Partial bivoltinism and emergence patterns in the North African endemic damselfly Calopteryx exul: conservation implications

Calopteryx exul is an endemic endangered damselfly that suffers considerable habitat degradation and local extinctions throughout its geographic range. Although recent studies have investigated its distribution, ecology and larval systematics, the life history of the species is still unknown. In this study, a field survey was conducted to determine larval development, temporal pattern of emergence and teneral spatial distribution of the species in the Seybouse watershed, north‐east Algeria. Larval growth was investigated in two populations: one at about 200 m (low‐elevation population) and the second at 600 m of elevation (high‐elevation population). The species showed partial bivoltine life cycle in both low‐ and high‐elevation population. The temporal pattern of emergence of the first flight season of the year at low‐elevation population was asynchronous with an emergence season lasting 46 days and half of the population emerging in 15 days. The second flight season was shorter with a most likely smaller population size. Sex ratio at emergence was slightly male biased. After ecdysis, tenerals stayed next to the water within a mean distance of 4.76 ± 4.35 m (± SD) with no significant difference between sexes. Conservation measures that should be taken into account in the elaboration of future management plans for the species are discussed.     

Cell Death in Cells Overlying Lateral Root Primordia Facilitates Organ Growth in Arabidopsis

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Life history theory and dental development in four species of catarrhine primates

Dental development was reconstructed in several individuals representing four species of catarrhine primates--Symphalangus syndactylus, Hylobates lar, Semnopithecus entellus priam, and Papio hamadryas--using the techniques of dental histology. Bar charts assumed to represent species-typical dental development were constructed from these data and estimated ages at first and third molar emergence were plotted on them along with ages at weaning, menarche, and first reproduction from the literature. The estimated age at first molar emergence appears to occur at weaning in the siamang, lar gibbon, and langur, and just after weaning in the baboon. Age at menarche and first reproduction occur earlier relative to dental development in both cercopithecoids than in the hylobatids, suggesting that early reproduction may be a derived trait in cercopithecoids. The results are examined in the context of life history theory.     

Adult emergence pattern of parasitoidApanteles angaleti and its known hosts during off-season in Punjab

Observations on emergence pattern of parasitoidApanteles angaleti Muesebeck and its 2 hosts, cotton pink bollwormPectinophora gossypiella (Saunders) and saprophyteSathrobrota simplex Wlsm. were made during 1980–81 to 1983–84. The adult emergence of parasitoidA. angaleti and non-pestS. simplex was similar and completed by end April. ParasitoidA. angaleti overwintered mostly in the larvae of non-pestS. simplex and not in pink bollworm larvaeP. gossypiella. The early breeding activity ofS. simplex in the rotten bolls in the cotton stacks helped in the carryover and initial build-up ofA. angaleti to the main crop season. The initiation and peak moth emergence in pink bollworm varied with different sources of its carryover but all adults emerged until end August.     

What do we mean by biological complexity?

The purpose of the present paper is to offer a precise definition of the concepts of integration, emergence and complexity in biological networks through the use of the information theory. If two distinct properties of a network are expressed by two discrete variables, the classical subadditivity principle of Shannon's information theory applies when all the nodes of the network are associated with these properties. If not, the subadditivity principle may not apply. This situation is often to be encountered with enzyme and metabolic networks, for some nodes may well not be associated with these two properties. This is precisely what is occurring with an enzyme that binds randomly its two substrates. This situation implies that an enzyme, or a metabolic network, may display a joint entropy equal, smaller, or larger than the corresponding sum of individual entropies of component sub-systems. In the first case, the collective properties of the network can be reduced to the individual properties of its components. Moreover, the network is devoid of any information. In the second case, the system displays integration effects, behaves as a coherent whole, and has positive information. But if the joint entropy of the network is smaller than the sum of the individual entropies of its components, then the system has emergent collective properties and can be considered complex. Moreover, under these conditions, its information is negative. The extent of negative information is enhanced if the enzyme, or the metabolic network, is far away from equilibrium.     

