Charles F. Nadler

G-band patterns as chromosomal markers, and the interpretation of chromosomal evolution in wild sheep (Ovis)

Хромосомы и Г-полосы диких баранов из Палеарктика и Неарктика были изучалы. ЕвропейскийOvis musimon (2n=54) и АзиатскийO. orientalis (2n=54) имели кариотипы и Г-полосы трех пар две-плеуных аутосом одинаковый и этими Северо-АмериканогоO. canadensis mexicana (2n=54) ВO. musimon x O. canadensis Φ1иΦ2 гибриды гомологи которые составляли три иары две-плечных аутосом были легко олоэнаванны и были неразличимые. Изучениэ меиосис в Φ2 гибриде показало 27 бивалентых. Эволюционное зхачение гомологическиых две-плечных в баранах через Голарктик ыыло обсужденно.

Chromosomes and Systematics of American Ground Squirrels of The Subgenus Spermophilus

Chromosome counts, karyotypes and possible mechanisms of karyotype evolution are presented for seven of the eight American species comprising the subgenus Spermophilus . Within S. townsendi , the subspecies vigilis, mollis and townsendi have a 2n of 46, 38 and 36, respectively. S. washingtoni , 2n = 36, has a karyotype that differs from that of S. townsendi townsendi . The chromosomes of S. richardsoni also exhibit intraspecific variation; the subspecies elegans and nevadensis have a 2n of 34 and similar karyotypes, whereas richardsoni has 36 chromosomes. S. undulatus and S. armatus also have 34 chromosomes and autosomes that are indistinguishable from those of S. richardsoni elegans and nevadensis . However, on the basis of X and Y chromosome morphology, S. armatus can be differentiated from S. undulatus and S. richardsoni. S. columbianus and S. beldingi have diploid numbers of 32 and 30 respectively, and each has a distinctive karyotype. Karyotypes suggest a close relationship between three subspecies of S. townsendi and S. washingtoni . A second group of closely related species consists of S. undulatus, S. armatus and S. richardsoni . The first two of these three species and two subspecies of S. richardsoni, elegans and nevadensis all have identical autosomes. Evidence from this study of the chromosomes supports other lines of evidence which suggest that the subgenus Spermophilus contains two species groups, one composed of S. townsendi and S. washingtoni and the second consisting of S. richardsoni, S. undulatus, S. armatus, S. columbianus and S. beldingi . A revision of interspecific relationships within the subgenus Spermophilus is presented.

Pattern Analysis of Acoustical Behavior in Four Species of Ground Squirrels

Acoustical behaviors of Spermophilus armatus, S. columbianus, S. elegans, S. richardsonii , and S. elegans × S. richardsonii hybrids were studied in an area of sympatry in southwestern Montana. Calls, categorized as chirps, churrs, squeals, growls, and teeth-clatters, were described in detail; further distinctions were noted for some taxa. Audiospectrograms were coded into two-dimensional arrays for correlation, and subsequent cluster analysis of call syllable patterns determined both within-call structure, and phenetic relationships between species. Tests to determine whether chirp, churr, and preface syllables paralleled systematic relationships were inconclusive but chirp calls seemed to be convergent where species were sympatric while churr calls seemed unaffected.

System Atics of the Holarctic Chipmunks (Tamias)

Electrophoretic data for 20 proteins were obtained from 17 species of chipmunks, including all three presently recognized subgenera. Average heterozygosity was higher than for ground squirrels ( Spermophilus ) but was generally within the range reported for other rodents; Tamias minimus , however, had a higher heterozygosity value than almost any other rodent species. Cladistic analyses of the electrophoretic data resulted in species groupings which differed from traditional analyses of morphological data. The species T. Sibiricus and T. striatus were grouped together, separate from all other chipmunks, thereby contradicting traditional supra-specific classifications. We recognize one genus ( Tamias ) with two subgenera, Tamias (composed of Sibiricus and striatus ) and Neotamias with five species groups. A hypothesis concerning dispersal in the ancestral chipmunk lineage was formulated and a phylogram constructed on the basis of cladistic and biogeographic analyses. Multivariate analyses then were conducted on cranial and body measurements of 53 taxa of chipmunks, representing all recognized species and subgenera. Variation among individual taxa was detected in both general size and cranial shape. Phenetic morphological relationships among the chipmunks were ascertained by cluster analysis. The proposed phylogenetic groupings were compared with the morphological groupings in an assessment of divergent and convergent evolution within the genus.

