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Philippe Fernandez‐Fournier Samantha Straus Ruth Sharpe Leticia Avils 《Ecological Entomology》2019,44(2):157-162
1. Manipulation of host behaviour by parasitoids has long captured the imagination of ecologists. Parasitoid wasps in the Polysphincta group of genera develop as external parasitoids of spiders. 2. In the present study, the previously undescribed interaction between a Zatypota sp. wasp (Ichneumonidae) and a social spider Anelosimus eximius (Theridiidae) is described. The larva of this Zatypota wasp is found to induce its host to disperse from their communal web and build an entirely enclosed web consisting of densely spun silk. 3. The wasp is observed to target primarily immature A. eximius individuals, with 37.5–44% of nests in a given area being parasitised. Of those nests, approximately 1.3–2.0% of individuals are hosts to the parasitoid larvae. Larger spider colonies had a significantly higher probability of harbouring parasitoids. 4. This interaction results in unusual behaviours for A. eximius induced by the parasitoid: (i) leaving the protection of the social nest and (ii) building a unique, altered web that it would not otherwise build. It is suggested that the wasp may be tapping into ancestral dispersal behaviours in its host and that a social species provides this wasp an evolutionary advantage by allowing a stable host source. 相似文献
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David Gutirrez‐Larruscain Santiago Andrs‐Snchez Enrique Rico María Montserrat Martínez‐Ortega 《植物分类学报:英文版》2019,57(1):42-54
Forty-five populations of Pentanema corresponding to seven species included in the Pentanema conyzae clade have been studied using AFLP fingerprinting. The results show that allopolyploidization could have been involved in the diversification of this group, specifically in species P. langeanum and P. maletii. Molecular data confirm the presence of P. britannicum in the Iberian Peninsula and key steps are provided to identify the species that are morphologically the most challenging. 相似文献
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Large‐scale biodiversity maps are essential to macroecology. However, between‐region comparisons can be more useful if patterns of observed species richness are supplemented by variations in dark diversity – the absent portion of the species pool. We aim to quantify and map plant diversity across Europe by using a measure that accounts for both observed and dark diversity. To do this we need to delimit suitable species pools, and evaluate the potential and limitation of a large‐scale dataset. We used Atlas Florae Europaeae (ca 20% of European plant species mapped within 50 × 50 km grid cells) and defined for each grid cell several species pools by applying various geographical and environmental filters: geographic species pool (number of species within 500 km radius), biogeographic species pool (additionally incorporating species distribution patterns, i.e. dispersion fields), site‐specific species pool (additionally integrating environmental preferences of species based on species co‐occurrence). We integrated dark diversity and observed diversity at a relative scale to calculate the completeness of site diversity: logistic expression of observed and dark diversity. We tested whether our results are robust against regional variation in data availability. We used independent regional databases to test if Atlas Florae Europaeae is a representative subset of total species richness. Environmental filtering was the most influential determinant of species pool size with more species filtered out in southern Europe. Both observed and dark diversity adhered to the well‐known latitudinal gradient, but completeness of site diversity varied throughout Europe with no latitudinal trend. Dark diversity patterns were fairly insensitive to variations in regional sampling intensity. Atlas Florae Europaeae represented well the total variation in plant diversity. In summary, dark diversity and completeness of site diversity add valuable information to broad‐scale diversity patterns since observed diversity is expressed at a relative scale. 相似文献
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1. Time perception is seldom studied in invertebrates, with the limited experimental evidence being insufficient to provide a comprehensive pattern of the capacity of invertebrates to measure time and use it in decision‐making processes. 2. In this study, it was hypothesized that insect parasitoids have evolved the capacity to measure time precisely and to use it to optimize foraging decisions related to host exploitation. To examine time perception in females of the gregarious egg parasitoid Trichogramma euproctidis, the present study used their ability to adjust their investment (number of eggs laid) in a host to the initial transit duration (interval between the first contact with the host and the following contact with the substrate). Females utilize this method to assess host egg size, as a large egg necessarily requires more time to evaluate than a small host. In this study, the initial transit duration for a given sized egg was artificially extended by suspending it. 3. For similar sized hosts, female T. euproctidis significantly increased both oviposition duration and progeny allocation following a longer initial transit duration. 4. These results demonstrate the intrinsic capacity of this parasitoid to measure time and to adjust their progeny investment accordingly. This is believed to be one of the few demonstrations of a retrospective measure of time in an invertebrate. 相似文献
