Co-occurrence of the cirolanid isopodEurydice nipponica Bruce & Jones and the ghost shrimpCallianasa japonica Ortmann on an intertidal sand flat

On a moderately protected intertidal sand flat in west Kyushu, Japan, most of the population of the cirolanid isopodEurydice nipponica Bruce & Jones (89%–100%) was found in the zones occupied by the thalassinidean ghost shrimpCallianassa japonica Ortmann in July, August and December 1980.C. japonica later extensively expanded its habitat, and in July 1984, when almost the whole sand flat had been densely populated byC. japonica, the range of the distribution ofE. nipponica was the same as that ofC. japonica with a density about 10 times greater than in July 1980. The occurrence ofE. nipponica has previously been recorded from several exposed sandy beaches as well as their adjacent subtidal areas of well oxygenated sands along the coast of Kyushu, but not on more protected shores like the present sand flat. It is suggested thatC. japonica, through its bioturbating activities, produces sediment characteristics approximating those of the exposed sandy beaches which are the preferred habitat ofE. nipponica. It is supposed thatE. nipponica is a facultative commensal ofC. japonica. In a field experiment to excludeC. japonica and to detect its positive influence onE. nipponica, the densities ofE. nipponica were found to be lower in the experimental plots than in the intact plots. Statistically, however, the difference was only weakly significant, and the possible reasons for this are discussed.     

Ecological and morphological shifts in Lake Michigan fishes: glimpses of the ghost of competition past

Synopsis Both historical patterns and recent evidence of resource partitioning and complementarity within the Lake Michigan fish community provide circumstantial evidence for interspecific competition. But competition is difficult to document in the field without controlled experimentation. In Lake Michigan, controlled experiments on competition within the fish community are nearly impossible, but we still need to understand the interactions among the dominant fishes. For this purpose, I have relied upon hypothesis-based field observation, natural experiments in the field and designed laboratory experiments to evaluate competitive interactions. Resource use patterns and trophic morphology of the bloater, Coregonus hoyi, a native cisco, from samples taken before alewife, Alosa pseudoharengus, became abundant (1960) were compared to more recent data (1979–80). After the alewife density increase, bloaters had significantly fewer and shorter gill rakers. This suggests a morphological shift toward greater benthic foraging efficiency in response to high abundances of an efficient pelagic planktivore, alewife. Resource use comparisons suggested that bloaters now shift from pelagic zooplanktivory to benthic habitats and diets at least two years earlier in their life history than they did before alewife became abundant. This evidence, albeit not experimental, provides strong support for the importance of competition in the structure of the current Lake Michigan fish community.In Lake Michigan, seasonal thermal habitat compression can pack fish into a narrow thermal zone across the lake bottom, leading to increased habitat overlap, reduced prey availability and fish diets containing fewer and smaller prey. Thermal habitat compression, which can occur intermittently through the season, may create competitive bottlenecks which help maintain the observed resource partitioning among these fishes.     

Limits to food intake and fiber utilization in the prairie vole,Microtus ochrogaster: effects of food quality and energy need

We fed prairie voles (Microtus ochrogaster) rat chow diluted with variable amounts of -cellulose to determine 1) how much fiber the voles could tolerate in their diet; 2) changes in food intake and digestibility of dry matter and of fiber; 3) the extent to which voles utilized fiber as an energy source; and 4) whether any of these variables differed between groups of animals maintained at 5 or 22°C. Fiber content of the diets ranged from 20 to 84%. Animals held at 5°C maintained body mass through a diet containing 69% fiber, while animals held at 22°C maintained body mass through the 84% fiber diet. Dry matter intake increased with fiber level from 9.3 to 15.0 g·day^-1 for animals at 5°C and from 5.6 to 14.0 g·day^-1 for animals at 22°C; intake on the highest fiber diet eaten by either group was not different. Dry matter digestibility decreased significantly as the fiber in the diets increased, but was not affected by temperature treatments. Digestible dry matter intake for each group remained constant regardless of diet quality, but on each diet digestible dry matter intake for animals at 5°C was significantly higher than that of the animals held at 22°C. Digestibility of the fiber portion of the experimental diets remained constant as food quality decreased, so the percent of daily energy need met by fiber utilization increased with higher food intake. On the lowest quality diet each group tolerated, fiber digestion provided approximately 42 and 68% of the energy needs of voles at 5 and 22°C, respectively.Abbreviations BM body mass - BMR basal metabolic rate - DE digestible energy - DM dry matter - DMD dry matter digestibility - DDMI digestible dry matter intake - MR metabolic rate - NDF neutral detergent fiber (=cell walls) - NDS neutral detergent solubles (=cell solubles) - SEM standard error of mean - T _a ambient temperature     

