1
|
Lan Z, Song Z, Wang Z, Li L, Liu Y, Zhi S, Wang R, Wang J, Li Q, Bleckmann A, Zhang L, Dresselhaus T, Dong J, Gu H, Zhong S, Qu LJ. Antagonistic RALF peptides control an intergeneric hybridization barrier on Brassicaceae stigmas. Cell 2023; 186:4773-4787.e12. [PMID: 37806310 PMCID: PMC10615786 DOI: 10.1016/j.cell.2023.09.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2022] [Revised: 05/24/2023] [Accepted: 09/06/2023] [Indexed: 10/10/2023]
Abstract
Pollen-pistil interactions establish interspecific/intergeneric pre-zygotic hybridization barriers in plants. The rejection of undesired pollen at the stigma is crucial to avoid outcrossing but can be overcome with the support of mentor pollen. The mechanisms underlying this hybridization barrier are largely unknown. Here, in Arabidopsis, we demonstrate that receptor-like kinases FERONIA/CURVY1/ANJEA/HERCULES RECEPTOR KINASE 1 and cell wall proteins LRX3/4/5 interact on papilla cell surfaces with autocrine stigmatic RALF1/22/23/33 peptide ligands (sRALFs) to establish a lock that blocks the penetration of undesired pollen tubes. Compatible pollen-derived RALF10/11/12/13/25/26/30 peptides (pRALFs) act as a key, outcompeting sRALFs and enabling pollen tube penetration. By treating Arabidopsis stigmas with synthetic pRALFs, we unlock the barrier, facilitating pollen tube penetration from distantly related Brassicaceae species and resulting in interspecific/intergeneric hybrid embryo formation. Therefore, we uncover a "lock-and-key" system governing the hybridization breadth of interspecific/intergeneric crosses in Brassicaceae. Manipulating this system holds promise for facilitating broad hybridization in crops.
Collapse
Affiliation(s)
- Zijun Lan
- State Key Laboratory for Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences, New Cornerstone Science Laboratory, College of Life Sciences, Peking University, Beijing 100871, People's Republic of China
| | - Zihan Song
- State Key Laboratory for Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences, New Cornerstone Science Laboratory, College of Life Sciences, Peking University, Beijing 100871, People's Republic of China
| | - Zhijuan Wang
- State Key Laboratory for Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences, New Cornerstone Science Laboratory, College of Life Sciences, Peking University, Beijing 100871, People's Republic of China
| | - Ling Li
- State Key Laboratory for Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences, New Cornerstone Science Laboratory, College of Life Sciences, Peking University, Beijing 100871, People's Republic of China
| | - Yiqun Liu
- State Key Laboratory for Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences, New Cornerstone Science Laboratory, College of Life Sciences, Peking University, Beijing 100871, People's Republic of China
| | - Shuaihua Zhi
- State Key Laboratory for Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences, New Cornerstone Science Laboratory, College of Life Sciences, Peking University, Beijing 100871, People's Republic of China
| | - Ruihan Wang
- School of Advanced Agricultural Sciences, Peking University, Beijing 100871, People's Republic of China
| | - Jizong Wang
- School of Advanced Agricultural Sciences, Peking University, Beijing 100871, People's Republic of China
| | - Qiyun Li
- State Key Laboratory for Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences, New Cornerstone Science Laboratory, College of Life Sciences, Peking University, Beijing 100871, People's Republic of China
| | - Andrea Bleckmann
- Cell Biology and Plant Biochemistry, University of Regensburg, 93053 Regensburg, Germany
| | - Li Zhang
- State Key Laboratory for Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences, New Cornerstone Science Laboratory, College of Life Sciences, Peking University, Beijing 100871, People's Republic of China
| | - Thomas Dresselhaus
- Cell Biology and Plant Biochemistry, University of Regensburg, 93053 Regensburg, Germany
| | - Juan Dong
- The Waksman Institute of Microbiology, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
| | - Hongya Gu
- State Key Laboratory for Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences, New Cornerstone Science Laboratory, College of Life Sciences, Peking University, Beijing 100871, People's Republic of China
| | - Sheng Zhong
- State Key Laboratory for Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences, New Cornerstone Science Laboratory, College of Life Sciences, Peking University, Beijing 100871, People's Republic of China.
