环境因子对荒漠沙蜥种群密度影响的研究

本文研究人类改造荒漠的活动,植被,潜在的可利用的食物资源,竞争种的密度,土壤理化性质等坏境因子对荒漠沙蜥种群密度的影响。结果说明：人类的活动对沙蜥种群密度没有显著影响;决定沙蜥种群密度的主导因子是潜在的可利用的食物资源,植被,土壤含水量,竞争种的密度。这些因子的任何改变都能改变沙蜥的种群密度,均具有调节种群的作用。     

Habitat selection and space use overlap between feral horses,pronghorn, and greater sage-grouse in cold arid steppe

Populations of feral horses (Equus ferus caballus) in the western United States have increased during the past decade, consequently affecting co-occurring wildlife habitat. Feral horses may influence 2 native wildlife species, greater sage-grouse (Centrocercus urophasianus; sage-grouse) and pronghorn (Antilocapra americana) through mechanisms of habitat alteration and competition. Wyoming, USA, contains the largest populations of pronghorn and sage-grouse of any state and also has the highest degree of range overlap between feral horses and these species. Consequently, the effects that horses may have on pronghorn and sage-grouse populations in Wyoming have implications at local, state, and population-wide levels. Managers need information concerning habitat selection and space use overlap among these species to develop appropriate management strategies; yet this information is absent for most feral horse management areas. To address this knowledge need, we attached global positioning system (GPS) transmitters to horses, pronghorn, and sage-grouse within the greater Bureau of Land Management–Adobe Town Herd Management Area in southern Wyoming and northern Colorado, USA, between 2017 and 2021 to evaluate habitat selection and space use of all species during 3 biologically relevant seasons: spring (Apr–Jun; sage-grouse breeding, nesting, and early-brood rearing; pronghorn late gestation and early parturition), summer (Jul–Oct; sage-grouse summer and late-brood rearing; pronghorn late parturition and breeding), and winter (Nov–Mar; non-breeding season). Feral horses selected flatter slopes and shorter mean shrub height across all seasons and were closer to water in spring and summer. Pronghorn habitat selection was similar to horses, but they also avoided oil and gas well pads year-round. During spring, sage-grouse selected greater herbaceous cover, flatter slopes, and areas farther from well pads. In summer, sage-grouse selected greater mean shrub height, flatter slopes, and were closer to water. In winter, sage-grouse selected flatter slopes and areas with greater vegetation production during the preceding summer. Our results indicate strong year-round overlap in space use between horses and pronghorn, whereas overlap between horses and sage-grouse is greatest during the summer in this region. Consequently, managers should recognize the potential for horses to influence habitat quality of pronghorn and sage-grouse in the region.     

青海湖裸鲤寄生舌状绦虫的空间格局研究

舌状绦虫裂头蚴只寄生在体长小于２２０ｍｍ的青海湖裸鲤中,其种群在宿主种群中呈聚集分布。其聚集分布的强度随寄生虫种群平均密度的增加而降低。由于舌状绦虫在宿主体腔生长,产生明显的空间拥挤效应,可能导致宿主死亡或被食鱼鸟类捕食而转移到终末宿主中。在体长小于１２０ｍｍ的宿主中,密度依赖的死亡过程可能是使聚集强度降低的原因;而体长１４０－２００ｍｍ的鱼中,则是非密度依赖的全死过程使聚集强度增加．     

Mitochondrial DNA sequences of various species of the genus Equus with special reference to the phylogenetic relationship between Przewalskii's wild horse and domestic horse

The noncoding region between tRNA^Pro and the large conserved sequence block is the most variable region in the mammalian mitochondrial DNA D-loop region. This variable region (ca. 270 bp) of four species of Equus, including Mongolian and Japanese native domestic horses as well as Przewalskii's (or Mongolian) wild horse, were sequenced. These data were compared with our recently published Thoroughbred horse mitochondrial DNA sequences. The evolutionary rate of this region among the four species of Equus was estimated to be 2–4 × 10^–8 per site per year. Phylogenetic trees of Equus species demonstrate that Przewalskii's wild horse is within the genetic variation among the domestic horse. This suggests that the chromosome number change (probably increase) of the Przewalskii's wild horse occurred rather recently.Correspondence to: N. Ishida     

Distribution of Competition Potential Between Native Ungulates and Free-Roaming Equids on Western Rangelands

