澜沧江流域北部中华蜜蜂有毒蜂蜜孢粉学和营养生态位分析

为分析澜沧江流域北部人食用蜂蜜中毒的原因,于2013年6—9月份,对该区域蜜蜂和蜜源植物的分布情况进行了调查,观察蜜蜂采集有毒蜜源植物的行为,并进一步调查了蜜蜂巢内蜂蜜、蜂花粉的储存情况,采集了中华蜜蜂蜂蜜样品,进行蜂蜜孢粉学与营养生态位分析。该区域有大量采用传统方式进行人工饲养的中华蜜蜂(Apis cerana cerana),及少量野生中华蜜蜂、黑色小蜜蜂(Apis audreniformis)、黑色大蜜蜂(Apis laboriosa smith)群体分布;人工饲养的中华蜜蜂蜂巢内部结构与野生中华蜜蜂蜂巢相似,为自然蜂巢,内有充足的蜜粉储存,部分蜂群蜂巢内虫害严重。该区域内主要蜜源植物为荞麦(Fagopyrum esculentum Moench),其他零星辅助蜜源较多,部分地点南烛(Vaccinium bracteatum Thunb)、昆明山海棠(Tripterygium hypoglaucum(Levl.)Hutch)连片集中分布。对中华蜜蜂蜂蜜进行孢粉学和营养生态位分析,结果表明:中华蜜蜂蜂蜜标本中含有有毒蜜源植物南烛、昆明山海棠花粉,部分样品中南烛、昆明山海棠的花粉含所占比例较高;中华蜜蜂的营养生态位宽度为0.22,比其他地区中华蜜蜂生态位指数小,推测澜沧江水电枢纽的修建等人为原因已对蜜蜂种类、蜜源植物的物种组成、群落结构造成了较大影响。     

云南中华蜜蜂与意大利蜜蜂的蜂蜜孢粉学和营养生态位

2010-2011年分别在云南昆明和蒙自地区采集中华蜜蜂与意大利蜜蜂的蜂蜜样品,进行蜂蜜孢粉学与营养生态位分析.结果表明:中华蜜蜂蜂蜜绝对花粉浓度为1.55万个·g-1,显著高于意大利蜜蜂(1.01万个·g-1).中华蜜蜂采集的蜜源植物种类为12.9个,显著多于意大利蜜蜂(7.7个).说明意大利蜜蜂对蜜源植物的选择性更强,中华蜜蜂则能利用更多的蜜源植物资源.中华蜜蜂的营养生态位宽度为0.35,显著大于意大利蜜蜂(0.23).中华蜜蜂和意大利蜜蜂之间的营养生态位重叠度为0.71,种间竞争系数为0.93,表明2种蜜蜂对食物资源的竞争激烈.     

封面说明

正封面图片由内江师范学院四川省高等学校特色农业资源研究与利用重点实验室陈发军老师2015年1月摄于四川省内江城区,展示了中华蜜蜂(Apis cerana cerana)对开花园林植物的采集行为.蜜蜂是极为重要的传粉昆虫,其数量的多少关系到自然生态系统的稳定和作物生产.目前,蜜蜂等传粉昆虫数量的下降趋势引起了世界各国的广泛关注.中华蜜蜂为我国土著蜂种,分布广泛,拜访的植物种类繁多.由于栖息地破坏、蜜粉源植物减少和西方蜜蜂引入等原因,中华蜜蜂种群受到     