| | - Li-Jia Qu
- State Key Laboratory for Protein and Plant Gene Research, Peking-Tsinghua Center for Life Sciences, New Cornerstone Science Laboratory, College of Life Sciences, Peking University, Beijing 100871, People's Republic of China.
| |
Collapse
|
2
|
Liu S, Tengstedt ANB, Jacobsen MW, Pujolar JM, Jónsson B, Lobón-Cervià J, Bernatchez L, Hansen MM. Genome-wide methylation in the panmictic European eel (Anguilla anguilla). Mol Ecol 2022; 31:4286-4306. [PMID: 35767387 DOI: 10.1111/mec.16586] [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: 03/09/2022] [Revised: 06/21/2022] [Accepted: 06/27/2022] [Indexed: 11/30/2022]
Abstract
The role of methylation in adaptive, developmental and speciation processes has attracted considerable interest, but interpretation of results is complicated by diffuse boundaries between genetic and non-genetic variation. We studied whole genome genetic and methylation variation in the European eel, distributed from subarctic to subtropical environments, but with panmixia precluding genetically based local adaptation beyond single-generation responses. Overall methylation was 70.9%, with hypomethylation predominantly found in promoters and first exons. Redundancy analyses involving juvenile glass eels showed 0.06% and 0.03% of the variance at SNPs to be explained by localities and environmental variables, respectively, with GO terms of genes associated with outliers primarily involving neural system functioning. For CpGs 2.98% and 1.36% of variance was explained by localities and environmental variables. Differentially methylated regions particularly included genes involved in developmental processes, with hox clusters featuring prominently. Life stage (adult versus glass eels) was the most important source of inter-individual variation in methylation, likely reflecting both ageing and developmental processes. Demethylation of transposable elements relative to pure European eel was observed in European X American eel hybrids, possibly representing postzygotic barriers in this system characterized by prolonged speciation and ongoing gene flow. Whereas the genetic data are consistent with a role of single-generation selective responses, the methylation results underpin the importance of epigenetics in the life cycle of eels and suggests interactions between local environments, development and phenotypic variation mediated by methylation variation. Eels are remarkable by having retained eight hox clusters, and the results suggest important roles of methylation at hox genes for adaptive processes.
Collapse
Affiliation(s)
- Shenglin Liu
- Department of Biology, Aarhus University, Aarhus, Denmark
| | | | - Magnus W Jacobsen
- Section for Marine Living Resources, National Institute of Aquatic Resources, Technical University of Denmark, Silkeborg, Denmark
| | - Jose Martin Pujolar
- Centre for Gelatinous Plankton Ecology and Evolution, National Institute of Aquatic Resources, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Bjarni Jónsson
- North West Iceland Nature Center, Iceland.,The Icelandic Parliament, Reykjavík, Iceland
| | | | - Louis Bernatchez
- IBIS (Institut de Biologie Intégrative et des Systèmes), Université Laval, Québec, Canada
| | | |
Collapse
|
3
|
Pujolar JM, Jacobsen MW, Bertolini F. Comparative genomics and signatures of selection in North Atlantic eels. Mar Genomics 2022; 62:100933. [PMID: 35182837 DOI: 10.1016/j.margen.2022.100933] [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: 11/11/2021] [Revised: 02/04/2022] [Accepted: 02/04/2022] [Indexed: 11/17/2022]
Abstract
Comparative genomic approaches can identify putative private and shared signatures of selection. We performed a comparative genomic study of North Atlantic eels, European eel (Anguilla Anguilla) and American eel (A. rostrata). The two sister species are nearly undistinguishable at the phenotypic level and despite a wide non-overlapping continental distribution, they spawn in partial sympatry in the Sargasso Sea. Taking advantage of the newly assembled and annotated genome, we used genome wide RAD sequencing data of 359 individuals retrieved from Sequence Nucleotide Archive and state-of-the-art statistic tests to identify putative genomic signatures of selection in North Atlantic eels. First, using the FST and XP-EHH methods, we detected apparent islands of divergence on a total of 7 chromosomes, particularly on chromosomes 6 and 10. Gene ontology analyses suggested candidate genes mainly related to energy production, development and regulation, which could reflect strong selection on traits related to eel migration and larval duration time. Gene effect prediction using SNPeff showed a high number of SNPs in noncoding regions, pointing to a possible regulatory role. Second, using the iHS method we detected shared regions under selection on a total of 11 chromosomes. Several hypotheses might account for the detection of shared islands of selection in North Atlantic eels, including parallel evolution due to adaptation to similar environments and introgression. Future comparative genomic studies will be needed to further clarify the causes and consequences of introgression, including the directionality of these introgression events.
