Trophic links,nutrient fluxes,and natural history in the Allium ursinum food web,with particular reference to life history traits of two hoverfly herbivores (Diptera: Syrphidae)

The food web centering on Allium ursinum (Liliaceae) in a beech forest (Germany) is described, and temporal variation of active trophic links is related to species' life cycles. The most important insect herbivores are Cheilosia fasciata (a larval leaf miner) and Portevinia maculata (a larva bulb miner) (Diptera: Syrphidae). Energy, carbon and nitrogen flow in the food chain (Allium-Cheilosia-Phygadeuon ursini) are investigated and analysed with respect to differences in resource allocation by the leaf miner and its hymenoptereous parasitoid. In C. fasciata nitrogen is likely to be the limiting resource, while growth in Phygadeuon ursini appears energy-limited. Larval feeding habits of C. fasciata and Portevinia maculata determined the timing of the species' life cycles and, as a consequence, appeared to preclude the existence of a pupal parasitoid in Portevinia maculata. Further details of life history traits are demonstrated and discussed.     

小麦根系特征对干旱胁迫的响应

干旱胁迫时, 小麦(Triticum aestivum)根系率先产生应激响应, 同时向地上部发出信号, 诱导地上部发生生理反应, 从而提高植株抗旱能力。根系构型包括平面几何性状和立体几何结构(即拓扑构型), 具有遗传稳定性和可塑性。干旱胁迫影响根系理化特性, 如根源化学信号、根系细胞酶类和根系渗透作用的响应。根系通过调整其解剖学结构和水分吸收动力等来适应干旱胁迫。该文从根系构型、理化特性和解剖学结构3个方面, 系统阐述了小麦根系特征对干旱胁迫的响应, 并探讨了其与干旱胁迫的关系和当前研究中存在的问题, 以期为相关研究提供参考。     

子莲新品种‘武植子莲1号’和‘武植子莲2号’产量与营养品质分析

对子莲（Nelumbo nucifera Gaertn.）新品种‘武植子莲1号’和‘武植子莲2号’与其他12个主栽子莲品种的莲子产量和品质性状进行分析,并通过隶属函数分析法对他们的营养品质性状进行综合评价。结果显示：不同子莲品种的产量和营养品质性状差异显著,同一品种在不同发育时期莲子的可溶性糖和淀粉含量等营养指标差异较大;鲜莲子的可溶性糖含量显著高于成熟莲子,而蛋白质和淀粉含量显著低于成熟莲子。与12个主栽子莲品种相比,‘武植子莲1号’在产量上较为突出,成熟莲子的淀粉含量达52.15%,是生产天然淀粉的优良品种;‘武植子莲2号’鲜莲子的直链淀粉和支链淀粉含量低,可溶性糖含量达23.43%,适合鲜食。隶属函数分析结果表明,‘武植子莲1号’和‘武植子莲2号’的综合营养品质较好,具有很高的应用价值。     

Reproductive ecology of dioecious Siparuna (Monimiaceae) in Ecuador–a case of gall midge pollination

The reproductive ecology of the dioecious genus Siparuna , belonging to the primitive family Monimiaceae, was investigated in Ecuador. Thirteen species were studied, and species growing at high altitudes (above 500 m) were compared with species growing at lower altitudes. The genus has specialized flowers pollinated by Cecidomyiidae (Asynapta sp. and other genera) that lay eggs chiefly in male flowers since these are more easily accessible than female flowers due to their morphology. Several traits ensure that pollen transfer is accomplished: 1. long flowering of individuals and single flowers; 2. specific floral morphology (unisexuality, landing platform, restricted pore) allowing the flowers to be visited by Cecidomyiidae seeking egg-laying sites, and 3. a low number of ovules that have to be pollinated in each flower. The low number of ovules per flower results in a high pollen-ovule (P/O) ratio even though pollen production in male flowers is only moderate.
High altitude species had larger flowers, higher pollen-ovule ratios, fewer ovules per female flower, and longer periods of anthesis. Gender differences were seen in the longer functionality of female flowers; the larger numbers of male flowers produced; and the average diameter at breast height (DBH) biased for one of the two sexes depending on the species investigated, with no clear trend in the size distributions of individuals of both sexes. Sex ratios departed significantly from unity both to male and female bias but usually were in favour of males. There were no general differences in the ratio of functional male to female flowers at the time of observation nor in the sizes of male and female flowers. The evolution of unisexual flowers in Siparuna can be explained as a result of the differential predation by larvae: unimportant in male flowers, destructive if occurring in female flowers.     

