No long-term effect of black bear removal on elk calf recruitment in the southern Appalachians

In 2001 and 2002, 52 elk (Cervus canadensis; 21 males, 31 females), originally obtained from Elk Island National Park, Alberta, Canada, were transported and released into Cataloochee Valley in the northeastern portion of Great Smoky Mountains National Park (GRSM, Park), North Carolina, USA. The annual population growth rate (λ) was negative (0.996, 95% CI = 0.945–1.047) and predation by black bears (Ursus americanus) on elk calves was identified as an important determinant of population growth. From 2006 to 2008, 49 bears from the primary elk calving area (i.e., Cataloochee Valley) were trapped and translocated about 70 km to the southwestern portion of the Park just prior to elk calving. Per capita recruitment (i.e., the number of calves produced per adult female that survive to 1 year of age) increased from 0.306 prior to bear translocation (2001–2005) to 0.544 during years when bears were translocated (2006–2008) and λ increased to 1.118 (95% CI = 1.096–1.140). Our objective was to determine whether per capita calf recruitment rates after bear removal (2009–2019) at Cataloochee were similar to the higher rates estimated during bear removal (i.e., long-term response) or if they returned to rates before bear removal (i.e., short-term response), and how those rates compared with recruitment from portions of our study area where bears were not relocated. We documented 419 potential elk calving events and monitored 129 yearling and adult elk from 2001 to 2019. Known-fate models based on radio-telemetry and observational data supported calf recruitment returning to pre-2006 levels at Cataloochee (short-term response); recruitment of Cataloochee elk before and after bear relocation was lower (0.184) than during bear relocation (0.492). Recruitment rates of elk outside the removal area during the bear relocation period (0.478) were similar to before and after rates (0.420). In the Cataloochee Valley, cause-specific annual calf mortality rates due to predation by bears were 0.319 before, 0.120 during, and 0.306 after bear relocation. In contrast, the cause-specific annual mortality rate of calves in areas where bears were not relocated was 0.033 after the bear relocation period, with no bear predation on calves before or during bear relocation. The mean annual population growth rate for all monitored elk was 1.062 (95% CI = 0.979–1.140) after bear relocation based on the recruitment and survival data. Even though the effects of bear removal were temporary, the relocations were effective in achieving a short-term increase in elk recruitment, which was important for the reintroduction program given that the elk population was small and vulnerable to extirpation.     

Army ant invasions reveal phylogeographic processes across the Isthmus of Panama

Female army ants cannot fly, making them very poor dispersers across water barriers. This dependence on terrestrial corridors motivated the investigation by Winston et al. ( 2017 ), published in this issue of Molecular Ecology, into the role of Panamanian isthmus formation in the diversification of Eciton army ants. Complete closure of this isthmus occurred around three million years ago (3 Ma), but it has also been hypothesized that earlier, temporary land connections facilitated additional colonization events between South and Central America over the past 13 million years or more. The phylogenomic and population genomic analyses by Winston et al. ( 2017 ) uncovered multiple incursions of Eciton lineages into Central America between 4 and 7 Ma. Their study contributes to a growing body of evidence arguing that transitory land bridges predating 3 Ma supported substantial intercontinental biotic exchange.     

基于景观格局的胶州湾大沽河口湿地生态安全

以胶州湾大沽河口湿地为研究区,利用TM遥感影像为数据源,运用ENVI 4.4软件在GIS技术支持下,提取1986、2002和2010年研究区自然湿地、人工湿地、非湿地3大景观类型的空间信息;运用景观格局指数原理和方法构建生态安全指数,定量分析研究区景观动态变化,阐明景观格局变化下,生态安全状况及驱动机制.结果表明:1986-2010年,研究区在自然与人为双重干扰下陆地面积萎缩,斑块数增多,优势景观消失,景观趋于复杂化、破碎化、分离化;1986-2010年,人类活动对景观干扰愈加明显,景观干扰指数与生态安全指数存在负相关性,研究区各景观损失度上升,生态安全指数下降,其中以自然湿地中河流与河口湿地和芦苇湿地景观的恶化程度最大.基于面积因素构建的各景观生态安全度依次为:非湿地＞人工湿地＞自然湿地;新建并发育的人工林景观和新整合的少海东湖人工湿地公园,在一定程度上弥补了研究区的生态损失,缓和了生态保护与经济发展之间的矛盾,探索出一条湿地保护新型道路.     

