食物大小对棕果蝠和犬蝠取食行为的影响

按照最优化觅食理论,动物在取食时需在能量获取与捕食风险之间权衡。本文通过室内行为实验,研究两种旧大陆果蝠棕果蝠和犬蝠对食物大小的选择规律与取食策略。按体积由小到大将苹果分为Ⅰ型、Ⅱ型、Ⅲ型、Ⅳ型4 种类型的食物块,通过红外相机观察果蝠对不同大小食块的取食情况,并就其对各类型食块的取食率、取食次数和停留时间进行统计分析。结果表明:这两种果蝠对Ⅱ型和Ⅲ型食块的取食率显著高于Ⅰ型和Ⅳ型;对Ⅰ型食块的取食次数显著高于Ⅱ型和Ⅳ型;对Ⅳ型食块的停留时间显著高于Ⅰ型和Ⅱ型。它们在摄取体积较小的食块时,以取走后进食为主要取食方式,但摄取大体积食块时则主要在原地进食。取食过程中,果蝠优先选择大小适于搬运的食块,是捕食风险与能量收益权衡的结果。     

西双版纳地区降雨和食物资源可获得程度对犬蝠分娩时机的影响

繁殖是动物权衡不同自然选择压力和自身生理限制的结果。蝙蝠的繁殖受气候(温度、光周期和降雨量)和食物资源等非生物因素影响。本文通过野外调查犬蝠食物资源、设网捕捉和标志重捕的方法研究西双版纳地区降雨、食物资源可获得程度对犬蝠分娩时机的影响。研究发现,随着3 - 8 月降雨量逐渐增加(19.82 -41.13 kg/ m2 ),犬蝠取食的植物种类呈明显的增加趋势(4 - 9 种)。幼蝠捕捉量与植物资源可获得程度呈显著正相关关系(r = 0. 94,P = 0.01)。西双版纳犬蝠虽然具有一年两次动情和分娩的能力,但是绝大多数个体一年只分娩一次,且集中于3 -5 月。犬蝠分娩时机的选择使得幼蝠飞行学习和捕食时间与食物资源可获得程度高峰期相吻合,有利于提高幼体的生存适合度。     

犬蝠对小果野芭蕉的取食及种子传播

2004年9月到12月,在西双版纳热带植物园沟谷雨林内,通过详细的野外观察和雾网实验以及种子的定时收集方法,对犬蝠(Cynopterussphinx)取食小果野芭蕉(Musaacuminata)的行为及规律进行了研究。发现在夜晚24:00以前,犬蝠取食小果野芭蕉有明显的2个活动高峰,分别发生在20:30和22:30左右,这一结果与雾网采样结果较为一致。在研究期间的雨季(9-10月)和干季(11-12月),犬蝠平均被捕获量为2.2±0.3只/d、1.4±0.3只/d,二者之间没有显著的差异;同时这两个季节收集的种子团数量分别为9.0±1.1个/d和7.2±1.4个/d,也没有显著差异。犬蝠对小果野芭蕉种子的传播受生境影响较为显著,各样地间种子传播的结果大不相同;地点和季节对犬蝠传播种子也不存在交互影响。犬蝠对小果野芭蕉种子的传播距离为50-200m,是小果野芭蕉有效的种子传播者     

狐蝠科3种蝙蝠舌长度及结构比较

为探讨旧大陆食果和食蜜蝙蝠的食性类型不同是否造成其取食器官舌长度及结构的差异,本研究以2种食果蝙蝠犬蝠(Cynopterus sphinx)和棕果蝠(Rousettus leschenaultii)以及1种食蜜蝙蝠长舌果蝠(Eonycteris spelaea)为研究对象,比较了这3个物种间舌的差异.犬蝠、棕果蝠和长舌果蝠伸入直径为2 cm试管的最大舌长度L1(包括伸入试管的吻部和吻部以外的舌长)分别为(29.19±0.52)mm、(35.05±0.82) mm、(49.34±1.64) mm;伸出吻端外部的舌长L3分别为(16.25±0.53)mm、(19.25±0.79) mm、(31.88 ± 1.56) mm;与体重转换后的最大舌长度,即转换L1分别为(8.57±0.17) mm/g1/3、(7.90 ±0.27) mm/g1/3、(12.41 ±0.40) mm/g1/3;与体重转换后的伸出吻端外部的舌长,即转换L3分别为(4.77±0.16) mm/g1/3、(4.34±0.22) mm/g1/3、(8.01 ±0.38) mm/g1/3;与体重转换后的解剖舌长分别为(5.56 ±0.16) mm/g1/3、(5.35 ±0.14) mm/g1/3、(6.65±0.38)mm/g1/3.此5个参数种间比较均差异显著,食蜜类的长舌果蝠的5个参数均显著长于食果类犬蝠和棕果蝠的相应参数.通过比较3种蝙蝠的舌结构发现,长舌果蝠的舌尖尖细且具有毛刷状丝状乳头结构,舌面及两侧凹槽较多;犬蝠和棕果蝠的舌尖钝圆,舌面乳头和凹槽较少而平缓.本文结果表明,旧大陆食蜜蝙蝠与食果蝙蝠在舌长度和舌结构上存在明显差异,可能与捕食行为的差异有关.     

