荒漠草原三种蝗虫成虫种内和种间竞争的研究

荒漠草原三种蝗虫成虫种内和种间竞争的研究贺达汉方成郑哲民（宁夏农学院农学系,永宁７５０１０５）（陕西师范大学动物研究所,西安７１００６２）Ｉｎｔｒａ＿ａｎｄＩｎｔｅｒｓｐｅｃｉｆｉｃＣｏｍｐｅｔｉｔｉｏｎａｍｏｎｇｔｈｅＡｄｕｌｔｓｏｆＴｈｒｅｅＧｒ...     

Spatial arrangement and diet overlap between colonies of desert ants

Summary The spatial patterns and diets of three desert ant species were examined. The results indicate that food competition may account for the spatial arrangement of these species, and that only intraspecific interactions may be required. Each ant species was significantly overdispersed, and the average intraspecific nearest neighbor distances were greater than the interspecific nearest neighbor distances. A test of pairwise spatial arrangment showed that all three species pairs were aggregated interspecifically. The level of the interspecific aggregation was related to the diet similarity of the species. The two species pairs with the lowest diet overlaps were significantly aggregated, and the species pair with the most similar diets was not significantly aggregated. Pairwise dietary overlaps between colonies showed that average intraspecific overlaps were significantly greater than interspecific diet overlaps. Furthermore, the diet overlap was significantly positively correlated to the mean nearest neighbor distance for the three intraspecific and three interspecific comparisons. These data indicate competition for food, especially within species, may be regulating the intercolony distances of these ant species. A computer simulation tested whether only intraspecific territoriality is necessary to produce the observed nearest neighbor distances. A simulation that placed colonies randomly on a patch confirmed that these colonies are intraspecifically overdispersed. By adding intraspecific territoriality, the simulation nearest neighbor distances fit the empirical data reasonably well. Thus interspecific competitive interactions seem unnecessary to account for the spatial arrangement of these species.     

模糊聚类法在小翅雏蝗种群动态分析中的应用

1　引　　言小翅雏蝗 (Ｃｈｏｒｔｈｉｐｐｕｓｆａｌｌａｘ)是我国北方草地蝗虫的优势种之一 ,主要分布在我国的内蒙古、新疆、宁夏、甘肃、青海、河北、山西、陕西等省区及国外的西伯利亚、哈萨克斯坦、蒙古等地[7,8,10 ,12 ,13 ,16] .刘长仲等[11] 对小翅雏蝗的生物学特性进行了研究 ,李鸿昌等[9] 研究了小翅雏蝗的取食行为 ,冯光翰等[1,2 ] 提出了小翅雏蝗的防治指标 ,康乐[3～ 6] 、邱星辉[5] 、颜忠诚等[17] 研究了内蒙古典型草原小翅雏蝗的时空异质性、营养生态位以及形态特征与扩散能力之间的关系 .本文依据甘肃省夏河县甘加高山草…     

内蒙古典型草原蝗虫食性的研究1.罩笼供食下的取食特性

欧亚大陆东部的我国内蒙古地区空间,系由生命系统及其无机环境组成的复合草原生态系统,并在其内部进行着能量与物质的新陈代谢,它包括全部生命和无生命物质的繁衍演替及传递,以及人为活动所施加的可能影响。蝗虫Acridoids——动物亚系统结构中的功能单位之一,做为生态系统中的次级生产者(消费者),通过对不同植物群落中一些植物类群的     

Accounting for interspecific competition and age structure in demographic analyses of density dependence improves predictions of fluctuations in population size

Understanding species coexistence has long been a major goal of ecology. Coexistence theory for two competing species posits that intraspecific density dependence should be stronger than interspecific density dependence. Great tits and blue tits are two bird species that compete for food resources and nesting cavities. On the basis of long‐term monitoring of these two competing species at sites across Europe, combining observational and manipulative approaches, we show that the strength of density regulation is similar for both species, and that individuals have contrasting abilities to compete depending on their age. For great tits, density regulation is driven mainly by intraspecific competition. In contrast, for blue tits, interspecific competition contributes as much as intraspecific competition, consistent with asymmetric competition between the two species. In addition, including age‐specific effects of intra‐ and interspecific competition in density‐dependence models improves predictions of fluctuations in population size by up to three times.     