Intra- and intraspecific variation of Juniperus virginiana and J. scopulorum seedling based on volatile oil composition

Comparisons of volatile oil constituents were made among samples of juvenile foliage collected from 78 Juniperus virginiana and 28 J. scopulorum seedling sources growing in a “common garden” environment. A canonical variate analysis, a principal coordinates analysis and hybrid distance diagrams of 30 chemical characters indicate both taxa are good species and that they exhibit clinical patterns in the Great Plains. In addition, a possible evoluitonary link between present-day J. virginiana populations in southern Texas and ancient J. scopulorum populations is indicated.     

Dispersal in the spiny damselfish,Acanthochromis polyacanthus,a coral reef fish species without a larval pelagic stage

The spiny damselfish, Acanthochromis polyacanthus, is widely distributed throughout the Indo‐Australian archipelago. However, this species lacks a larval dispersal stage and shows genetic differentiation between populations from closely spaced reefs. To investigate the dispersal strategy of this unique species, we used microsatellite markers to determine genetic relatedness at five dispersal scales: within broods of juveniles, between adults within a collection site (~30 m²), between sites on single reefs, between nearby reefs in a reef cluster, and between reef clusters. We sampled broods of juveniles and adults from seven reefs in the Capricorn‐Bunker and Swain groups of the Great Barrier Reef. We found that extra‐pair mating is rare and juveniles remain with their parents until fledged. Adults from single sites are less related than broods but more related than expected by chance. However, there is no evidence of inbreeding suggesting the existence of assortative mating and/or adult migration. Genetic differences were found between all of the reefs tested except between Heron and Sykes reefs, which are separated only by a 2‐km area of shallow water (less than 10 m). There was a strong correlation between genetic distance, geographical distance and water depth. Apparently, under present‐day conditions spiny damselfish populations are connected only between sites of shallow water, through dispersal of adults over short distances. Assuming that dispersal behaviour has not changed, the broad distribution of A. polyacanthus as a species is likely based on historical colonization patterns when reefs were connected by shallow water at times of lower sea levels.     

PHYTOPLANKTON PIGMENTS IN COASTAL LAKE MICHIGAN: DISTRIBUTIONS DURING THE SPRING ISOTHERMAL PERIOD AND RELATION WITH EPISODIC SEDIMENT RESUSPENSION1

Phytoplankton pigment distributions during the spring isothermal periods of 1998 and 1999 and their association with episodic sediment resuspension were characterized in coastal waters of southern Lake Michigan. Total and phylogenetic group chl a concentrations (derived using chemical taxonomy matrix factorization of diagnostic carotenoids) corresponded with assemblage and group biovolumes estimated from microscopic enumeration (P≤ 0.001). Diatoms and cryptophytes dominated assemblages and together typically comprised greater than 85% of relative chl a. Total chl a concentrations and both fucoxanthin·chl a ^{? 1} and alloxanthin·chl a ^{? 1} ratios were similar across depths (P> 0.05), indicating uniform distributions of and photophysiological states for assemblages and diatoms and cryptophytes, respectively, throughout the mixed water column. Total chl a concentrations were not always spatially uniform from near‐shore to offshore waters, with the greatest variability reflecting the influence of tributary inflows upon coastal assemblages. Sediment resuspension strongly influenced water column particle density and light climate; however, total and group chl a concentrations did not correspond with coefficients of K_d and suspended particulate matter concentrations (P> 0.05). The correspondence of both light attenuation and suspended particulate matter concentration with relative diatom chl a (P≤ 0.001) indicated an apparent association between sediment resuspension and diatoms. This, and the negative association (P≤ 0.0001) between relative diatom and cryptophyte chl a, corresponded with the spatial dominance of diatom and cryptophyte chl a in near‐shore and offshore waters, respectively. The presence of viable chl a and fucoxanthin within the surficial sediment layer, established this layer as a potential source of meroplanktonic diatoms for near‐shore assemblages.     

The effects of predation and unionid burrowing on bivalve communities in a Laurentian Great Lake coastal wetland