南蝠对鸟的捕食及其对昆虫的选择

2005年11月和2006年5、7、9月在贵州兴义研究了南蝠(Iaio)的食性。通过对南蝠粪便分析,发现7、9和11月份,鸟的残留羽毛在粪便中占很大比例,尤其是在11月份,鸟的羽毛占了食物组成的82%(体积百分比,下同),结果证实南蝠是一种食鸟蝙蝠。但在5月份的粪便中未发现鸟毛,而鞘翅目所占比例很大(85%);7和9月份,鸟的羽毛和鞘翅目残遗物所占的比例相当(7月份分别为44.6%和48.7%;9月份分别为51.1%和43.4%)。5、7、9、11月份南蝠取食鸟类的比例逐渐增加,而对鞘翅目的取食则逐渐减少。除取食鞘翅目外,南蝠还捕食鳞翅目、半翅目、直翅目和膜翅目等昆虫。对比捕食区内潜在的食物,发现南蝠对部分昆虫表现出明显的选择性,说明南蝠为选择性捕食者。     

棕果蝠对龙眼的取食行为及进食量

棕果蝠(Rousettus leschenaulti)在云南西双版纳地区是比较常见的果蝠。本文研究了棕果蝠对当地经济作物龙眼(Dimocarpus longan)的取食模式和取食时间规律,并在实验室条件下研究了其对龙眼的整夜进食量。野外观察发现:棕果蝠叼取龙眼后不在母树上停留,而是携带龙眼到其他进食地点进食。棕果蝠在19:30～5:30时有3个取食高峰期,分别是在20:30～21:00时、22:00～22:30时和1:00～1:30时之间。此外,室内笼养实验结果表明,棕果蝠对龙眼的取食个数因体重不同而有差异,个数在6～20之间,实际进食量相当于其体重的1.0～1.8倍。     

地标对犬蝠空间记忆的影响

为了研究地标（landmarks）是否影响犬蝠（Cynopterus sphinx）的空间记忆,我们通过室内模拟试验研究犬蝠和地标在觅食过程中空间记忆形成的关系。实验组按照每天地标数分别为0、2、4、8、0的数目连续进行5天实验,对照组不设地标进行相同条件的实验。结果显示,两组犬蝠第一次取食所用的时间与实验天数之间极显著相关（Pearson Correlations: 实验组r=-0.593, P<0.01;对照组r=-0.581, P<0.01）;实验组取食成功率与实验天数之间无明显相关性（Pearson Correlations: r=0.177, P>0.05）;对照组取食成功率与实验天数之间显著相关（Pearson Correlations: r=0.445, P<0.05）。实验组与对照组犬蝠第一次取食的时间差异不显著（GLM: F_0.05,1=4.703, P>0.05）,两组间取食的成功率差异也不显著（GLM: F_0.05,1=0.849, P>0.05）。这些结果说明了随着时间增加,犬蝠对取食地的空间记忆逐渐形成,放置地标在犬蝠对取食地空间记忆形成的过程中无显著影响。     