西方蜜蜂对东方蜜蜂采集行为及食物资源利用的影响

【目的】在云南省腾冲市界头镇油菜花期,比较西方蜜蜂Apis mellifera L.不同放蜂密度下东方蜜蜂Apis cerana F.采集行为和对食物资源利用的变化,以期从食物资源竞争的角度为合理保护我国本土蜂种和维持植物群落结构及其稳定性提供科学依据。【方法】以界头镇为研究区域,在油菜花期根据西方蜜蜂的蜂场分布、蜂群数量及放蜂密度,确定了三个样点两种生境,观察西方蜜蜂不同放蜂密度下对东方蜜蜂的采集行为、访花频率、单花采集停留时间及粉源植物利用的影响。【结果】在农田生境中,西方蜜蜂放蜂密度最大的沙坝地试验点东方蜜蜂的访花频率最高(14.93朵/min),单花采集停留时间最短(1.96 s/朵),采集油菜花粉的数量比例最低(37%),采集花粉的种类最多(11种植物),与放蜂密度最小的新庄试验点相比,上述指标差异均显著。在山林生境中,西方蜜蜂放蜂密度最小的新庄试验点,东方蜜蜂的访花频率最低(8.48朵/min),单花采集停留时间最长(4.55 s/朵),采集油菜花粉的数量比例最高(33%),采集花粉的种类最少(8种植物),与放蜂密度最大的沙坝地试验点相比,上述指标差异均显著。【结论】在两种生境下,西方蜜蜂放蜂密度对东方蜜蜂采集行为和粉源植物利用均有显著影响,西方蜜蜂放蜂密度越大,东方蜜蜂对大宗蜜源植物(油菜)花粉的采集量越少,其采集区域由农田向山林转移的趋势越明显。     

基于蜂蜜孢粉学鉴定秦岭中华蜜蜂的蜜源木本植物

蜜源木本植物的鉴定能为中华蜜蜂Apis cerana cerana保护和利用提供依据.本研究从在秦岭地区收集的4份中华蜜蜂蜂蜜中分离出植物花粉,然后在扫描电镜下观察花粉形态,根据花粉大小、赤道面观、极面观、表面纹饰对花粉所属植物的种类进行鉴定.共鉴定出中华蜜蜂利用的蜜源木本植物13科,19属,20种.其中以壳斗科Fagaceae、忍冬科Caprifoliaceae最多,卫矛科Celastraceae、桦木科Betulaceae、蔷薇科Rosaceae次之.这些蜜源木本植物中有13种是药用植物.秦岭地区丰富的蜜源木本植物为中华蜜蜂的生存提供了食物资源;同时中华蜜蜂作为传粉昆虫,对维持秦岭地区蜜源植物的生存和生态系统稳定起着重要的作用.     

中华蜜蜂种群遗传分化与环境适应机制研究进展

中华蜜蜂Apis cerana cerana是我国十分关键和重要的传粉媒介昆虫，在不同栖息地中广泛分布，表现出飞行敏捷、采蜜期长和适应性强等优点。但近些年中华蜜蜂正面临前所未有的种群多样性下降，为保护这些特定的中华蜜蜂种群的遗传资源，研究人员基于几何形态学、分子生物学和基因组学等技术手段对中华蜜蜂遗传分化和环境适应机制进行了研究，而在我国这些多样化的中华蜜蜂种群为揭示其种群适应性进化规律提供了绝佳材料。本文从中华蜜蜂种群遗传分化与环境变化的相关性、形态变异与环境适应、环境适应性生理和行为改变及这些表型变化的遗传机制4个方面综述了相关研究进展。研究发现，物理屏障和生态环境的变化，特别是海拔和纬度相关环境变化是造成中华蜜蜂种群分化的主要原因。气候因子中，温度、氧气、辐射和湿度等对中华蜜蜂环境适应性的形态发育和生理生态特征产生重要影响。形态特征的变化主要体现在体型大小和体色上，代谢生理和行为改变是其环境适应的重要策略。基于现代基因组学和分子生物学技术的种群遗传学和种群基因组学研究发现，与社会分工行为、学习感知行为、信息感知、生长发育、温度适应和代谢等相关的基因或通路受到自然选择作用，这为中华...     

