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2.
DENNIS P. GORDON 《Zoologica scripta》1993,22(2):203-221
Umbonuloid frontal shields arc described in the type species of Lepraliella, Drepanophora, Frurionella, Tessaradoma, Hincksipora, Stephanopora , and Pseudolepralia. Consequences to classification include the following: the family group names Lepralielloidea and Lepralicllidae have subjective priority over Umbonuloidea and Celleporariidae, respectively; Cylindroporeh is excluded from the Tessaradomidae and included in the Gigantoporidae; Tessarudoma bifax Cheetham is included in Srnithsonius (Bifaxariidae); Hincksiporidae is confirmed as a family of Lepralielloidea; Stephanoporu , with newly discovered dimorphic orifices, comprises two species which are the basis for a new exechonellid subfamily Stephanoporinae; and a new umbonulomorph superfamily, Pseudolepralioidea, is established for Pseudolepraliu (Pseudolepraliidae). Kladapheles gen.n., is established for an erect branching species of Lepraliellidae from New Zealand. 相似文献
3.
4.
YORAM YOM-TOV SHLOMITH YOM-TOV GORDON JARRELL 《Biological journal of the Linnean Society. Linnean Society of London》2008,93(4):701-707
Using museum specimens, we studied recent changes in skull size of the American marten Martes americana , in continental Alaska. In Alaska, global warming has resulted in milder winters that may contribute to an improved food supply in the wild. In the present study, we tested the hypothesis that body size of the marten had increased during the second half of the 20th century, in response to global warming. We found that skull size, and by implication body size, increased significantly during the second half of the 20th century, possibly due to an improved food supply and/or lower metabolic demands in winter. Improved food availability in winter may result from the improved nutritional conditions for prey, and/or from increased access to prey resulting from a longer snow-free season. Longitude had a significant positive effect on skull size and a significant negative effect on teeth size. In Alaska, the climate is milder along the western coast and becomes harsher inland. Hence, the milder climate was associated with larger body size providing further support for our prediction that body size of the American marten was influenced by food availability and reduced energy expenditure. The negative relationship between longitude and teeth size may indicate a trend towards a larger prey in inland marten populations, but we have no data to support or refute this hypothesis. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 93 , 701–707. 相似文献
5.
The effects of repeated annual application of methiocarb-based slug pellets, broadcast on the soil surface and drilled into the seed bed, on carabid beetle activity were investigated over a four year period on a winter-sown cereal field using pitfall traps in barriered plots. Following applications in late autumn all winter-active carabid populations were severely depressed; total carabid activity falling to less than 5% and 10–15% following broadcast and drilled applications, respectively, compared with untreated plots. Spring and summer-active species, not active at the time of application, were largely unaffected by applications and were responsible for a gradual recovery of total activity from early spring onwards. Activity of all affected winter species remained demonstrably depressed on treated areas for the remainder of their seasonal incidence. However, all except one species, Bembidion obtusum, recovered to normal activity levels in the following season prior to reapplication. Recovery patterns are discussed in terms of the known biology of the species involved. Evidence that a minority of summer-active species were also affected by treatments, sometimes positively and sometimes negatively, were attributed to indirect effects possibly involving prey availability and foraging behaviour. The long-term ecological and short-term agronomic implications of methiocarb effects on carabid populations in winter-sown cereals are discussed. 相似文献
6.
MAJOR CLADES OF THE ANGIOSPERMS 总被引:2,自引:0,他引:2
ROLF DAHLGREN KÅRE BREMER 《Cladistics : the international journal of the Willi Hennig Society》1985,1(4):349-368
Abstract— Our knowledge of fundamental angiosperm interrelationships is still very incomplete. The absence of a narrowly circumscribed gymnosperm outgroup, ideally the sister group, makes character evaluation, necessary for a cladistic analysis, difficult. According to current views the superorder Magnoliiflorae with a number of other groups, for example the monocotyledons, may represent a complex of families near the base of the angiosperms. Interrelationships of groups within the monocotyledons are much better understood than those between groups within the dicotyledons. A cladogram of monocotyledon orders based on earlier work by R. Dahlgren, H. T. Clifford, and F. N. Rasmussen is presented. A data matrix for a sample of the angiosperms with 61 characters for 49 taxa, mostly magnoliifloran and related families, is presented. The characters are polarized mainly according to the current view that the primitive angiosperm morphotype is a woody dicotyledon with strobiloid flowers. As an alternative the matrix is adjusted following W. C. Burger's conjecture that the primitive angiosperm was a herbaceous monocotyledon with trimerous flowers. Both matrices were run in a computerized parsimony analysis, resulting in numerous equally parsimonious solutions. This result is illustrative of the great homoplasy in the available character information, and also of how little actually is known about fundamental angiosperm interrelationships or phylogeny. 相似文献
7.