两种果蝠对光叶桑(Morus macroura)果实的取食及种子传播

从2005年3月到2006年5月,在中国科学院西双版纳热带植物园沟谷雨林保护区内研究了两种果蝠——棕果蝠（Rousettus leschenaulti）和犬蝠（Cynopterus sphinx）取食光叶桑（Morus macroura）果实的行为、夜栖息地分布、散布种子方式及范围等。借助月光对果蝠的行为进行直接观察,发现它们的取食活动一般在天黑20～40min开始,取食高峰发生在22：00～22：30和23：00～23：30之间,这两个取食高峰期平均取食次数（平均值±标准误）为（13．5±2．5）和（15．0±2．3）次,最低的取食频率发生在19：00～19：30和20：30-21：00之间,分别取食（0．2±0．2）和（0．7±0．5）次。果蝠很少在母树上取食成熟的果实,相反它们用嘴叼下果实并携带到夜栖息地去进食,通常这些夜栖息地是具有密闭树冠、密集枝条的树种。夜栖息地在母树周围的分布根据环境中适合它们栖息的树种和分布而决定,不同母树周围其夜栖息地分布具有非常大的变异与空间异质性。钝叶榕（Ficus curtipes）、铁力木（Mesua ferrea）和糖胶树（Alstonia scholaris）是果蝠最喜爱的夜栖息地。在同样的情况下,尽管需要飞行更远的距离,两种果蝠都比较喜欢寻找具有许多枝条和小枝并且有复杂树冠的树木作为夜栖息地。两种果蝠取食光叶桑果实时,一部分种子通过消化道消化后被排泄出来,另外的一部分伴随着咀嚼后的果渣被吐出来,通过这两种方式,散布了大量的种子,再加上在飞行中也有排泄的习性,它们传播的种子在空间上更广泛。     

三种旧大陆狐蝠科蝙蝠舌长度及结构比较

为探讨旧大陆食果和食蜜蝙蝠的食性类型不同是否造成其取食器官舌长度及结构的差异,本研究以2种食果蝙蝠犬蝠（Cynopterus sphinx）和棕果蝠（Rousettus leschenaultii）以及1种食蜜蝙蝠长舌果蝠（Eonycteris spelaea）为研究对象,比较了这3个物种间舌的差异。犬蝠、棕果蝠和长舌果蝠伸入直径为2 cm试管的最大舌长度L1（包括伸入试管的吻部和吻部以外的舌长）,分别为（29.19?0.52）mm、（35.05?0.82）mm、（49.34?1.64）mm;伸出吻端外部的舌长L3分别为（16.25?0.53）mm、（19.25?0.79）mm、（31.88?1.56）mm;与体重转换后的最大舌长度,即转换L1分别为（8.57?0.17）mm/3√g、（7.90?0.27）mm/3√g、（12.41?0.40）mm/3√g;与体重转换后的伸出吻端外部的舌长,即转换L3分别为（4.77?0.16）mm/3√g、（4.34?0.22）mm/3√g、（8.01?0.38）mm/3√g;与体重转换后的解剖舌长分别为（5.56?0.16）mm/3√g、（5.35?0.14）mm/3√g、（6.65?0.38）mm/3√g。此5个参数种间比较均差异显著,食蜜类的长舌果蝠的5个参数均显著长于食果类犬蝠和棕果蝠的。通过比较3种蝙蝠的舌结构发现,长舌果蝠的舌尖尖细且具有毛刷状丝状乳头结构,舌面及两侧凹槽较多;犬蝠和棕果蝠的舌尖钝圆,舌面乳头和凹槽较少而平缓。本文结果表明,旧大陆食蜜蝙蝠与食果蝙蝠在舌长度和舌结构上存在明显差异,可能与捕食行为上的差异有关。     

广州市犬蝠对栖息地的选择

2006年9月-2007年3月,在广州市区对犬蝠(Cynopterus sphinx angulatus)的分布和栖息地的选择进行了研究.结果表明:共发现犬蝠栖巢45个,有犬蝠栖息的26个;犬蝠对栖息植物的选择具有专一性,主要利用景观树蒲葵(Livistona chinensis)的叶片建造栖巢,其栖息地跟人类活动区域高度重合.捕获的18个栖群中5个栖群为全捕,13个栖群有部分个体未捕获;其中17个栖群中包括有雄性个体,占群体总数的94%;5个全捕栖群中,2个为一雄多雌,一个为一雄一雌群体,一个为独栖雄性,另一个为多个雄性的"单身汉群体".     