围栏禁牧对羊草草原和大针茅草原蝗虫丰富度的影响

报道了围栏封育后羊草草原和大针茅草原蝗虫丰富度的变化,比较了蝗虫在羊 草草原和大针茅草原的发生特点．结果表明,以毛足棒角蝗为主导种的大针茅草原蝗虫生 物量是以小翅雏蝗为主导种的羊草草原蝗虫生物量的４～５倍;围栏封育后,羊草草原蝗 虫的生物量增加 ２４％,而大针茅蝗虫的生物量略有减少;围栏措施改变蝗虫的结构组成, 使毛足棒角蝗、鼓翅皱膝蝗、宽须蚁蝗、亚洲小车蝗等旱生和中旱生的地栖或兼栖偏地栖 种类的发生减少,条纹鸣蝗、小翅雏蝗、红腹牧草蝗等中生的植栖或兼栖偏植栖种类增加, 短星翅蝗及狭翅雏蝗的生物量在大针茅草原增加而在羊草草原减少．     

Differential responses to warming and increased precipitation among three contrasting grasshopper species

We conducted a field manipulation experiment to investigate developmental and demographic responses to warming and increased precipitation in three Inner Mongolian grasshopper species that differ in phenology (an early-season species Dasyhippus barbipes , a mid-season species Oedaleus asiaticus , and a late-season species Chorthippus fallax ). Infrared heaters were used for warming the ground surface by 1–2 °C above the ambient condition and periodic irrigations were applied to simulate a 50% increase in annual precipitation. We found that warming advanced the timing for egg hatching and grasshopper eclosion in each of the three species. However, grasshopper diapause and increased precipitation appeared to offset the effect of warming on egg development. Hatching and development were more strongly affected by warming in the mid-season O. asiaticus and the late-season C. fallax relative to the early-season D. barbipes . Warming by ∼1.5 °C advanced the occurrence of the mid-season O. asiaticus by an average of 4.96 days; while warming and increased precipitation interactively affected the occurrence of the late-season C. fallax , which advanced by 5.53 days. Our data and those of others suggest that most grasshopper species in the Inner Mongolian grassland are likely to extend their distribution northward with climate change. However, because of the differential response to warming we demonstrate for these species, the different grasshopper species are predicted to aggregate toward the middle period of the growing season, potentially increasing interspecific competition and grazing pressure on grasslands.     

Food partitioning among scorpaenid fishes in Mediterranean seagrass beds

Diets of three scorpaenid fishes, Scorpaena notata, S. porcus and S. scrofa , from a Posidonia seagrass bed off Marseilles were quantitatively analysed and categorized according to the size and sex of individuals, to elucidate diel and seasonal rhythms. All three preyed on the same crustacean and fish species, but in different proportions: S. notata mostly fed on Caridae, S. porcus on brachyurans and S. scrofa on fishes. Individual size and diel period were the main factors responsible for diet variation and food partitioning that evolved according to both cyclic (temporal) and continuous (ontogenic) trends. A strong interspecific food overlap was observed in juveniles (S.L. < 50 mm), whereas intraspecific potential competition was low between juveniles and adults. Among medium and large size classes, intra- and interspecific food overlaps were high and of equal intensity. Narrower food niches at night, due to a stronger specialization on type and size of prey, diminished the intra- and interspecific potential competition during this period of maximum feeding activity. This probably allowed the high number of coexisting scorpaenid populations in Mediterranean seagrass beds. Nevertheless, microhabitat and time partitioning seemed as important as food partitioning in the structuring of fish assemblages.     

Is different degree of individual specialization in three spider species caused by distinct selection pressures?

Individual specialization (IS), i.e. the relatively narrower niche of individuals compared to their population, can be caused by the interplay between intrinsic and extrinsic factors. We studied IS on prey type and size in three congeneric euryphagous sympatrically occurring species: Philodromus albidus, Philodromus aureolus, and Philodromus cespitum. We performed prey acceptance experiments in standardized laboratory conditions using adult females. We also studied possible factors affecting IS. As intrinsic factors, we measured aggressiveness toward prey and spider size as the measures of behavioral and morphological differences, respectively. As extrinsic factors, we studied the composition of the guild of actively hunting spiders in the area from where the philodromids were collected. We computed the degree of inter- and intraspecific crowding as a measure of inter- and intraspecific competition, respectively. Then we computed competition coefficients from census data in order to estimate the strength of interspecific competition among three species. There was no IS on prey type in any studied species. In terms of prey size, only P. albidus was found to be individually specialized, while there was no IS in the other two species. There was a significant effect of aggressiveness, but no significant effect of body size on IS in P. albidus. This species was the least aggressive of the studied species. The philodromids were the dominant actively hunting spiders in the study area. P. albidus was exposed to a relatively higher degree of interspecific than intraspecific competition, whereas in the other philodromids the situation was reversed. The presence of interspecific competition between P. albidus and the other two species was confirmed by the census data analysis. We documented context-dependent IS in Philodromus species. We argue that the higher degree of IS in P. albidus was influenced by interference competition mainly from the other two philodromid species. The niches of the other two species were influenced by food limitation, which decreased their IS.     