城市园林生境冬季中华蜜蜂的活动规律和采集行为

蜜蜂等传粉昆虫是生物多样性的重要组成部分,关系植物繁殖和农业生产.为探讨城市园林在土著蜂种中华蜜蜂保护中的作用,对川南地区冬季中华蜜蜂的活动格局、访花行为和蜜粉源植物等进行观测.结果表明:工蜂在冬季适宜天气积极外出采集,活动持续时间长,出巢、回巢和未带粉采集蜂数量在14:00—15:00最多,呈双峰格局,而采粉蜂数量在11:00达到峰值,呈单峰格局,时间对蜜蜂活跃程度影响显著;蜂群对花蜜和花粉采集投入存在差异,只有近20%的采集蜂携带花粉;温湿度对蜜蜂活动具有一定影响;不同日期蜂群活动格局大体相似,但个别时段体现出差异.冬季园林生境中开花植物较少,但多种类群皆为可采集的蜜粉资源,中华蜜蜂通过调节其行为策略可实现有效采集;山茶等主要园林植物花上蜜蜂的拜访表现出较强规律性.可通过科学的园林管理增加冬季蜜粉资源,以利于营造中华蜜蜂的适宜生境和维持野外种群.     

基于几何形态学方法的秦巴山区中华蜜蜂翅形态变异研究

【目的】本研究拟揭示陕西省秦巴山区的中华蜜蜂Apis cerana cerana翅形态变异规律,为研究中华蜜蜂种下形态分化提供依据。【方法】基于几何形态测量学方法对陕西省秦巴山区17个样地的中华蜜蜂前翅进行量化分析,并结合主成分分析(Principal Component Analysis,PCA)、典型变量分析(Canonical variate analysis,CVA)、薄板样条分析(Thin-plate spline,TPS)等方法探讨该地区中华蜜蜂形态分化规律及影响因素。【结果】不同采样地的中华蜜蜂种群在翅大小上存在显著性差异,同时翅大小与所处地理位置存在显著的相关性。前翅形态变异主成分分析结果显示来自秦岭北坡的5个种群与秦岭南坡以及巴山地区的种群在PC1方向上存在一定的分化。TPS分析结果显示北坡5个采样地种群具有较宽的翅。马氏距离和普氏距离结果均显示秦岭北坡种群与秦岭南坡种群以及巴山种群之间均存在显著性差异,且秦岭南坡种群与巴山种群之间的差异较小。普氏距离随着地理距离的增大而变大,但南北坡之间存在一定的差异。【结论】翅大小与其所处地理位置存在明显的相关性,海拔和纬度上的差异是造成翅大小变化的主要因素。处于秦岭北坡的种群与秦岭南坡以及巴山地区中华蜜蜂种群出现一定程度的翅脉形态分化。     

不同类型蜂箱对中华蜜蜂Apis cerana cerana Fabricius生产性能的影响

【目的】为了研究不同类型蜂箱对中华蜜蜂Apis cerana cerana Fabricius生产性能的影响。【方法】我们在综合考虑甘肃南部地区中华蜜蜂饲养模式、规模、当地环境等因素的基础上,选用标准蜂箱、原始蜂箱和生态蜂箱3种类型蜂箱在当地主要流蜜期进行蜂蜜生产试验。【结果】结果发现,蜂箱类型对蜂群的年产蜜量、存蜜量和取蜜次数存在显著影响(P<0.05),其中标准蜂箱在4个试验点的年产蜜量最高,原始蜂箱的存蜜量最高,而生态蜂箱在这2个指标上表现适中,标准蜂箱的年取蜜次数稍多。本研究中海拔和蜜源植物对蜂群生产性能没有明显影响。【结论】采用何种类型蜂箱进行中华蜜蜂养殖,应根据当地的环境状况、蜜源条件、文化及养蜂基础等多种因素综合考虑。     

