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An expanded surface-water palaeotemperature inference model for use with fossil midges from eastern Canada 总被引：4，自引：0，他引：4
Ian R. Walker André J. Levesque Les C. Cwynar André F. Lotter 《Journal of Paleolimnology》1997,18(2):165-178
Using an expanded surface sample data set, representing lakes distributed across a transect from southernmost Canada to the Canadian High Arctic, a revised midge-palaeotemperature inference model was developed for eastern Canada. Modelling trials with weighted averaging (with classical and inverse deshrinking; with and without tolerance downweighting) and weighted averaging partial least squares (WA-PLS) regression, with and without square-root transformation of the species data, were used to identify the best model. Comparison of measured and predicted temperatures revealed that a 2 component WA-PLS model for square-root transformed percentage species data provided the model with the highest explained variance (r
=0.88) and the lowest error estimate (RMSEP
jack
=2.26 °C). Comparison of temperature inferences based on the new and old models indicates that the original model may have seriously under-estimated the magnitude of late-glacial temperature oscillations in Atlantic Canada. The new inferences suggest that summer surface water temperatures in Splan Pond, New Brunswick were approximately 10 to 12 °C immediately following deglaciation and during the Younger Dryas. During the Allerod and early Holocene, surface water temperatures of 20 to 24 °C were attained. The new model thus provides the basis for more accurate palaeotemperature reconstructions throughout easternmost Canada. 相似文献
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A new biting midge Archiculicoides andersoni sp. nov. from Upper Cretaceous Burmese amber is described and illustrated. An unknown male of Leptoconops myanmaricus Szadziewski, 2004 is described and an undetermined female of the genus Archiaustroconops and Austroconops in the collection of National Museums Scotland is reported. A key for the determination of 10 named species in 6 genera of biting midges reported from Burmese amber is also provided. 相似文献
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Three new species, Lebanoculicoides excantabris, Archiaustroconops borkenti, and Atriculicoides szadziewskii are described from the Early Cretaceous (early Albian) El Soplao amber deposit (Rábago, Cantabria, northern Spain). Protoculicoides skalskii Szadziewski and Arillo, found in the other Albian Spanish ambers from Peñacerrada I (in Burgos) and San Just (in Teruel), and Austroconops sp., are identified from this new outcrop. The find of a new species of Lebanoculicoides Szadziewski is especially significant since this genus is considered the basalmost known among ceratopogonids. To date, the new species of Atriculicoides Remm is the oldest occurrence for this genus. A general review of the taxonomy and phylogeny of the family Ceratopogonidae, and the palaeoecological significance and palaeogeographic distribution of its basalmost lineages are given. The new data extend knowledge about biting midges during the Early Cretaceous, a key period for understanding the phylogenetic relationships of the ancient members of the family. 相似文献
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Chironomidae (Diptera) remains in surficial lake sediments from the Canadian Cordillera: analysis of the fauna across an altitudinal gradient 总被引：3，自引：0，他引：3
The altitudinal distribution of Chironomidae (Diptera) in the southern Canadian Cordillera was analyzed by means of head capsules preserved in surficial sediments of 30 lakes. Taxa characteristic of late-glacial deposits of southern, coastal British Columbia are extant at high elevations, particularly in the Rocky Mountains, and in large, deep, low-elevation lakes. Many chironomid taxa common at low elevations in the southern Canadian Cordillera were not found in alpine and upper subalpine lakes. These faunal differences are probably climatically related. The differences in fauna between high and low-elevation lakes parallel differences between arctic and temperate lakes. 相似文献
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