舟山群岛红楠林种内和种间竞争研究

红楠（Machilus thunbergii）林是浙江沿海地区典型森林类型之一,研究竞争强度的动态变化规律及红楠种群的生态适应机制,对舟山群岛常绿阔叶林的保护与可持续利用具有重要意义。利用Hegyi单木竞争指数模型,对舟山桃花岛次生林优势种红楠的种内和种间竞争强度进行定量分析。结果表明：红楠3种类型的竞争强度均随对象木胸径的增大而逐渐减小,小径级的红楠承受的竞争压力较大;红楠的种内和种间竞争强度分别占总竞争强度的44.55%和55.45%,两者大致相等,说明其受到的种内和种间竞争压力均衡;落叶树种的平均竞争指数大,常绿树种的平均竞争指数小,使红楠受压的主要树种是朴树和枫香树;红楠种内和种间竞争强度的顺序为：红楠种内 > 朴树 > 枫香树 > 椿叶花椒 > 柘 > 梾木 > 化香树 > 赛山梅 > 黄檀 > 日本珊瑚树 > 天仙果等;3种类型的竞争强度与对象木胸径均呈显著负相关,且服从幂函数关系CI=AD^-B,当红楠胸径达到20 cm以上时,竞争强度变化很小,利用所得的预测模型能很好地预测红楠种内和种间竞争强度。当红楠胸径小于20 cm时,应对其进行抚育管理以提高红楠成活率和促进植被恢复。     

Inter-and intraspecific effects of density manipulations upon females of two orb-weaving spiders (araneae: araneidae)

Summary A field experiment was conducted to establish whether or not inter-and intraspecific competition occurs between two syntopic species of orb-weaving spiders. Replicated single-species and mixed-species adult populations of the basilica spider, Mecynogea lemniscata, and the labyrinth spider, Metepeira labyrinthea, were established at a range of densities on open experimental units in the species' natural habitat. Each experimental unit was a 4mx1.6mx1m wood frame supporting branches upon which introduced spiders built webs. Survival and reproduction on the units were monitored from 1 August through 1 November 1978,There were no significant negative interspecific effects of density upon either survival or reproduction, which indicates that interspecific competition was not occurring during the experiment. There was statistically significant evidence of intraspecific competition between females for both species, but the negative density effects were small. They explained 5% of the variance in Mecynogea web height, 2% of the variance in Metepeira survival, and 1% of the variation in number of eggs per sac for Mecynogea.Hence inter-and intraspecific competition was either absent or weak in 1978, despite the fact that a field experiment conducted the previous year (Wise 1979) demonstrated that prey abundance was limiting the egg production of both species. Evidence of food limitation in 1977 followed by only weak competitive interactions the following year suggests that the significance of resource limitation and competition may vary temporally for the basilica and labyrinth spiders.     

青海四种雏蝗染色体核型的比较分析

采用常规染色体制片方法对雏蝗属的褐色雏蝗Chorthippusbrunneus(Thunb .) ,异色雏蝗C .big uttulus(Linnaeus) ,小翅雏蝗C .fallax(Zub .) ,青藏雏蝗C .qingzangensis(Ying)的染色体核型进行分析 ,结果 :染色体数目均为 2n(♂ ) =1 7=1 6+XO ;常染色体类型为两类 ,中着丝点染色体 (m ,6条 )和端着丝点染色体 (T ,1 0条 ) ;性染色体类型为端着丝点。褐色雏蝗、异色雏蝗和青藏雏蝗的核型公式和染色体的相对长度组成为K( 2n ,♂ ) =1 7=6m +1 1T =6L +6M +4S +XO ,K( 2n ,♀ ) =1 8=6m +1 2T =6L +6M +4S +XX ;小翅雏蝗的为K( 2n,♂ ) =1 7=6m +1 1T =6L +4M +6S +XO ,K( 2n ,♀ ) =1 8=6m +1 2T =6L +4M +6S+XX。褐色雏蝗性染色体中部有次缢痕。染色体臂数 4种均为NF =2 3(♂ ) ,2 4 (♀ )。     

Can environmental fluctuation prevent competitive exclusion in sympatric flycatchers?