福建中华蜜蜂种群形态数值分析

为了探明福建中华蜜蜂Apis cerana cerana的种群分布和种群形态特征, 探索中华蜜蜂种群分化规律, 本文对福建不同生态区的11个样点780头中华蜜蜂工蜂, 采用Ruttner (1988)提出的30个形态标记, 运用差异显著性分析、 逐步判别分析和聚类分析方法, 进行形态特征分析。结果显示： 福建中华蜜蜂存在较大的形态差异和种群分化, 至少存在3个中华蜜蜂种群： 福建北部种群、 福建中部种群和福建南部种群。福建北部中华蜜蜂种群具有较大的蜜蜂个体和器官, 包括吻长、 前翅、 蜡镜、 后足等以及独特的前翅翅脉角： 武夷中华蜜蜂具有最大的翅脉角G18, J10和L13, 最小翅脉角E9 (P<0.01); 光泽和政和中华蜜蜂表现较小翅脉角K19, O26和L13, 较大的翅脉角B4和N23 (P<0.01)。福建中部福州、 尤溪、 将乐、 宁德中华蜜蜂种群具有相对较大的蜜蜂个体和器官, 较大的翅脉角G18和K19 (P<0.01), 以及中等大小的翅脉角N23。福建南部龙岩、 永定、 武平、 漳州中华蜜蜂种群具有较小的个体 (P<0.01)。前翅翅脉角分析有可能成为一种更有效、 准确的种群形态分析方法。本研究结果对福建中华蜜蜂资源的保护和合理利用具有重要的指导意义。     

Nectar and Pollen Sources for Honeybee （Apis cerana cerana Fabr.） in Qinglan Mangrove Area, Hainan Island, China

In the present study, nectar and pollen sources for honeybee （Apls cerana cerana Fabr.） were studied in Qlnglan mangrove area, Hainan Island, China, based on microscopic analysis of honey and pollen load （corblcular and gut contents） from honeybees collected In October and November 2004. Qualitative and quantitative melittopalynologlcal analysis of the natural honey sample showed that the honey is of unlfloral type with Mimosa pudlca L. （Mlmosaceae） as the predominant （89.14%） source of nectar and pollen for A. cerana cerana In October. Members of Araceae are an Important minor （3%-15%） pollen type, whereas those of Arecaceae are a minor （〈3%） pollen type. Pollen grains of Nypa fruticans Wurmb., Rhlzophora spp., Excoecarla agallocha L., Lumnitzera spp., Brugulera spp., Kandella candel Druce, and Ceriops tagal （Perr.） C. B. Rob. are among the notable mangrove texa growing In Qinglan mangrove area recorded as minor taxa In the honey. The absolute pollen count （I.e. the number of pollen grains/10 g honey sample） suggests that the honey belongs to Group V （〉1 000 000）. Pollen analysis from the corblcular and gut contents of A. cerana cerana revealed the highest representation （95.60%） of members of Sonneratia spp. （Sonneratlaceae）, followed by Bruguiera spp. （Rhizophoraceae）, Euphorblaceae, Poaceae, Fabaceae, Arecaceae, Araceae, Anacardlaceae, and Rublaceae. Of these plants, those belonging to Sonneratla plants are the most Important nectar and pollen sources for A. cerana cerana and are frequently foraged and pollinated by these bees in November.     

The trophic niche of sculpins Cottus spp. in forage fish assemblages of boreal lakes

We compared the trophic niches of freshwater sculpins Cottus spp. with those of other co-habiting forage fishes in two groups of boreal lakes with distinct habitats and fish communities. Near North Lakes (45° 00′ to 47° 30′ N) were deeper, stratified and contained lake trout Salvelinus namaycush as the apex piscivore, whereas Far North Lakes (51° 10′ to 52° 20′ N) were shallower, did not stratify and contained pike Esox lucius and walleye Sander vitreus as the apex piscivores. Trophic niches of sculpins and other forage fishes were compared based on niche metrics calculated from muscle stable carbon (δ¹³C) and nitrogen (δ¹⁵N) isotope ratios. In Near North Lakes, sculpins were found almost exclusively in deep, offshore waters and their niche positions reflected a greater reliance on pelagic production (lower δ¹³C) and a higher trophic elevation (higher δ¹⁵N) compared with most other forage fishes. Furthermore, sculpins in Near North Lakes tended to have larger trophic niches (occupied greater area in δ¹³C– δ¹⁵N space), particularly in the food chain (δ¹⁵N) dimension, than other cohabiting forage fishes. In contrast, sculpins in Far North Lakes were commonly found in the nearshore and had trophic niche positions and sizes that were similar to those of the other cohabiting forage fishes. This study illustrates the flexibility in the realised trophic niches of sculpins in relation to habitat availability and fish community composition in boreal lakes.     

