, Volume 139, Issue 5, pp 663–676 | Cite as

Cryptic gametic interactions confer both conspecific and heterospecific advantages in the Chrysochus (Coleoptera: Chrysomelidae) hybrid zone

  • Merrill A. Peterson
  • Erica L. Larson
  • Margaret Brassil
  • Kati J. Buckingham
  • Danielle Juárez
  • Joseph Deas
  • Donna Mangloña
  • Michael A. White
  • Jonathan Maslan
  • Andrew Schweitzer
  • Kirsten J. Monsen


Most species pairs are isolated through the collective action of a suite of barriers. Recent work has shown that cryptic barriers such as conspecific sperm precedence can be quite strong, suggesting that they evolve quickly. However, because the strength of multiple barriers has been formally quantified in very few systems, the relative speed with which conspecific sperm precedence evolves remains unclear. Here, we measure the strength of both conspecific sperm precedence and cryptic non-competitive isolation between the hybridizing sister species, Chrysochus auratus and C. cobaltinus (Coleoptera: Chrysomelidae), and compare the strength of those barriers to the strength of other known reproductive barriers in this system. Overall, cryptic barriers in this system are weaker than other barriers, indicating that they have not evolved rapidly. Furthermore, their evolution has been asymmetric. Non-competitive barriers substantially reduce the production of hybrid offspring by C. auratus females but not by C. cobaltinus females. In multiply-mated C. cobaltinus females, heterospecific sperm outcompete conspecific sperm, as evidenced by the fact that heterospecific males sired disproportionately more offspring than predicted from the results for singly-mated females. In C. auratus females, neither sperm type has a competitive advantage. Such asymmetries explain why nearly all F1 hybrids in the field are from crosses between C. cobaltinus females and C. auratus males. We discuss these findings in terms of understanding the cost of mating ‘mistakes’ in the Chrysochus hybrid zone. In addition, our discovery that 95% confidence intervals for commonly-used isolation statistics can be very wide has important implications for speciation research. Specifically, to avoid biases in the interpretation of such isolation metrics, we suggest that studies should routinely include error estimates in their analyses of reproductive isolation.


Asymmetric barriers Cryptic isolation Female choice Heterospecific sperm precedence Reproductive isolation Speciation 



This work would not have been possible without the assistance of many others, both in the lab and the field, to whom we are grateful. In particular, Timm Beeman, Tyler Bourcier, Monique Brewer, Jabin Green, Liam Hahn, Karina Helm, Barb Honchak, Stefanie Locke, Tracy McFarland, Jessica Mendoza, Meaghan McNeal, Amy Savage, Steven Schwartz, Erik Walker, and Carol Yoon helped collect virgin beetles, perform crosses, and conduct beetle husbandry. In addition, Jillian Bearden, Erin Beardsley, Theresa Black, Barb Honchak, Hallie Kerins, Flordeliza Lilagan, and Joe Skillman assisted with larval genotyping. We are also grateful to Ben Miner for help with the bootstrap analysis, and Doug Schemske and Carol Yoon for stimulating discussions on the ideas discussed herein. Funding for this research was provided by the Biology Department and Office of Research and Sponsored Programs at Western Washington University and the National Science Foundation (DEB-0212652), including supplemental National Science Foundation funding to establish a summer internship, Minority Opportunities for Research on Evolution, in which several of this paper’s coauthors participated. Finally, the first two authors, both of whom have had the privilege of working under the advisement of Rick Harrison, thank Rick for the inspiration to conduct research in hybrid zones and for his unflagging support and encouragement.