Collapse
Affiliation(s)
- Jose Martin Pujolar
- Centre for Gelatinous Plankton Ecology and Evolution, National Institute of Aquatic Resources, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Magnus Wulff Jacobsen
- Section for Marine Living Resources, National Institute of Aquatic Resources, Technical University of Denmark, Silkeborg, Denmark
| | - Francesca Bertolini
- Section for Marine Living Resources, National Institute of Aquatic Resources, Technical University of Denmark, Kongens Lyngby, Denmark.
| |
Collapse
|
4
|
Enbody ED, Pettersson ME, Sprehn CG, Palm S, Wickström H, Andersson L. Ecological adaptation in European eels is based on phenotypic plasticity. Proc Natl Acad Sci U S A 2021; 118:e2022620118. [PMID: 33479174 PMCID: PMC7848574 DOI: 10.1073/pnas.2022620118] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
The relative role of genetic adaptation and phenotypic plasticity is of fundamental importance in evolutionary ecology [M. J. West-Eberhard, Proc. Natl. Acad. Sci. U.S.A. 102 (suppl. 1), 6543-6549 (2005)]. European eels have a complex life cycle, including transitions between life stages across ecological conditions in the Sargasso Sea, where spawning occurs, and those in brackish and freshwater bodies from northern Europe to northern Africa. Whether continental eel populations consist of locally adapted and genetically distinct populations or comprise a single panmictic population has received conflicting support. Here we use whole-genome sequencing and show that European eels belong to one panmictic population. A complete lack of geographical genetic differentiation is demonstrated. We postulate that this is possible because the most critical life stages-spawning and embryonic development-take place under near-identical conditions in the Sargasso Sea. We further show that within-generation selection, which has recently been proposed as a mechanism for genetic adaptation in eels, can only marginally change allele frequencies between cohorts of eels from different geographic regions. Our results strongly indicate plasticity as the predominant mechanism for how eels respond to diverse environmental conditions during postlarval stages, ultimately solving a long-standing question for a classically enigmatic species.