Beyond ecological opportunity: Prey diversity rather than abundance shapes predator niche variation

1. Ecological opportunity (i.e. the diversity of available resources) has a pivotal role in shaping niche variation and trophic specialisation of animals. However, ecological opportunity can be described with regard to both diversity and abundance of resources. The degree to which these two components contribute to niche variation remains unexplored.
2. To address this, we used an extensive dataset on fish diet and benthic invertebrate diversity and density from 73 sampling events in three Norwegian rivers in order to explore realised trophic niches and the response of dietary niche variation along gradients of resource diversity (potential trophic niches), resource density (as a proxy of resource abundance) and fish density (as a proxy of inter‐ and intra‐specific competition) in a freshwater top predator (the brown trout, Salmo trutta L.).
3. Linear models indicated that individual and population niche variation increased with increasing ecological opportunity in terms of prey diversity. However, no simple cause‐and‐effect associations between niche indices and prey abundance were found. Our multiple regression analyses indicated that the abundance of certain resources (e.g. Chironomidae) can interact with prey diversity to determine individual and population realised trophic niches. Niche variation (within‐individual component and inter‐individual diet variation) decreased with increasing inter‐ and intra‐specific competition.
4. This study extends prevailing trophic ecology theory by identifying diversity, rather than density, of available prey resources as a primary driver of niche variation in fish of temperate riverine systems with no extensive resource limitation. The study also shows that ecological opportunity may mask the direction of the effect (compression or expansion) of competition on niche variation when food resources are diverse.
5. Our study provides novel empirical insight to the driving forces behind niche variation and reveals that diversity, rather than density, of available prey resources may be a primary driver of niche variation in freshwater fish. Our study supports the view that a broader potential trophic niche promotes broader realised trophic niche variation by individuals, which leads to individual niche diversification by opening access to alternatives resources, resulting in a concomitant rise in the realised trophic niche width of the population.

     

Trophic niche similarities of sympatric Turdus thrushes determined by fecal contents,stable isotopes,and bipartite network approaches

An ecological niche has been defined as an n‐dimensional hypervolume formed by conditions and resources that species need to survive, grow, and reproduce. In practice, such niche dimensions are measurable and describe how species share resources, which has been thought to be a crucial mechanism for coexistence and a major driver of broad biodiversity patterns. Here, we investigate resource partitioning and trophic interactions of three sympatric, phylogenetically related and morphologically similar species of thrushes (Turdus spp.). Based on one year of data collected in southern Brazil, we investigated niche partitioning using three approaches: diet and trophic niche assessed by fecal analysis, diet and niche estimated by stable isotopes in blood and mixing models, and bipartite network analysis derived from direct diet and mixing model outputs. Approaches revealed that the three sympatric thrushes are generalists that feed on similar diets, demonstrating high niche overlap. Fruits from C3 plants were one of the most important food items in their networks, with wide links connecting the three thrush species. Turdus amaurochalinus and T. albicollis had the greatest trophic and isotopic niche overlap, with 90% and 20% overlap, respectively. There was partitioning of key resources between these two species, with a shared preference for fig tree fruits—Ficus cestrifolia (T. amaurochalinus PSIRI% = 11.3 and T. albicollis = 11.5), which was not present in the diet of T. rufiventris. Results added a new approach to the network analysis based on values from the stable isotope mixing models, allowing comparisons between traditional dietary analysis and diet inferred by isotopic mixing models, which reflects food items effectively assimilated in consumer tissues. Both are visualized in bipartite networks and show food‐consumers link strengths. This approach could be useful to other studies using stable isotopes coupled to network analysis, particularly useful in sympatric species with similar niches.     