The influence of forager number and colony size on food distribution in the odorous house ant, Tapinoma sessile

Stomodeal trophallaxis plays a major role in ant colony nutrition and communication. While the rate of food distribution at the individual level (worker to worker) is rapid, factors affecting the rate of food distribution at the colony level remain poorly understood. We used the odorous house ant, Tapinoma sessile (Say), as a model species to investigate the factors affecting the rate of spread of liquid carbohydrate food throughout a colony. To track the movement of the food we used protein marking and double antibody sandwich enzyme-linked immunosorbent assay, DAS-ELISA. Increasing colony size while keeping the number of donor workers constant significantly decreased the number of individuals testing positive for the marker. After 8 h of trophallactic interactions with ten donors, 92 ± 5% of recipient workers tested positive in a colony of 125 and 38 ± 5% tested positive in a colony of 1,000. Interestingly, as colony size increased and the percentage of workers testing positive decreased, the proportion of workers actually receiving food increased. Food originating from a single donor fed approximately 12 individuals in colonies comprised of 125 recipients and approximately 38 individuals in colonies comprised of 1,000 recipients. Thus, the per capita consumption of food decreased as colony size increased, most likely because the amount of food reaching the colony was limited. Increasing the number of donors while keeping colony size constant significantly increased the number of recipient ants testing positive for the marker. As the number of donor workers doubled, the percentage of recipients testing positive more than doubled suggesting that the number of individuals receiving food increases with increasing colony size, while the per capita amount of food decreases. When food was available ad libitum and in close proximity to the nest, numerous workers fed directly at the food source. This dramatically increased the rate and the extent of food distribution to both the workers and the queens and colony size had no significant effect on the spread of the marker in the workers or the queens. The rate and the extent of food distribution at the colony level may depend on a number of factors including the number of successful foragers, the size and density of the recipient colony, and the recipient caste.     

The gut morphology of the African ice rat,<Emphasis Type="Italic"> Otomys sloggetti robertsi</Emphasis>, shows adaptations to cold environments and sex-specific seasonal variation

We studied the gut morphology of the ice rat Otomys sloggetti robertsi, a non-hibernating murid rodent endemic to the sub-alpine and alpine regions of the southern African Drakensberg and Maluti mountains. The gut structure of O. s. robertsi is well adapted for a high fibre, herbivorous diet, as is the case with other members of its subfamily Otomyinae. Despite the broad similarity in gross gut morphology with mesic- and arid-occurring otomyines, O. s. robertsi has a larger small intestine, caecum, stomach volume and parts of the colon, which we suggest are adaptations for increased energy uptake and/or poor diet quality in alpine environments. However, O. s. robertsi has a smaller larger intestine than other otomyines, perhaps because it occupies a mesic habitat. Seasonal sexual differences occurred, with females increasing dimensions of the stomach, small intestine length, caecum, and large intestine in summer. Sexual asymmetry in gut morphology may be related to increased energy requirements of females during pregnancy and lactation, indicating phenotypic plasticity in response to poor quality vegetation and a shorter growing season in alpine habitats.Communicated by G. Heldmaier     

Variability of kokanee and rainbow trout food habits,distribution, and population dynamics,in an ultraoligotrophic lake with no manipulative management