Ecology has been characterized by a central controversy for decades: namely, whether the distribution and abundance of organisms are determined by species interactions, such as competitive exclusion, or by environmental conditions. In part, this is because competitive exclusion has not been convincingly demonstrated in open, natural systems. In addition, traditional theoretical models cannot predict the outcome of competitive interactions in the presence of environmental variability. In this paper we document the limiting influence of strong interspecific competition on population dynamics and nestling mortality in a mixed population of pied flycatchers (Ficedula hypoleuca) and collared flycatchers (F. albicollis in a narrow zone of sympatry. Whereas the former species was limited mainly by interspecific competition, the latter species was limited by the concerted influences of intraspecific competition and climate. The analysis suggests a march towards competitive exclusion of the pied flycatcher during warm periods. However, competitive exclusion is apparently prohibited on a local scale because intraspecific competition among individual collared flycatchers intensifies when they are forced to cope with severe environmental conditions, promoting the temporary and local presence of pied flycatchers.     

浙江天台山甜槠种内与种间竞争研究

采用Hegyi的单木竞争指数模型对天台山的甜槠种内、种间的竞争强度进行定量分析。结果表明 ,甜槠种内竞争强度随着林木径级的增大而逐渐减小 ,种内竞争较之与其伴生树种间的竞争剧烈。甜槠种内、种间竞争强度的顺序为 :甜楮 >木荷 >马尾松 >尾叶冬青 >虎皮楠 >短柄木包 >珍珠栗。竞争木对对象木的竞争强度与对象木的个体大小服从幂函数关系 ,竞争强度和对象木个体的大小呈极显著的负相关关系。当甜槠胸径达到 30cm后 ,竞争强度变化不明显 ,说明此时该生态系统已基本达到稳定状态。     

Diet,feeding patterns,and prey selection of subyearling Atlantic salmon (Salmo salar) and subyearling chinook salmon (Oncorhynchus tshawytscha) in a tributary of Lake Ontario

Since juvenile Atlantic salmon (Salmo salar) and Chinook salmon (Oncorhynchus tshawytscha) occupy a similar habitat in Lake Ontario tributaries, we sought to determine the degree of diet similarity between these species in order to assess the potential for interspecific competition. Atlantic salmon, an historically important but currently extirpated component of the Lake Ontario fish community, are the focus of a bi‐national restoration effort. Presently this effort includes the release of hatchery produced juvenile Atlantic salmon in Lake Ontario tributaries. These same tributaries support substantial numbers of naturally reproduced juvenile Pacific salmonids including Chinook salmon. Subyearling Atlantic salmon and subyearling Chinook salmon had significantly different diets during each of the three time periods examined. Atlantic salmon fed slightly more from the benthos than from the drift and consumed mainly chirononmids (47.0%) and ephemeropterans (21.1%). The diet of subyearling Chinook salmon was more closely associated with the drift and consisted mainly of chironomids (60.2%) and terrestrial invertebrates (16.0%). Low diet similarity between subyearling Atlantic salmon and subyearling Chinook salmon likely minimizes competitive interactions for food between these species in Lake Ontario tributaries. However, the availability of small prey such as chironomids which comprise over 50% of the diet of each species, soon after emergence, could constitute a short term resource limitation. To our knowledge this is the first study of interspecific diet associations between these two important salmonid species.     

Small-scale demographic variability of the biocolor damselfish, <Emphasis Type="Italic">Stegastes partitus</Emphasis>, in the Florida Keys USA

The demographic responses of reef fish to their environment can be complex and in many cases, quite strong. Growth, mortality, longevity, and even reproductive effort have been demonstrated to vary for the same species of reef fish over scales of 100s to 1,000s of kilometers due to physiological and ecological interactions. Though few studies have explicitly documented it, this sort of habitat-mediated demography can also exist at very local scales. Here we present the results of a 2-year study of the bicolor damselfish, Stegastes partitus, in the Florida Keys, USA. We measured density and distribution, calculated key demographic rates (growth, survival, and fecundity), and characterized the environment (resident fish assemblage, substrate type and complexity, and food availability) of populations living in two adjacent but different habitats, the continuous fore reef and patchy back reef. Fish on the fore reef had an elevated growth rate and asymptotic size, increased mortality, and higher fecundity than fish on the back reef. We identified four potential causative mechanisms for these differences: food availability; competition; intraspecific density-dependent effects; and predation risk. Our data did not support an effect of either food availability or intraspecific density-dependence, but rather suggested that demographic responses are affected by both competition and predation risk.     

