The origin of the Chorthippus parallelus hybrid zone: chromosomal evidence of multiple refugia for Iberian populations

A study of the variation in pattern and frequency of constitutive heterochromatin and nucleolar organizing regions of the X chromosomes of male Chorthippus parallelus grasshoppers in 25 populations within the Iberian peninsula requires us to revise our interpretation of the biogeography and evolutionary history of this species. Hybridization between the subspecies Cp erythropus and Cp parallelus, previously only known from populations in the Pyrenean cols, is shown to extend at least 400 km further into north‐west Spain. A novel X‐chromosome variant is described that appears to be close to fixation in 18 populations, mainly from the centre and south of Spain. Our findings indicate a possible independent origin for each of three distinct, nonderivative X variants present in Spain: the northern Cp erythropus and Cp parallelus variants, and a central‐southern Cp erythropus variant. The first two are distinguished by interstitial and distal C bands, respectively, whereas the central‐southern form has neither. This central‐southern form is probably the current representative of the ancestral Iberian X variant. The pattern of variation supports the hypotheses of multiple refugia for Iberian populations and that more hybrid zones exist between these chromosomal variants.

[1]  D. Lunt,et al.  Refugia within Refugia: Patterns of Phylogeographic Concordance in the Iberian Peninsula , 2007 .

[2]  M. G. Ritchie,et al.  An unusual phylogeography in the bushcricket Ephippiger ephippiger from Southern France , 2006, Heredity.

[3]  C. López‐Fernández,et al.  Differential staining of a heterochromatic zone inArcyptera fusca (Orthoptera) , 1981, Experientia.

[4]  R. Butlin,et al.  The genetic basis of speciation in a grasshopper hybrid zone. , 2005 .

[5]  E. Benavente,et al.  Meiotic pairing in wheat-rye derivatives detected by genomic in situ hybridization and C-banding — A comparative analysis , 1995, Chromosoma.

[6]  G. Hewitt,et al.  Testing for recombination in a short nuclear DNA sequence of the European meadow grasshopper, Chorthippus parallelus , 2002, Molecular ecology.

[7]  N. Barton.  The role of hybridization in evolution , 2001, Molecular ecology.

[8]  G. Hewitt.  The genetic legacy of the Quaternary ice ages , 2000, Nature.

[9]  L. Rieseberg,et al.  Transgressive segregation, adaptation and speciation , 1999, Heredity.

[10]  Hewitt,et al.  Chromosomal differentiation through an Alpine hybrid zone in the grasshopper Chorthippus parallelus , 1999 .

[11]  J. Vogel,et al.  Where are the glacial refugia in Europe? Evidence from pteridophytes , 1999 .

[12]  G. Hewitt,et al.  mtDNA phylogeography and postglacial patterns of subdivision in the meadow grasshopper Chorthippus parallelus , 1998, Heredity.

[13]  T. Dowling,et al.  The role of hybridization and introgression in the diversification of animals , 1997 .

[14]  G. Hewitt,et al.  A hybrid zone between two subspecies of Chorthippus parallelus. X‐chromosome variation through a contact zone , 1996 .

[15]  G. Hewitt,et al.  Postglacial expansion and genome subdivision in the European grasshopper Chorthippus parallelus , 1995, Molecular ecology.

[16]  R. Butlin,et al.  A hybrid zone between two subspecies of the grasshopper Chorthippus parallelus along the Pyrenees: the west end , 1994, Heredity.

[17]  G. Hewitt,et al.  Nuclear DNA sequence divergence between parapatric subspecies of the grasshopper Chorthippus parallelus , 1993, Insect molecular biology.

[18]  D. Hillis,et al.  Origin of a novel allele in a mammalian hybrid zone. , 1993, Proceedings of the National Academy of Sciences of the United States of America.

[19]  G. Hewitt,et al.  One way introgression of a subspecific sex chromosome marker in a hybrid zone , 1993, Heredity.

[20]  G. Hewitt,et al.  Heterochromatin heterogeneity and rapid divergence of the sex chromosomes in Chorthippus parallelus parallelus and C. p. erythropus (Orthoptera). , 1993, Genome.

[21]  J. Miguel.,et al.  Divergencia y especiación: marcadores cromosómicos y moleculares en el estudio de zonas híbridas entre dos superficies de Chorthipphus parallelus , 1992 .

[22]  G. Hewitt,et al.  Postzygotic isolation and Haldane's rule in a grasshopper , 1992, Heredity.

[23]  G. Hewitt,et al.  Meiotic imbalance in laboratory-produced hybrid males of Chorthippus parallelus parallelus and Chorthippus parallelus erythropus , 1990 .

[24]  R. Harrison,et al.  Hybrid zones: windows on evolutionary process. , 1990 .

[25]  R. Butlin,et al.  A hybrid zone between Chorthippus parallelus parallelus and Chorthippus parallelus erythropus (Orthoptera: Acrididae): Chromosomal differentiation , 1988 .

[26]  G. Hewitt.  Hybrid zones-natural laboratories for evolutionary studies. , 1988, Trends in ecology & evolution.

[27]  J. Gosálvez,et al.  Development of Silver Stained Structures During Spermatogenesis of Schistocerca Gregaria (Forsk.) (Orthoptera: Acrididae) , 1982 .

[28]  W. Reynolds.  A re-examination of the characters separating Chorthippus montanus and C. parallelus (Orthoptera: Acrididae) , 1980 .

[29]  W. Gerlach,et al.  Cloning and characterization of ribosomal RNA genes from wheat and barley. , 1979, Nucleic acids research.