Crater Lake is a unique environment to evaluate the ecology of introduced kokanee and rainbow trout because of its otherwise pristine state, low productivity, absence of manipulative management, and lack of lotic systems for fish spawning. Between 1986 and 2004, kokanee displayed a great deal of variation in population demographics with a pattern that reoccurred in about 10 years. We believe that the reoccurring pattern resulted from density dependent growth, and associated changes in reproduction and abundance, driven by prey resource limitation that resulted from low lake productivity exacerbated by prey consumption when kokanee were abundant. Kokanee fed primarily on small-bodied prey from the mid-water column; whereas rainbow trout fed on large-bodied prey from the benthos and lake surface. Cladoceran zooplankton abundance may be regulated by kokanee. And kokanee growth and reproductive success may be influenced by the availability of Daphnia pulicaria, which was absent in zooplankton samples collected annually from 1990 to 1995, and after 1999. Distribution and diel migration of kokanee varied over the duration of the study and appeared to be most closely associated with prey availability, maximization of bioenergetic efficiency, and fish density. Rainbow trout were less abundant than were kokanee and exhibited less variation in population demographics, distribution, and food habits. There is some evidence that the population dynamics of rainbow trout were in-part related to the availability of kokanee as prey.     

Seasonal changes in abundance and spatial distribution of the soil arthropods in a Japanese cedar (Cryptomeria japonica D.Don) plantation,with special reference to collembola and acarina

Seasonal changes in abundance and distribution pattern of soil micro-arthropods were studied in connection with a few environmental factors in a Japanese cedar (Cryptomeria japonica D. Don) plantation. The soil arthropods were sampled from three different depths at intervals of two months for two years. Of the collected animals (total 51000–155000 m⁻²), Collembola (20000–76000 m⁻²), oribatid mites (19000–55000 m⁻²) and carnivorous mites (6200–21000 m⁻²) were the numerically dominant animal groups. Low seasonal variations in abundance indicated their seasonal stability in population levels. The trends in seasonal fluctuation were similar among these groups and between the two years, showing bimodal pattern with little peaks in early summer and winter. The pattern of seasonal fluctuation in abundance of carnivorous mites (P _d) was significantly synchronized with that in the total abundance of Collembola and oribatid mites (P _τ). Thus, the number-ratios (P _d/P _τ) were fairly constant, ranging from 0.10 to 0.25. Seasonal changes in vertical distribution of the three animal groups showed a similar pattern for both years. The downward migrations were shown to be more affected by low temperatures in winter accompanied by snow coverage rather than by the desiccation of the surface soil in summer. All the three groups demonstrated as a whole slightly aggregated patterns of horizontal distribution throughout the two years. Temporal increases in the patchiness indices were observed from summer to autumn when the moisture content of the surface soil was low.     

江西武夷山珍稀濒危植物南方铁杉种群动态与空间分布

明晰江西武夷山国家级自然保护区内180年生的珍稀濒危植物南方铁杉(Tsuga chinensis var.tchekiangensis)的种群特征,并提出针对性的保护策略,对南方铁杉种群的就地保护具有现实意义。通过分析保护区内6.4 hm~2动态监测固定样地的南方铁杉种群数据,编制了静态生命表,绘制了存活曲线、死亡率和消失率曲线、生存函数曲线,采用了时间序列模型对种群数量特征进行未来预测;同时,运用点格局分析Ripley′s K函数中的成对相关函数g(r)判断不同生长阶段的南方铁杉种群在不同尺度下的空间分布格局。结果表明：(1)南方铁杉种群的年龄结构呈“金字塔”型,属于衰退型种群;各龄级间的数量变化动态关系显示该种群在当前阶段呈增长型,但是种群的天然更新能力较差;(2)南方铁杉种群的存活曲线表现为Deevey-I型,种群个体在进入生理死亡阶段后产生一定的波动;(3)南方铁杉种群的生存率随龄级增加而逐渐下降,累积死亡率逐渐递增;死亡密度整体偏低,在第1—2龄级较高,总体波动幅度较小;危险率曲线总体呈现上升的趋势;(4)在经过不同龄级的时间后,南方铁杉幼龄树数量降低,中龄树和老龄树数量持平...     