  1. Aldridge G, Campbell DR (2006) Asymmetrical pollen success in Ipomopsis (Polemoniaceae) contact sites. Am J Bot 93:903–909CrossRefGoogle Scholar
  2. Andres JA, Maroja LS, Bogdanowicz SM, Swanson WJ, Harrison RG (2006) Molecular evolution of seminal proteins in field crickets. Mol Biol Evol 23:1574–1584PubMedCrossRefGoogle Scholar
  3. Barton NH, Hewitt GM (1985) Analysis of hybrid zones. Annu Rev Ecol Syst 16:113–148CrossRefGoogle Scholar
  4. Chang A (2004) Conspecific sperm precedence in sister species of Drosophila with overlapping ranges. Evolution 58:781–789PubMedGoogle Scholar
  5. Civetta A, Rosing KR, Fisher JH (2008) Differences in sperm competition and sperm competition avoidance in Drosophila melanogaster. Anim Behav 75:1739–1746CrossRefGoogle Scholar
  6. Coyne JA (1992) Genetics and speciation. Nature 355:511–515PubMedCrossRefGoogle Scholar
  7. Coyne JA, Orr HA (2004) Speciation. Sinauer Associates, SunderlandGoogle Scholar
  8. Dickinson JL (1995) Trade-offs between postcopulatory riding and mate location in the blue milkweed beetle. Behav Ecol 6:280–286CrossRefGoogle Scholar
  9. Dixon SM, Coyne JA, Noor MAF (2003) The evolution of conspecific sperm precedence in Drosophila. Mol Ecol 12:1179–1184PubMedCrossRefGoogle Scholar
  10. Dobler S, Farrell BD (1999) Host use evolution in Chrysochus milkweed beetles: evidence from behaviour, population genetics and phylogeny. Mol Ecol 8:1297–1307PubMedCrossRefGoogle Scholar
  11. Dobzhansky T (1940) Speciation as a stage in evolutionary divergence. Am Nat 74:312–321CrossRefGoogle Scholar
  12. Eberhard WG (2009) Postcopulatory sexual selection: Darwin’s omission and its consequences. Proc Natl Acad Sci (USA) 106:10025–10032CrossRefGoogle Scholar
  13. Fricke C, Arnqvist G (2004a) Conspecific sperm precedence in flour beetles. Anim Behav 67:729–732CrossRefGoogle Scholar
  14. Fricke C, Arnqvist G (2004b) Divergence in replicated phylogenies: the evolution of partial post-mating prezygotic isolation in bean weevils. J Evol Biol 17:1345–1354PubMedCrossRefGoogle Scholar
  15. Gilchrist AS, Partridge L (1997) Heritability of pre-adult viability differences can explain apparent heritability of sperm displacement ability in Drosophila melanogaster. Proc R Soc Lond Ser B 269:1701–1707Google Scholar
  16. Gregory PG, Howard DJ (1994) A post-insemination barrier to fertilization isolates two closely related ground crickets. Evolution 48:705–710CrossRefGoogle Scholar
  17. Harrison RG (1983) Barriers to gene exchange between closely related cricket species. I. Laboratory hybridization studies. Evolution 37:245–251CrossRefGoogle Scholar
  18. Harrison RG (1990) Hybrid zones: windows on evolutionary process. In: Futuyma DJ, Antonovics J (eds) Oxford surveys in evolutionary biology, vol 7. Oxford University Press, Oxford, pp 69–128Google Scholar
  19. Harrison RG (1998) Linking evolutionary pattern and process: the relevance of species concepts for the study of speciation. In: Howard DJ, Berlocher SH (eds) Endless forms: species and speciation. Oxford University Press, Oxford, pp 19–31Google Scholar
  20. Hebert PDN, Beaton MJ (1993) Methodologies for allozyme analysis using cellulose acetate electrophoresis. Helena Laboratories, BeaumontGoogle Scholar
  21. Hewitt GM, Mason P, Nichols RA (1989) Sperm precedence and homogamy across a hybrid zone in the alpine grasshopper Podisma pedestris. Heredity 62:343–353CrossRefGoogle Scholar
  22. Howard DJ (1999) Conspecific sperm and pollen precedence and speciation. Annu Rev Ecol Syst 30:109–132CrossRefGoogle Scholar
  23. Howard DJ, Gregory PG (1993) Post-insemination signalling systems and reinforcement. Philos Trans R Soc Lond B 340:231–236CrossRefGoogle Scholar
  24. Howard DJ, Gregory PG, Chu J, Cain ML (1998) Conspecific sperm precedence is an effective barrier to hybridization between closely related species. Evolution 52:511–516CrossRefGoogle Scholar
  25. Kay KM (2006) Reproductive isolation between two closely related hummingbird-pollinated neotropical gingers. Evolution 60:538–552PubMedGoogle Scholar
  26. Lee Y-H, Vacquier VD (1992) The divergence of species-specific abalone sperm lysins is promoted by positive Darwinian selection. Biol Bull 182:97–104CrossRefGoogle Scholar
  27. Lessios HA, Cunningham CW (1990) Gametic incompatibility between species of the sea urchin Echinometra on the two sides of the isthmus of Panama. Evolution 44:933–941CrossRefGoogle Scholar
  28. Lorch PD, Servedio MR (2007) The evolution of conspecific gamete precedence and its effect on reinforcement. J Evol Biol 20:937–949PubMedCrossRefGoogle Scholar
  29. Lowry DB, Rockwood RC, Willis JH (2008a) Ecological reproductive isolation of coast and inland races of Mimulus guttatus. Evolution 62:2196–2214PubMedCrossRefGoogle Scholar
  30. Lowry DB, Modliszewski JL, Wright KM, Wu CA, Willis JH (2008b) The strength and genetic basis of reproductive isolating barriers in flowering plants. Phil Trans R Soc Lond B 363:3009–3021CrossRefGoogle Scholar
  31. Markow TA (1997) Assortative fertilization in Drosophila. Proc Natl Acad Sci (USA) 94:7756–7760CrossRefGoogle Scholar
  32. Marshall JL, Arnold ML, Howard DJ (2002) Reinforcement: the road not taken. Trends Ecol Evol 17:558–563CrossRefGoogle Scholar
  33. Martin NH, Willis JW (2007) Ecological divergence associated with mating system causes nearly complete reproductive isolation between sympatric Mimulus species. Evolution 61:68–82PubMedCrossRefGoogle Scholar
  34. Martin-Coello J, Benavent-Corai J, Roldan ERS, Gomendio M (2009) Sperm competition promotes asymmetries in reproductive barriers between closely related species. Evolution 63:613–623PubMedCrossRefGoogle Scholar
  35. Matsubayashi KW, Katakura H (2009) Contribution of multiple isolating barriers to reproductive isolation between a pair of phytophagous ladybird beetles. Evolution 63:2563–2580PubMedCrossRefGoogle Scholar