Chromosomes and systematics of some North American species of the genus Marmota (Rodentia: Sciuridae).

Die Zahl der diploiden Chromosomen vonMarmota caligata undM. flaviventris ist 42 in Bevölkerungen der nördlichen und südlichen Verbreitungsgebiete beider Spezies. Ein Vergleich zwischen den bisher veröffentlichten Informationen überMarmota-Chromosomen mit Angaben über ihre Morphologie, Ekologie, Zoogeographie legt nahe, dass die ursprüngliche Chromosomenzahl 2n 38–40 war.

G-band patterns, chromosomal homologies, and evolutionary relationships among wild sheep, goats, and aoudads (mammalia, artiodactyla)

Хромосмы и Г-полосы диких баранов, Африканских гривистых баранов, и безоаровых козлов изучалы.Capra aegagrus из Ирана показало 2n=60, и кариотип содержит 29 пары акроцентических аутосом. Шесть из этих аутосомов одинаковый с трёх пар двеплечных аутосом у диких баранов и домашых овец (2n=54).Ammotragus lervia иOvis vignei (2n=58) имели кариотнпы и Г-полосы пар две-плыечных аутосом неразличимый.

Evolution in ground squirrels—I. Transferrins in holarctic populations of Spermophilus

Abstract 1. 1. Serum transferrins were analyzed by starch-gel electrophoresis from populations of North American Spermophilus armatus, S. beldingi, S. brunneus, S. columbianus, S. parryii, S. richardsonii, S. townsendii and S. washingtoni and from Eurasian S. citellus, S. dauricus, S. erythrogenys, S, fulvus, S. major, S. musicus, S. parryii, S. pygmaeus, S. relictus, S. suslicus and S. undulatus. 2. 2. Eighteen co-dominant transferrin alleles were identified in the 1229 specimens studied. 3. 3. Six alleles characterized North American species, 7 distinguished Eurasian taxa and 5 alleles were common to species of the Holarctic Region. 4. 4. Some taxa (S. undulatus) exhibited transferrin monomorphism throughout a wide distribution whereas S. columbianus and S. parryii showed polymorphism involving four and five alleles respectively. 5. 5. Yearly differences in allelic frequencies were observed in S. townsendii. 6. 6. The application of transferrins to Holarctic evolution in Spermophilus was discussed and intraspecific divergence in S. undulatus, S. parryii and S. richardsonii was evaluated.

Chromosomal Evolution in Rodents

The order Rodentia, composed of 1687 recent species belonging to 43 families and 354 genera, occupies a wide range of habitats throughout the world (Anderson and Jones, 1967). Rodents have been classified within three suborders: the Sciuromorpha, Myomorpha, and the Hys-tricomorpha, although the validity of suborders has been questioned (Wood, 1958). The various gross morphological features characterizing these groups, as well as the families and genera of rodents, are presented in several recent publications (Walker, 1964; Anderson and Jones, 1967). An invaluable taxonomic reference that described species and subspecies of North American rodents is the publication by Hall and Kelson (1959).

Chromosomes and Serum Proteins of Prairie Dogs and a Model of Cynomys Evolution

The karyotypes of Cynomys leucurus ( 2N = 50) and C. gunnisoni ( 2N = 40) are described and compared with the previously published karyotype of C. ludovicianus ( 2N = 50). Sera from the three taxa are also compared electrophoretically and five transferrin fractions diagnostic at the species level are identified. A model of the evolution of Cynomys from an ancestral Spermophilus population is proposed that integrates available cytological, serological, morphological, paleontological, and zoogeographical data.

Chromosomes of the siberian snow sheep, Ovis nivicola, and implications concerning the origin of amphiberingian wild sheep (subgenus Pachyceros)

Abstract The chromosomes of Ovis nivicola , described for the first time, exhibit 2 n = 52, the lowest diploid number to be reported for wild sheep and goats. The new chromosomal data, together with a review of the fossil history of the genus, lead us to conclude that the bighorned wild sheep (subgenus Pachyceros ) evolved their distinctive characteristics while isolated in the ice-free Beringian refugium, and then migrated southward into western North America when the glacial barriers melted, as first suggested by Cowan (1940) .