基因组水平蝙蝠嗅觉受体基因的分子进化

翼手目动物（俗称蝙蝠）的食性分化显著,不同食性的蝙蝠具有显著不同的嗅球大小。为了研究嗅觉是否影响了蝙蝠食性的进化,我们利用网上已公布的10种蝙蝠基因组的数据,通过同源比对的方法鉴定出所有的嗅觉受体基因,并进行嗅觉受体基因亚家族的分类,进而比较嗅觉受体基因亚家族的数目差异。结果显示,蝙蝠的嗅觉受体基因与其它哺乳动物一样,都可以分为13个单系起源的亚家族;在Yinpterochiroptera亚目中,OR1/3/7、OR2/13、OR5/8/9等3个嗅觉受体亚家族在食果蝙蝠中均发生了不同程度的扩张,基因数目显著地多于食虫蝙蝠,提示嗅觉在食果蝙蝠取食过程中具有重要的作用。因此,本研究在基因组水平上重现了蝙蝠嗅觉受体基因的进化历史,揭示了3个嗅觉受体基因亚家族的功能可能与食果蝙蝠的食性相关,突出了嗅觉对动物食性的重要作用.     

Dwelling at the oxycline: does increased stratification provide a predation refugium for the Lake Victoria sardine Rastrineobola argentea?

1. We tested the hypothesis that increased hypoxia in Lake Victoria provides a refugium for the cyprinid dagaa ( Rastrineobola argentea ) against hypoxia-sensitive Nile perch ( Lates niloticus ).
2. Hypoxia in the main habitat of dagaa was rare during 1979–80, but lasted 3–5 months in 1987 and 1988, during which time adult dagaa spent the day just above the oxycline instead of near the bottom.
3. Dissolved oxygen concentrations in the layer just above the oxycline were not critical for Nile perch, but a mass kill of this species following a sudden upwelling of hypoxic water suggested that oxycline-dwelling is risky.
4. Our data suggest no difference between dagaa and Nile perch in the level at which dissolved oxygen starts to limit their vertical distribution in the water column, but dagaa seems to be even more sensitive to extreme hypoxia (<1–2 mg O2 L−1) than Nile perch.
5. We argue that oxycline-dwelling dagaa are not seeking a predation refugium but that they are limited by low oxygen levels in reaching their feeding areas near the bottom.     

Haematology and iron status of the Egyptian fruit bat, Rousettus aegyptiacus

1. Haematological values and iron status of wild and captive fruit bats (Rousettus aegyptiacus) were determined. 2. Plasma iron concentrations were 175 micrograms/dl in wild males, and 286-316 micrograms/dl in captive bats. 3. Total splenic stores were small (around 100 micrograms) in relation to hepatic stores (3 mg) and total haem iron (2.6 mg). 4. Haemoglobin levels, red cell counts and haematocrits were unusually high and mean corpuscular volumes low. 5. Lactating wild bats showed no deficits in iron status or in haematological values. 6. It is concluded that the ascorbic acid content of fruit, together with the bats' high food requirement, has ensured an ample iron supply in this vegetarian species.     

Permutation Tests for Stochastic Ordering and ANOVA: Theory and Applications with R by BASSO, D., PESARIN, F., SALMASO, L., and SOLARI, A.

Permutation Tests for Stochastic Ordering and ANOVA: Theory and Applications with R
(D. Basso, F. Pesarin, L. Salmaso, and A. Solari)
Vance W. Berger

A Comprehensive Guide to Factorial Two-Level Experimentation
(R. W. Mee)
Steven G. Gilmour

Data and Safety Monitoring Committees in Clinical Trials
(J. Herson)
Roger F. Liddle

Marginal Models for Dependent, Clustered, and Longitudinal Categorical Data
(W. Bergsma, M. Croon, and J. A. Hagenaars)
Ivy Liu

Applying Quantitative Bias Analysis to Epidemiologic Data
(T. L. Lash, M. P. Fox, and A. K. Fink)
Lawrence McCandless

The Phylogenetic Handbook: A Practical Approach to Phylogenetic Analysis and Hypothesis Testing, 2nd edition
(P. Lemey, M. Salemi, and A.-M. Vandamme, Editors)
Mike Steel     