Collapse
Affiliation(s)
- Erik D Enbody
- Department of Medical Biochemistry and Microbiology, Uppsala University, 751 23 Uppsala, Sweden
| | - Mats E Pettersson
- Department of Medical Biochemistry and Microbiology, Uppsala University, 751 23 Uppsala, Sweden
| | - C Grace Sprehn
- Department of Medical Biochemistry and Microbiology, Uppsala University, 751 23 Uppsala, Sweden
| | - Stefan Palm
- Department of Aquatic Resources, Institute of Freshwater Research, Swedish University of Agricultural Sciences, 178 93 Drottningholm, Sweden
| | - Håkan Wickström
- Department of Aquatic Resources, Institute of Freshwater Research, Swedish University of Agricultural Sciences, 178 93 Drottningholm, Sweden
| | - Leif Andersson
- Department of Medical Biochemistry and Microbiology, Uppsala University, 751 23 Uppsala, Sweden;
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, TX 77843
- Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, 750 07 Uppsala, Sweden
| |
Collapse
|
5
|
Barth JMI, Gubili C, Matschiner M, Tørresen OK, Watanabe S, Egger B, Han YS, Feunteun E, Sommaruga R, Jehle R, Schabetsberger R. Stable species boundaries despite ten million years of hybridization in tropical eels. Nat Commun 2020; 11:1433. [PMID: 32188850 PMCID: PMC7080837 DOI: 10.1038/s41467-020-15099-x] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Accepted: 02/07/2020] [Indexed: 02/01/2023] Open
Abstract
Genomic evidence is increasingly underpinning that hybridization between taxa is commonplace, challenging our views on the mechanisms that maintain their boundaries. Here, we focus on seven catadromous eel species (genus Anguilla) and use genome-wide sequence data from more than 450 individuals sampled across the tropical Indo-Pacific, morphological information, and three newly assembled draft genomes to compare contemporary patterns of hybridization with signatures of past introgression across a time-calibrated phylogeny. We show that the seven species have remained distinct for up to 10 million years and find that the current frequencies of hybridization across species pairs contrast with genomic signatures of past introgression. Based on near-complete asymmetry in the directionality of hybridization and decreasing frequencies of later-generation hybrids, we suggest cytonuclear incompatibilities, hybrid breakdown, and purifying selection as mechanisms that can support species cohesion even when hybridization has been pervasive throughout the evolutionary history of clades.
Collapse
Affiliation(s)
- Julia M I Barth
- Department of Environmental Sciences, Zoological Institute, University of Basel, Vesalgasse 1, 4051, Basel, Switzerland
| | - Chrysoula Gubili
- Fisheries Research Institute, Hellenic Agricultural Organisation-DEMETER, Nea Peramos, 64 007, Kavala, Greece
| | - Michael Matschiner
- Department of Palaeontology and Museum, University of Zurich, Karl-Schmid-Strasse 4, 8006, Zurich, Switzerland.
- Centre for Ecological and Evolutionary Synthesis, Department of Biosciences, University of Oslo, P.O. Box 1066 Blindern, 0316, Oslo, Norway.
| | - Ole K Tørresen
- Centre for Ecological and Evolutionary Synthesis, Department of Biosciences, University of Oslo, P.O. Box 1066 Blindern, 0316, Oslo, Norway
| | - Shun Watanabe
- Faculty of Agriculture, Kindai University, 3327-204 Nakamachi, Nara, 631-8505, Japan
| | - Bernd Egger
- Department of Environmental Sciences, Zoological Institute, University of Basel, Vesalgasse 1, 4051, Basel, Switzerland
| | - Yu-San Han
- Institute of Fisheries Science, College of Life Science, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei, 10617, Taiwan
| | - Eric Feunteun
- Laboratoire Biologie des Organismes et Écosystèmes Aquatiques (BOREA), Muséum National d'Histoire Naturelle, CNRS, Sorbonne Université, Université de Caen Normandie, Université des Antilles, IRD, 61 Rue Buffon, CP 53, 75231, Paris Cedex 05, France
- MNHN-Station Marine de Dinard, Centre de Recherche et d'Enseignement Sur les Systèmes Côtiers (CRESCO), 38 Rue du Port Blanc, 35800, Dinard, France
| | - Ruben Sommaruga
- Department of Ecology, University of Innsbruck, Technikerstr. 25, 6020, Innsbruck, Austria
| | - Robert Jehle
- School of Science, Engineering and Environment, University of Salford, Salford Crescent, Salford, M5 4WT, UK.
| | - Robert Schabetsberger
- Department of Biosciences, University of Salzburg, Hellbrunnerstrasse 34, 5020, Salzburg, Austria.