Unionid (Mollusca: Unionidae) densities have declined dramatically throughout the Laurentian Great Lakes after the introduction of dreissenid mussels (Mollusca: Dreissenidae). Recent surveys in some Great Lake coastal wetlands have found abundant unionid populations, but the factors that reduce zebra mussels on unionids in these habitats are not well understood. In 2001–2002, we tested effects of predation and unionid burrowing on corbiculids, sphaeriids and dreissenids in a Great Lake coastal wetland in western Lake Erie. In one experiment, we reduced access by molluscivores using exclosures with two mesh sizes (1.3 cm × 1.3 cm; 5 cm × 10 cm) and sampled bivalves after 15 months. Small mesh exclosures had higher numbers of dreissenids, Corbicula fluminea and sphaeriids (54.9, 3.8, 22.6 individuals/m², respectively) than large mesh exclosures (0.0, 1.13, 0.13 individuals/m², respectively) or open controls (0.3, 1.0, 0.1 individuals/m², respectively). Numbers of dreissenids on C. fluminea were higher in small mesh exclosures (3.8 dreissenids/Corbicula) than in large mesh exclosures (0.1 dreissenids/Corbicula) or cageless controls (0␣dreissenids/Corbicula). In a second experiment, we held two species of live unionids (Leptodea fragilis, Quadrula quadrula) and immobile Pyganodon grandis shells in exclosures (2.5 cm × 2.5 cm mesh) with either 5 cm, 10 cm, or 20 cm deep sediments and sampled bivalves after 2 months. There were fewer dreissenids on L. fragilis than P. grandis shells, but there was no difference in the number of dreissenids on Q. quadrula and P. grandis shells. Numbers of attached dreissenids were higher inside (189–494 dreissenids/unionid) than outside (8–11 dreissenids/unionid) exclosures, and densities of sphaeriid and C. fluminea clams were also higher inside (21.8, 4.7 individuals/m², respectively) than outside (0.4, 0.9 individuals/m², respectively) exclosures. Numbers of attached dreissenids were higher on unionids that could burrow below the sediments (20 cm depth) than unionids in shallow sediments (5 cm depth) for unexplained reasons. Our data suggest that molluscivores can play a pivotal role in limiting numbers of bivalves including dreissenids in coastal wetlands.     

选择性冠状静脉动脉化搭桥术中不同移植物的应用疗效比较

目的:对比选择性冠状静脉动脉化(SCVBG)搭桥治疗弥漫性右冠状动脉狭窄病变中选择乳内动脉和大隐静脉作为桥血管的治疗效果。方法:选择2008年10月到2014年10月在我院行SCVBG搭桥的84例患者资料,其中选择大隐静脉作为桥血管进行冠状静脉动脉化搭桥患者46例(大隐静脉桥组),选择乳内动脉作为桥血管进行冠状静脉动脉化搭桥患者38例(乳内动脉桥组)。随访记录两组患者的生存情况、近期复查超声心动图、冠状动脉CTA及心绞痛复发率。结果:乳内动脉桥组患者总生存率(100%)明显高于大隐静脉桥组(82.6%)(P0.05)。乳内动脉桥组患者桥血管和心中静脉通畅率(100%)明显大于大隐静脉桥组(54.35%)(P0.05)。两组患者左心室射血分数(LVEF)较治疗前明显增加,左心室舒张期末内径(LVEDD)较治疗前明显减小(P0.05)。治疗后,乳内动脉桥组患者心绞痛复发率明显小于大隐静脉桥组(P0.05)。结论:SCVBG搭桥治疗弥漫性右冠状动脉狭窄病变中,选择乳内动脉桥效果优于大隐静脉桥,能明显提高桥血管和心中静脉通畅率,降低心绞痛复发率。     

以小时为步长的大兴安岭典型林分地表死可燃物含水率模型预测及外推精度

地表死可燃物含水率是火险天气和火行为预报中的重要指标.本研究基于时滞平衡含水率法(Nelson和Simard方法)及气象要素回归方法,于2010年9—10月对黑龙江省大兴安岭地区盘古林场不同郁闭度的山杨-白桦混交林、红皮云杉纯林,以及采伐迹地(原1∶1樟子松-白桦混交林)地表死可燃物含水率进行以小时为步长的连续测定,建立其预测模型,得到预测误差,并使用相应的模型对其他林分地表死可燃物含水率进行外推精度分析.结果表明:采用Nelson平衡含水率法构建的地表死可燃物含水率变化模型的平均绝对误差、平均相对误差和均方误差根(0.0154、0.104和0.0226)低于Simard法(0.0185、0.117和0.0256)和气象要素回归法(0.0222、0.150和0.0331).在外推效果方面,气象要素回归法的平均绝对误差、平均相对误差和均方误差根(0.0410、0.0300和0.0740)低于Simard法(0.610、0.492和0.846),但前两者均高于Nelson法(0.034、0.021和0.0660),说明以小时为步长的时滞平衡含水率法,尤其是Nelson法适用于大兴安岭地区所测林分.外推虽不能降低误差,但有助于提高现有模型应用至不同林分条件或大尺度范围内的地表死可燃物含水率预测精度和利用率.模型建模和外推误差与不同树种和郁闭度条件差异有关,研究时应根据不同林分和地点选择合适的平衡含水率模型.