Habitat utilization patterns of sympatric populations of Pseudomys gracilicaudatus and Rattus lutreolus in coastal heathland: A multivariate analysis

Abstract Habitat usage characteristics of two species of native murid rodents, Pseudomys gracilicaudatus and Rattus lutreolus were investigated on an area of coastal heathland at Myall Lakes National Park. A grid of 151 trap stations comprising 17 traplines was positioned across a mosaic of habitats. At each trap station 19 structural vegetation and physical variables known to affect the microdistribution of small mammals were measured. Multivariate statistical procedures identified those microhabitat variables that contribute to individual species' habitat use and habitat partitioning, and reduce potential competition for space. Cluster analysis classified trap stations into one of six habitat types that were mapped on the study area, identifying a heterogeneous assemblage of interlocking habitats. The pattern is a consequence of topographic variation on the site and, to a lesser extent, its fire history. Trapping results show P. gracilicaudatus and R. lutreolus exhibit similar macrohabitat selection, preferring topographically low habitats, with both species predominantly occupying short dense heath with dense sedge cover. The high overlap in macrohabitat use is greatly reduced when considered trap station by trap station, so that discriminant function and multiple regression analyses demonstrate marked microhabitat selection. Elevation was a highly significant variable, accounting for 41% and 27% of the variance in the habitat used by P. gracilicaudatus and R. lutreolus, respectively. This variable represents a soil moisture gradient that determines changes in the floristic and structural components of the biotic environment. Two other structural vegetation variables and vegetation height contributed 30% of the variance in P. gracilicaudatus distribution. Sedge cover was found to be significant and explained 13% of the variance in R. lutreolus distribution. Within-habitat separation was explained best with a linear combination of variables in a discriminant function, rather than by any single variable. Differential microhabitat selection, interference competition and diet separation appear to be the major factors facilitating coexistence of these two species.     

不同生境区稻田节肢动物群落相似性分析

根据不同生境区稻田节肢动物群落系统调查结果,应用组平均聚类分析法及主成分分析法,讨论节肢动物群落的相似（相异）性问题。结果表明：生境条件及管理措施的差异对群落的结构影响较为明显,不同生境区的稻田节肢动物群落,都能在一定距离取值时聚合成一类,而水稻品种对此影响较小。主成分分析结果由二维图表达已基本满足要求。结果说明大八镇生境区稻田节肢动物群落与岗列镇生境区稻田节肢动物群落差异较大,分别列于两个极端。海陵镇生境区稻田介于两者之间,而与岗列镇生境区稻田节肢动物群落重叠。与聚类分析结果有所差异。这可能与主成分分析法损失部分信息有关。     

Relationships between food resources, foraging patterns, and reproductive success in the water pipit, Anthus sp. spinoletta

A basic but rarely tested assumption in optimal foraging theoryis that positive relationships exist between the foraging patternof an animal, its short-term benefits in feeding, and its long-termfitness. We present evidence for these relationships for a centralplace foraging situation. We studied the foraging behavior ofadult water pipits (Anthus sp. spinoletta) feeding nestlingsin an Alpine habitat near Davos, Switzerland, with the followingresults: (1) searching effort decreases with increasing distancefrom the nest, (2) the amount of prey and the proportion oflarge items brought to the nest increases with increasing foragingdistance, (3) water pipits do not forage according to habitatavailability, but prefer vegetation types with the highest fooddensity (mainly grass and herbs) and avoid those with the lowest,and (4) this selectivity is only expressed when the birds foragemore than 50 m from the nest, i.e., usually outside the territory.Among the several potential interpretations of these results,the most parsimonious is that foraging decisions are based onprofitability, i.e., on the net energy gain per time unit. Additionally,we found that food conditions translate into fitness: the numberof fledglings per nest is related positively to the averageprey biomass at the foraging place and negatively to the averagedistance between the foraging place and the nest. Maximum economicdistances, which were predicted from this food-fitness relationship,agreed well with the actual foraging distances observed. Thissuggests a dose connection between foraging decisions and fitness.In addition to the theoretical issues, some conservation issuesare also briefly discussed.     

新疆地区小麦白粉病菌寄主范围的研究

用小麦白粉病菌11个生理小种的混合菌种,对新疆地区的小麦近缘植物的7个属22个种的47份材料进行接种,除6份免疫外,其余均接种成功.用其中6个属19个种的29份小麦近缘植物产生的白粉病菌,对小麦回接,参试的29份材料全部回接成功.小麦白粉病菌对小麦近缘植物的寄生像在小麦上一样,有明显的寄生专化性.感病的小麦近缘植物的78.0%对小麦白粉病菌的感病性,随生育期增长而急剧下降.文中并对小麦白粉病中间寄主的作用进行了讨论.     

Three conditions for the evolution of eusociality: Are they sufficient?