Control of foraging behavior of individuals within an ecosystem context: the clam Macoma balthica,flow environment,and siphon-cropping fishes

Macoma balthica (L.), an abundant clam, ubiquitous in temperate estuaries across the North Atlantic, is known to practice both alternative basic modes of feeding available to seafloor invertebrates. It either holds its feeding organ, the siphon, at a fixed position just above the sediment surface to filter out food particles suspended in the overlying water or else extends and moves its siphon around to vacuum up deposited food particles on the sediment surface. Previous laboratory experiments have established an understanding of the role of current flow in dictating the choice of whether suspension or deposit feeding will be used by marine invertebrates with the facultative flexibility to choose. Faster flows imply greater fluxes of suspended particles so that the energetic rewards of suspension feeding are enhanced. Slower flows imply reduced renewal rates of suspended foods in the bottom boundary layers and enhanced deposition of food particles on the seafloor so that a switch to deposit feeding is favored. Like early optimal foraging theory, this understanding is based on energetic considerations alone without incorporation of broader implications of how population interactions such as predation and competition influence individual foraging behavior. Feeding behavior of Macoma balthica is influenced in the Neuse River estuary by both hydrodynamics and siphon-cropping by juvenile demersal fishes. Under conditions of identical concentrations of suspended particulates in the water column and organic contents of surface sediments, Macoma exhibited much higher levels of deposit feeding where currents were slower. In addition, exclosure and fish inclosure experiments demonstrated that juvenile demersal fishes influence feeding behavior of Macoma by cropping exposed siphons and inducing reduction in deposit-feeding activity. Effects of croppers were substantial in early to midsummer, when juvenile fish abundances were greatest in trawl samples from this estuarine nursery and before the growing fish exhibited ontogenetic changes in diet away from early concentration on bivalve siphons. Field experiments in which siphon-cropping fish were caged at varying distances off the bottom failed to detect any effective behavioral avoidance by Macoma of cropping in response to proximity of fish. One might have hypothesized that under high risk of cropping, Macoma would switch to suspension feeding and away from deposit feeding, the feeding method entailing more risk of losses to croppers because of greater siphon activity and greater extension of siphons on the sediment surface. Consequently, partial predation by siphon-cropping fishes greatly reduces deposit-feeding activity by Macoma balthica during summer as an apparent direct effect of disfigurement and reduction of siphons, the organ required for efficient deposit feeding. Information on current flows alone would not suffice to predict feeding behavior of this marine invertebrate: the influence of partial predation must also be included.     

Comparative analysis of methods for measurements of food intake and utilization using the soybean looper, Pseudoplusia includens and artificial media

An analysis of intake and utilization of an artificial medium by larvae of the soybean looper, Pseudoplusia includens Walker, Lepidoptera: Noctuidae, was performed using 4 methods: standard gravimetric, chromic oxide, Calco Oil Red, and ¹⁴C-glucose. Each method was used in conjunction with standard gravimetry. The relative merits of the indirect methods were analyzed in terms of precision and accuracy for ECI and ECD estimation, cost, and overall versatility. Only the gravimetric method combined ca. 80% precision in ECI and ECD estimation with low cost and maximum versatility. Calco Oil Red at 0.1% w/v was detrimental to the larvae. Cr₂O₃ caused reduced intake but conversion was increased resulting in normal development and growth of larvae. The radioisotopic method had the advantage of providing a direct means of measuring expired CO₂. The need to operate under a totally enclosed system, however, poses some serious difficulties in the use of radioisotopes. There seems to be little advantage in any of the proposed indirect methods, except if there are unusual difficulties in separating the excreta from the medium.Supported in part by the Brazilian Programa de Ensino Agricola Superior (PEAS/Michigan State University Contract); by NSF and EPA through grant (NSF GB-37418) to the University of California; and USDA-SEA grant 616-15-68. The findings and opinions expressed herein are those of the authors and not necessarily those of the sponsoring agencies or institutions.     