Trophic niches and feeding relationships of shorebirds in southern Brazil

Niche theory predicts that sympatric species should differ in some ecological characteristic, to allow co-existence and reduce competition for key resources. Food is critical on wintering grounds and stopover areas for migratory species that need to accumulate reserves in order to complete their migration. Wetlands of the Rio Grande do Sul coastal plain, in southern Brazil, host several species of shorebirds with similar morphology, foraging methods and diet. When these species are in sympatry, some trophic niche overlap is expected. Diets and trophic niches of migratory and resident shorebirds were investigated during the austral summer on Torotama Island, Lagoa dos Patos Estuary, Brazil. Complementary methods were used to determine the trophic ecology of three shorebird species; diet was determined through analysis of feces and food samples, using stable isotopes of carbon and nitrogen. The local invertebrate community was sampled to determine potential prey and ascertain feeding preferences of birds. Coleoptera was the most abundant taxon in the feces of all shorebirds. Trophic niche overlap in the diets was high, with the widest trophic niche found for the buff-breasted sandpiper Calidris subruficollis. Isotopic mixing models indicated differences in the main food sources of shorebirds. The isotopic niche breadth was widest for the American golden-plover Pluvialis dominica. These species, as well as the resident southern lapwing Vanellus chilensis, consumed some prey in higher proportions over others, although they had generalist diets. Migratory species with generalist habits benefit from heterogeneous environments such as floodplains during the non-breeding season.     

Trophic level and basal resource use of soil animals are hardly affected by local plant associations in abandoned arable land

Plants provide resources and shape the habitat of soil organisms thereby affecting the composition and functioning of soil communities. Effects of plants on soil communities are largely taxon‐dependent, but how different functional groups of herbaceous plants affect trophic niches of individual animal species in soil needs further investigation. Here, we studied the use of basal resources and trophic levels of dominating soil meso‐ and macrofauna using stable isotope ratios of carbon and nitrogen in arable fallow systems 3 and 14–16 years after abandonment. Animals were sampled from the rhizosphere of three plant species of different functional groups: a legume (Medicaco sativa), a nonlegume herb (Taraxacum officinale), and a grass (Bromus sterilis). We found virtually no consistent effects of plant identity on stable isotope composition of soil animals and on thirteen isotopic metrics that reflect general food‐web structure. However, in old fallows, the carbon isotope composition of some predatory macrofauna taxa had shifted closer to that of co‐occurring plants, which was particularly evident for Lasius, an aphid‐associated ant genus. Trophic levels and trophic‐chain lengths in food webs were similar across plant species and fallow ages. Overall, the results suggest that variations in local plant diversity of grassland communities may little affect the basal resources and the trophic level of prey consumed by individual species of meso‐ and macrofauna belowground. By contrast, successional changes in grassland communities are associated with shifts in the trophic niches of certain species, reflecting establishment of trophic interactions with time, which shapes the functioning and stability of soil food webs.     

Molecular and phylogenetic characterization of honey bee viruses,Nosema microsporidia,protozoan parasites,and parasitic mites in China

