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Jönsson M, Morin M, Wang CK, Craik DJ, Degnan SM, Degnan BM. Sex-specific expression of pheromones and other signals in gravid starfish. BMC Biol 2022; 20:288. [PMID: 36528687 PMCID: PMC9759900 DOI: 10.1186/s12915-022-01491-0] [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: 04/13/2022] [Accepted: 12/01/2022] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Many echinoderms form seasonal aggregations prior to spawning. In some fecund species, a spawning event can lead to population outbreaks with detrimental ecosystem impacts. For instance, outbreaks of crown-of-thorns starfish (COTS), a corallivore, can destroy coral reefs. Here, we examine the gene expression in gravid male and female COTS prior to spawning in the wild, to identify genome-encoded factors that may regulate aggregation and spawning. This study is informed by a previously identified exoproteome that attracts conspecifics. To capture the natural gene expression profiles, we isolated RNAs from gravid female and male COTS immediately after they were removed from the Great Barrier Reef. RESULTS: Sexually dimorphic gene expression is present in all seven somatic tissues and organs that we surveyed and in the gonads. Approximately 40% of the exoproteome transcripts are differentially expressed between sexes. Males uniquely upregulate an additional 68 secreted factors in their testes. A suite of neuropeptides in sensory organs, coelomocytes and gonads is differentially expressed between sexes, including the relaxin-like gonad-stimulating peptide and gonadotropin-releasing hormones. Female sensory tentacles-chemosensory organs at the distal tips of the starfish arms-uniquely upregulate diverse receptors and signalling molecules, including chemosensory G-protein-coupled receptors and several neuropeptides, including kisspeptin, SALMFamide and orexin. CONCLUSIONS Analysis of 103 tissue/organ transcriptomes from 13 wild COTS has revealed genes that are consistently differentially expressed between gravid females and males and that all tissues surveyed are sexually dimorphic at the molecular level. This finding is consistent with female and male COTS using sex-specific pheromones to regulate reproductive aggregations and synchronised spawning events. These pheromones appear to be received primarily by the sensory tentacles, which express a range of receptors and signalling molecules in a sex-specific manner. Furthermore, coelomocytes and gonads differentially express signalling and regulatory factors that control gametogenesis and spawning in other echinoderms.
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Affiliation(s)
- Mathias Jönsson
- grid.1003.20000 0000 9320 7537Centre for Marine Science, School of Biological Sciences, University of Queensland, Brisbane, QLD 4072 Australia
| | - Marie Morin
- grid.1003.20000 0000 9320 7537Centre for Marine Science, School of Biological Sciences, University of Queensland, Brisbane, QLD 4072 Australia
| | - Conan K. Wang
- grid.1003.20000 0000 9320 7537Institute for Molecular Bioscience, ARC Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, QLD 4072 Australia
| | - David J. Craik
- grid.1003.20000 0000 9320 7537Institute for Molecular Bioscience, ARC Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, Brisbane, QLD 4072 Australia
| | - Sandie M. Degnan
- grid.1003.20000 0000 9320 7537Centre for Marine Science, School of Biological Sciences, University of Queensland, Brisbane, QLD 4072 Australia
| | - Bernard M. Degnan
- grid.1003.20000 0000 9320 7537Centre for Marine Science, School of Biological Sciences, University of Queensland, Brisbane, QLD 4072 Australia
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A protein bridging the gap between sea urchin generations. Proc Natl Acad Sci U S A 2021; 118:2114056118. [PMID: 34497126 DOI: 10.1073/pnas.2114056118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/19/2021] [Indexed: 11/18/2022] Open
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3
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Guerra V, Haynes G, Byrne M, Yasuda N, Adachi S, Nakamura M, Nakachi S, Hart MW. Nonspecific expression of fertilization genes in the crown-of-thorns Acanthaster cf. solaris: Unexpected evidence of hermaphroditism in a coral reef predator. Mol Ecol 2019; 29:363-379. [PMID: 31837059 DOI: 10.1111/mec.15332] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Revised: 11/28/2019] [Accepted: 12/10/2019] [Indexed: 01/04/2023]
Abstract
