Biological Invasions

, Volume 15, Issue 1, pp 225–241 | Cite as

Long-term population genetic structure of an invasive urochordate: the ascidian Botryllus schlosseri

  • Eitan Reem
  • Jacob Douek
  • Gadi Katzir
  • Baruch Rinkevich
Original Paper


The accelerated pace of marine biological invasions raises questions pertaining to genetic traits and dynamics underlying the successful establishment of invasive species. Current research stresses the importance of multiple introductions and prolonged gene flow as the main sources for genetic diversity, which, along with genetic drift, affect invasive species success. We here attempt to determine the relative contribution of gene flow and mutation rates as sources of genetic variability using the invasive tunicate Botryllus schlosseri as a model. The study was performed over a 13-year period in the Santa Cruz Harbor, California. With a characteristic life history of five generations/year, the Santa Cruz Botryllus population has already experienced approximately 155 generations since the onset of its invasion. The results (278 specimens, 127 scored alleles, five microsatellite loci) support limited gene flow rate (2.89 × 10−3) and relative genetic isolation. Furthermore, the study population was found to be influenced by both, genetic drift and a high mutation rate (2.47 × 10−2). These findings were supported by high fluctuations in the frequencies of microsatellite alleles, the appearance of new alleles and the loss of others. The balance between genetic drift and a high mutation rate is further elucidated by the high, stable level of genetic variation. We suggest that rapid mutation rates at the microsatellite loci reflect genome-wide phenomena, helping to maintain high genetic variability in relatively isolated populations. The potential adaptability to new environments is discussed.