China has the largest number of managed honey bee colonies, which produce the highest quantity of honey and royal jelly in the world; however, the presence of honey bee pathogens and parasites has never been rigorously identified in Chinese apiaries. We thus conducted a molecular survey of honey bee RNA viruses, Nosema microsporidia, protozoan parasites, and tracheal mites associated with nonnative Apis mellifera ligustica and native Apis cerana cerana colonies in China. We found the presence of black queen cell virus (BQCV), chronic bee paralysis virus (CBPV), deformed wing virus (DWV), Israeli acute paralysis virus (IAPV), and sacbrood virus (SBV), but not that of acute bee paralysis virus (ABPV) or Kashmir bee virus (KBV). DWV was the most prevalent in the tested samples. Phylogenies of Chinese viral isolates demonstrated that genetically heterogeneous populations of BQCV, CBPV, DWV, and A. cerana‐infecting SBV, and relatively homogenous populations of IAPV and A. meliifera‐infecting new strain of SBV with single origins, are spread in Chinese apiaries. Similar to previous observations in many countries, Nosema ceranae, but not Nosema apis, was prevalent in the tested samples. Crithidia mellificae, but not Apicystis bombi was found in five samples, including one A. c. cerana colony, demonstrating that C. mellificae is capable of infecting multiple honey bee species. Based on kinetoplast‐encoded cytochrome b sequences, the C. mellificae isolate from A. c. cerana represents a novel haplotype with 19 nucleotide differences from the Chinese and Japanese isolates from A. m. ligustica. This suggests that A. c. cerana is the native host for this specific haplotype. The tracheal mite, Acarapis woodi, was detected in one A. m. ligustica colony. Our results demonstrate that honey bee RNA viruses, N. ceranae, C. mellificae, and tracheal mites are present in Chinese apiaries, and some might be originated from native Asian honey bees.     

Generalist trophic ecology in a changing habitat: The case of the four‐striped mouse in a woody‐encroached savannah

Trophic generalists tolerate greater habitat change than specialists; however, few studies explore how generalist trophic ecology is affected. We established how the trophic ecology of an extreme generalist, Rhabdomys pumilio, changed in relation to a directionally changing woody‐encroached savannah in Eastern Cape, South Africa by investigating (a) foraging behaviour, (b) trophic niche and (c) feedback effects. (a) Giving‐up densities showed that R. pumilio preferred foraging in subcanopy microhabitat during the night as a result of lower thermoregulatory costs, but had similar preferences for sub‐ and intercanopy microhabitats during the day. (b) An isotope analysis revealed that the dietary composition and trophic niche occupied by R. pumilio differed among tree canopy cover levels (0%, 30% and 80%), which appeared to be related to changes in C₄ grass material and invertebrate availability. (c) Artificial seed patches suggested that R. pumilio was a potentially important postdispersal seed predator of the woody‐encroaching species, Vachellia karroo. Thus, an increase in tree canopy cover altered the trophic niche of R. pumilio by reducing foraging costs at night and providing alternative food resources in terms of availability and source. These findings demonstrate how an extreme generalist adapted to human‐induced habitat change through changes in its trophic ecology.     

柔鱼科近缘种茎柔鱼与鸢乌贼营养生态位及相互关系

同域近缘种由于进化选择的压力,会形成不同的行为适应策略。研究同域近缘种生态位格局,有助于理解近缘物种的竞争和共存机制,是深入了解种群动态变化的基础性问题。选取东太平洋赤道海域的柔鱼科头足类近缘种茎柔鱼和鸢乌贼为研究对象,利用生物地球化学示踪物(稳定同位素和脂肪酸)分析两种头足类的营养生态位及相互关系。结果显示,茎柔鱼和鸢乌贼肌肉的部分必需脂肪酸(C18∶2n6、C20∶2n6、C20∶3n3、C20∶4n6和C20∶5n3)含量存在差异,说明二者食物来源不同,但其碳、氮稳定同位素比值无显著差异,可能是因为相同个体大小的茎柔鱼和鸢乌贼营养级相近,且摄食空间相似。这些结果在营养生态位的分析结果中也得到了验证,稳定同位素营养生态位的重叠程度高于脂肪酸营养生态位,表明脂肪酸组成更能体现同域近缘种的食性差异。本研究可加深对头足类进化过程中摄食行为适应机制的理解,并为评估同域近缘种的营养生态位关系提供有益参考。