The characterization of gene expression in gametes has advanced our understanding of the molecular basis for ecological variation in reproductive success and the evolution of reproductive isolation. These advances are especially significant for ecologically important keystone predators such as the coral-eating crown-of-thorns sea stars (COTS, Acanthaster) which are the most influential predator species in Indo-Pacific coral reef ecosystems and the focus of intensive management efforts. We used RNA-seq and transcriptome assemblies to characterize the expression of genes in mature COTS gonads. We described the sequence and domain organization of eight genes with sex-specific expression and well known functions in fertilization in other echinoderms. We found unexpected expression of genes in one ovary transcriptome that are characteristic of males and sperm, including genes that encode the sperm-specific guanylate cyclase receptor for an egg pheromone, and the sperm acrosomal protein bindin. In a reassembly of previously published RNA-seq data from COTS testes, we found a complementary pattern: strong expression of four genes that are otherwise well known to encode egg-specific fertilization proteins, including the egg receptor for bindin (EBR1) and the acrosome reaction-inducing substance in the egg coat (ARIS1, ARIS2, ARIS3). We also found histological evidence of both eggs and sperm developing in the same gonad in several COTS individuals from a parallel study. These results suggest the occurrence of hermaphrodites, and the potential for reproductive assurance via self-fertilization. Our findings have implications for management of COTS populations, especially in consideration of the large size and massive fecundity of these sea stars.
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Affiliation(s)
- Vanessa Guerra
- Department of Biological Sciences, Simon Fraser University, Burnaby, BC, Canada.,Department of Invertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington, DC, USA
| | - Gwilym Haynes
- Department of Biological Sciences, Simon Fraser University, Burnaby, BC, Canada.,Department of Biology, Langara College, Vancouver, British Columbia, Canada
| | - Maria Byrne
- Schools of Medical and Biological Sciences, The University of Sydney, Sydney, Australia
| | - Nina Yasuda
- Department of Marine Biology and Environmental Science, Faculty of Agriculture, University of Miyazaki, Miyazaki, Japan
| | - Souta Adachi
- School of Marine Science and Technology, Tokai University, Shimizu, Shizuoka, Japan
| | - Masako Nakamura
- School of Marine Science and Technology, Tokai University, Shimizu, Shizuoka, Japan
| | | | - Michael W Hart
- Department of Biological Sciences, Simon Fraser University, Burnaby, BC, Canada
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Balakirev ES, Anisimova M, Pavlyuchkov VA, Ayala FJ. DNA polymorphism and selection at the bindin locus in three Strongylocentrotus sp. (Echinoidea). BMC Genet 2016; 17:66. [PMID: 27176219 PMCID: PMC4866015 DOI: 10.1186/s12863-016-0374-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Accepted: 05/02/2016] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND The sperm gene bindin encodes a gamete recognition protein, which plays an important role in conspecific fertilization and reproductive isolation of sea urchins. Molecular evolution of the gene has been extensively investigated with the attention focused on the protein coding regions. Intron evolution has been investigated to a much lesser extent. We have studied nucleotide variability in the complete bindin locus, including two exons and one intron, in the sea urchin Strongylocentrotus intermedius represented by two morphological forms. We have also analyzed all available bindin sequences for two other sea urchin species, S. pallidus and S. droebachiensis. RESULTS The results show that the bindin sequences from the two forms of S. intermedius are intermingled with no evidence of genetic divergence; however, the forms exhibit slightly different patterns in bindin variability. The level of the bindin nucleotide diversity is close for S. intermedius and S. droebachiensis, but noticeably higher for S. pallidus. The distribution of variability is non-uniform along the gene; however there are striking similarities among the species, indicating similar evolutionary trends in this gene engaged in reproductive function. The patterns of nucleotide variability and divergence are radically different in the bindin coding and intron regions. Positive selection is detected in the bindin coding region. The neutrality tests as well as the maximum likelihood approaches suggest the action of diversifying selection in the bindin intron. CONCLUSIONS Significant deviation from neutrality has been detected in the bindin coding region and suggested in the intron, indicating the possible functional importance of the bindin intron variability. To clarify the question concerning possible involvement of diversifying selection in the bindin intron evolution more data combining population genetic and functional approaches are necessary.