Assignment of orthologous relationships among mammalian alpha-globin genes by examining flanking regions reveals a rapid rate of evolution 总被引:1,自引:0,他引:1
In order to study the relationships among mammalian alpha-globin genes, we
have determined the sequence of the 3' flanking region of the human alpha 1
globin gene and have made pairwise comparisons between sequenced
alpha-globin genes. The flanking regions were examined in detail because
sequence matches in these regions could be interpreted with the least
complication from the gene duplications and conversions that have occurred
frequently in mammalian alpha-like globin gene clusters. We found good
matches between the flanking regions of human alpha 1 and rabbit alpha 1,
human psi alpha 1 and goat I alpha, human alpha 2 and goat II alpha, and
horse alpha 1 and goat II alpha. These matches were used to align the
alpha-globin genes in gene clusters from different mammals. This alignment
shows that genes at equivalent positions in the gene clusters of different
mammals can be functional or nonfunctional, depending on whether they
corrected against a functional alpha-globin gene in recent evolutionary
history. The number of alpha-globin genes (including pseudogenes) appears
to differ among species, although highly divergent pseudogenes may not have
been detected in all species examined. Although matching sequences could be
found in interspecies comparisons of the flanking regions of alpha- globin
genes, these matches are not as extensive as those found in the flanking
regions of mammalian beta-like globin genes. This observation suggests that
the noncoding sequences in the mammalian alpha-globin gene clusters are
evolving at a faster rate than those in the beta-like globin gene clusters.
The proposed faster rate of evolution fits with the poor conservation of
the genetic linkage map around alpha-globin gene clusters when compared to
that of the beta-like globin gene clusters. Analysis of the 3' flanking
regions of alpha-globin genes has revealed a conserved sequence
approximately 100-150 bp 3' to the polyadenylation site; this sequence may
be involved in the expression or regulation of alpha-globin genes.
相似文献
8.
GORDON B. CURRY 《Lethaia: An International Journal of Palaeontology and Stratigraphy》1983,16(4):311-312
Recently the author presented data which supported the suggestion (Owen & Williams 1969) that the brachiopod caeca can inhibit boring organisms and store excess nutrients (Curry 1983). In the light of this work it is appropriate to describe and discuss an additional function which has been proposed for the caeca, especially as the data appear in a zoological journal which may not otherwise come to the attention of brachiopod palaeontologists. 相似文献
9.
GORDON B. CURRY 《Lethaia: An International Journal of Palaeontology and Stratigraphy》1983,16(2):119-127
Microborings in the primary shell layer of Recent brachiopods are clearly seen to avoid endopunctamicroscopic canals pervading the shell fabric and housing papillose extcnlions of the mantle (the caeca). This avoidance confirms the suggestion that the caecal contents inhibit boring organisms (Owen & Williams 1969; Proc. R. Soc. Loud. B, 172 ), and as such the caecum can be considered as an important instrument in protecting the brachiopod shell. A comparison of the relative fecundity of co-habitating impunctate and cndopunctate New Zealand brachiopods provides indirect evidence that the caecum may indeed also function in a nutrient storage capacity. Brachiopods, microborings, primary shell layer, endopuncta, defence, storage. 相似文献
10.
AVRAM HERSHKO PIERRE MAMONT ROBERT SHIELDS GORDON M. TOMKINS 《Nature: New biology》1971,232(33):206-211
A hypothesis has been developed to relate stringent control in bacteria to a set of interactions involved in the regulation of growth of transformed and untransformed mammalian cells. 相似文献