Food consumption and growth of Atlantic salmon Salmo salar parr in sub-Arctic rivers: empirical support for food limitation and competition

The quantitative food consumption and somatic growth of Atlantic salmon Salmo salar parr were compared between three sub-Arctic rivers in northern Norway and Finland, addressing the potential occurrence of resource limitation and interspecific competition. In one of the rivers, previous resource partitioning studies have suggested severe dietary competition between juvenile S. salar and a dense population of alpine bullheads Cottus poecilopus . It was hypothesized that S. salar parr in this river would have restricted food consumption and growth rates compared to the S. salar populations in the other two rivers where interspecific competition was less likely to occur. The feeding and growth performance differed significantly between the S. salar populations. The lowest food acquisition and growth rates were in the S. salar parr population living in sympatry with C. poecilopus , confirming a restricted food supply for the S. salar parr and providing empirical support for the presence of resource limitation and interspecific food competition in this river system. The study reveals that S. salar parr in sub-Arctic rivers may experience food limitations resulting in diminished growth rates.     

Pollination outcomes reveal negative density‐dependence coupled with interspecific facilitation among plants

Pollination is thought to be under positive density‐dependence, destabilising plant coexistence by conferring fitness disadvantages to rare species. Such disadvantage is exacerbated by interspecific competition but can be mitigated by facilitation and intraspecific competition. However, pollinator scarcity should enhance intraspecific plant competition and impose disadvantage on common over rare species (negative density‐dependence, NDD). We assessed pollination proxies (visitation rate, pollen receipt, pollen tubes) in a generalised plant community and related them to conspecific and heterospecific density, expecting NDD and interspecific facilitation due to the natural pollinator scarcity. Contrary to usual expectations, all proxies indicated strong intraspecific competition for common plants. Moreover interspecific facilitation prevailed and was stronger for rare than for common plants. Both NDD and interspecific facilitation were modulated by specialisation, floral display and pollinator group. The combination of intraspecific competition and interspecific facilitation fosters plant coexistence, suggesting that pollination can be a niche axis maintaining plant diversity.     

Interspecific competition among urban cockroach species

The aim of this study was to quantify and to compare the effects of intraspecific and interspecific competition among pairs of urban cockroaches [Blatta orientalis L., Periplaneta americana (L.), and Periplaneta australasiae Fabricius (Dictyoptera: Blattodea)] in relation to the limitation of resources such as shelter or food. Our approach was to assess whether the presence of one species affected the resource exploitation of another. A reduction in access to shelters or to food for one species revealed dominant/subordination relationships among species and induced spatial segregation in shelters and temporal segregation during food exploitation. The fragmentation of available resources facilitated spatial segregation and the access of more individuals of the subordinate species. Individuals of each species were aware of the presence of non‐conspecifics. The outcome of interspecific competition under laboratory conditions should help us to understand how segregated spatial distributions occur under natural conditions in urban areas.     

Active dispersal is differentially affected by inter‐ and intraspecific competition in closely related nematode species

Competition is one of the main drivers of dispersal, which can be an important mechanism to achieve permanent or temporal coexistence of multiple species. This coexistence can be achieved by a dispersal‐competition tradeoff, spatial store effects or neutral dynamics. Here we test the effect of inter‐ and intraspecific competition on dispersal of four species of the marine nematode species complex Litoditis marina. A previous study in closed microcosms without a possibility for dispersal had demonstrated pronounced interspecific competition, leading to the exclusion of one species. We now investigated whether 1) the dispersal is affected by interspecific interactions, by intraspecific competition (density) or by food availability, 2) the dispersal dynamics influence assemblage composition and can lead to co‐occurrence of the species, and 3) the abiotic environment (here salinity) can affect these dynamics. We show that density is the main driver for dispersal in two of the four species. Dispersal of a third species always started at the same time irrespective of density, whereas in the fourth species interspecific interactions accelerated dispersal. Remarkably, this fourth species was not a strong competitor, suggesting that a dispersal–competition tradeoff does not explain the observed coexistence. Salinity did not alter the timing of dispersal when interspecific interactions were present but did affect assemblage composition. Consequently, spatial store effects may influence coexistence. All four species co‐occurred in fairly stable abundances throughout the present experiment indicating the importance of species specific dispersal strategies for coexistence. Co‐occurrence can be facilitated because competition is postponed or avoided by dispersal. Neutral dynamics also played a role as intra‐ and interspecific competition were of similar importance in three of the four species. We conclude that dispersal is a driver of the coexistence of closely related nematode species, and that population density and interspecific interactions shape these dynamics.