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Affiliation(s)
- Evgeniy S Balakirev
- A. V. Zhirmunsky Institute of Marine Biology, Far Eastern Branch of the Russian Academy of Science, Vladivostok, 690041, Russia.
- Department of Ecology and Evolutionary Biology, University of California, 321 Steinhaus Hall, Irvine, CA, 92697-2525, USA.
- Far Eastern Federal University, Vladivostok, 690950, Russia.
| | - Maria Anisimova
- Institute of Applied Simulation, School of Life Sciences and Facility Management, Zürich University of Applied Sciences, Wädenswil, 8820, Switzerland
- Swiss Institute of Bioinformatics, Lausanne, 1015, Switzerland
| | | | - Francisco J Ayala
- Department of Ecology and Evolutionary Biology, University of California, 321 Steinhaus Hall, Irvine, CA, 92697-2525, USA
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Patiño S, Keever CC, Sunday JM, Popovic I, Byrne M, Hart MW. SpermBindinDivergence under Sexual Selection and Concerted Evolution in Sea Stars. Mol Biol Evol 2016; 33:1988-2001. [DOI: 10.1093/molbev/msw081] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
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6
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Stewart MJ, Stewart P, Rivera-Posada J. De novo assembly of the transcriptome ofAcanthaster plancitestes. Mol Ecol Resour 2014; 15:953-66. [DOI: 10.1111/1755-0998.12360] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2014] [Revised: 12/04/2014] [Accepted: 12/08/2014] [Indexed: 11/29/2022]
Affiliation(s)
- Michael James Stewart
- Genecology Research Centre; Faculty of Science, Health, Education and Engineering; University of the Sunshine Coast; Maroochydore DC Queensland 4558 Australia
| | - Praphaporn Stewart
- Genecology Research Centre; Faculty of Science, Health, Education and Engineering; University of the Sunshine Coast; Maroochydore DC Queensland 4558 Australia
| | - Jairo Rivera-Posada
- ARC Centre of Excellence for Coral Reefs Studies; James Cook University; Townsville Queensland 4812 Australia
- Australian Institute of Marine Science; PMB No. 3 Townsville Queensland 4810 Australia
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Popovic I, Marko PB, Wares JP, Hart MW. Selection and demographic history shape the molecular evolution of the gamete compatibility protein bindin in Pisaster sea stars. Ecol Evol 2014; 4:1567-88. [PMID: 24967076 PMCID: PMC4063459 DOI: 10.1002/ece3.1042] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2013] [Revised: 02/15/2014] [Accepted: 02/26/2014] [Indexed: 12/18/2022] Open
Abstract
Reproductive compatibility proteins have been shown to evolve rapidly under positive selection leading to reproductive isolation, despite the potential homogenizing effects of gene flow. This process has been implicated in both primary divergence among conspecific populations and reinforcement during secondary contact; however, these two selective regimes can be difficult to discriminate from each other. Here, we describe the gene that encodes the gamete compatibility protein bindin for three sea star species in the genus Pisaster. First, we compare the full-length bindin-coding sequence among all three species and analyze the evolutionary relationships between the repetitive domains of the variable second bindin exon. The comparison suggests that concerted evolution of repetitive domains has an effect on bindin divergence among species and bindin variation within species. Second, we characterize population variation in the second bindin exon of two species: We show that positive selection acts on bindin variation in Pisaster ochraceus but not in Pisaster brevispinus, which is consistent with higher polyspermy risk in P. ochraceus. Third, we show that there is no significant genetic differentiation among populations and no apparent effect of sympatry with congeners that would suggest selection based on reinforcement. Fourth, we combine bindin and cytochrome c oxidase 1 data in isolation-with-migration models to estimate gene flow parameter values and explore the historical demographic context of our positive selection results. Our findings suggest that positive selection on bindin divergence among P. ochraceus alleles can be accounted for in part by relatively recent northward population expansions that may be coupled with the potential homogenizing effects of concerted evolution.
