Landscape features influence genetic structure of black-tailed prairie dogs (Cynomys ludovicianus)

Black-tailed prairie dogs (Cynomys ludovicianus) currently live in metapopulations in the parts of their range where plague, caused by the bacterium Yesinia pestis, has invaded. Prairie dogs are highly susceptible to the pathogen, with most animals within towns dying during Y. pestis outbreaks. A review of population genetic studies of prairie dogs demonstrates considerable differentiation between prairie dog towns. Despite declines and fluctuations in size of prairie dog populations, they continue to harbor considerable genetic variation. This results from continual dispersal and gene flow, likely along low-lying drainages that connect towns. When combined with estimates of population size, the landscape genetic approach described here will provide precise estimates of dispersal and gene flow, in addition to evaluation of long-term stability of prairie dog metapopulations.     

红松林种子、鼠类和幼苗动态数学模型

本文把红松林的种子,鼠类和幼苗幼树作为森林发生和演替的钮带。把它们之间的相互调节和相互依存关系归结为3条基本假设:①不考虑其它干扰因素时,红松种子按理想的自养发育过程指数增长,受鼠类的影响而不断减少;②鼠量随种子数量增加而增加,随自身的衰亡而减少;③幼苗幼树随鼠埋藏作用而增加,随自身稀疏过程而减少。其数学模型为 通过对(Ⅰ)解行为的分析给出红松林生态系统稳定条件为a_2=b_1,a_2b_1>b_2~2(=a_1~2),同时也证明了数学稳定与生物学生态学稳定的,关系,指出了动态平衡和种群波动应是红松林生态系统的典型特征。为开发森林资源维护生态系统平衡提供科学依据,并建立和分析了人为采种和捕鼠条件下的数学模型。     

Geometric morphometric study of the skull shape diversification in Sciuridae (Mammalia,Rodentia)

It is generally accepted that the high phenotypic diversity of mammals is a combined result of developmental constraint and ecological adaptation, although the influence of these endogenous and exogenous factors varies in different mammal groups. The rodent family Sciuridae represents an ideal candidate for examining phenotypic diversity in relation to phylogeny and ecological adaptations. In the present study, we investigate the effects of phylogeny and lifestyle on the skull shape in different species of Sciuridae by applying geometric morphometric methods. In addition, we investigate the importance of allometry on sciurid skull shape, because results from geometric morphometrics sometimes dispute those of traditional morphometry. Here, we identify significant associations between patristic distances obtained from molecular phylogeny and shape distances in all 3 views of the cranium and the lateral view of the mandible. Multivariate regression demonstrates that shape differences among lifestyle categories are substantial, especially in the dorsal and ventral structures after the influence of phylogeny is taken into account. Allometry plays an important role in the shape variation, although its importance on different skull structures varies. Our results indicate that complex structures of this highly diverse mammal group, which occupies different niches, are affected by ecological factors and developmental constraint.     

Multi-locus sequence analysis reveals host specific association between Bartonella washoensis and squirrels

To clarify phylogenetic relationships and genetic diversity among Bartonella washoensis strains obtained from squirrels, multi-locus sequence analysis (MLSA) with the 16S rRNA, ftsZ, gltA, groEL, ribC, and rpoB genes was applied for 20 strains of B. washoensis isolated from five genera of squirrels (Tamias, Tamiasciurus, Glaucomys, Sciurus, and Spermophilus) within the family Sciuridae. Sequence similarities in the concatenated sequences of B. washoensis strains from squirrels of different genera ranged from 94.7% (Sciurus vs. Spermophilus) to 98.4% (Tamiasciurus vs. Glaucomys). Phylogenetic trees based on the concatenated sequences revealed that B. washoensis strains formed five distinct clades and each clade correlated with the genus of squirrel from which the strains were originally obtained. The discrimination was supported by 100% bootstrap values and posterior probabilities, respectively. These results suggest that B. washoensis strains may have co-speciated with their squirrel hosts and provide new insights into the application of the MLSA to identify sources of B. washoensis infection with accuracy.     

松鼠消化系统的形态学研究

[目的]了解松鼠消化系统与食性的关系。[方法]对5只成体松鼠的消化系统进行解剖,并对各器官进行研究。[结果]松鼠的消化管总长为（1 845.7±171.07）mm,是体长的（7.69±0.57）倍。其中,小肠占消化管总长的65.0%±2.0%,为体长的4.97±0.32倍。[结论]松鼠小肠最发达,而松鼠消化道结构是与其食性相适应的。     

SURGICAL MANAGEMENT OF PANCREATIC NODULAR HYPERPLASIA BY PARTIAL PANCREATECTOMY IN A BLACK-TAILED PRAIRIE DOG (CYNOMYS LUDOVICIANUS)

A 7.5-year-old male black-tailed prairie dog was presented for diarrhea of 3 weeks’ duration. Clinical examination revealed a multinodular mass in the left cranial quadrant of the abdomen that was confirmed with ultrasound. An exploratory laparotomy was performed and the majority of the mass and adherent spleen were removed. Histological diagnosis was severe pancreatic nodular hyperplasia associated with secondary pancreatitis and passive splenic congestion. The prairie dog recovered without complications. Three weeks following the surgical procedure, follow-up ultrasound showed no evidence of abnormal tissue in the pancreaticoduodenal area. Two months postsurgery, a follow-up computed tomographic scan revealed no significant abnormalities. No recurrence was noted 13 months following the mass removal. This article describes the diagnosis of pancreatic nodular hyperplasia in a prairie dog and successful treatment of complications arising from the condition by partial pancreatectomy.