Genetic diversity Genetic drift Invasions Microsatellites Mutations 


  1. Amos W, Harwood J (1998) Factors affecting levels of genetic diversity in natural populations. Philos Trans R Soc Lond B Biol Sci 353:177–186PubMedCrossRefGoogle Scholar
  2. Ben-Shlomo R, Douek J, Rinkevich B (2001) Heterozygote deficiency and chimerism in remote populations of a colonial ascidian from New Zealand. Mar Ecol Prog Ser 209:109–117CrossRefGoogle Scholar
  3. Ben-Shlomo R, Paz G, Rinkevich B (2006) Postglacial-period and recent invasions shape population genetics of botryllid ascidians along European Atlantic coasts. Ecosystems 9:1118–1127CrossRefGoogle Scholar
  4. Ben-Shlomo R, Motro U, Paz G, Rinkevich B (2008) Pattern of settlement and natural chimerism in the colonial urochordate Botryllus schlosseri. Genetica 132:51–58PubMedCrossRefGoogle Scholar
  5. Ben-Shlomo R, Reem E, Douek J, Rinkevich B (2010) Population genetics of the invasive ascidian Botryllus schlosseri from South American coasts. Mar Ecol Prog Ser 412:85–92CrossRefGoogle Scholar
  6. Bernier YR, Locke A, Hanson JM (2009) Lobsters and crabs as potential vectors for tunicate dispersal in the southern gulf of St. Lawrence, Canada. Aquat Invas 4:105–110CrossRefGoogle Scholar
  7. Berrill NJ (1950) The Tunicata with an account of the British species. Ray Society, LondonGoogle Scholar
  8. Bock DG, Zahn A, Lejeusne C, Macisaac HJ, Cristescu ME (2011) Looking at both sides of the invasion: patterns of colonization in the violet tunicate Botrylloides violaceus. Mol Ecol 20:503–516PubMedCrossRefGoogle Scholar
  9. Chadwick-Furman NE, Weissman IL (1995) Life histories and senescence of Botryllus schlosseri (Chordata, Ascidiacea) in Monterey bay. Biol Bull 189:36–41PubMedCrossRefGoogle Scholar
  10. Cockerham CC, Weir BS (1993) Estimation of gene flow from F-statistics. Evolution 47:855–863CrossRefGoogle Scholar
  11. Cohen AN, Carlton JT (1995) Nonindigenous aquatic species in a United States estuary: a case study of the biological invasions of the San Francisco bay and delta. United States Fish and Wildlife Service Washington D.C. and the national sea grant college program connecticut sea grant, pp 112, 117Google Scholar
  12. Corander J, Marttinen P, Sirén J, Tang J (2009) BAPS: Bayesian analysis of population. Structure version 5.3. Department of Mathematics, Åbo Akademi University Finland, 27 pp. Available from
  13. Crawford NG (2010) SMOGD: software for the measurement of genetic diversity. Mol Ecol Resour 10:556–557PubMedCrossRefGoogle Scholar
  14. Crow JF, Aoki K (1984) Group selection for a polygenic behavioral trait: estimating the degree of population subdivision. Proc Natl Acad Sci USA 81:6073–6077PubMedCrossRefGoogle Scholar
  15. Dlugosch KM, Parker IM (2008) Founding events in species invasions: genetic variation, adaptive evolution, and the role of multiple introductions. Mol Ecol 17:431–449PubMedCrossRefGoogle Scholar
  16. Durka W, Bossdorf O, Prati D, Auge H (2005) Molecular evidence for multiple introductions of garlic mustard (Alliaria petiolata, Brassicaceae) to North America. Mol Ecol 14:1697–1706PubMedCrossRefGoogle Scholar
  17. El Mousadik A, Petit RJ (1996) High level of genetic differentiation for allelic richness among populations of the argan tree [Argania spinosa (L.) Skeels] endemic to Morocco. Theor Appl Genet 92:832–839CrossRefGoogle Scholar
  18. Frankham R (2005) Resolving the genetic paradox in invasive species. Heredity 94:385PubMedCrossRefGoogle Scholar
  19. Geller JB, Darling JA, Carlton JT (2010) Genetic perspectives on marine biological invasions. Annu Rev Mar Sci 2:367–393CrossRefGoogle Scholar
  20. Genton BJ, Shykoff A, Giraud T (2005) High genetic diversity in French invasive populations of common ragweed, Ambrosia artemistiifolia, as a result of multiple sources of introduction. Mol Ecol 14:4275–4285PubMedCrossRefGoogle Scholar
  21. Gerlach G, Jueterbock A, Kraemer P, Deppermann J, Harmand P (2010) Calculations of population differentiation based on GST and D: forget GST but not all of statistics! Mol Ecol 19:3845–3852PubMedCrossRefGoogle Scholar
  22. Goudet J (2001) FSTAT, a program to estimate and test gene diversities and fixation indices (version 2.9.3). Available
  23. Graham DE (1978) The isolation of high molecular weight DNA from whole organisms or large tissue masses. Anal Biochem 85:609–613PubMedCrossRefGoogle Scholar
  24. Grapputo A, Bisazza A, Pilastro A (2006) Invasion success despite reduction of genetic diversity in the European populations of eastern mosquitofish (Gambusia holbruki). Ital J Zool 73:67–73CrossRefGoogle Scholar