| |
Collapse
|
6
|
Nikolic N, Liu S, Jacobsen MW, Jónsson B, Bernatchez L, Gagnaire PA, Hansen MM. Speciation history of European (Anguilla anguilla) and American eel (A. rostrata), analysed using genomic data. Mol Ecol 2019; 29:565-577. [PMID: 31863605 DOI: 10.1111/mec.15342] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 12/11/2019] [Accepted: 12/16/2019] [Indexed: 02/01/2023]
Abstract
Speciation in the ocean could differ from terrestrial environments due to fewer barriers to gene flow. Hence, sympatric speciation might be common, with American and European eel being candidates for exemplifying this. They show disjunct continental distributions on both sides of the Atlantic, but spawn in overlapping regions of the Sargasso Sea from where juveniles are advected to North American, European and North African coasts. Hybridization and introgression are known to occur, with hybrids almost exclusively observed in Iceland. Different speciation scenarios have been suggested, involving either vicariance or sympatric ecological speciation. Using RAD sequencing and whole-genome sequencing data from parental species and F1 hybrids, we analysed speciation history based on the joint allele frequency spectrum (JAFS) and pairwise sequentially Markovian coalescent (PSMC) plots. JAFS supported a model involving a split without gene flow 150,000-160,000 generations ago, followed by secondary contact 87,000-92,000 generations ago, with 64% of the genome experiencing restricted gene flow. This supports vicariance rather than sympatric speciation, likely associated with Pleistocene glaciation cycles and ocean current changes. Whole-genome PSMC analysis of F1 hybrids from Iceland suggested divergence 200,000 generations ago and indicated subsequent gene flow rather than strict isolation. Finally, simulations showed that results from both approaches (JAFS and PSMC) were congruent. Hence, there is strong evidence against sympatric speciation in North Atlantic eels. These results reiterate the need for careful consideration of cases of possible sympatric speciation, as even in seemingly barrier-free oceanic environments palaeoceanographic factors may have promoted vicariance and allopatric speciation.
Collapse
Affiliation(s)
- Natacha Nikolic
- Agence de Recherche pour la Biodiversité à la Réunion, ARBRE, Saint-Leu, Réunion
| | - Shenglin Liu
- Department of Bioscience, Aarhus University, Aarhus C, Denmark
| | | | | | - Louis Bernatchez
- IBIS (Institut de Biologie Intégrative et des Systèmes), Université Laval, Québec, QC, Canada
| | | | | |
Collapse
|
7
|
Miller MJ, Westerberg H, Sparholt H, Wysujack K, Sørensen SR, Marohn L, Jacobsen MW, Freese M, Ayala DJ, Pohlmann JD, Svendsen JC, Watanabe S, Andersen L, Møller PR, Tsukamoto K, Munk P, Hanel R. Spawning by the European eel across 2000 km of the Sargasso Sea. Biol Lett 2019; 15:20180835. [PMID: 30966898 DOI: 10.1098/rsbl.2018.0835] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
It has been known for about a century that European eels have a unique life history that includes offshore spawning in the Sargasso Sea about 5000-7000 km away from their juvenile and adult habitats in Europe and northern Africa. Recently hatched eel larvae were historically collected during Danish, German and American surveys in specific areas in the southern Sargasso Sea. During a 31 day period of March and April 2014, Danish and German research ships sampled for European eel larvae along 15 alternating transects of stations across the Sargasso Sea. The collection of recently hatched eel larvae (≤12 mm) from 70° W and eastward to 50° W showed that the European eel had been spawning across a 2000 km wide region of the North Atlantic Ocean. Historical collections made from 1921 to 2007 showed that small larvae had also previously been collected in this wide longitudinal zone, showing that the spatial extent of spawning has not diminished in recent decades, irrespective of the dramatic decline in recruitment. The use of such a wide spawning area may be related to variations in the onset of the silver eel spawning migration, individual differences in their long-term swimming ability, or aspects of larval drift.
