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951.
MICHAEL HEADS 《Botanical journal of the Linnean Society. Linnean Society of London》1998,127(3):239-285
The trees and shrubs in Olearia sect. Divaricaster, sect. nov., are found in North, South, and Stewart Islands of New Zealand. They are distinguished by their small, opposite leaves borne on brachyblasts (short shoots), long shoots which abort apically, solitary or fascicled capitula, flowers with purple style arms, and a very distinctive insect fauna. The ten species and three subspecies, including the new O. fimbriata, O. gardneri and O. virgata subsp. centralis are revised and a key and distribution maps provided. The section includes four threatened species: O. hectorii, O. polita and the two new species. Species density is mapped in grid cells 1° latitude by 1° longitude. Areas west of the geological Median Tectonic Zone (Nelson, Westland and Fiordland) show relatively low diversity. The highest diversity, six species in one grid cell, is recorded in north-west Otago, around Mt Aspiring and the Humboldt Mountains. This region is also geologically significant as several allochthonous terranes are juxtaposed there. In the central South Island O. laxiflora, O. fimbriata and O. odorata have concentric distributions around what were Tertiary basins and inland seas. Members of the section favour fertile, lowland sites on alluvium and have suffered reduction in population size over the last century due to agricultural development. Several species, such as O. hectorii, the 'swamp gum', occur in sites which are periodically flooded. Olearia solandri is a coastal species, often growing as a mangrove associate, but occasionally found inland. The anomalous inland populations are discussed and their location attributed to geological uplift. 相似文献
952.
VARIATION IN GENOMIC FORM IN PLANTS AND ITS ECOLOGICAL IMPLICATIONS 总被引:28,自引:6,他引:22
MICHAEL D. BENNETT 《The New phytologist》1987,106(S1):177-200
953.
MARK S. LENARZ MICHAEL E. NELSON MICHAEL W. SCHRAGE ANDREW J. EDWARDS 《The Journal of wildlife management》2009,73(4):503-510
ABSTRACT The earth is in the midst of a pronounced warming trend and temperatures in Minnesota, USA, as elsewhere, are projected to increase. Northern Minnesota represents the southern edge to the circumpolar distribution of moose (Alces alces), a species intolerant of heat. Moose increase their metabolic rate to regulate their core body temperature as temperatures rise. We hypothesized that moose survival rates would be a function of the frequency and magnitude that ambient temperatures exceeded the upper critical temperature of moose. We compared annual and seasonal moose survival in northeastern Minnesota between 2002 and 2008 with a temperature metric. We found that models based on January temperatures above the critical threshold were inversely correlated with subsequent survival and explained >78% of variability in spring, fall, and annual survival. Models based on late-spring temperatures also explained a high proportion of survival during the subsequent fall. A model based on warm-season temperatures was important in explaining survival during the subsequent winter. Our analyses suggest that temperatures may have a cumulative influence on survival. We expect that continuation or acceleration of current climate trends will result in decreased survival, a decrease in moose density, and ultimately, a retreat of moose northward from their current distribution. 相似文献
954.
MOHAMMED S. ALI-SHTAYEH MICHAEL W. DICK F.L.S 《Botanical journal of the Linnean Society. Linnean Society of London》1985,91(1-2):297-317
Five new species of Pythium are described, following ecological studies of the genus in the Reading (U.K.) area. Two of the new species were found abundantly, three were rarely isolated. Neither of the abundant species produces sporangia and both have very small oospores. Of the rarer species, two have filamentous sporangia and all three have rather large oospores. 相似文献
955.
Sipwise and flowise presentation of taste stimuli were compared and better taste discrimination was noted for flowise presentation. Using a model system, discrimination between NaCl solutions and purified water, analysis with atomic absorption spectrophotometry indicated that the superiority of flowise presentation was due to reduction in stimulus variance. Flowise presentation was also superior for discrimination between commercially available natural spring waters. 相似文献
956.
957.
