Management, University of Freiburg, 79106, Freiburg, Germany
| | - Viktoria Polyvas
- Dep. of Chemical Ecology 190T, Institute of Biology, University of Hohenheim, 70593, Stuttgart, Germany
| | - Marie Pollmann
- Dep. of Chemical Ecology 190T, Institute of Biology, University of Hohenheim, 70593, Stuttgart, Germany
| | - Lea von Berg
- Dep. of Chemical Ecology 190T, Institute of Biology, University of Hohenheim, 70593, Stuttgart, Germany
| | - Christian König
- Akademie für Natur- und Umweltschutz Baden-Württemberg beim Ministerium für Umwelt, Klima und Energiewirtschaft, 70192, Stuttgart, Germany
| | - Johannes L M Steidle
- Dep. of Chemical Ecology 190T, Institute of Biology, University of Hohenheim, 70593, Stuttgart, Germany.
| |
Collapse
|
4
|
Ahmed-Braimah YH, Wolfner MF, Clark AG. Differences in Postmating Transcriptional Responses between Conspecific and Heterospecific Matings in Drosophila. Mol Biol Evol 2021; 38:986-999. [PMID: 33035303 PMCID: PMC7947788 DOI: 10.1093/molbev/msaa264] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
In many animal species, females undergo physiological and behavioral changes after mating. Some of these changes are driven by male-derived seminal fluid proteins and are critical for fertilization success. Unfortunately, our understanding of the molecular interplay between female and male reproductive proteins remains inadequate. Here, we analyze the postmating response in a Drosophila species that has evolved strong gametic incompatibility with its sister species; Drosophila novamexicana females produce only ∼1% fertilized eggs in crosses with Drosophila americana males, compared to ∼98% produced in within-species crosses. This incompatibility is likely caused by mismatched male and female reproductive molecules. In this study, we use short-read RNA sequencing to examine the evolutionary dynamics of female reproductive genes and the postmating transcriptome response in crosses within and between species. First, we found that most female reproductive tract genes are slow-evolving compared to the genome average. Second, postmating responses in con- and heterospecific matings are largely congruent, but heterospecific matings induce expression of additional stress-response genes. Some of those are immunity genes that are activated by the Imd pathway. We also identify several genes in the JAK/STAT signaling pathway that are induced in heterospecific, but not conspecific mating. While this immune response was most pronounced in the female reproductive tract, we also detect it in the female head and ovaries. These results show that the female's postmating transcriptome-level response is determined in part by the genotype of the male, and that divergence in male reproductive genes and/or traits can have immunogenic effects on females.
Collapse
Affiliation(s)
- Yasir H Ahmed-Braimah
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 13850
- Department of Biology, Syracuse University, Syracuse, NY 13244
| | - Mariana F Wolfner
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 13850
| | - Andrew G Clark
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 13850
| |
Collapse
|
5
|
Garlovsky MD, Yusuf LH, Ritchie MG, Snook RR. Within-population sperm competition intensity does not predict asymmetry in conpopulation sperm precedence. Philos Trans R Soc Lond B Biol Sci 2020; 375:20200071. [PMID: 33070721 PMCID: PMC7661444 DOI: 10.1098/rstb.2020.0071] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Postcopulatory sexual selection can generate evolutionary arms races between the sexes resulting in the rapid coevolution of reproductive phenotypes. As traits affecting fertilization success diverge between populations, postmating prezygotic (PMPZ) barriers to gene flow may evolve. Conspecific sperm precedence is a form of PMPZ isolation thought to evolve early during speciation yet has mostly been studied between species. Here, we show conpopulation sperm precedence (CpSP) between Drosophila montana populations. Using Pool-seq genomic data we estimate divergence times and ask whether PMPZ isolation evolved in the face of gene flow. We find models incorporating gene flow fit the data best indicating populations experienced considerable gene flow during divergence. We find CpSP is asymmetric and mirrors asymmetry in non-competitive PMPZ isolation, suggesting these phenomena have a shared mechanism. However, we show asymmetry is unrelated to the strength of postcopulatory sexual selection acting within populations. We tested whether overlapping foreign and coevolved ejaculates within the female reproductive tract altered fertilization success but found no effect. Our results show that neither time since divergence nor sperm competitiveness predicts the strength of PMPZ isolation. We suggest that instead cryptic female choice or mutation-order divergence may drive divergence of postcopulatory phenotypes resulting in PMPZ isolation. This article is part of the theme issue ‘Fifty years of sperm competition’.
