摘要:

AbstractIn the summer of 1990, the pollination ecology ofPedicularis megalanthawas studied in the montane‐subalpine spruce‐fir forest zone (2750‐3050 m) on the north slope of Mt. Huttoo at Narkanda, Himachal Pradesh, in the Indian Himalaya. Its yellow, long‐tubed, nectarless flower with a curled rostrum overarched by a broad, inverted lower corolla lip was pollinated exclusively byBombus albopleuralisandB. tunicatusworkers hanging inverted from the corolla and vibrating pollen from introrse anthers concealed within the galea and releasing pollen through a small ventral opening in the galea base. The stigma, protruding from the tip of the rostrum, contacted pollen deposited on the ventral side of the insect's thorax. Corbicular pollen loads fromP. megalanthapollinators indicated equal numbers of monolectic and oligolectic foragers.P. megalanthaappeared to suffer from competition for pollinators byCynoglossum wallichiiat one site but to be favored in a mixed plant community with nectariferous species offering a forage resource complementary toPedicularispollen. As inP. punctata, the long, nectarless corolla tube ofP. megalanthaappears to function in extending the rostrate vibration pollination mechanism beyond the plant's foliage, which would interfere with its function. It is not an adaptation for nectar‐foraging lepidopteran pollinators.P. megalanthawas also found to be a root hem

ISSN:0913-557X    

DOI:10.1111/j.1442-1984.1991.tb00212.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractEnzyme electrophoresis was used to measure genetic diversity in two populations ofCoreopsis intermediaof sectionCoreopsis, a rare species endemic to a small area of Texas and Louisiana. Genetic diversity is higher inC. intermediathan has been reported for many other geographically restricted species.C. intermediacontains levels of genetic variation comparable to those of other species in sectionCoreopsis, and a greater amount of diversity than either the rare congener,C. latifolia(sectionSilphidium), or the Florida endemic,C. leavenworthii(sectionCalliopsis). The two populations, although greatly different in size, exhibited similar levels of genetic diversity.

ISSN:0913-557X    

DOI:10.1111/j.1442-1984.1991.tb00213.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractThe California Peony (Paeonia californica), a regional endemic and outcrossing species, is almost completely monomorphic for 23 isozyme loci. The level of genetic diversity in the California Peony is similar to that of narrow endemics and/or self‐fertilizing species. This paradoxical result may be explained by either of two hypotheses: 1) low initial polymorphism of the ancestral genome, or 2) population bottle nec

ISSN:0913-557X    

DOI:10.1111/j.1442-1984.1991.tb00214.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractPedicularis bracteosavar.atrosanguineaoccurs locally in association withP. racemosaorP. groenlandicain the Olympic Mountains in Washington. Other plant species, e.g.,Polygonum bistortoides, Lupinus argenteusvar.parviflorusandValeriana sitchensiscompete for space and bumblebee pollinators within the study area. Pollinator sharing, resulting from such competition, may increase the frequency of unvisited flowers ofP. bracteosavar.atrosanguinea. P. bracteosavar.atrosanguinea, with blood purple nectariferous flowers, is presumed to lack intense reflections of blue spectral components from its corollas in attracting bumblebees compared to those ofP. racemosaandP. groenlandica. Six species of bumblebees (Bombus) and cuckoo bees (Psithyrus) pollinateP. bracteosavar.atrosanguinea. Of these,Bombus mixtusandB. occidentalisoccur in higher frequencies and are the major pollinators ofP. bracteosavar.atrosanguinea. Queen and larger worker bumblebees pollinate nototribically as they probe for nectar, while smaller worker bumblebees pollinate sternotribically while scraping pollen from anthers deeply hidden in the dome‐shaped galea. Corbicular pollen loads of bumblebees collected in the study area containPedicularispollen alone/in combination ofPolygonum, Valeriana, Lupinus, ErigeronandBidens, or exclusively ofPolygonumorValeriana. P. bracteosavar.atrosanguineadoes not suffer seriously from deficient pollination but seedlings resulting from pollinated flowers may be subjected to natural selection pressure exerted by colonial plant species for space.P. bracteosavar.atrosanguineadoes not propagate asexually but resumes aerial growth seasonally from the self‐same underground root stocks. If seedlings are under continuous selection pressure for lack of space,P. bracteosavar.atrosanguineais presumed to regenerate primarily by perennial root stocks. This behavior may favor endemism inP. bracteosavar.atrosangui

ISSN:0913-557X    

DOI:10.1111/j.1442-1984.1991.tb00215.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractThe bird speciesHypsipetes amaurotisandZosterops palpebrosavar.yonakuni, but no insects, were recorded regularly feeding on flower‐nectar ofBruguiera gymnorrhizain the Miyara River Biological Preserve, Ishigaki Island, Japan, at 7:00‐9:15 a.m. during the investigation from December 20, 1987, to January 19, 1988. In contrast,Anthreptes malacensisforaged for nectar from 7:00 a.m. to 17:00 p.m.Oriolus chinensisvisited the flowers mainly between 6:30 and 7:30 a.m. in Phangnga, Thailand, during the investigation from November 30 to December 19, 1986. Pollen grains were sprayed onto the birds’faces and bills and into the air. The highest mean volume of 0.24 pollen grains/l/minute was triggered in calm air by the most frequent nectarivore between 6:45 and 7:00 a.m. at a height of 1.5m under a tree‐branch carrying 145 fresh flowers in the Miyara River population, Japan. The highest mean volume of 0.27 pollen grains/l/minute under the same conditions in the Phangnga population, Thailand.Bruguiera gymnorrhizais bird‐pollinated but with the possibility of some pollination indirectl

ISSN:0913-557X    

DOI:10.1111/j.1442-1984.1991.tb00216.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

AbstractFreshly‐matured achenes ofKrigia oppositifoliaRaf. were buried in soil at near‐natural temperatures for 0–35 months and then exhumed and tested in light and darkness at (12/12 hr) daily thermoperiods of 15/6, 20/10, 25/15, 30/15 and 35/20°C. Achenes required light for germination and exhibited an annual dormancy/nondormancy cycle, being dormant in spring and nondormant in autumn. High summer temperatures (30/15, 35/20°C) fully promoted afterripening, whereas low temperatures (5, 15/6°C) prevented it. As buried seeds came out of dormancy in summer, they first germinated at medium temperatures (20/10, 25/15°C), but with additional afterripening the maximum and minimum temperatures for germination increased and decreased, respectively. Thus, during afterripening, achenes exhibit type 3 temperature responses, which otherwise are known only in two perennial Asteraceae and one perennial Liliaceae. The physiological responses of achenes ofK. oppositifoliaare unlike those of most winter annuals, which have type 1 responses—i.e., the maximum temperature for germination increases during afterripening. Also, they are unlike the majority of Asteraceae, which have type 2 responses—i.e., the minimum temperature for germination decreases during afterripening. Type 1 responses, typical of most winter annuals, have yet to be reported in t

ISSN:0913-557X    

DOI:10.1111/j.1442-1984.1991.tb00217.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

ISSN:0913-557X    

DOI:10.1111/j.1442-1984.1991.tb00218.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY