When is a species not a species? Uncoupled phenotypic, karyotypic and genotypic divergence in two species of South African laminate-toothed rats (Murinae: Otomyini)

Chromosomal polytypy, morphological conservatism and absence of data have frustrated the taxonomic revision of two species of southern African-endemic laminate-toothed rats (Otomys irroratus and Otomys saundersiae s.l.). New cytogenetic (G-banding and fluorescence in situ hybridization), DNA sequence [cytochrome b (cyt b) gene] and geometric morphometric data demonstrate the synonymy of O. saundersiae from Grahamstown (Eastern Cape, South Africa) under O. irroratus, and the validity of Otomys karoensis from the Fynbos Biome of the Western Cape. Phenotypic dimorphism in pelage colour and cranial morphology in O. irroratus from the climatically unpredictable Albany Thicket (=Savanna) Biome of the Eastern Cape results from the retention of allometric paedomorphic traits in some adults (saundersiae morph) but not others. The same paedomorphic traits are associated with speciation and karyotypic and genetic differentiation in O. karoensis. Within O. irroratus, two phenotypically and genotypically (cyt b divergence=6.4%) divergent lineages correspond with the Fynbos/Albany Thicket and Grassland biomes. Incipient speciation in O. irroratus seems to be associated with ecology rather than karyotype. © 2009 The Zoological Society of London.Articl

A Cluster Method for the Ashkin--Teller Model

A cluster Monte Carlo algorithm for the Ashkin-Teller (AT) model is constructed according to the guidelines of a general scheme for such algorithms. Its dynamical behaviour is tested for the square lattice AT model. We perform simulations on the line of critical points along which the exponents vary continuously, and find that critical slowing down is significantly reduced. We find continuous variation of the dynamical exponent $z$ along the line, following the variation of the ratio $\alpha/\nu$, in a manner which satisfies the Li-Sokal bound $z_{cluster}\geq\alpha/\nu$, that was so far proved only for Potts models.Comment: 18 pages, Revtex, figures include

Hierarchy of Scales in Language Dynamics

Methods and insights from statistical physics are finding an increasing variety of applications where one seeks to understand the emergent properties of a complex interacting system. One such area concerns the dynamics of language at a variety of levels of description, from the behaviour of individual agents learning simple artificial languages from each other, up to changes in the structure of languages shared by large groups of speakers over historical timescales. In this Colloquium, we survey a hierarchy of scales at which language and linguistic behaviour can be described, along with the main progress in understanding that has been made at each of them − much of which has come from the statistical physics community. We argue that future developments may arise by linking the different levels of the hierarchy together in a more coherent fashion, in particular where this allows more effective use of rich empirical data sets

When is a species not a species? Uncoupled phenotypic, karyotypic and genotypic divergence in two species of South African laminate-toothed rats (Murinae: Otomyini)

Chromosomal polytypy, morphological conservatism and absence of data have frustrated the taxonomic revision of two species of southern African-endemic laminate-toothed rats (Otomys irroratus and Otomys saundersiae s.l.). New cytogenetic (G-banding and fluorescence in situ hybridization), DNA sequence [cytochrome b (cyt b) gene] and geometric morphometric data demonstrate the synonymy of O. saundersiae from Grahamstown (Eastern Cape, South Africa) under O. irroratus, and the validity of Otomys karoensis from the Fynbos Biome of the Western Cape. Phenotypic dimorphism in pelage colour and cranial morphology in O. irroratus from the climatically unpredictable Albany Thicket (=Savanna) Biome of the Eastern Cape results from the retention of allometric paedomorphic traits in some adults (saundersiae morph) but not others. The same paedomorphic traits are associated with speciation and karyotypic and genetic differentiation in O. karoensis. Within O. irroratus, two phenotypically and genotypically (cyt b divergence=6.4%) divergent lineages correspond with the Fynbos/Albany Thicket and Grassland biomes. Incipient speciation in O. irroratus seems to be associated with ecology rather than karyotype.Centre of Excellence for Invasion Biolog

When is a species not a species? Uncoupled phenotypic, karyotypic and genotypic divergence in two species of South African laminate-toothed rats (Murinae: Otomyini)

Chromosomal polytypy, morphological conservatism and absence of data have frustrated the taxonomic revision of two species of southern African-endemic laminate-toothed rats (Otomys irroratus and Otomys saundersiae s.l.). New cytogenetic (G-banding and fluorescence in situ hybridization), DNA sequence [cytochrome b (cyt b) gene] and geometric morphometric data demonstrate the synonymy of O. saundersiae from Grahamstown (Eastern Cape, South Africa) under O. irroratus, and the validity of Otomys karoensis from the Fynbos Biome of the Western Cape. Phenotypic dimorphism in pelage colour and cranial morphology in O. irroratus from the climatically unpredictable Albany Thicket (=Savanna) Biome of the Eastern Cape results from the retention of allometric paedomorphic traits in some adults (saundersiae morph) but not others. The same paedomorphic traits are associated with speciation and karyotypic and genetic differentiation in O. karoensis. Within O. irroratus, two phenotypically and genotypically (cyt b divergence=6.4%) divergent lineages correspond with the Fynbos/Albany Thicket and Grassland biomes. Incipient speciation in O. irroratus seems to be associated with ecology rather than karyotype.Centre of Excellence for Invasion Biolog

Crystallization And Preliminary X-ray Diffraction Studies Of Isoform α1 Of The Human Thyroid Hormone Receptor Ligand-binding Domain

Thyroid hormone receptors (TR) play critical roles in virtually all tissues. The TR ligand-binding domain (LBD) participates in important activities, such as transcriptional activation and repression, through conformational changes induced by hormone binding. Two crystal forms of isoform α1 of the human thyroid hormone receptor LBD (hTRα1) in complex with the thyroid hormones T3 and Triac were obtained. The hTRα1-T3 complex was crystallized in a previously unobserved crystal form (space group P2 12121, a = 59.98, b = 80.80, c = 102.21 Å), with diffraction patterns extending to 1.90 Å resolution on a rotating-anode X-ray source, and in space group C2 (a = 117.54, b = 80.66, c = 62.55 Å, β = 121.04°), with data extending to 2.32 Å resolution. The hTRα1-Triac complex was also crystallized in the new space group P212121, with unit-cell parameters a = 60.01, b = 80.82, c = 102.39 Å its resolution limit extended to 2.20 Å on a home source. Phasing was carried out by the molecular-replacement method and structural refinement is currently in progress. The refined structures may provide insight into the design of new thyromimetics. © 2004 International Union of Crystallography.601018671870Altschul, S.F., Madden, T., Schffer, A.A., Zhang, J., Zhang, Z., Miller, W., Lipman, D.J., (1997) Nucleic Acids Res., 25, pp. 3389-3402(1994) Acta Cryst., D50, pp. 760-763. , Collaborative Computational Project, Number 4Darimont, B.D., Wagner, R.L., Apriletti, J.W., Stallcup, M.R., Kushner, P.J., Baxter, J.D., Fletterick, R.J., Yamamoto, K.R., (1998) Genes Dev., 12, pp. 3343-3356Dow, R.L., (2003) Bioorg. Med. Chem. Lett., 13, pp. 379-382Evans, R.M., (1988) Science, 240, pp. 889-895Forrest, D., Vennström, B., (2000) Thyroid, 10, pp. 41-52Garman, E.F., Schneider, T.R., (1997) J. Appl. Cryst., 30, pp. 211-237Gloss, B., Trost, S., Bluhm, W., Swanson, E., Clark, R., Winkfein, R., Janzen, K., Dillmann, W., (2001) Endocrinology, 142, pp. 544-550Jancarik, J., Kim, S.-H., (1991) J. Appl. Cryst., 24, pp. 409-411Johansson, C., Vennström, B., Thoren, P., (1998) Am. J. Physiol., 275, pp. R640-R646Kleywegt, G., Zou, J., Kjeldgaard, M., Jones, T., (2001) International Tables for Crystallography, F, pp. 353-356. , edited by M. G. Rossmann & E. Arnold, ch. 17.1, Dordrecht: Kluwer Academic PublishersLaudet, V., Hanni, C., Coll, J., Catzeflis, F., Stehelin, D., (1992) EMBO J., 11, pp. 1003-1013Nakai, A., Sakurai, A., Bell, G.I., DeGroot, L.J., (1988) Mol. Endocrinol., 2, pp. 1087-1092Navaza, J., (1994) Acta Cryst., A50, pp. 157-163Ribeiro, R.C., Kushner, P., Baxter, J.D., (1995) Annu. Rev. Med., 46, pp. 443-453Sakurai, A., Nakai, A., DeGroot, L.J., (1990) Mol. Cell. Endocrinol., 71, pp. 83-91Schwartz, H.L., Strait, K.A., Ling, N.C., Oppenheimer, J.H., (1992) J. Biol. Chem., 267, pp. 11794-11799Tsai, M., O'Malley, B.W., (1994) Annu. Rev. Biochem., 63, pp. 451-486Wagner, R.L., Apriletti, J.W., McGrath, M.E., West, B.L., Baxter, J.D., Fletterick, R.J., (1995) Nature (London), 378, pp. 690-697Wagner, R.L., Huber, B.R., Shiau, A.K., Kelly, A., Cunha Lima, S.T., Scanlan, T.S., Apriletti, J.W., Fletterick, R.J., (2001) Mol. Endocrinol., 15, pp. 398-410Weinberger, C., Thompson, C.C., Ong, E.S., Lebo, R., Gruol, D.J., Evans, R.M., (1986) Nature (London), 324, pp. 641-646Wikström, L., Johansson, C., Salto, C., Barlow, C., Campos Barros, A., Bass, F., Forrest, D., Vennström, B., (1998) EMBO J., 17, pp. 455-461Winn, M., Dodson, E.J., Ralph, A., (1997) Methods Enzymol., 277, pp. 620-633Ye, L., Li, Y., Mellstrom, K., Mellin, C., Bladh, L.G., Koehler, K., Garg, N., Malm, J., (2003) J. Med. Chem., 46, pp. 1580-1588Yen, P.M., (2001) Physiol Rev., 81, pp. 1097-114