Collapse
Affiliation(s)
- Martin D Garlovsky
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK
| | - Leeban H Yusuf
- Centre for Biological Diversity, University of St Andrews, St Andrews KY16 9TH, UK
| | - Michael G Ritchie
- Centre for Biological Diversity, University of St Andrews, St Andrews KY16 9TH, UK
| | - Rhonda R Snook
- Department of Zoology, Stockholm University, Stockholm 106-91, Sweden
| |
Collapse
|
6
|
Garlovsky MD, Evans C, Rosenow MA, Karr TL, Snook RR. Seminal fluid protein divergence among populations exhibiting postmating prezygotic reproductive isolation. Mol Ecol 2020; 29:4428-4441. [DOI: 10.1111/mec.15636] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2020] [Revised: 08/23/2020] [Accepted: 09/04/2020] [Indexed: 12/25/2022]
Affiliation(s)
- Martin D. Garlovsky
- Department of Animal and Plant Sciences The University of Sheffield Sheffield UK
| | - Caroline Evans
- Department of Chemical and Biological Engineering The University of Sheffield Sheffield UK
| | | | - Timothy L. Karr
- Centre for Mechanisms of Evolution The Biodesign Institute Arizona State University Tempe AZ USA
| | | |
Collapse
|
7
|
Singh P, Ballmer DN, Laubscher M, Schärer L. Successful mating and hybridisation in two closely related flatworm species despite significant differences in reproductive morphology and behaviour. Sci Rep 2020; 10:12830. [PMID: 32732887 PMCID: PMC7393371 DOI: 10.1038/s41598-020-69767-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Accepted: 07/20/2020] [Indexed: 12/16/2022] Open
Abstract
Reproductive traits are some of the fastest diverging characters and can serve as reproductive barriers. The free-living flatworm Macrostomum lignano, and its congener M. janickei are closely related, but differ substantially in their male intromittent organ (stylet) morphology. Here, we examine whether these morphological differences are accompanied by differences in behavioural traits, and whether these could represent barriers to successful mating and hybridization between the two species. Our data shows that the two species differ in many aspects of their mating behaviour. Despite these differences, the species mate readily with each other in heterospecific pairings. Although both species have similar fecundity in conspecific pairings, the heterospecific pairings revealed clear postmating barriers, as few heterospecific pairings produced F1 hybrids. These hybrids had a stylet morphology that was intermediate between that of the parental species, and they were fertile. Finally, using a mate choice experiment, we show that the nearly two-fold higher mating rate of M. lignano caused it to mate more with conspecifics, leading to assortative mating, while M. janickei ended up mating more with heterospecifics. Thus, while the two species can hybridize, the mating rate differences could possibly lead to higher fitness costs for M. janickei compared to M. lignano.
Collapse
Affiliation(s)
- Pragya Singh
- Department of Environmental Sciences, Zoological Institute, University of Basel, Vesalgasse 1, 4051, Basel, Switzerland.
| | - Daniel N Ballmer
- Department of Environmental Sciences, Zoological Institute, University of Basel, Vesalgasse 1, 4051, Basel, Switzerland.,Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Max Laubscher
- Department of Environmental Sciences, Zoological Institute, University of Basel, Vesalgasse 1, 4051, Basel, Switzerland
| | - Lukas Schärer
- Department of Environmental Sciences, Zoological Institute, University of Basel, Vesalgasse 1, 4051, Basel, Switzerland
| |
Collapse
|
8
|
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.
Collapse
Affiliation(s)
- Hunter Davis
- Department of BiologyUniversity of WinnipegWinnipegMBCanada
| | | | | |
Collapse
|
9
|
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]
|
10
|
Larson EL, Brassil MM, Maslan J, Juárez D, Lilagan F, Tipton H, Schweitzer A, Skillman J, Monsen-Collar KJ, Peterson MA. The effects of heterospecific mating frequency on the strength of cryptic reproductive barriers. J Evol Biol 2019; 32:900-912. [PMID: 31162735 DOI: 10.1111/jeb.13495] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2019] [Revised: 05/22/2019] [Accepted: 05/28/2019] [Indexed: 01/02/2023]
Abstract
Heterospecific mating frequency is critical to hybrid zone dynamics and can directly impact the strength of reproductive barriers and patterns of introgression. The effectiveness of post-mating prezygotic (PMPZ) reproductive barriers, which include reduced fecundity via heterospecific matings and conspecific sperm precedence, may depend on the number, identity and order of mates. Studies of PMPZ barriers suggest that they may be important in many systems, but whether these barriers are effective at realistic heterospecific mating frequencies has not been tested. Here, we evaluate the strength of cryptic reproductive isolation in two leaf beetles (Chrysochus auratus and C. cobaltinus) in the context of a range of heterospecific mating frequencies observed in natural populations. We found both species benefited from multiple matings, but the benefits were greater in C. cobaltinus and extended to heterospecific matings. We found that PMPZ barriers greatly limited hybrid production by C. auratus females with moderate heterospecific mating frequencies, but that their effectiveness diminished at higher heterospecific mating frequencies. In contrast, there was no evidence for PMPZ barriers in C. cobaltinus females at any heterospecific mating frequency. We show that integrating realistic estimates of cryptic isolation with information on relative abundance and heterospecific mating frequency in the field substantially improves our understanding of the strong directional bias in F1 production previously documented in the Chrysochus hybrid zone. Our results demonstrate that heterospecific mating frequency is critical to understanding the impact of cryptic post-copulatory barriers on hybrid zone structure and dynamics, and that future studies of such barriers should incorporate field-relevant heterospecific mating frequencies.
Collapse
Affiliation(s)
- Erica L Larson
- Department of Biological Sciences, University of Denver, Denver, Colorado, USA.,Biology Department, Western Washington University, Bellingham, Washington, USA
| | - Margaret M Brassil
- Biology Department, Western Washington University, Bellingham, Washington, USA
| | - Jonathan Maslan
- Biology Department, Western Washington University, Bellingham, Washington, USA
| | - Danielle Juárez
- Biology Department, Western Washington University, Bellingham, Washington, USA
| | - Flordeliza Lilagan
- Biology Department, Western Washington University, Bellingham, Washington, USA
| | - Hallie Tipton
- Biology Department, Western Washington University, Bellingham, Washington, USA
| | - Andrew Schweitzer
- Biology Department, Western Washington University, Bellingham, Washington, USA
| | - Joe Skillman
- Biology Department, Western Washington University, Bellingham, Washington, USA
| | | | - Merrill A Peterson
- Biology Department, Western Washington University, Bellingham, Washington, USA
| |
Collapse
|
11
|
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.
Collapse
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
| |
Collapse
|
12
|
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.
Collapse
Affiliation(s)
| | - Rhonda R. Snook
- Department of Animal and Plant SciencesUniversity of SheffieldSheffieldUK
- Department of ZoologyStockholm UniversityStockholmSweden
| |
Collapse
|