Summary I hypothesize that three conditions, (1) food-shelter coincidence, (2) strong selection for defense, and (3) ability to defend, are sufficient, although not necessary, for the evolution of eusociality in group-living animals. Reasons for this association between ecology and eusociality include extremely high value of the habitat, possibilities for habitat inheritance, high relatedness in claustral situations, self-sufficiency of juveniles, greater ability of workers to reproduce, and trade-offs between defensive ability and dispersal.     

A comparative study of the distribution and density of stomata in the British flora

The distribution of stomata over both leaf surfaces may affect both the photosynthetic rate and water use efficiency of species, implying that species with different photosynthetic and water requirements may also have different stomatal distributions. A database containing data on the distribution of stomata on the leaves of 469 British plant species was used to look for relationships between stomatal distribution (including both location on the leaf and density) and both habitat and morphological variables. Statistical models were applied to the data that minimized any effects that phylogenetic constraints may have had on the data.
Hypostomaty is common in woody species, species which typically occur in shaded habitats and species with large or glabrous leaves. Amphistomaty, however, predominates in species which occur in non-shaded habitats, species with small, dissected or hairy leaves, and in annual species. Amphistomaty, therefore, tends to occur in species where CO₂ may be limiting photosynthesis (unshaded environments), or where there are structures to prevent water loss from the leaf (e.g. hairs). Hypostomaty, however, occurs in slow-growing species (e.g. trees), species with leaves which have large boundary layers (large or entire leaves) and in species where CO₂ is unlikely to limit photosynthesis (shaded habitats).     

Host-associated fitness variation in a seed beetle (Coleoptera: Bruchidae): evidence for local adaptation to a poor quality host

The geographic distributions of many generalist herbivores differ from those of their host plants, such that they experience coarse-grained spatial variation in natural selection on characters influencing adaptation to host plants. Thus, populations differing in host use are expected to differ in their ability to survive and grow on these host plants. We examine host-associated variation in larval performance (survivorship, development time, and adult body weight) and oviposition preference, within and between two populations ofStator limbatus (Coleoptera: Bruchidae) that differ in the hosts available to them in nature. In one population,Acacia greggii (Fabaceae: Mimosoideae) andCercidium microphyllum (Fabaceae: Caesalpininoideae) are each abundant, while in the second population onlyC. floridum andC. microphyllum are present. In both populations, egg-to-adult survivorship was less than 50% onC. floridum, while survivorship was greater than 90% onA. greggii. Most of the mortality onC. floridum occurred as larvae were burrowing through the seed coat; very low mortality occurred during penetration of the seed coat ofA. greggii. Significant variation was present between populations, and among families (within populations), in survivorship and egg-to-adult development time onC. floridum; beetles restricted toCercidium in nature, without access toC. floridum, survived better and developed faster onC. floridum than beetles that had access toA. greggii. Large host effects on body size were detected for female offspring: females reared onA. greggii were larger than those reared onC. floridum, whereas male offspring wee approximately the same size regardless of rearing host. Trade-offs between performance onC. floridum andC. floridum were not detected in this experiment. Instead, our data indicate that development time and survivorship onC. floridum may be largely independent of development time and survivorship onA. greggii. Patterns of oviposition preference corresponded to the observed patterns of host suitability: in laboratory preference tests, beetles with access toA. greggii in nature tended to prefer this host more than beetles without access to this host in nature.     

芦毒蛾越冬场所及越冬习性的研究

芦毒蛾是洞庭湖区重要的芦苇害虫,1年发生3代,以1龄幼虫在芦苇或杂草的枯叶中越冬。对于幼虫在其寄主植物之间的转移行为亦进行了观察。     

灵长类家域的研究

灵长类家域的研究李保国刘安宏（西北大学生物学系,西安７１００６９）（西安市林业局,７１０００３）ＨｏｍｅＲａｎｇｅＳｔｕｄｙｏｆＰｒｉｍａｔｅｓ．￥ＬｉＢａｏｇｕｏ（ＤｅｐａｒｔｍｅｎｔｏｆＢｉｏｌｇｙ,ＮｏｒｔｈｗｅｓｔＵｎｉｖｅｒｓｉｔｙ,Ｘｉａ...     

The natural history of de Brazza's monkey in Kenya

Polygynous groups of de Brazzas monkeys (Cercopithecus neglectus) were observed in the Kisere Forest Reserve between December 1987 and March 1989. Total number of contact hours was 528. Three troops numbered 11, 13, and 16 monkeys. Three solitary adult males were seen. All troops had a single adult male, at least three adult females, and juveniles. Five births occurred in the course of the study. Home range varied from 4.1 to 6 ha, and flooded areas of the forest were heavily used. This species was only found near rivers and spent more than 50% of the time below 5 m. Daily path length ranged from 330 to 1001 m. The de Brazza's monkeys were mainly frugivorous, but leave and invertebrates also formed a substantial part of the diet. Other guenons avoided de Brazza's, which did not join polyspecific interactions.