  25. Grosberg RK (1987) Limited dispersal and proximity-dependent mating success in the colonial ascidian Botryllus schlosseri. Evolution 41:372–384CrossRefGoogle Scholar
  26. Grosberg RK (1988) Life history variation within a population of a colonial ascidian Botryllus schlosseri, I. The genetic and environmental control of seasonal variation. Evolution 42:900–920CrossRefGoogle Scholar
  27. Han YS, Sun YL, Sun YF, Liao YF, Liao IC, Shen KN, Tzeng WN (2008) Temporal analysis of population genetic composition in the overexploited Japanes eel Anguilla japonica. Mar Biol 155:613–621CrossRefGoogle Scholar
  28. Harrison XA, Bearhop S, Iinger R, Colhoun K, Gudmundsson GA, Hodgson D, McElwaine G, Tregenza T (2011) Heterozygosity–fitness correlations in a migratory bird: an analysis of inbreeding and single-locus effects. Mol Ecol 20:4786–4795PubMedCrossRefGoogle Scholar
  29. Hartl DL, Clark AG, (1997) Principles of population genetics. Sinauer Associates Inc. Sunderland, MA, pp 289–290Google Scholar
  30. Hedrick PW (2005a) A standardized genetic differentiation measure. Evolution 59:1633–1638PubMedGoogle Scholar
  31. Hedrick PW (2005b) Genetics of populations. Jones and Bartlet Publishers, Sudbury, MA, pp 501–502Google Scholar
  32. Heller R, Siegismund HR (2009) Relationship between three measures of genetic differentiation GST, DEST and G’ST: how wrong have we been? Mol Ecol 18:2080–2083PubMedCrossRefGoogle Scholar
  33. Holland BS (2000) Genetics of marine bioinvasions. Hydrobiologia 420:63–71CrossRefGoogle Scholar
  34. Holland BS (2001) Invasion without a bottleneck: microsatellite variation in natural and invasive populations of the brown mussel, Perna perna (L). Mar Biotechnol 3:407–415PubMedCrossRefGoogle Scholar
  35. Jarne P, Lagoda PJL (1996) Microsatellites, from molecules to populations and back. Trends Ecol Evol 11:424–429PubMedCrossRefGoogle Scholar
  36. Johannesson K, André C (2006) Life on the margin: genetic isolation and diversity loss in a peripheral marine ecosystem, the Baltic Sea. Mol Ecol 15:2013–2029PubMedCrossRefGoogle Scholar
  37. Johnson RN, Starks PT (2004) A surprising level of genetic diversity in an invasive wasp:Polistes dominulus in the northeastern United States. Ann Entomolog Soc Am 97:732–737CrossRefGoogle Scholar
  38. Johnson SL, Yund PO (2007) Variation in multiple paternity in natural populations of a free spawning marine invertebrate. Mol Ecol 16:3253–3262PubMedCrossRefGoogle Scholar
  39. Jorde PE, Ryman N (1996) Demographic genetics of brown trout (Salmo trutta) and estimation of effective population size from temporal change of allele frequencies. Genetics 143:1369–1381PubMedGoogle Scholar
  40. Jorde PE, Ryman N (2007) Unbiased estimator for genetic drift and effective population size. Genetics 177:927–935PubMedCrossRefGoogle Scholar
  41. Jost L (2008) GST and its relatives do not measure differentiation. Mol Ecol 17:4015–4026PubMedCrossRefGoogle Scholar
  42. Jost L (2009) D vs. Gst: response to Heller and Siegismund (2009) and Ryman and Leimar (2009). Mol Ecol 18:2088–2091CrossRefGoogle Scholar
  43. Karlsson S, Mork J (2005) Deviation from Hardy-Weinberg equilibrium, and temporal instability in allele frequencies at microsatellite loci in a local population of Atlantic cod. ICES J Mar Sci 62:1588–1596CrossRefGoogle Scholar
  44. Kashi Y, King DG (2006) Simple sequence repeats as advantageous mutators in evolution. Trends Genet 22:253–259PubMedCrossRefGoogle Scholar
  45. Kolbe JJ, Glor RE, Schettino LR, Ada Chamizo L, Larson A, Losos JB (2004) Genetic variation increases during biological invasion by a Cuban lizard. Nature 431:177–181PubMedCrossRefGoogle Scholar
  46. Lambert G (2001) A global overview of ascidian introductions and their possible impact on the endemic fauna. In: Sawada H, Yokosawa H, Lambert CC (eds) The biology of ascidians. Springer, Tokyo, pp 249–257Google Scholar
  47. Lambert CC, Lambert G (1998) Non-indigenous ascidians in southern California harbors and marinas. Mar Biol 130:675–688CrossRefGoogle Scholar
  48. Lambert CC, Lambert G (2003) Persistence and differential distribution of nonindigenous ascidians in harbors of southern California bight. Mar Ecol Prog Ser 259:145–161CrossRefGoogle Scholar
  49. Lavergne S, Molofski J (2007) Increased genetic variation and evolutionary potential drive the success of an invasive grass. Proc Natl Acad Sci USA 104:3883–3888PubMedCrossRefGoogle Scholar