  36. Mayr E (1947) Ecological factors in speciation. Evolution 1:263–288CrossRefGoogle Scholar
  37. Mendelson TC, Imhoff VE, Venditti JJ (2007) The accumulation of reproductive barriers during speciation: postmating barriers in two behaviorally isolated species of darters (Percidae: Etheostoma). Evolution 61:2596–2606PubMedCrossRefGoogle Scholar
  38. Metz EC, Palumbi SR (1996) Positive selection and sequence rearrangements generate extensive polymorphism in the gamete recognition protein binding. Mol Biol Evol 13:397–406PubMedGoogle Scholar
  39. Monsen KJ, Honchak BM, Locke SE, Peterson MA (2007) Cytonuclear disequilibria in Chrysochus hybrids is not due to patterns of mate choice. J Hered 98:325–330PubMedCrossRefGoogle Scholar
  40. Nosil P (2007) Divergent host plant adaptation and reproductive isolation between ecotypes of Timema cristinae walking sticks. Am Nat 169:151–162PubMedCrossRefGoogle Scholar
  41. Nosil P, Crespi BJ (2006) Ecological divergence promotes the evolution of cryptic reproductive isolation. Proc R Soc Lond Ser B 273:991–997CrossRefGoogle Scholar
  42. Nosil P, Vines TH, Funk DJ (2005) Perspective: reproductive isolation caused by natural selection against immigrants from divergent habitats. Evolution 59:705–719PubMedGoogle Scholar
  43. Palumbi SR, Metz RC (1991) Strong reproductive isolation between closely related tropical sea urchins (genus Echinometra). Mol Biol Evol 8:227–239PubMedGoogle Scholar
  44. Peterson MA, Dobler S, Holland J, Tantalo L, Locke S (2001) Behavioral, molecular, and morphological evidence for a hybrid zone between Chrysochus auratus and C. cobaltinus (Coleoptera: Chrysomelidae). Ann Entomol Soc Am 94:1–9CrossRefGoogle Scholar
  45. Peterson MA, Monsen K, Pedersen H, Bearden J, McFarland T (2005a) Direct and indirect evidence of low hybrid fitness in the Chrysochus hybrid zone. Biol J Linn Soc 84:273–286CrossRefGoogle Scholar
  46. Peterson MA, Honchak B, Locke S, Beeman T, Mendoza J, Green J, Buckingham K, White MA, Monsen K (2005b) Relative abundance and the species-specific reinforcement of male mating preference in the Chrysochus (Coleoptera: Chrysomelidae) hybrid zone. Evolution 59:2639–2655PubMedGoogle Scholar
  47. Peterson MA, Dobler S, Larson EL, Juárez D, Schlarbaum T, Monsen KJ, Francke W (2007) Profiles of cuticular hydrocarbons mediate male mate choice and sexual isolation between hybridising Chrysochus (Coleoptera: Chrysomelidae). Chemoecology 17:87–96CrossRefGoogle Scholar
  48. Price CSC (1997) Conspecific sperm precedence in Drosophila. Nature 388:663–666PubMedCrossRefGoogle Scholar
  49. Price CSC, Kim CH, Posluszny J, Coyne JA (2000) Mechanisms of conspecific sperm precedence in Drosophila. Evolution 54:2028–2037PubMedGoogle Scholar
  50. Price CSC, Kim CH, Gronlund CJ, Coyne JA (2001) Cryptic reproductive isolation in the Drosophila simulans species complex. Evolution 55:81–92PubMedGoogle Scholar
  51. R Development Core Team (2009) R: a language and environment for statistical computing. R Foundation for Statistical Computing, ViennaGoogle Scholar
  52. Rahmé J, Widmer A, Karrenberg S (2009) Pollen competition as an asymmetric reproductive barrier between two closely related Silene species. J Evol Biol 22:1937–1943PubMedCrossRefGoogle Scholar
  53. Ramsey J, Bradshaw HD Jr, Schemske DW (2003) Components of reproductive isolation between the monkeyflowers Mimulus lewisii and M. cardinalis (Phrymaceae). Evolution 57:1520–1534PubMedGoogle Scholar
  54. Richardson BJ, Baverstock PR, Adams M (1986) Allozyme electrophoresis: a handbook for animal systematics and population studies. Academic Press, SydneyGoogle Scholar
  55. Rieseberg LH, Desrochers AM, Youn SJ (1995) Interspecific pollen competition as a reproductive barrier between sympatric species of Helianthus (Asteraceae). Am J Bot 82:515–519CrossRefGoogle Scholar
  56. Schwander T, Suni SS, Cahan SH, Keller L (2008) Mechanisms of reproductive isolation between an ant species of hybrid origin and one of its parents. Evolution 62:1635–1643PubMedCrossRefGoogle Scholar
  57. Schwartz S, Peterson MA (2006) Strong material benefits and no longevity cost of multiple mating in an extremely polyandrous beetle. Behav Ecol 17:1004–1010CrossRefGoogle Scholar
  58. Servedio MR, Noor MAF (2003) The role of reinforcement in speciation: theory and data meet. Annu Rev Ecol Evol Syst 34:339–364CrossRefGoogle Scholar
  59. Snook RR, Chapman T, Moore PJ, Wedell N, Crudgington HS (2009) Interactions between the sexes: new perspectives on sexual selection and reproductive isolation. Evol Ecol 23:71–91CrossRefGoogle Scholar
  60. Sobel JM, Chen GF, Watt LR, Schemske DW (2010) The biology of speciation. Evolution 64:295–315PubMedCrossRefGoogle Scholar
  61. Sokal RR, Rohlf FJ (1981) Biometry, 2nd edn. Freeman, New YorkGoogle Scholar
  62. SPSS (2005) SPSS 11.0.4 for Mac OS X. SPSS Inc, ChicagoGoogle Scholar
  63. Swanson WJ, Clark AG, Waldrip-Dail HM, Wolfner MF, Aquadro CF (2001) Evolutionary EST analysis identifies rapidly evolving male reproductive proteins in Drosophila. Proc Natl Acad Sci (USA) 95:4051–4054Google Scholar
  64. Takami Y, Nagata N, Sasabe M, Sota T (2007) Asymmetry in reproductive isolation and its effect on directional mitochondrial introgression in the parapatric ground beetles Carabus yamato and C. albrechti. Popul Ecol 49:337–346CrossRefGoogle Scholar
  65. Turelli M, Moyle LC (2007) Asymmetric postmating isolation: Darwin’s corollary to Haldane’s rule. Genetics 176:1059–1088PubMedCrossRefGoogle Scholar
  66. Wu CI, Hollocher H, Begun DJ, Aquadro CF, Xu Y, Wu M-L (1995) Sexual isolation in Drosophila melanogaster: a possible case of incipient speciation. Proc Natl Acad Sci (USA) 92:2519–2523CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media B.V. 2011

