Molecular phylogeny of the marmots (Rodentia: Sciuridae): tests of evolutionary and biogeographic hypotheses.

There are 14 species of marmots distributed across the Holarctic, and despite extensive systematic study, their phylogenetic relationships remain largely unresolved. In particular, comprehensive studies have been lacking. A well-supported phylogeny is needed to place the numerous ecological and behavioral studies on marmots in an evolutionary context. To address this situation, we obtained complete cytochrome (cyt) b sequences for 13 of the species and a partial sequence for the 14th. We applied a statistical approach to both phylogeny estimation and hypothesis testing, using parsimony and maximum likelihood-based methods. We conducted statistical tests on a suite of previously proposed hypotheses of phylogenetic relationships and biogeographic histories. The cyt b data strongly support the monophyly of Marmota and a western montane clade in the Nearctic. Although some other scenarios cannot be rejected, the results are consistent with an initial diversification in North America, followed by an invasion and subsequent rapid diversification in the Palearctic. These analyses reject the two major competing hypotheses of M. broweri's phylogenetic relationships--namely, that it is the sister species to M. camtschatica of eastern Siberia, and that it is related closely to M. caligata of the Nearctic. The Alaskan distribution of M. broweri is best explained as a reinvasion from the Palearctic, but a Nearctic origin can not be rejected. Several other conventionally recognized species groups can also be rejected. Social evolution has been homoplastic, with large colonial systems evolving in two groups convergently. The cyt b data do not provide unambiguous resolution of several basal nodes in the Palearctic radiation, leaving some aspects of pelage and karyotypic evolution equivocal.

Chromosome number of Severtzov's sheep (Ovis ammon severtzovi): G-banded karyotype comparisons within ovis.

Severtzov's sheep (Ovis ammon severtzovi; Nasonov 1914) has a 2n = 56 diploid chromosome number and a karyotype consisting of two pairs of biarmed and 25 pairs of acrocentric autosomes, a large acrocentric X, and a minute biarmed Y. The G-banding patterns of the largest pair of biarmed chromosomes were identical to those of the largest biarmed chromosomes in all wild and domestic sheep of the genus Ovis. The banding patterns of the second pair of biarmed chromosomes were identical to the third pair of biarmed chromosomes in all sheep of the genus Ovis with 2n = 54 and to the third largest pair of chromosomes in the 2n = 52 karyotype of the Siberian snow sheep (O. nivicola). The G-banded karyotype of Severtzov's sheep is consistent with all subspecies of argali (O. ammon spp.) that have been karyotyped. Numerical ascription of acrocentric chromosome equivalents based upon the fundamental karyotype of Ovis that gave rise to the biarmed chromosomes of severtzovi are 1 and 3, and 5 and 11 for the largest and second largest biarmed chromosomes, respectively. Based upon diploid chromosome number and G bands, Severtzov's sheep should be considered a subspecies of argali and not a urial.

[The characteristics of the distribution of the great gerbil (Rhombomys opimus) on the territory of China]. / Osobennosti rasprostraneniia bol'shoi peschanki (Rhombomys opimus) na territorii Kitaia.

The distribution of the great gerbil (Rh. opimus) in China was analyzed on the basis of published data, museum collections, natural maps, and authors' field observations. A preliminary scheme was plotted for range regionalization, in which three parts have been isolated or, according to classification of Dubrovskii and Kucheruk (1971), three regional complexes of autonomous groups of populations: Dzungarian, Beishanian and Alashanian. West of the main area of the great gerbil distribution, an isolated colony is located in the Ili River valley, connected with the Kazakhstan portion of the range (Ili regional complex of autonomous groups of populations). Additional field observations are required for more detailed description of the great gerbil range.

The primary structure and functional properties of the hemoglobins of a ground squirrel (Spermophilus townsendii, Rodentia).

The hemoglobin of the ground squirrel Spermophilus townsendii consists of two components which are present in a ratio of ca. 2:1. The two hemoglobins have identical alpha-chains, but differ in their beta-chains. We present the primary structures of the alpha- and the two beta-globin chains. Following chain separation by chromatography on carboxymethyl-cellulose CM-52, the amino-acid sequences were established by automatic Edman degradation of the globin chains and the tryptic peptides, as well as of a peptide obtained by acid hydrolysis of the Asp-Pro bond of the beta-chains. The two beta-chains differ by only one amino-acid residue, Ala being present in the main and Asp in the minor component in position 58 (E2). The comparison with human hemoglobin showed only 14 exchanges in the alpha-chains but 33 in the beta-chains. Whereas no contact positions are affected in the alpha-chains, we found four such substitutions in the beta-chains, including one heme contact, two alpha 1/beta 1-contacts, and one alpha 1/beta 2-contact. It seems however, that the substitution found in the beta-chains has no effect on the oxygen affinity.