Collapse
Affiliation(s)
- Michael J Miller
- 1 Department of Marine Science and Resources, Nihon University , Fujisawa 252-0880 , Japan
| | - Håkan Westerberg
- 2 Department of Aquatic Resources, Institute of Freshwater Research, Swedish University of Agricultural Sciences , Stångholmsvägen 2, 17893, Drottningholm , Sweden
| | - Henrik Sparholt
- 3 National Institute of Aquatic Resources, Technical University of Denmark , 2800 Lyngby , Denmark
| | - Klaus Wysujack
- 4 Thünen Institute of Fisheries Ecology , Herwigstrasse 31, 27572 Bremerhaven , Germany
| | - Sune R Sørensen
- 3 National Institute of Aquatic Resources, Technical University of Denmark , 2800 Lyngby , Denmark
| | - Lasse Marohn
- 4 Thünen Institute of Fisheries Ecology , Herwigstrasse 31, 27572 Bremerhaven , Germany
| | - Magnus W Jacobsen
- 5 National Institute of Aquatic Resources, Technical University of Denmark , 8600 Silkeborg , Denmark.,6 Department of Bioscience, Aarhus University , DK-8000 Aarhus C , Denmark
| | - Marko Freese
- 4 Thünen Institute of Fisheries Ecology , Herwigstrasse 31, 27572 Bremerhaven , Germany
| | - Daniel J Ayala
- 3 National Institute of Aquatic Resources, Technical University of Denmark , 2800 Lyngby , Denmark
| | - Jan-Dag Pohlmann
- 4 Thünen Institute of Fisheries Ecology , Herwigstrasse 31, 27572 Bremerhaven , Germany
| | - Jon C Svendsen
- 3 National Institute of Aquatic Resources, Technical University of Denmark , 2800 Lyngby , Denmark
| | - Shun Watanabe
- 7 Department of Fisheries, Kindai University , Nara 631-8505 , Japan
| | - Line Andersen
- 6 Department of Bioscience, Aarhus University , DK-8000 Aarhus C , Denmark
| | - Peter R Møller
- 8 Natural History Museum of Denmark, University of Copenhagen , 2100 Copenhagen , Denmark
| | - Katsumi Tsukamoto
- 1 Department of Marine Science and Resources, Nihon University , Fujisawa 252-0880 , Japan
| | - Peter Munk
- 3 National Institute of Aquatic Resources, Technical University of Denmark , 2800 Lyngby , Denmark
| | - Reinhold Hanel
- 4 Thünen Institute of Fisheries Ecology , Herwigstrasse 31, 27572 Bremerhaven , Germany
| |
Collapse
|
8
|
Hurley LL, Rowe M, Griffith SC. Differential sperm-egg interactions in experimental pairings between two subspecies and their hybrids in a passerine bird. Ecol Evol 2018; 8:11725-11732. [PMID: 30598770 PMCID: PMC6303703 DOI: 10.1002/ece3.4624] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2018] [Accepted: 09/03/2018] [Indexed: 12/11/2022] Open
Abstract
Speciation research has largely overlooked reproductive barriers acting between copulation and the formation of the zygote (i.e., postmating, prezygotic [PMPZ] barriers), especially in internally fertilizing vertebrates. Nonetheless, it is becoming clear that PMPZ reproductive barriers can play a role in the formation and maintenance of species boundaries. We investigated sperm-egg interactions in the recently diverged subspecies pairs of the long-tailed finch, Poephila acuticauda acuticauda and P. a. hecki, to explore potential PMPZ barriers. Specifically, we compared the number of sperm reaching the perivitelline layer (PVL) of the ova, and hence the site of fertilization, in both intra- and inter-subspecies pairings and pairings of F1 hybrid adults with one parental subspecies. Although we found no difference in PVL sperm number among intra- and inter-subspecific pairs, a significantly lower number of sperm reached the site of fertilization in a backcross pairing. As low numbers of PVL sperm appear to be associated with low fertilization success in birds, our findings offer insight into the potential role of postcopulatory processes in limiting gene flow between the subspecies and may help explain the relatively narrow hybrid zone that exists in the wild in this species. Though further work is needed to gain a comprehensive understanding of the morphological, physiological, and molecular mechanisms underlying our results, our study supports the role of PMPZ reproductive barriers in avian speciation, even in recently diverged taxa, that may not yet be fully genetically incompatible.