Authors and Affiliations

  • Merrill A. Peterson
    • 1
  • Erica L. Larson
    • 1
    • 4
  • Margaret Brassil
    • 1
    • 5
  • Kati J. Buckingham
    • 1
    • 6
  • Danielle Juárez
    • 1
    • 7
  • Joseph Deas
    • 2
    • 8
  • Donna Mangloña
    • 3
  • Michael A. White
    • 1
    • 9
  • Jonathan Maslan
    • 1
    • 10
  • Andrew Schweitzer
    • 1
  • Kirsten J. Monsen
    • 1
    • 11
  1. 1.Biology DepartmentWestern Washington UniversityBellinghamUSA
  2. 2.Department of BiologySan Diego State UniversitySan DiegoUSA
  3. 3.Department of BiologyCalifornia State UniversityNorthridgeUSA
  4. 4.Department of Ecology and Evolutionary BiologyCornell UniversityIthacaUSA
  5. 5.Department of ImmunologyUniversity of WashingtonSeattleUSA
  6. 6.Department of PediatricsUniversity of WashingtonSeattleUSA
  7. 7.School of DentistryUniversity of WashingtonSeattleUSA
  8. 8.Department of EntomologyUniversity of ArizonaTucsonUSA
  9. 9.Laboratory of GeneticsUniversity of WisconsinMadisonUSA
  10. 10.Wake Forest University School of MedicineWinston-SalemUSA
  11. 11.Department of Biology and Molecular BiologyMontclair State UniversityMontclairUSA

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