南京地区落叶栎林主要木本植物的展叶动态研究

 植物的展叶过程是由自身遗传因子决定的,同时又受到多种生态因子的调节,反映了植物的生活史对策和群落物种多样性的维持机制。在2001和2002年的3～6月间,不定期记录了南京地区三个落叶栎(Quercus spp.)林中主要木本植物的展叶情况,包括被标记标准枝的叶数、叶的长度、宽度、叶面积、叶干重等参数。结果表明在所调查的落叶栎林中,林冠层物种的成熟叶面积和单位叶面积干重都显著大于林下层物种;最早展叶的物种为林下层物种,但林冠层展叶顺序与林下层无显著差异。叶面积越大、单位叶面积干重越小的物种展叶越晚;林冠层物种展叶较林下层快,物种成熟叶面积越大,展叶速率越大。最后对展叶顺序和展叶速度的生态学意义作了讨论。     

Plant traits: Their role in the regeneration of alpine plant communities in sub‐arctic Finland

Abstract. Question: How do the relative frequencies of plant traits (clonality, growth form, seed weight, diaspore morphology) vary during the life cycle and how does this affect regeneration? Location: Alpine meadow and heath communities at Kilpisjärvi, sub‐Arctic Finland. Methods: Control plots and three treatments were used to measure relative species abundances for five life cycle stages: standing vegetation, seed rain, seed bank and seedlings emerging in gaps and in closed vegetation. Results: The relative frequencies of plant traits varied between the life cycle stages. The meadows were dominated by weakly clonal herbs, small or intermediate seeds and unappendaged diaspores, while the heaths were dominated by clonal dwarf shrubs, small seeds and fleshy fruits. In the meadows, species with small seeds dominated during the seed rain and in the seedling stage in gaps, while species with intermediate seeds dominated the seed bank and the seedling stage in closed vegetation. Species with unappendaged diaspores dominated throughout the life cycle. In the heaths, seed bank and seedling stage were practically absent. Conclusions: The observed differences in plant trait spectra between life cycle stages indicate that important environmental factors differ among the stages. Small seeds are advantageous for dispersal, whereas intermediate seeds have a greater probability of germinating and establishing in closed vegetation. Appendages facilitate dispersal, whereas unappendaged diaspores favour seed burial. Although the plant growth form spectrum largely reflects environmental constraints during the regeneration cycle, information on seed weight and diaspore morphology improves our knowledge of the relative importance of morphological adaptations of sexual structures in different stages during the life cycle.     

Pathogenicity and life cycle of Meloidogyne javanica on broccoli

A pathogenicity trial conducted against root-knot nematode, Meloidogyne javanica on broccoli indicated that a gradual increase in the nematode inoculum from 500 to 8000 juveniles/kg soil was associated with a progressive decline in all the plant growth parameters and reproduction factor of the nematode. Although 8000 juveniles/kg soil showed maximum plant growth reduction and root knot index, statistical analysis of the data revealed that the population of 1000 juveniles/kg soil was associated with a significant decline in plant growth. Hence, this level was indicative of being the pathogenic level. The significant reduction in seedling emergence was recorded at and above 2000 juveniles/kg soil and it decreased further with increasing inoculum levels. Meloidogyne javanica required 27 days to complete the life cycle on broccoli at a temperature range of 28–35°C.     

小麦种质贮藏过程中生活力丧失特性及田间出苗率表现

通过对贮藏2～20年的378份中期库小麦种质进行生活力测定(每一贮藏年份测定种质份数为10～30),结果表明贮藏年限为2～12年的种质平均发芽率都高于83％,而贮藏年限为15年的种质平均发芽率已降至20％,这表明小麦种质在中期库贮藏过程中,生活力丧失存在着骤降特性。同时对同一品种分别来自中期库低活力和长期库高活力种质进行田间出苗率和农艺性状调查,发现中期库种质的室内发芽率与田间出苗率相关极显,其相关显性高于长期库种质,且不论是来自中期库低活力种质还是长期库高活力种质,总体上田间出苗率都比室内发芽率低20％以上,在子一代种子的农艺性状上两之间无显差异。