The pattern of segment formation, as revealed by engrailed expression, in a centipede with a variable number of segments

SUMMARY Arthropods vary enormously in segment number, from less than 20 to more than 200. This between‐species variation must have originated, in evolution, through divergent selection operating in ancestral arthropod species with variable segment numbers. Although most present‐day arthropod species are invariant in this respect, some are variable and so can serve as model systems. Here, we describe a study based on one such species, the coastal geophilomorph centipede Strigamia maritima. We investigate the way in which segments are formed using in situ hybridization to demonstrate the expression pattern of the engrailed gene during embryogenesis. We also analyze segment number data in mother–offspring broods and thereby demonstrate a significant heritable component of the variation. We consider how natural selection might act on this intraspecific developmental variation, and we discuss the similarities and differences in segment formation between the geophilomorphs and their phylogenetic sister‐group.

[1]  P. Whitington,et al.  Segmentation, neurogenesis and formation of early axonal pathways in the centipede,Ethmostigmus rubripes (Brandt) , 1991, Roux's archives of developmental biology.

[2]  W. Arthur,et al.  Observations on the eggs and early postembryonic stages of Strigamia maritima , 2002 .

[3]  T. Kaufman,et al.  Exploring myriapod segmentation: the expression patterns of even-skipped, engrailed, and wingless in a centipede. , 2002, Developmental biology.

[4]  T. Kaufman,et al.  Exploring the myriapod body plan: expression patterns of the ten Hox genes in a centipede. , 2002, Development.

[5]  A. Minelli,et al.  Hox gene sequences from the geophilomorph centipede Pachymerium ferrugineum (C. L. Koch, 1835) (Chilopoda: Geophilomorpha: Geophilidae): implications for the evolution of the Hox class genes of arthropods. , 2002, Molecular phylogenetics and evolution.

[6]  A. Minelli,et al.  Analysis of segment number and enzyme variation in a centipede reveals a cryptic species, Geophilus easoni sp. nov., and raises questions about speciation , 2001 .

[7]  A. Minelli,et al.  engrailed sequences from four centipede orders: strong sequence conservation, duplications and phylogeny , 2001, Development Genes and Evolution.

[8]  W. Arthur,et al.  Geographic patterning of variation in segment number in geophilomorph centipedes: clines and speciation , 2001, Evolution & development.

[9]  Matthew J. Hayden.  Embryology: Constructing the Organism , 2001, The Yale Journal of Biology and Medicine.

[10]  W. Arthur,et al.  Latitudinal cline in segment number in an arthropod species, Strigamia maritima , 2000, Proceedings of the Royal Society of London. Series B: Biological Sciences.

[11]  Alessandro Minelli,et al.  The evolution of segmentation of centipede trunk and appendages , 2000 .

[12]  A. Minelli.  Holomeric vs. meromeric segmentation: a tale of centipedes, leeches, and rhombomeres , 2000, Evolution & development.

[13]  A. Minelli,et al.  Homeotic transformation in a centipede. , 1999, Trends in genetics : TIG.

[14]  Arthur,et al.  The pattern of variation in centipede segment number as an example of developmental constraint in evolution , 1999, Journal of theoretical biology.

[15]  W. Arthur,et al.  Segments, limbs, homology, and co‐option , 1999, Evolution & development.

[16]  R. Chapman,et al.  The stability of thoracic segmentation in trilobites: a case study in developmental and ecological constraints , 1999, Evolution & development.

[17]  S. Carranza,et al.  Internal phylogeny of the Chilopoda (Myriapoda, Arthropoda) using complete 18S rDNA and partial 28S rDNA sequences. , 1999, Philosophical transactions of the Royal Society of London. Series B, Biological sciences.

[18]  S. Carroll,et al.  Evolution of the entire arthropod Hox gene set predated the origin and radiation of the onychophoran/arthropod clade , 1997, Current Biology.

[19]  T. Jowett.  Tissue In Situ Hybridization: Methods in Animal Development , 1997 .

[20]  N. Patel,et al.  Developmental evolution: insights from studies of insect segmentation. , 1994, Science.

[21]  N. Patel.  The evolution of arthropod segmentation: insights from comparisons of gene expression patterns. , 1994, Development (Cambridge, England). Supplement.

[22]  Teri,et al.  Molecular Cloning A Laboratory Manual Second Edition Sambrook , 1989 .

[23]  P. Ingham.  The molecular genetics of embryonic pattern formation in Drosophila , 1988, Nature.

[24]  A. Minelli,et al.  Myriapod metamerism and arthropod segmentation , 1988 .

[25]  Erling O. Horneland,et al.  The epimorphosis of Strigamia maritima (Leach, 1817) (Chilopoda: Geophilidae) , 1986 .

[26]  A. Minelli.  Post-embryonic development and the phylogeny of geophilomorph centipedes (Chilopoda) , 1985 .

[27]  W. Dohle.  Phylogenetic pathways in the Chilopoda , 1985 .

[28]  J. G. E. Lewis,et al.  The biology of centipedes , 1981 .

[29]  Ralph I. Smith,et al.  Embryology and Phylogeny in Annelids and Arthropods , 1974 .

[30]  E. Eason.  Centipedes of the British Isles , 1964 .

[31]  J. G. Lewis.  The ecology, distribution and taxonomy of the centipedes found on the shore in the Plymouth area , 1962, Journal of the Marine Biological Association of the United Kingdom.

[32]  A. D. Imms.  Embryology of Insects and Myriapods , 1941, Nature.