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121.
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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Atherosclerosis     
William Dock 《CMAJ》1953,69(4):355-363
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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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