  50. Li YC, Korol AB, Fahima T, Beilis A, Nevo E (2002) Microsatellites: genomic distribution, putative functions and mutational mechanisms: a review. Mol Ecol 11:2453–2465PubMedCrossRefGoogle Scholar
  51. Light SF (1954) Intertidal Invertebrates of the Central California Coast: S.F. Light’s Laboratory and field text in invertebrate zoology, 2nd edn. (Revised by Smith RI, Pitelka FA, Abbott DO, Weesner FM). University of California Press, CA, USAGoogle Scholar
  52. Light SF, Smith RI, Carlton JT (1975) Light’s Manual: Intertidal Invertebrates of the Central California Coast: S. F. Light’s Laboratory and field text in invertebrate zoology, 3rd edn. Fourth printing, corrected and updated. University of California Press, CA, USAGoogle Scholar
  53. Ljungqvist M, Åkesson M, Hansson B (2010) Do microsatellites reflect genome-wide genetic diversity in natural populations? A comment on Väli et al. (2008). Mol Ecol 19:851–855PubMedCrossRefGoogle Scholar
  54. Lockwood JL, Cassey P, Blackburn T (2005) The role of propagule pressure in explaining species invasions. Trends Ecol Evol 20:223–228PubMedCrossRefGoogle Scholar
  55. Luquet E, David P, Lena JP, Joly P, Konecny L, Dufresnes C, Perrin N, Plenet S (2011) Heterozygosity–fitness correlations among wild populations of European tree frog (Hyla arborea) detect fixation load. Mol Ecol 20:1877–1887PubMedCrossRefGoogle Scholar
  56. Meirmans PG, Hedrick PW (2011) Assessing population structure: FST and related measures. Mol Ecol Resour 11:5–18PubMedCrossRefGoogle Scholar
  57. Michalakis Y, Excoffier L (1996) A generic estimation of population subdivision using distances between alleles with special reference for microsatellite loci. Genetics 142:1061–1064PubMedGoogle Scholar
  58. Miller MP (1997) Tools for population genetic analyses (Tfpga), version 1.3. Department of Biological Sciences, Northern Arizona University, Flagstaff (AZ)Google Scholar
  59. Montgomery ME, Woodworth LM, England PR, Briscoe DA, Frankham R (2010) Widespread selective sweeps affecting microsatellites in Drosophila populations adapting to captivity: implications for captive breeding programs. Biol Conserv 143:1842–1849CrossRefGoogle Scholar
  60. Mooney HA, Cleland EE (2001) The evolutionary impact of invasive species. Proc Natl Acad Sci USA 98:5446–5451PubMedCrossRefGoogle Scholar
  61. Novak SJ (2007) The role of evolution in the invasion process. Proc Natl Acad Sci USA 104:3671–3672PubMedCrossRefGoogle Scholar
  62. Pancer Z, Gershon H, Rinkevich B (1994) Direct typing of microsatellites in the colonial tunicate Botryllus schlosseri (Ascidiacea). Biochem Bioph Res Co 203:646–651CrossRefGoogle Scholar
  63. Paz G, Douek J, Caiquing M, Goren M, Rinkevich B (2003) Genetic structure of Botryllus schlosseri (Tunicata) populations from the Mediterranean coast of Israel. Mar Ecol Prog Ser 250:153–162CrossRefGoogle Scholar
  64. Peakall R, Smouse PE (2006) GENALEX 6: genetic analysis in Excel. Population genetic software for teaching and research. Mol Ecol Notes 6:288–295CrossRefGoogle Scholar
  65. Pérez-Portela R, Turon X, Bishop JDD (2012) Bottlenecks and loss of genetic diversity: spatio-temporal patterns of genetic structure in an ascidian recently introduced in Europe. Mar Ecol Prog Ser 451:93–105Google Scholar
  66. Puillandre N, Dupas S, Dangles O, Zeddam J-L, Capdevielle-Dulac C, Barbin K, Torres-Leguizamon M, Silvain J-F (2008) Genetic bottleneck in invasive species: the potato tuber moth adds to the list. Biol Invasions 10:319–333CrossRefGoogle Scholar
  67. Raymond M, Rousset F (1995) An exact test for population differentiation. Evolution 49:1280–1283CrossRefGoogle Scholar
  68. Reed DH, Frankham R (2001) How closely correlated are molecular and quantitative measures of genetic variation? A meta-analysis. Evolution 55:1095–1103PubMedGoogle Scholar
  69. Reed DH, Frankham R (2003) Correlation between fitness and genetic diversity. Conserv Biol 17:230–237CrossRefGoogle Scholar
  70. Rinkevich B (2005) Natural chimerism in colonial Urochordates. J Exp Mar Biol Ecol 322:93–109CrossRefGoogle Scholar
  71. Rinkevich B, Weissman IL (1987) The fate of Botryllus (Ascidiacea) larvae cosettled with parental colonies: beneficial or deleterious consequences? Biol Bull 173:474–488CrossRefGoogle Scholar
  72. Rinkevich B, Porat R, Goren M (1995) Allorecognition elements on a urochordate histocompatibility locus indicate unprecedented extensive polymorphism. Proc R Soc Lond B 259:319–324CrossRefGoogle Scholar
  73. Rinkevich B, Paz G, Douek J, Ben-Shlomo R (2001) Allorecognition and microsatellite allele polymorphism of Botryllus schlosseri from the Adriatic Sea. In: Sawada H, Yokosawa H, Lambert CC (eds) The biology of Ascidians. Springer, Tokyo, pp 426–435Google Scholar