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Affiliation(s)
- Iva Popovic
- Department of Biological Sciences, Simon Fraser UniversityBurnaby, British Columbia, Canada
| | - Peter B Marko
- Department of Biology, University of Hawai'iMānoa, Hawaii
| | - John P Wares
- Department of Genetics, University of GeorgiaAthens, Georgia
| | - Michael W Hart
- Department of Biological Sciences, Simon Fraser UniversityBurnaby, British Columbia, Canada
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Hart MW, Sunday JM, Popovic I, Learning KJ, Konrad CM. Incipient speciation of sea star populations by adaptive gamete recognition coevolution. Evolution 2014; 68:1294-305. [PMID: 24410379 DOI: 10.1111/evo.12352] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Accepted: 12/16/2013] [Indexed: 12/12/2022]
Abstract
Reproductive isolation--the key event in speciation--can evolve when sexual conflict causes selection favoring different combinations of male and female adaptations in different populations. Likely targets of such selection include genes that encode proteins on the surfaces of sperm and eggs, but no previous study has demonstrated intraspecific coevolution of interacting gamete recognition genes under selection. Here, we show that selection drives coevolution between an egg receptor for sperm (OBi1) and a sperm acrosomal protein (bindin) in diverging populations of a sea star (Patiria miniata). We found positive selection on OBi1 in an exon encoding part of its predicted substrate-binding protein domain, the ligand for which is found in bindin. Gene flow was zero for the parts of bindin and OBi1 in which selection for high rates of amino acid substitution was detected; higher gene flow for other parts of the genome indicated selection against immigrant alleles at bindin and OBi1. Populations differed in allele frequencies at two key positively selected sites (one in each gene), and differences at those sites predicted fertilization rate variation among male-female pairs. These patterns suggest adaptively evolving loci that influence reproductive isolation between populations.
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Affiliation(s)
- Michael W Hart
- Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada.
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Evans JP, Sherman CDH. Sexual selection and the evolution of egg-sperm interactions in broadcast-spawning invertebrates. THE BIOLOGICAL BULLETIN 2013; 224:166-183. [PMID: 23995741 DOI: 10.1086/bblv224n3p166] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Many marine invertebrate taxa are broadcast spawners, where multiple individuals release their gametes into the water for external fertilization, often in the presence of gametes from heterospecifics. Consequently, sperm encounter the considerable challenges of locating and fertilizing eggs from conspecific females. To overcome these challenges, many taxa exhibit species-specific attraction of sperm toward eggs through chemical signals released from eggs (sperm chemotaxis) and species-specific gamete recognition proteins (GRPs) that mediate compatibility of gametes at fertilization. In this prospective review, we highlight these selective forces, but also emphasize the role that sexual selection, manifested through sperm competition, cryptic female choice, and evolutionary conflicts of interest between the sexes (sexual conflict), can also play in mediating the action of egg chemoattractants and GRPs, and thus individual reproductive fitness. Furthermore, we explore patterns of selection at the level of gametes (sperm phenotype, gamete plasticity, and egg traits) to identify putative traits targeted by sexual selection in these species. We conclude by emphasizing the excellent, but relatively untapped, potential of broadcast-spawning marine invertebrates as model systems to illuminate several areas of research in post-mating sexual selection.
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Affiliation(s)
- Jonathan P Evans
- Centre for Evolutionary Biology, School of Animal Biology, University of Western Australia, Crawley, Australia.
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Sunday JM, Hart MW. Sea star populations diverge by positive selection at a sperm-egg compatibility locus. Ecol Evol 2013; 3:640-54. [PMID: 23532786 PMCID: PMC3605852 DOI: 10.1002/ece3.487] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Accepted: 12/24/2012] [Indexed: 11/27/2022] Open
Abstract
Fertilization proteins of marine broadcast spawning species often show signals of positive selection. Among geographically isolated populations, positive selection within populations can lead to differences between them, and may result in reproductive isolation upon secondary contact. Here, we test for positive selection in the reproductive compatibility locus, bindin, in two populations of a sea star on either side of a phylogeographic break. We find evidence for positive selection at codon sites in both populations, which are under neutral or purifying selection in the reciprocal population. The signal of positive selection is stronger and more robust in the population where effective population size is larger and bindin diversity is greater. In addition, we find high variation in coding sequence length caused by large indels at two repetitive domains within the gene, with greater length diversity in the larger population. These findings provide evidence of population-divergent positive selection in a fertilization compatibility locus, and suggest that sexual selection can lead to reproductive divergence between conspecific marine populations.
