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1

Praktyka w Pensylwanii

100%
Biuletyn Informacyjno-Handlowy. Ośrodek Doradztwa Rolniczego Boguchwała
|
1994
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nr 12
8-9
2

Intraspecies structure of Paramecium pentaurelia

100%
Przybos E.
Folia Biologica
|
1999
|
tom 47
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nr 1-2
3
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New palaeoscolecidan worms from the Lower Cambrian: Sirius Passet, Latham Shale and Kinzers Shale

80%
Morris S. C., Peel J. S.
Acta Palaeontologica Polonica
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2010
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tom 55
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nr 1
Palaeoscolecidan worms are an important component of many Lower Palaeozoic marine assemblages, with notable occurrences in a number of Burgess Shale−type Fossil−Lagerstätten. In addition to material from the lower Cambrian Kinzers Formation and Latham Shale, we also describe two new palaeoscolecidan taxa from the lower Cambrian Sirius Passet Fossil−Lagerstätte of North Greenland: Chalazoscolex pharkus gen. et sp. nov and Xystoscolex boreogyrus gen. et sp. nov. These palaeoscolecidans appear to be the oldest known (Cambrian Series 2, Stage 3) soft−bodied examples, being somewhat older than the diverse assemblages from the Chengjiang Fossil−Lagerstätte of China. In the Sirius Passet taxa the body is composed of a spinose introvert (or proboscis), trunk with ornamentation that includes regions bearing cuticular ridges and sclerites, and a caudal zone with prominent circles of sclerites. The taxa are evidently quite closely related; generic differentiation is based on degree of trunk ornamentation, details of introvert structure and nature of the caudal region. The worms were probably infaunal or semi−epifaunal; gut contents suggest that at least X. boreogyrus may have preyed on the arthropod Isoxys. Comparison with other palaeoscolecidans is relatively straightforward in terms of comparable examples in other Burgess Shale−type occurrences, but is much more tenuous with respect to the important record of isolated sclerites. These finds from Greenland provide further evidence that palaeoscolecidans possessed a complex anterior introvert directly comparable to a number of priapulid−like taxa from other Burgess Shale−type assemblages. Although these palaeoscolecidans have been allied with the nematomorphs, molecular data in conjunction with our observations suggest that this hypothesis is untenable. Palaeoscolecidans and similar priapulid−like taxa are probably primitive cycloneuralians and as such may indicate the original bodyplan of this important group of ecdysozoans. In addition, we describe another sclerite−bearing fossil from the Sirius Passet Fossil−Lagerstätte that may be related to the cambroclaves.
4

A new species of Heligmosomoides [Nematoda, Heligmosomidae] parasitic in Peromyscus maniculatus [Rodentia, Cricetidae] from Pennsylvania, USA

80%
Durette-Desset M. C., Kinsella J. M.
Acta Parasitologica
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2007
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tom 52
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nr 4
Heligmosomoides vandegrifti sp. nov. (Nematoda, Heligmosomidae) is described from Peromyscus maniculatus (Rodentia, Cricetidae) from Pennsylvania, USA. It differs from its closest congener, H. douglasi, in the number of cuticular ridges (35 vs. 32 in male, 36 vs. 41 in female at mid-body), longer bursal rays 2 in relation to rays 3, and in having smaller spicules (635–740 μm long vs. 1 mm). It is proposed that both H. douglasi and H. vandegrifti sp. nov. are parasites of capture from species in North American arvicoline rodents.
5

Factors influencing perceived community structure in nearctic forest small mammals

70%
Kirkland G. L., Sheppard P. K., Shaughnessy M. J., Woleslagle B. A.
Acta Theriologica
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1998
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tom 43
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nr 2
Arrays of pitfalls and drift fences were deployed in five deciduous forest habitats in southcentral Pennsylvania to assess the characteristics, and temporal and spatial dynamics of forest small-mammal communities, and to determine the impact of precipi­tation, sampling method, and length of sampling period on perceived small-mammal abundance and community structure. Results revealed that soricid assemblages were more diverse and generally more abundant than rodent assemblages, which were dominated by the white-footed mouse Peromyscus leucopus. Precipitation dramatically increased the capture rates of shrews; the response was less pronounced in rodents. Individual species responded independently to precipitation. The response was more pronounced in three species of arvicoline rodents (Clethrionomys gapperi, Microtus pinetorum, and M. pennsylvanicus) than in P. leucopus, a sigmodontine. Comparisons of sampling with pitfalls and Museum Special snap-traps, with and without drift fencing, revealed that arrays of pitfalls with drift fences produced significantly higher capture rates for all small mammals, shrews, rodents, and P. leucopus, greater num­bers of species, and higher Shannon indices than other sampling methods, Comparison of the results of sampling for 3, 5, 7, and 10 days revealed that extending sampling to 7 or more days yielded significantly more species, higher Shannon indices, and greater numbers of individuals than sampling for less than 7 days.
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