Free-roaming equids (i.e., feral horses [Equus caballus] and burros [Equus asinus]) are widely distributed and locally abundant across the rangelands of the western United States. The 1971 Wild Free Roaming Horse and Burro Act (WFRHBA) gave the Bureau of Land Management (BLM) and United States Forest Service (USFS) the legal authority to manage these animals on designated public lands. To fulfill this responsibility, federal agencies established an Appropriate Management Level (AML), defined as the number of horses or burros that can be sustained on a given management unit under prevailing environmental conditions and land uses. Although the WFRHBA specifies that feral equids must be managed in ecological balance with other land uses, including conservation of native wildlife, population control measures such as gathers, contraception, and adoptions have failed to keep pace with intrinsic growth rates. Over 80% of federally managed herds currently exceed prescribed population levels, making the potential for competition between native ungulates and feral equids a growing concern among state wildlife agencies. Mule deer (Odocoileus hemionus), pronghorn (Antilocapra americana), elk (Cervus canadensis), and bighorn sheep (Ovis canadensis) are of ecological and economic value to the states where they occur, and all exhibit some degree of distributional, habitat, or dietary overlap with horses or burros. Notwithstanding the scale of the problem, to date there have been no range-wide assessments of competition potential among native and feral ungulates for space, forage, or water. To address this need, we compiled demographic, jurisdictional, and species occurrence data collected from 2010–2019 by federal and state agencies. We used these data to map the distributions of 4 native ungulate species across federal equid management units (FEMUS) in 10 western states (n = 174). We then made within-state rankings of the 50 units that were ≥2 times over AML and encompassed ≥3 native ungulates. Collectively, FEMUs covered approximately 225,000 km², representing 18% of all BLM and USFS lands in affected states. Each FEMU supported ≥1 native ungulate and 14% contained all 4. The degree of overlap between native and feral species varied by state, ranging from <1% for mule deer in Montana, to 40% for bighorn sheep in Nevada. Oregon had the largest proportion of units that supported all 4 native ungulates (58%), whereas Montana and New Mexico had the fewest equids, but all populations were over target densities. Despite the perception that the problem of equid abundance is limited to the Great Basin states, high intrinsic growth rates and social constraints on management practices suggest all affected states should monitor range conditions and native ungulate demography in areas where forage and water resources are limited and expanding equid populations are a concern. © 2021 The Wildlife Society.     

Circadian Intraocular Pressure Rhythms in Athletic Horses under Different Lighting Regime

The present study was undertaken to investigate the existence of intraocular pressure (IOP) rhythms in athletic thoroughbred horses maintained under a 24 h cycle of light and darkness (LD) or under constant light (LL) or constant dark (DD) conditions. We identified an IOP circadian rhythm that is entrained to the 24 h LD cycle. IOP was low during the dark phase and high during the light phase, with a peak at the end of the light phase (ZT10). The circadian rhythm of IOP persisted in DD (with a peak at CT9.5), demonstrating an endogenous component in IOP rhythm. As previously shown in other mammalian species, horse IOP circadian rhythmicity was abolished in LL. Because tonometry is performed in horses for the diagnosis of ophthalmologic diseases, such as glaucoma or anterior uveitis, the daily variation in IOP must be taken into account in clinical practice to properly time tests and to interpret clinical findings.     

甘西鼠尾草化学成分研究

采用硅胶柱色谱、凝胶柱色谱及其他分离手段从甘西鼠尾草中分离得到12个化合物,根据化合物理化性质和波谱数据分别鉴定为:丹参酮ⅡA(1)、丹参酮Ⅰ(2)、丹参内酯(3)、隐丹参酮(4)、丹参酸甲酯(5)、间羟基苯甲醛(6)、迷迭香酚(7)、异迷迭香酚(8)、紫丹参甲素(9)、紫丹参乙素(10)、二氢丹参酮Ⅰ(11)、丹参新醌甲(12)。其中化合物7、8为首次从该植物中分离得到,化合物6为首次从该属植物分离得到。     

蒙古野驴的繁殖行为观察

2014年6月至2015年8月期间,对分布在内蒙古自治区包头市达尔罕茂明安联合旗中蒙边境地区(41°14′~42°40′N,109°16′~110°26′E)和内蒙古自治区巴彦淖尔市乌拉特梭梭林-蒙古野驴国家级自然保护区(41°50′~42°27′N,106°15′~108°00′E)的两个野驴群(1♂3♀和2♂3♀)的繁殖行为进行研究。采用目标取样法以及目标取样法与扫描取样法相结合的方法对蒙古野驴的发情交配、产前反应、生产过程及产后行为进行观察。共记录到4类35种繁殖行为,分别为争斗行为、性行为、分娩行为和母幼联系行为。结果表明,雄驴平均日爬跨(4.2±1.7)次(n=14),射精(3.7±1.3)次(n=13),平均邀配持续时间(从雌雄驴靠近调情始到爬跨或其中一个走开止)为(26.6±22.0)s(n=13),平均抽动持续时间为(10.6±1.9)s(n=14),平均阴茎置入持续时间为(18.3±8.8)s(n=13),平均爬跨间隔为(685.7±569.6)s(n=14),平均射精间隔为(924.0±790.0)s(n=10)。蒙古野驴的交配模式属于Dewsbury分类系统中的第11种(无锁结、有抽动、单次插入、多次射精)类型和Dixon分类系统中的第12种(无锁结、有抽动、单次插入、无单次长时间插入)类型。本研究较完整地建立了蒙古野驴繁殖行为谱,提供了繁殖行为方面的基础资料。     

Mitochondrial control region and 12S rRNA variation in Przewalski's horse (Equus przewalskii)

Variation in the control region and the 12S rRNA gene of all surviving mitochondrial lineages of Przewalski's horse was investigated. Variation is low despite the present day population being descended from 13 individuals probably representing animals from three different regions of its range. Phylogenetic comparison of these sequences, with sequences for the domestic horse, does not resolve the ancestral status of either horse.