  74. Roman J, Darling JA (2007) Paradox lost: genetic diversity and the success of aquatic invasions. Trends Ecol Evol 22:454–464PubMedCrossRefGoogle Scholar
  75. Ruiz GM, Fofonoff PW, Carlton JT, Wonham MJ, Hines AN (2000) Invasions of coastal marine communities in North America: apparent patterns, processes, and biases. Annu Rev Ecol Syst 31:481–531CrossRefGoogle Scholar
  76. Ruiz GM, Huber T, Larson K, McCann L, Steves B, Fofonoff P, Hines AH (2006) Biological invasions in Alaska’s coastal marine ecosystems: establishing a baseline. Smithsonian Environmental Research Center Edgewater, Maryland, USAGoogle Scholar
  77. Ryman N, Leimar O (2009) GST is still a useful measure of differentiation -a comment on Jost’s D. Mol Ecol 18:2084–2087PubMedCrossRefGoogle Scholar
  78. Sakai AK, Allendorf FW, Holt JS, Lodge DM, Molofsky J, With KA, Baughman S, Cabin RJ, Cohen JE, Ellstrand NC, McCauley DE, O’Neil P, Parker IM, Thompson JN, Weller SG (2001) The population biology of invasive species. Annu Rev Ecol Syst 32:305–332CrossRefGoogle Scholar
  79. Slatkin M (1995) A measure of population subdivision based on microsatellite allele frequencies. Genetics 139:457–462PubMedGoogle Scholar
  80. Stepien CA, Brown JE, Neilson ME, Tumeo MA (2005) Genetic diversity of invasive species in the Great Lakes versus their Eurasian source populations: insights for risk analysis. Risk Anal 25:1043–1060PubMedCrossRefGoogle Scholar
  81. Stoner DS, Quattro JM, Weissman IL (1997) Highly polymorphic microsatellite loci in the colonial ascidian Botryllus schlosseri. Mol Mar Biol Biotech 6:163–171Google Scholar
  82. Stoner DS, Ben-Shlomo R, Rinkevich B, Weissman IL (2002) Genetic variability of Botryllus schlosseri invasions to the east and west coasts of the USA. Mar Ecol Prog Ser 243:93–100CrossRefGoogle Scholar
  83. Strelow Consulting In association with Santa Cruz Port District (2009) Final Santa Cruz Harbor dredge management plan, pp 2–2, 3–3. Available from
  84. Suarez AV, Tsutsui ND (2008) The evolutionary consequences of biological invasions. Mol Ecol 17:351–360PubMedCrossRefGoogle Scholar
  85. Templeton AR (2006) Population genetics and microevolutionary theory. Wiley, Hoboken, NJ, pp 56–58Google Scholar
  86. Templeton AR (2008) The reality and importance of founder speciation in evolution. BioEssays 30:470–479PubMedCrossRefGoogle Scholar
  87. Tsutsui ND, Suarez AV, Holway DA, Case TJ (2000) Reduced genetic variation and the success of an invasive species. Proc Natl Acad Sci USA 97:5948–5953PubMedCrossRefGoogle Scholar
  88. Väli Ü, Einarsson A, Waits L, Ellegren H (2008) To what extent do microsatellite markers reflect genome-wide genetic diversity in natural populations? Mol Ecol 17:3808–3817PubMedCrossRefGoogle Scholar
  89. Van Oosterhout C, Hutchinson WF, Wills DPM, Shipley PF (2004) Micro-checker: software for identifying and correcting genotyping errors in microsatellite data. Mol Ecol Notes 4:535–538CrossRefGoogle Scholar
  90. Voisin M, Engel CR, Viard F (2005) Differential shuffling of native genetic diversity across introduced regions in a brown algae: aquaculture vs. maritime traffic effects. Proc Natl Acad Sci USA 102:5432–5437PubMedCrossRefGoogle Scholar
  91. Ward SM, Gaskin JF, Wilson LM (2008) Ecological genetics of plant invasion: what do we know? Invasive Plant Sci Manage 1:98–109CrossRefGoogle Scholar
  92. Xu H, Fu YX (2004) Estimating effective population size or mutation rate with microsatellites. Genetics 166:555–563PubMedCrossRefGoogle Scholar
  93. Yund PO, Feldgarden M (1992) Rapid proliferation of historecognition alleles in populations of a colonial Ascidian. J Exp Zool 263:442–452CrossRefGoogle Scholar
  94. Zayed A, Constantin ŞA, Packer L (2007) Successful Biological invasion despite a severe genetic load. PLoS ONE 2:e868. doi:10.1371/journal.pone.0000868 PubMedCrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media B.V. 2012

Authors and Affiliations

  • Eitan Reem
    • 1
    • 2
  • Jacob Douek
    • 1
  • Gadi Katzir
    • 2
    • 3
  • Baruch Rinkevich
    • 1
  1. 1.Israel Oceanography and Limnological Research, National Institute of OceanographyHaifaIsrael
  2. 2.Department of Evolutionary and Environmental Biology, Faculty of Science and Science EducationUniversity of HaifaHaifaIsrael
  3. 3.School of Marine SciencesUniversity of HaifaHaifaIsrael
  4. 4.Department of Neurobiology and Ethology, Faculty of ScienceUniversity of HaifaHaifaIsrael

Personalised recommendations