Collapse
Affiliation(s)
- Laura L. Hurley
- Department of Biological SciencesMacquarie UniversitySydneyNew South WalesAustralia
| | - Melissah Rowe
- Natural History Museum, University of OsloOsloNorway
- Centre for Ecological and Evolutionary Synthesis, Department of BiosciencesUniversity of OsloOsloNorway
| | - Simon C. Griffith
- Department of Biological SciencesMacquarie UniversitySydneyNew South WalesAustralia
| |
Collapse
|
9
|
Babin C, Gagnaire PA, Pavey SA, Bernatchez L. RAD-Seq Reveals Patterns of Additive Polygenic Variation Caused by Spatially-Varying Selection in the American Eel (Anguilla rostrata). Genome Biol Evol 2018; 9:2974-2986. [PMID: 29136139 PMCID: PMC5714190 DOI: 10.1093/gbe/evx226] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/09/2017] [Indexed: 12/17/2022] Open
Abstract
The American Eel (Anguilla rostrata) has an exceptional life cycle characterized by panmictic reproduction at the species scale, random dispersal, and selection in a highly heterogeneous habitat extending from subtropical to subarctic latitudes. The genetic consequences of spatially-varying selection in this species have been investigated for decades, revealing subtle clines in allele frequency at a few loci that contrast with complete panmixia on the vast majority of the genome. Because reproduction homogenizes allele frequencies every generation, sampling size, and genomic coverage are critical to reach sufficient power to detect selected loci in this context. Here, we used a total of 710 individuals from 12 sites and 12,098 high-quality single nucleotide polymorphisms to re-evaluate the extent to which local selection affects the spatial distribution of genetic diversity in this species. We used environmental association methods to identify markers under spatially-varying selection, which indicated that selection affects ∼1.5% of the genome. We then evaluated the extent to which candidate markers collectively vary with environmental factors using additive polygenic scores. We found significant correlations between polygenic scores and latitude, longitude and temperature which are consistent with polygenic selection acting against maladapted genotypes in different habitats occupied by eels throughout their range of distribution. Gene functions associated with outlier markers were significantly enriched for the insulin signaling pathway, indicating that the trade-offs inherent to occupying such a large distribution range involve the regulation of metabolism. Overall, this study highlights the potential of the additive polygenic scores approach in detecting selective effects in a complex environment.
Collapse
Affiliation(s)
- Charles Babin
- IBIS (Institut de biologie intégrative et des systèmes), Département de biologie, Université Laval, Québec, Canada
| | | | - Scott A Pavey
- Department of Biological Sciences and Canadian Rivers Institute, University of New Brunswick, Saint-John, Canada
| | - Louis Bernatchez
- IBIS (Institut de biologie intégrative et des systèmes), Département de biologie, Université Laval, Québec, Canada
| |
Collapse
|
10
|
Whole-Genome Sequencing of 84 Japanese Eels Reveals Evidence against Panmixia and Support for Sympatric Speciation. Genes (Basel) 2018; 9:genes9100474. [PMID: 30274234 PMCID: PMC6210723 DOI: 10.3390/genes9100474] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Revised: 09/17/2018] [Accepted: 09/21/2018] [Indexed: 12/30/2022] Open
Abstract
The Japanese eel (Anguilla japonica), European eel (Anguilla anguilla), and American eel (Anguilla rostrata) are migratory, catadromous, temperate zone fish sharing several common life cycle features. The population genetics of panmixia in these eel species has already been investigated. Our extensive population genetics analysis was based on 1400 Gb of whole-genome sequence (WGS) data from 84 eels. It demonstrated that a Japanese eel group from the Kuma River differed from other populations of the same species. Even after removing the potential adapted/selected single nucleotide polymorphism (SNP) data, and with very small differences (fixation index [Fst] = 0.01), we obtained results consistently indicating that panmixia does not occur in Japanese eels. The life cycle of the Japanese eel is well-established and the Kuma River is in the center of its habitat. Nevertheless, simple reproductive isolation is not the probable cause of non-panmixia in this species. We propose that the combination of spawning area subdivision, philopatry, and habitat preference/avoidance accounts for the non-panmixia in the Japanese eel population. We named this hypothesis the “reproductive isolation like subset mapping” (RISM) model. This finding may be indicative of the initial stages of sympatric speciation in these eels.