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Affiliation(s)
- Jennifer M Sunday
- Department of Biological Sciences, Simon Fraser University Burnaby, British Columbia, Canada
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Hart MW. Structure and evolution of the sea star egg receptor for sperm bindin. Mol Ecol 2013; 22:2143-56. [PMID: 23432510 DOI: 10.1111/mec.12251] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2012] [Revised: 01/10/2013] [Accepted: 01/12/2013] [Indexed: 02/03/2023]
Abstract
Selection on coevolving sperm- and egg-recognition molecules is a potent engine of population divergence leading to reproductive isolation and speciation. The study of receptor-ligand pairs can reveal co-evolution of male- and female-expressed genes or differences between their evolution in response to selective factors such as sperm competition and sexual conflict. Phylogeographical studies of these patterns have been limited by targeted gene methods that favour short protein-coding sequences amplifiable by PCR. Here, I use high-throughput transcriptomic methods to characterize the structure and divergence of full-length coding sequences for the gene encoding the protein component of a large complex egg surface glycopeptide receptor for the sperm acrosomal protein bindin from the sea star Patiria miniata. I used a simple but effective method for resolving nucleotide polymorphisms into haplotypes for phylogeny-based analyses of selection. The protein domain organization of sea star egg bindin receptor (EBR1) was similar to sea urchins and included a pair of protein-recognition domains plus a series of tandem repeat domains of two types. Two populations separated by a well-characterized phylogeographical break included lineages of EBR1 alleles under positive selection at several codons (similar to selection on sperm bindin in the same populations). However, these populations shared the same alleles that were under selection for amino acid differences at multiple codons (unlike the pattern of selection for population divergence in sperm bindin). The significance of positively selected EBR1 domains and alleles could be tested in functional analyses of fertilization rates associated with EBR1 (and bindin) polymorphisms.
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Affiliation(s)
- Michael W Hart
- Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada.
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Hart MW, Popovic I, Emlet RB. LOW RATES OF BINDIN CODON EVOLUTION IN LECITHOTROPHIC HELIOCIDARIS SEA URCHINS. Evolution 2012; 66:1709-21. [DOI: 10.1111/j.1558-5646.2012.01606.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Vacquier VD, Swanson WJ. Selection in the rapid evolution of gamete recognition proteins in marine invertebrates. Cold Spring Harb Perspect Biol 2011; 3:a002931. [PMID: 21730046 PMCID: PMC3220358 DOI: 10.1101/cshperspect.a002931] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Animal fertilization is governed by the interaction (binding) of proteins on the surfaces of sperm and egg. In many examples presented herein, fertilization proteins evolve rapidly and show the signature of positive selection (adaptive evolution). This review describes the molecular evolution of fertilization proteins in sea urchins, abalone, and oysters, animals with external fertilization that broadcast their gametes into seawater. Theories regarding the selective forces responsible for the rapid evolution driven by positive selection seen in many fertilization proteins are discussed. This strong selection acting on divergence of interacting fertilization proteins might lead to prezygotic reproductive isolation and be a significant factor in the speciation process. Since only a fraction of all eggs are fertilized and only an infinitesimal fraction of male gametes succeed in fertilizing an egg, gametes are obviously a category of entities subjected to intense selection. It is curious that this is never mentioned in the literature dealing with selection, perhaps because we know so little about fitness differences among gametes. (Ernst Mayr, 1997).
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Affiliation(s)
- Victor D Vacquier
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California San Diego, La Jolla, California 92093-0202, USA.
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Lessios HA. Speciation Genes in Free-Spawning Marine Invertebrates. Integr Comp Biol 2011; 51:456-65. [DOI: 10.1093/icb/icr039] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Is HAP2-GCS1 an ancestral gamete fusogen? Trends Cell Biol 2010; 20:134-41. [DOI: 10.1016/j.tcb.2009.12.007] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2009] [Revised: 12/17/2009] [Accepted: 12/17/2009] [Indexed: 12/31/2022]
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