--- _id: '3670' abstract: - lang: eng text: The grasshopper Podisma pedestris includes two chromosomal races, which differ by a Robertsonian fusion involving the sex chromosome. The two races meet in a cline which runs for 100 km across the Alpes Maritimes in south-eastern France. An intensive study of the easternmost end of this cline shows that it is about 800 m wide; the cline is not smooth, containing substantial spikes in chromosome frequency which might be due to sampling drift. Though the cline seems narrow, it is wide compared with the dispersal rate of the insect; a selective force of only 0.5% would be enough to maintain the cline. It is difficult to determine the nature of this force, but some evidence comes from the position of the cline, and from the presence of coincident clines at other loci. An estimate of the distribution of Podisma has been made, and the cline seems to follow, for the most part, a region of low population density, suggesting that it is maintained by hybrid unfitness. However, in the one region where the cline is relatively free to move, the XY race bulges forwards more than would be expected if hybrids are unfit. The observation of severe inviability in crosses between the races, though it is not associated with the chromosomal difference, also indicates that this cline is the result of some sort of genetic incompatibility. acknowledgement: "Many thanks are due to the Hewitt family (Elizabeth, Daniel, Matthew, and James), Bruce and Helen Halliday, Mike\r\n Shaw, Alan Jenyon, and Bob Williams for their help in collecting the grasshoppers; to M. and Mme. Aviotti for their hospitality in Casterino; and to Marise East for her help in karyotyping the samples. The work was supported by a grant from the S.R.C. to G. Hewitt, and N. Barton was supported by a N.E.R.C. studentship." article_processing_charge: No article_type: original author: - first_name: Nicholas H full_name: Barton, Nicholas H id: 4880FE40-F248-11E8-B48F-1D18A9856A87 last_name: Barton orcid: 0000-0002-8548-5240 - first_name: Godfrey full_name: Hewitt, Godfrey last_name: Hewitt citation: ama: Barton NH, Hewitt G. A chromosomal cline in the grasshopper Podisma pedestris. Evolution; International Journal of Organic Evolution. 1981;35(5):1008-1018. doi: 10.1111/j.1558-5646.1981.tb04966.x apa: Barton, N. H., & Hewitt, G. (1981). A chromosomal cline in the grasshopper Podisma pedestris. Evolution; International Journal of Organic Evolution. Wiley-Blackwell. https://doi.org/ 10.1111/j.1558-5646.1981.tb04966.x chicago: Barton, Nicholas H, and Godfrey Hewitt. “A Chromosomal Cline in the Grasshopper Podisma Pedestris.” Evolution; International Journal of Organic Evolution. Wiley-Blackwell, 1981. https://doi.org/ 10.1111/j.1558-5646.1981.tb04966.x. ieee: N. H. Barton and G. Hewitt, “A chromosomal cline in the grasshopper Podisma pedestris,” Evolution; International Journal of Organic Evolution, vol. 35, no. 5. Wiley-Blackwell, pp. 1008–1018, 1981. ista: Barton NH, Hewitt G. 1981. A chromosomal cline in the grasshopper Podisma pedestris. Evolution; International Journal of Organic Evolution. 35(5), 1008–1018. mla: Barton, Nicholas H., and Godfrey Hewitt. “A Chromosomal Cline in the Grasshopper Podisma Pedestris.” Evolution; International Journal of Organic Evolution, vol. 35, no. 5, Wiley-Blackwell, 1981, pp. 1008–18, doi: 10.1111/j.1558-5646.1981.tb04966.x. short: N.H. Barton, G. Hewitt, Evolution; International Journal of Organic Evolution 35 (1981) 1008–1018. date_created: 2018-12-11T12:04:32Z date_published: 1981-09-01T00:00:00Z date_updated: 2022-01-21T08:51:51Z day: '01' doi: ' 10.1111/j.1558-5646.1981.tb04966.x' extern: '1' external_id: pmid: - '28581059' intvolume: ' 35' issue: '5' language: - iso: eng main_file_link: - url: http://www.jstor.org/stable/2407871 month: '09' oa_version: None page: 1008 - 1018 pmid: 1 publication: Evolution; International Journal of Organic Evolution publication_identifier: eissn: - 1558-5646 issn: - 0014-3820 publication_status: published publisher: Wiley-Blackwell publist_id: '2713' quality_controlled: '1' status: public title: A chromosomal cline in the grasshopper Podisma pedestris type: journal_article user_id: ea97e931-d5af-11eb-85d4-e6957dddbf17 volume: 35 year: '1981' ...