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Breast muscle of young chicks fed chow diets containing the creatine analog 1-carboxymethyl-2-iminoimidazolidine (cyclocreatine) accumulated up to 40 mumol/g wet weight of the synthetic phosphagen 1-carboxymethyl-2-imino-3-phosphonoimidazolidine (cyclocreatine-P2-). ATP levels were sustained at high values substantially longer in breast muscle of cyclocreatine-fed chicks, compared to control-fed chicks, during total ischemia initiated 2 h after injection of both groups with the beta-adrenergic agonist isoproterenol (5 mg/kg subcutaneous). For example, in chicks fed 0.5% cyclocreatine for 10-19 days ATP levels in isoproterenol-stimulated breast muscles after 1 h of ischemia at 37 degrees C were 6.1 mumol/g, compared to 1.9 mumol/g for the control-fed group, and after 2 h of ischemia were 3.5 mumol/g compared to 0.6 mumol/g for controls. Creatine-P reserves in isoproterenol-stimulated breast muscles of all dietary groups were essentially exhausted within the first hour of ischemia. In contrast, breast muscle of chicks fed either 1 or 0.5% cyclocreatine still contained 28 and 19 mumol/g of cyclocreatine-P, respectively, after 1 h of ischemia; after 2 h of ischemia, the respective cyclocreatine-P values were 20 and 13 mumol/g. Isoproterenol-stimulated chick breast muscle provides the first skeletal muscle model system for studying the molecular mechanisms by which dietary cyclocreatine helps sustain ATP levels during ischemia. Although adaptive factors are also involved, it is suggested that a significant portion of the ATP-sustaining activity of dietary cyclocreatine in ischemic breast muscle can be attributed to the unique thermodynamic properties of the accumulated cyclocreatine-P. These properties enable cyclocreatine-P to continue to thermodynamically buffer the adenylate system and transport high energy phosphate throughout the long muscle fibers at cytosolic pH values and phosphorylation potentials well below the range where the creatine-P system can function effectively. Synergism between glycolysis and this long-acting synthetic phosphagen might well help delay depletion of ATP levels in skeletal muscles during ischemia. Cyclocreatine feeding provides a unique experimental tool for quantitative evaluation of the proposed protective role of ATP against irreversible cellular damage in skeletal and cardiac muscles during ischemic episodes. 相似文献
79.
The nocturnally active weakly electric fish Gnathonemus petersii is known to employ active electrolocation for the detection of objects and for orientation in its environment. The fish emits pulse‐type electric signals with an electric organ and perceives these signals with more than 3,000 epidermal electroreceptor organs, the mormyromasts, which are distributed over the animal's skin surface. In this study, we measured the metric dimensions of the mormyromasts from different body regions to find structural and functional specialization of the various body parts. We focused on the two foveal regions of G. petersii, which are located at the elongated and movable chin (the Schnauzenorgan; SO) and at the nasal region (NR), the skin region between the mouth and the nares. These two foveal regions were compared to the dorsal part (back) of the fish, which contains typical nonfoveal mormyromasts. While the gross anatomy of the mormyromasts from all skin regions is similar, the metric dimensions of the main substructures differed. The mormyromasts at the SO are the smallest and contain the smallest receptor cells. In addition, the number of receptor cells per organ is lowest at the SO. In contrast, at the back the biggest receptor organs with the highest amount of receptor cells per organ occur. The mormyromasts at the NR are in several respects intermediate between those from the back and the SO. However, mormyromasts at the NR are longer than those at all other skin regions, the canal leading from the receptor pore to the inner chambers were the longest and the overlaying epidermal layers are the thickest. These results show that mormyromasts and the epidermis they are embedded in at both foveal regions differ specifically from those found on the rest of the body. The morphological specializations lead to functional specialization of the two foveae. J. Morphol., 2012. © 2012 Wiley Periodicals, Inc. 相似文献