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Garrett M. Street John Fieberg Arthur R. Rodgers Michelle Carstensen Ron Moen Seth A. Moore Steve K. Windels James D. Forester 《Landscape Ecology》2016,31(9):1939-1953
Context
Animals selectively use landscapes to meet their energetic needs, and trade-offs in habitat use may depend on availability and environmental conditions. For example, habitat selection at high temperatures may favor thermal cover at the cost of reduced foraging efficiency under consistently warm conditions.Objective
Our objective was to examine habitat selection and space use in distinct populations of moose (Alces alces). Hypothesizing that endotherm fitness is constrained by heat dissipation efficiency, we predicted that southerly populations would exhibit greater selection for thermal cover and reduced selection for foraging habitat.Methods
We estimated individual step selection functions with shrinkage for 134 adult female moose in Minnesota, USA, and 64 in Ontario, Canada, to assess habitat selection with variation in temperature, time of day, and habitat availability. We averaged model coefficients within each site to quantify selection strength for habitats differing in forage availability and thermal cover.Results
Moose in Ontario favored deciduous and mixedwood forest, indicating selection for foraging habitat across both diel and temperature. Habitat selection patterns of moose in Minnesota were more dynamic and indicated time- and temperature-dependent trade-offs between use of foraging habitat and thermal cover.Conclusions
We detected a scale-dependent functional response in habitat selection driven by the trade-off between selection for foraging habitat and thermal cover. Landscape composition and internal state interact to produce complex patterns of space use, and animals exposed to increasingly high temperatures may mitigate fitness losses from reduced foraging efficiency by increasing selection for foraging habitat in sub-prime foraging landscapes.34.
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We present a technique to programmatically collect comments made about videos on YouTube, a popular social media website, and use content analysis to categorize and compare the frequency of comment types across videos and topics. For this article, we collected and categorized the comments of the 10 most viewed videos (in 2013) of three common North American mammals: the coyote (Canis latrans), Virginia opossum (Didelphis virginiana), and raccoon (Procyon lotor) to demonstrate the potential of the technique. Half of the categorized comments for coyote encouraged their lethal control while the most popular comments for raccoon and opossum described these species as “cute” (47% and 34%, respectively). Analyzing YouTube comments is a promising avenue of research, and given proper development, could represent a useful approach to assess public opinions toward wildlife expressed online. 相似文献
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Gut microbes limit growth in house sparrow nestlings (Passer domesticus) but not through limitations in digestive capacity 
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下载免费PDF全文 Kevin D. KOHL Antonio BRUN Seth R. BORDENSTEIN Enrique CAVIEDES‐VIDAL William H. KARASOV 《Integrative zoology》2018,13(2):139-151
Recent research often lauds the services and beneficial effects of host‐associated microbes on animals. However, hosting these microbes may come at a cost. For example, germ‐free and antibiotic‐treated birds generally grow faster than their conventional counterparts. In the wild, juvenile body size is correlated with survival, so hosting a microbiota may incur a fitness cost. Avian altricial nestlings represent an interesting study system in which to investigate these interactions, given that they exhibit the fastest growth rates among vertebrates, and growth is limited by their digestive capacity. We investigated whether reduction and restructuring of the microbiota by antibiotic treatment would: (i) increase growth and food conversion efficiency in nestling house sparrows (Passer domesticus); (ii) alter aspects of gut anatomy or function (particularly activities of digestive carbohydrases and their regulation in response to dietary change); and (iii) whether there were correlations between relative abundances of microbial taxa, digestive function and nestling growth. Antibiotic treatment significantly