Efficiency of food utilization by fruit bats

Summary Neotropical fruit bats consume figs (Ficus spp.) and other fruit in small bites which they suck dry and drop as pellets. The swallowed juice transits the short digestive system in 0.5 h or less. The efficiency of this unusual mode of feeding was determined by comparing the nutritional content of pellets, feces and urine of captive Artibeus jamaicensis to that of the wild figs (Ficus insipida) they had been fed. The bats extracted 57% of the wet weight and 37% of the dry weight of the fruit. The swallowed juice contained 40% of the non-fiber carbohydrate present in whole figs and was digested almost completely. Of the 160±37 seeds per fig, roughly 80% were swallowed, but almost all of these were passed intact in the feces. Overall 25–30% of the metabolizable calories in the figs were swallowed and absorbed. This mode of feeding enables the bats to extract the readily digestable calories from up to 2x their 50 g body weights in figs each night while never having to fly with more than a few grams of food in their guts at any one time.     

Scale‐dependent effects of forest restoration on Neotropical fruit bats

Neotropical fruit bats (family Phyllostomidae) facilitate forest regeneration on degraded lands by dispersing shrub and tree seeds. Accordingly, if fruit bats can be attracted to restoration sites, seed dispersal could be enhanced. We surveyed bat communities at 10 sites in southern Costa Rica to evaluate whether restoration treatments attracted more fruit bats if trees were planted on degraded farmlands in plantations or island configurations versus natural regeneration. We also compared the relative influence of tree cover at local and landscape spatial scales on bat abundances. We captured 68% more fruit bat individuals in tree plantations as in controls, whereas tree island plots were intermediate. Bat activity also responded to landscape tree cover within a 200‐m radius of restoration plots, with greater abundance but lower species richness in deforested landscapes. Fruit bat captures in controls and tree island plots declined with increasing landscape tree cover, but captures in plantations were relatively constant. Individual species responded differentially to tree cover measured at different spatial scales. We attribute restoration effects primarily to habitat structure rather than food resources because no planted trees produced fruits regularly eaten by bats. The magnitude of tree planting effects on fruit bats was less than previous studies have found for frugivorous birds, suggesting that bats may play a particularly important role in dispersing seeds in heavily deforested and naturally regenerating areas. Nonetheless, our results show that larger tree plantations in more intact landscapes are more likely to attract diverse fruit bats, potentially enhancing seed dispersal.     

Evaluation of baits for trapping of Neotropical flower chafer beetles (Coleoptera: Scarabaeoidea: Cetoniinae)

The lack of a standardized protocol to efficiently capture flower chafer beetles (Coleoptera: Scarabaeoidea: Cetoniinae) in the wild limits studies regarding the ecology of the group, as well as systematic collections seeking species surveys for taxonomic studies, especially in the Neotropical region. We investigate the efficiency of different baits to capture flower chafer beetles in the Brazilian Cerrado: (i) banana; (ii) banana + sugarcane juice; (iii) pineapple; (iv) pineapple + sugarcane juice; (v) sugarcane juice; or (vi) water (control). From January to December 2014, we sampled these beetles using a typical aerial fruit‐baited trap, every 15 days in ten sites of Brazilian Cerrado, in Aquidauana, Mato Grosso do Sul, Brazil. Traps baited with banana + sugarcane juice, pineapple + sugarcane juice and sugarcane juice alone sampled the greatest species richness and abundance of flower chafer beetles when compared to the other baits used. Our results indicated the importance of sugarcane juice, either used in isolation or as a coadjutant in the fermentation process of the tested fruits for efficient sampling of flower chafer beetle biodiversity. Finally, studies that investigate the addition of other substances in the fermentation process of the fruits, as well as the attractiveness of other native or exotic fruits that are widely distributed in the Neotropical region, can advance our knowledge of sampling of these beetles.     

Effects of early plant growth regulator treatments on flavonoid levels in grapefruit

Early foliar spray treatments containing gibberellic acid(GA₃) significantly lower the concentration ofthe bitter flavonoid naringin in fruit tissues. Sprayscontaining a surfactant and different levels ofGA₃ (5, 50, 100, and 500 ppm) or abscisic acid(ABA) (5, 25, and 50 ppm) were applied to young,developing fruit on mature grapefruit (Citrusparadisi) trees during the period from April to June,beginning just after fruit set. The fruit were allowedto mature and were harvested early the following year.Harvested fruit were evaluated for weight, juicecharacteristics, and flavonoid concentrations.GA₃ application resulted in larger mature fruit,which yielded juice with the same soluble solids valueas juice from control fruit, but with slightly loweracid percentages and lower concentrations of naringin.ABA treatment had little effect on juice solublesolids, acid content and naringin content except atthe highest concentration of 50 ppm, which lowerednaringin levels slightly in juice.     