RICHARD M. BATEMAN RHIAN J. SMITH MICHAEL F. FAY 《Botanical journal of the Linnean Society. Linnean Society of London》2008,157(4):687-711
We report the first confirmed occurrence in Britain of Orchis × angusticruris Franch. ex Rouy, a hybrid between two closely related orchid species of anthropomorphic Orchis (O. purpurea Huds. × O. simia Lam.) that hybridize frequently in Continental Europe. Seven individual hybrids, most likely F1 plants representing a single interspecific pollination event, first flowered with both parents in May 2006 at a nature reserve in the Chiltern Hills near Goring, Oxfordshire. Univariate and multivariate morphometric analyses (43 characters plus 12 indices), internal transcribed spacer sequencing, plastid microsatellites and amplified fragment length polymorphism (AFLP) analyses together readily separate the parents and confirm that O. purpurea was the ovule parent and O. simia the pollen parent, presumably reflecting the greater frequency and/or later flowering period of the latter at the site. This study reinforces a more general observation that, in most orchids, the ovule parent contributes substantially more to the hybrid phenotype than does the pollen parent, perhaps reflecting cytoplasmic inheritance. In contrast, the hybrids are placed closer to O. simia than to O. purpurea in the AFLP tree. Apparently recent arrivals, the few O. purpurea plants at Goring contrast genetically with the two other small populations of this species known in the Chilterns, but rather are consistent with relatively uncommon Continental populations. This suggests that the plants may have been deliberately introduced at Goring by man, although transport from the Continent in high‐level air currents cannot be ruled out. The Goring population of O. simia is likely to have become genetically impoverished through (1) preferential removal of many relatively fit plants to herbaria in the 19th century and/or (2) a catastrophic population crash in the first half of the 20th century. However, both our re‐examination of herbarium specimens and our population genetic data indicate past hybridization among anthropomorphic Orchis species occurring naturally in the Chilterns. Thus, we tentatively recommend retention of the hybrid plants at Goring, despite their likely anthropogenic origin from Continental material and the partial viability of their pollen and seeds, which offers opportunities for future introgression. Although the Goring hybrids broadly resemble morphologically O. militaris, another anthropomorphic Orchis still found at two Chiltern localities, sufficient morphological and molecular differences were observed to strongly refute our initial hypothesis that O. militaris could have originated through hybridization between ancestors that resembled O. purpurea and O. simia. The comparatively complex genetic properties evident in both O. simia and O. purpurea merit further study. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 157 , 687–711. 相似文献
958.
Millipede assassins and allies (Heteroptera: Reduviidae: Ectrichodiinae,Tribelocephalinae): total evidence phylogeny,revised classification and evolution of sexual dimorphism
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Evolution of sexual dimorphism in animals has long been of interest to scientists, but relatively few studies have reconstructed evolutionary patterns of extreme sexual dimorphism at a phylogenetic scale, especially in insects. Millipede assassin bugs (Heteroptera: Reduviidae: Ectrichodiinae; 736 spp.) and their sister taxon, Tribelocephalinae (150 spp.), exhibit sexual dimorphism that ranges from limited to extreme, a phenomenon apparently modulated by female morphology. Here, we reconstruct the first phylogeny for the subfamilies Ectrichodiinae and Tribelocephalinae with comprehensive generic representation (152 taxa in 72 genera) using morphological and molecular data (six gene regions). The combined phylogenetic results indicate that Tribelocephalinae are paraphyletic with respect to Ectrichodiinae, and that Ectrichodiinae themselves are polyphyletic. Based on these results, we synonymize Tribelocephalinae with Ectrichodiinae syn.n. , describe three new tribes (Ectrichodiini trib.n. , Tribelocodiini trib.n. , and Abelocephalini trib.n. ) and two new subtribes (Opistoplatyina subtrib.n. and Tribelocephalina subtrib.n. ), and revise Tribelocephalini sensu n. Ancestral state reconstruction of sexual dimorphism reconstructed limited sexual dimorphism in the ancestor of Ectrichodiinae sensu n. with at least seven evolutionary transitions to extreme sexual dimorphism within the clade. This published work has been registered in ZooBank, http://zoobank.org/urn:lsid:zoobank.org:pub:C810E20F‐D66A‐461F‐A0E6‐AB1073EA3E3C . 相似文献
959.
960.
Repeated likelihood ratio tests 总被引:1,自引:0,他引:1