increased growth and food conversion efficiency in nestlings. Antibiotics did not alter aspects of gut anatomy that we considered but depressed intestinal maltase activity. There were no significant correlations between abundances of microbial taxa and aspects of host physiology. Overall, we conclude that microbial‐induced growth limitation in developing birds is not driven by interactions with digestive capacity. Rather, decreased energetic and material costs of immune function or beneficial effects from microbes enriched under antibiotic treatment may underlie these effects. Understanding the costs and tradeoffs of hosting gut microbial communities represents an avenue of future research. 相似文献
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旨在探究幼年牦牛皮肤毛囊的组织学结构和TGF-β2及HIF-1α对幼年牦牛皮肤毛囊生长发育的影响，选取10头健康幼年牦牛，采集其颈部、背部、胸部、腹部、小腿部、腋下及阴囊皮肤组织，制作石蜡切片后，采用HE和Sacpic染色，对各部位皮肤组织中毛囊进行观察和计数，并筛选出多毛及少毛部位。利用qRT-PCR、Western blot及免疫组织化学法对TGF-β2和HIF-1α在幼年牦牛多毛皮肤和少毛皮肤进行定位与定量的初步研究。结果表明，幼年牦牛皮肤的毛囊分布于真皮层，常与汗腺及皮脂腺伴行，毛髓质及内根鞘结构不完整。Sacpic染色可见毛囊内根鞘为红色，外根鞘为苍绿色，结缔组织鞘为蓝绿色。腹部皮肤的毛囊数量最多[（2 085±15）个·cm-2]，阴囊数量最少[（158±15）个·cm-2]。免疫组织化学结果显示，TGF-β2及HIF-1α主要表达在表皮层、毛囊外根鞘、皮脂腺及汗腺。TGF-β2在阴囊和腋下的mRNA转录水平和蛋白质表达水平均显著高于腹部和背部。HIF-1α在腹部的mRNA转录水平和蛋白质表达水平均显著高于其他三个部位。幼年牦牛的毛囊处于退行期，在腹部数量最多，背部次之，阴囊最少；TGF-β2和HIF-1α在不同部位皮肤中的表达水平存在显著差异，为进一步研究TGF-β2和HIF-1α对牦牛皮肤毛囊生长发育的影响提供理论依据。 相似文献
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Objective
To characterize the incidence, contributing risk factors, and healing characteristics of immediate postoperative corneal erosions (IPCE) in dogs undergoing routine phacoemulsification.Animals Studied
Medical records of 313 canine eyes (159 dogs) undergoing routine phacoemulsification surgery.Procedures
Medical records of dogs undergoing planned cataract surgery at UW Veterinary Care were retrospectively reviewed. Patient-related variables including age, skull conformation, diabetes status, and cataract stage at the time of surgery were recorded. Intraoperative variables per eye were also recorded including surgical technique, surgeon expertise level, average phacoemulsification power, and phacoemulsification time. Diagnosis of IPCE ≤ 24 h after completion of surgery and time to IPCE healing were recorded where follow-up data were available.Results
Immediate postoperative corneal erosions were observed in 48/313 (15.3%) operated eyes. The presence of diabetes mellitus or brachycephalic skull conformation, preoperative Schirmer tear test (STT) value, surgical technique and surgeon experience level, phacoemulsification time, and absolute phacoemulsification time were not statistically significant risk factors for IPCE. Average phacoemulsification power was associated with IPCE (RR 1.52, p = .001). Time to IPCE healing was similar in diabetic and non-diabetic dogs (median [IQR] 8 [6–11] days and 8 [6–15] days, respectively). Diabetes mellitus, brachycephaly, and phacoemulsification parameters were not associated with IPCE healing at 7 or 14 days postoperatively.Conclusions
Higher average phacoemulsification power may be associated with the development of IPCE in canine eyes. The presence of diabetes mellitus or brachycephaly are not risk factors for the development of IPCE, nor are they factors that influence IPCE healing. 相似文献40.
Summary Intra-increment circumferential variation in tracheid length at breast-height in deodar (Cedrus deodara (Roxb.) Loud. vern. diar) has been studied with the main objective of evolving an efficient sampling procedure for the purpose of comparing tracheid length amongst individual trees of forest stands. It has been studied in five sampling strata namely: whole-annual ring, whole-earlywood, whole-latewood, first-firmed earlywood and last-formed latewood. Tracheid length shows significant circumferential variation in whole-annual ring, whole-earlywood, whole-latewood and last-formed latewood. However, when the mean tracheid length of two opposite directions is compared with the mean tracheid length of eight cardinal directions in these sampling strata, then no significant difference is observed. First-formed stratum of an annual ring exhibits statistically consistent values around the circumference and thus sampling from any random radial direction can serve the purpose for the comparison of inherent values of tracheid length amongst the deodar trees.The financial assistance given by Himachal Pradesh University as H.P.U. Junior Research Fellowship to second author is highly acknowledged 相似文献