The internal synchronization of five circadian functions of the rabbit

Five different physiological functions of the rabbit (hard faeces and urine excretion, food and water intake and locomotor activity) were registered during LD 12:12 and during continuous light conditions (LL).

(1) In LD 12:12 a strong synchronization of the five parameters existed. The minima of all functions consistently occurred during the hours of light. The nocturnal percentage of overall 24-hr events was increased significantly in 'hard faeces excretion' (66±8 (S.D.) %), 'water intake' (64±15 (S.D.) %) and 'urine excretion' (58±10 (S.D.) %). The nocturnal percentage of locomotor activity was significantly increased during the dark-hours in 9 out of 14 animals. In the other five individuals prominent peaks were present even during the photoperiod. On the average of all 14 animals 5S±13 (S.D.) % of the 24 hr events of locomotor activity occurred during the night. Despite a trough during the cessation of hard faeces excretion the events of food intake were not elevated significantly during the dark hours.

(2) During LL the synchronization of the five functions within each animal persisted during the complete 90-day LL period. A free-running circadian rhythm with-: = 24.8±0.5 (S.D.) hr was present in the four rabbits kept in LL conditions within 5-16 days after the withdrawal of the zeitgeber.

(3) In addition to the circadian period the power spectrum analysis of data obtained during LD 12:12 revealed significant ultradian periods of an average period length of 11,6 hr (hard faeces and urine excretion), 8 hr (food and water intake, locomotor activity) and 4 hr (food intake, locomotor activity). During the free-run ultradian periods of 8 and 3.2-4.2 hr were significant in almost all parameters.

(4) During LL the level of locomotor activity was reduced for 13±16 (S.D.) %, the events of food intake were increased for 17±12 (S.D.) %.

(5) The reinserted LD 12:12 zeitgeber re-entrained the circadian rhythms within 25-45 days.

(6) These results provided evidence of a predominant nocturnality of the rabbits under investigation.     

Effect of Fruit Juice on Glucose Control and Insulin Sensitivity in Adults: A Meta-Analysis of 12 Randomized Controlled Trials

Background

Diabetes mellitus has become a worldwide health problem. Whether fruit juice is beneficial in glycemic control is still inconclusive. This study aimed to synthesize evidence from randomized controlled trials on fruit juice in relationship to glucose control and insulin sensitivity.

Methods

A strategic literature search of PubMed, EMBASE, and the Cochrane Library (updated to March, 2014) was performed to retrieve the randomized controlled trials that evaluated the effects of fruit juice on glucose control and insulin sensitivity. Study quality was assessed using the Jadad scale. Weighted mean differences were calculated for net changes in the levels of fasting glucose, fasting insulin, hemoglobin A1c (HbA1c), and homeostatic model assessment of insulin resistance (HOMA-IR) using fixed- or random-effects model. Prespecified subgroup and sensitivity analyses were performed to explore the potential heterogeneity.

Results

Twelve trials comprising a total of 412 subjects were included in the current meta-analysis. The numbers of these studies that reported the data on fasting glucose, fasting insulin, HbA1c and HOMA-IR were 12, 5, 3 and 3, respectively. Fruit juice consumption did not show a significant effect on fasting glucose and insulin concentrations. The net change was 0.79 mg/dL (95% CI: −1.44, 3.02 mg/dL; P = 0.49) for fasting glucose concentrations and −0.74 µIU/ml (95% CI: −2.62, 1.14 µIU/ml; P = 0.44) for fasting insulin concentrations in the fixed-effects model. Subgroup analyses further suggested that the effect of fruit juice on fasting glucose concentrations was not influenced by population region, baseline glucose concentration, duration, type of fruit juice, glycemic index of fruit juice, fruit juice nutrient constitution, total polyphenols dose and Jadad score.

Conclusion

This meta-analysis showed that fruit juice may have no overall effect on fasting glucose and insulin concentrations. More RCTs are warranted to further clarify the association between fruit juice and glycemic control.