What are the consequences of being a downy oak (quercus pubescens) or a holm oak (Q. ilex) for breeding blue tits (Parus caeruleus)?

By comparison with deciduous oaks, the lower yearly production of new leaves in sclerophyllous oaks is hypothesized to have several consequences on animal communities. In particular, the production of arthropod communities that feed upon the leaves should be lower in sclerophyllous than in deciduous oaks, this causing changes in breeding patterns and the demographic balance in insectivorous birds. Studies in both deciduous and sclerophyllous habitats in southern France have shown that: 1) the spring development of new leaves occurs later and more slowly in sclerophyllous than in deciduous oaks, 2) the biomass of caterpillars is much lower in sclerophyllous oak forests, and 3) there is a large variation in life history traits of the Blue Tit depending in which type of habitat they breed. Laying date occurs later and clutch size is lower in sclerophyllous habitats than in deciduous habitats. The evolution of life history traits is discussed according to whether poor sclerophyllous habitats are isolated (e.g. on Corsica) or are parts of landscapes including both habitat types.     

Morphological features of Jat dentition

Observations on morphological characters of milk and permanent teeth, based on 648 pairs of dental casts of 356 male and 292 female Jat children of Haryana (India) are reported. Deciduous teeth show high frequencies of bilateral winging of maxillary central incisor, Carabelli's cusp of maxillary second molar, and deflecting wrinkle of mandibular second molar. Reduction of maxillary molar cusps is more marked in males than in females. Y pattern is very common in deciduous molars. Permanent teeth have high frequencies of grooved cingulum of incisors, cingular nodule of lateral incisors and canines, and distal accessary ridge of canines. Low frequencies of Carabelli's cusp and winging are also common. The tendency towards faintly developed shovelling in milk incisors occurs more often than in the permanent teeth.     

Methods for the production of multi-marker strains

Summary The production of a multi-marker strain given a series of strains each carrying a single marker will require a considerable investment in time and resources when based on a series of formal crosses. Such strains can be produced rapidly and with only minimal resources by recurrent cycles of random mating and selection, with selection based on the number of desired alleles carried.     

Paleogenetics of the late Roman-early Byzantine cemeteries at Sayala,Egyptian Nubia

Out of the five late Roman-early Byzantine cemeteries at Sayala, the three large burial complexes CI-III were found to represent the same population not only on the basis of 76·6% of the metric features already studied, but also of 72·9% of the 48 non-metric features examined in the present paper. The remaining features, which show different frequencies, were most probably related to some social and/or genetic isolation of the three subgroups (“lineages”) of the same basic population.The left-right asymmetry of the frequencies was practically irrelevant; sex differences were however present in one-third of the features observed.Some of the traits showed unusually high frequencies, revealing a high rate of inbreeding within a homogeneous population.To evaluate the relationships among the CI-III people and the neighbouring populations, 22 discrete traits were compared with the same traits studied in 11 Ancient Egyptian samples by Berry, Berry & Ucko (1967) and in 6 contemporary African Negro samples by Rightmire (1972). It was shown that the Sayala CI-III population does not resemble either of these groups. The fourth contemporary Sayala sample from A cemetery was also found to be not related with the CI-III sample on the basis of the same traits. The fifth contemporary Sayala sample from N cemetery was too small to be tested. Moreover, the comparison between the CI-III population and the C-group population of Sayala also revealed the lack of genetic continuity. The isolated position found in the CI-III population of Sayala agrees with the hypothesis that it would represent the Blemmyes, people originating from the Eastern Desert.     

Relationship between abundance, growth, egg size and fecundity in a landlocked population of longfin smelt, Spirinchus thaleichthys

Sixteen year-classes of longfin smelt, Spirinchus thaleichthys , show a consistent pattern of alternating year-class strength between even (strong) and odd (weak) years. A recent (1989) odd year-class grew as well as, if not better than, the late 1960s odd year-classes. However, fish in the even year-classes (1988 and 1990) were significantly smaller in size then the 1966 and 1968 cohorts. Associated with this reduction in growth of the even year-class fish is a decline in fecundity. Fecundity of the odd year-classes of smelt was also smaller than in the early 1960s. Mean egg diameter and gonadosomatic index were not statistically different between 1988 and 1989 year-classes but the relative fecundity was higher for the 1988 year-class than for 1989, suggesting a higher reproductive investment in the even year-class. Reduction in growth and associated reproductive traits is considered to result from a reduction in the abundance of mysids, a preferred prey species.