Collapse
|
11
|
Plytycz B, Bigaj J, Osikowski A, Hofman S, Falniowski A, Panz T, Grzmil P, Vandenbulcke F. The existence of fertile hybrids of closely related model earthworm species, Eisenia andrei and E. fetida. PLoS One 2018; 13:e0191711. [PMID: 29370238 PMCID: PMC5784991 DOI: 10.1371/journal.pone.0191711] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Accepted: 01/10/2018] [Indexed: 12/20/2022] Open
Abstract
Lumbricid earthworms Eisenia andrei (Ea) and E. fetida (Ef) are simultaneous hermaphrodites with reciprocal insemination capable of self-fertilization while the existence of hybridization of these two species was still debatable. During the present investigation fertile hybrids of Ea and Ef were detected. Virgin specimens of Ea and Ef were laboratory crossed (Ea+Ef) and their progeny was doubly identified. 1 -identified by species-specific maternally derived haploid mitochondrial DNA sequences of the COI gene being either 'a' for worms hatched from Ea ova or 'f' for worms hatched from Ef ova. 2 -identified by the diploid maternal/paternal nuclear DNA sequences of 28s rRNA gene being either 'AA' for Ea, 'FF' for Ef, or AF/FA for their hybrids derived either from the 'aA' or 'fF' ova, respectively. Among offspring of Ea+Ef pairs in F1 generation there were mainly aAA and fFF earthworms resulted from the facilitated self-fertilization and some aAF hybrids from aA ova but none fFA hybrids from fF ova. In F2 generation resulting from aAF hybrids mated with aAA a new generations of aAA and aAF hybrids were noticed, while aAF hybrids mated with fFF gave fFF and both aAF and fFA hybrids. Hybrids intercrossed together produced plenty of cocoons but no hatchlings independently whether aAF+aAF or aAF+fFA were mated. These results indicated that Ea and Ef species, easy to maintain in laboratory and commonly used as convenient models in biomedicine and ecotoxicology, may also serve in studies on molecular basis of interspecific barriers and mechanisms of introgression and speciation. Hypothetically, their asymmetrical hybridization can be modified by some external factors.
Collapse
Affiliation(s)
- Barbara Plytycz
- Department of Evolutionary Immunology, Institute of Zoology and Biomedical Research, Jagiellonian University, Krakow, Poland
- * E-mail:
| | - Janusz Bigaj
- Department of Evolutionary Immunology, Institute of Zoology and Biomedical Research, Jagiellonian University, Krakow, Poland
| | - Artur Osikowski
- Department of Animal Anatomy, University of Agriculture in Krakow, Krakow, Poland
| | - Sebastian Hofman
- Department of Comparative Anatomy, Institute of Zoology and Biomedical Research, Jagiellonian University, Krakow, Poland
| | - Andrzej Falniowski
- Department of Malacology, Institute of Zoology and Biomedical Research, Jagiellonian University, Krakow, Poland
| | - Tomasz Panz
- Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland
| | - Pawel Grzmil
- Department of Genetics and Evolution, Institute of Zoology and Biomedical Research, Jagiellonian University, Krakow, Poland
| | - Franck Vandenbulcke
- Ecologie Numerique et Ecotoxicologie, University Lille Nord de France, Lille, France
| |
Collapse
|
12
|
Single nucleotide polymorphism markers for assessing potential maternal population structure in European eel (Anguilla anguilla). CONSERV GENET RESOUR 2017. [DOI: 10.1007/s12686-017-0917-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
|