Reproductive Ecology and Host Utilization of Four Sympatric Bitterling (Acheilognathinae,Cyprinidae) in a Lowland Reach of the Harai River in Mie,Japan

Bitterling are fishes that use freshwater mussels for oviposition. The reproductive ecology and pattern of mussel utilization of four sympatric species of bitterling, Acheilognathus rhombeus, A. tabira tabira, Tanakia lanceolata, and T. limbata, were investigated in a lowland river with seven sympatric mussel species. Three bitterling species are spring spawners with overlapping spawning seasons. A. rhombeus is an autumn-spawning species and is temporally isolated in its reproduction from the other species. Ovipositor length during oviposition of T. limbata and T. lanceolata was short, while those of A. tabira tabira and A. rhombeus were long. Most T. limbata inhabited near-shore areas, whereas the two other spring-spawning species were distributed across the entire river. All bitterling species used Inversidens brandti, Obovalis omiensis and Inversiunio jokohamensis as spawning hosts, but not the other mussel species available. T. lanceolata, A. tabira tabira and A. rhombeus showed spawning preferences for O. omiensis and I. brandti. However, T. limbata did not show clear preferences for any of the mussel species they used. A. t. tabira showed a significant preference for large I. brandti in offshore areas, while the other spring-spawning bitterling showed a preference for mussels inshore. These results are discussed in the context of reproductive resource partitioning.     

Viability and Management of an Endangered Capercaillie (Tetrao urogallus) Metapopulation in the Jura Mountains, Western Switzerland

The populations of Capercaillie (Tetrao urogallus), the largest European grouse, have seriously declined during the last century over most of their distribution in western and central Europe. In the Jura mountains, the relict population is now isolated and critically endangered (about 500 breeding adults). We developed a simulation software (TetrasPool) that accounts for age and spatial structure as well as stochastic processes, to perform a viability analysis and explore management scenarios for this population, capitalizing on a 24 years-long series of field data. Simulations predict a marked decline and a significant extinction risk over the next century, largely due to environmental and demographic stochasticity (average values of life-history parameters would otherwise allow stability). Variances among scenarios mainly stem from uncertainties about the shape and intensity of density dependence. Uncertainty analyses suggest to focus conservation efforts on enhancing, not only adult survival (as often advocated for long-lived species), but also recruitment. The juvenile stage matters when local populations undergo extinctions, because it ensures connectivity and recolonization. Besides limiting human perturbations, a silvicultural strategy aimed at opening forest structure should improve the quality and surface of available patches, independent of their size and localization. Such measures are to be taken urgently, if the population is to be saved.     

沙地樟子松天然林南缘分布区林木竞争、空间格局及其更新特征

以呼伦贝尔沙地樟子松地理分布南缘天然林为研究对象,采用Hegyi竞争指数与点格局等分析方法,研究了沙地樟子松天然林的种群结构、种内竞争、空间格局及幼树更新等特征。结果表明:1)所调查区域天然沙地樟子松纯林处于中幼龄阶段,属增长型种群;2)其竞争指数与对象木胸径服从幂函数关系CI=242.24D~(-1.12)(R~2=0.91);3)幼树在小尺度上呈聚集分布,中树与大树在中大尺度上呈随机分布;幼树与中树在小尺度上呈正相关性,中树与大树在小尺度呈负相关性;4)竞争指数与更新幼树和存活更新幼树的密度均呈显著正相关性。在林分管理中需要充分考虑林木竞争、空间格局以及种群更新的关系,本研究可为沙地樟子松天然林的经营管理与保护提供重要的科学依据。     

人工固沙区与流沙区准噶尔无叶豆种群数量特征与空间格局对比研究

准噶尔无叶豆(Eremosparton songoricum) 是中亚荒漠特有小半灌木,稀有种,在我国仅片段化分布于新疆古尔班通古特沙漠;它是流动沙丘的先锋物种,也能成功定居于人工固沙区(草方格)。对比研究了人工固沙区及自然流沙区的准噶尔无叶豆群落物种组成、种群密度、高度、盖度、生物量等特征及种群空间分布格局。结果表明:人工固沙区内的准噶尔无叶豆群落物种的科、属、种数均明显多于流沙区,而且2种生境物种相似性指数仅为0.522,表明人工固沙生境显著改变了群落物种组成与结构。除植株密度外,人工固沙区种群的高度,盖度,地上、地下及总生物量密度,单株地上、地下及总生物量等数量特征均显著高于流沙区。2种生境中准噶尔无叶豆种群空间分布的关联维数均接近2.0,体现了较强的个体空间相关性和空间占据能力。2种尺度(1 m和2 m)下的聚集度分析表明,2种生境中种群基本为随机分布。因而,人工固沙生境并未明显改变种群空间分布格局,这可能是种群的固有特性。人工固沙区的土壤有机质、全氮和有效氮含量显著高于流沙区,且与种群数量特征(植株密度除外)呈显著正相关。总之,与流沙区相比,人工固沙使地表得到固定,提高了土壤有机质和氮素含量,明显改变了定居于其中的准噶尔无叶豆种群主要数量特征,增强了种群的生存和适应能力。该结论对荒漠濒危植物的保育具有重要指示意义。     

Effects of chromium supplementation on food energy utilization and the trace-element composition in the liver and heart of glucose-exposed young mice

Essentiality of selenium (Se) for Japanese quail,Coturnix coturnix japonica, was confirmed using a formulated semipurified low-Se diet (basal) (0.05 ppm). Selenium-deficiency symptoms appeared in quails on this diet within 15 d, which corresponded to low levels of hemolysate glutathione peroxidase (GSH-Px) activity. Selenium administration at 0.05 and 2.0 ppm levels resulted in an increase of hemolysate GSH-Px activity by 64 and 116%, respectively, in both short- and long-term experiments. Growth over a 2-mo period increased the hemolysate GSH-Px activity by 120% at each level of dietary Se. A differential response was exhibited by hepatic mitochondrial and soluble GSH-Px activity to Se supplementation, the former increasing progressively with increments of Se at 0.05, 2.0, and 4.0 ppm by 45, 70 and 150%, respectively. The soluble GSH-Px activities of tissues, such as liver, kidney, and testis, and RBC membrane-bound activity remained unchanged in long-term studies at different levels of Se. Replenishment of Se to quails maintained on low-Se diets reflected no change in RBC membrane-bound and liver-soluble GSH-Px activities, although the activity in hemolysate increased consistently with Se. The GSH-Px activity in hemolysate was restored to the levels comparable to those of long-term studies only at Se administration at the 2.0-ppm level. The differential response of mitochondrial and soluble GSH-Px activities to Se and other related observations on mitochondrial functions suggest an additional role for Se in mitochondrial membrane processes and glutathione-related metabolic regulations.     

Biology,distribution and ecology of <Emphasis Type="Italic">Didymosphenia geminata</Emphasis> (Lyngbye) Schmidt an abundant diatom from the Indian Himalayan rivers

Three years of studies on some Indian Himalayan rivers in Jammu & Kashmir, Himachal Pradesh, and Sikkim revealed the presence of Didymosphenia geminata (Lyngbye) M. Schmidt, a large diatom, hitherto unreported from these areas. This is first report on the occurrence of this diatom in some Indian Himalayan rivers: Kishanganga in Jammu & Kashmir, Ravi in Himachal Pradesh in Western Himalaya and in Teesta river and its two tributaries, Lachen Chhu and Lachung Chhu from Sikkim in the Eastern Himalaya. D. geminata is the most abundant taxon in both suspended and benthic algal communities in these rivers. The species exhibits wide ecological amplitude, allowing it to inhabit both cold and warm waters. We also recorded the exotic brown trout, Salmo trutta fario in these Himalayan rivers. However, in Central Himalayan rivers, Alaknanda, Bhilangana, Mandakini and Dhauliganga in Uttarakhand, where this diatom was absent the trout were absent too. Our studies indicate that D. geminata may extend its distribution range to other Himalayan rivers, hitherto uninhabited by the diatom, depending on the mode of introduction of exotic trout in these rivers.     

Changes in biomass and spatial distribution of <Emphasis Type="Italic">Elodea nuttallii</Emphasis> (Planch.) St. John,an invasive submerged plant,in oligomesotrophic Lake Kizaki from 1999 to 2002

Distribution of pure Elodea nuttallii vegetation was surveyed from 1999 to 2002, immediately after the most recent expansion of the species in Lake Kizaki, Japan. During 2001 and 2002, areas of E. nuttallii vegetation rapidly diminished and the summer plant height decreased wherever the vegetation remained. The organic matter content, total phosphorus, and extracted P of the sediment from the vegetation bed were measured. A linear relationship was observed between the extracted P in the sediment and the biomass. The extracted P significantly decreased in the shallow littoral vegetation bed, where the biomass clearly diminished. A fertilization experiment using the shallow littoral sediment collected in the vegetation bed was conducted in 2001. In this experiment, apical shoots of E. nuttallii were planted in pots with fertilized sediment (nitrogen, phosphorus, and potassium additions). The growth of E. nuttallii shoots was significantly enhanced by enrichment with phosphorus alone. The ecological implication of sediment phosphorus limitation is discussed in relation to the cause of decline in the E. nuttallii population in Lake Kizaki.     

澜沧江流域北部中华蜜蜂食源和营养生态位随海拔梯度的变化特征

为了解澜沧江流域北部中华蜜蜂(Apis cerana cerana)的分布,探究中华蜜蜂的食源和营养生态位沿海拔梯度的变化特征,调查了澜沧江流域北部各海拔区域中华蜜蜂的种群分布,运用蜂蜜孢粉学(melissopalynology)分析了各海拔区域中华蜜蜂蜂蜜中花粉的组成特征和变化规律,并综合分析了海拔、中华蜜蜂营养生态位和蜂蜜中花粉的相关性,探讨了自然环境与中华蜜蜂的分布,海拔梯度与蜜粉源植物、中华蜜蜂的食源和营养生态位的关系。结果表明:澜沧江流域北部中华蜜蜂的食源种类丰富,中华蜜蜂种群主要分布于2200—2800 m海拔区域。不同海拔区域中华蜜蜂采食花粉的种类和数量不同,中华蜜蜂种群分布多的海拔区域,蜂蜜中花粉的种类较多,但花粉数量相对少。随着海拔梯度升高,中华蜜蜂蜂蜜中花粉的数量表现为先降后增,而花粉的种类则表现为先增后降。不同海拔区域的中华蜜蜂营养生态位存在差异,推测各海拔区域蜜粉源植物分布、中华蜜蜂种内和种间授粉昆虫及食草动物等竞争因素不同,但各海拔梯度间的变化差异不显著。海拔与中华蜜蜂营养生态位呈正相关(r=0.051),相关性不显著;海拔与蜂蜜中花粉数量呈正相关(r=0.047),与蜂蜜中花粉种类呈正相关(r=0.144),相关性都不显著;中华蜜蜂营养生态位与蜂蜜中花粉的种类呈负相关(r=-0.305),相关性显著(P!0.05);与花粉的数量呈负相关(r=-0.064),相关性不显著。蜂蜜中花粉的数量与种类呈正相关(r=-0.303),且相关性显著(P!0.05)。     

Incongruent phylogeographies in spite of similar morphology, ecology, and distribution:Phippsia algida andP. concinna (Poaceae) in the North Atlantic region

Phylogeographic and taxonomic relationships among 54 North Atlantic populations of the snowbed grass genusPhippsia were investigated based on isozymes and genetically based morphological variation. The results support recognition of two distinct species,P. algida andP. concinna, the latter with at least two subspecies. Both of these self-fertilizing arctic pioneer species were genetic allotetraploids almost without intrapopulational variation. The two species showed strikingly different phylogeographies in the North Atlantic region in spite of their similarity in morphology, habitat ecology, mating system, and dispersal ecology, and in spite of their present cooccurrence in many geographic areas, sometimes even in the same snowbeds. The same electrophoretic multilocus phenotype was observed in all populations ofP. algida, and although this species showed considerable morphological variation, the variation was unstructured geographically. Thus,P. algida showed a pattern similar to other arctic species investigated in the North Atlantic region; it has probably dispersed postglacially across the sea barriers among Greenland, Svalbard, Iceland, and Scandinavia. In contrast,P. concinna was virtually fixed for different multilocus phenotypes in the three main geographic areas analyzed (S Norway, Svalbard, Greenland), corresponding to fairly distinct divergence in morphology. This pattern suggests absence of postglacial among-area dispersal ofP. concinna in spite of all of its similarities with its congener; it may have immigrated to the North Atlantic from different source areas and/or survived the last glaciationin situ.