摘要:

AbstractVarious life history characteristics were studied and compared for 27 species of the genusTrilliumgrowing in Japan and eastern North America, in order to clarify the modes of life history, evolution within this genus. The 27 species showed notable differences in several life history traits, such as population structures and reproductive characteristics, including reproductive allocation, ovule number, reproductive output, propagule size, etc. Remarkable differences in life history traits were observed between pedicellate‐ and sessile‐flowered species. The pedicellate‐flowered species showed relatively larger individual biomasses, larger reproductive outputs, lower energy investment to a single propagule (RA), and smaller seeds. On the other hand, sessile‐flowered species were characterized by smaller individual biomasses, lower reproductive outputs, higher RA, and larger seeds. The results of the principal component analysis (PCA) on the reproductive traits clearly revealed that the morphological and geographical differentiations in the genusTrilliumwere very closely related to the modes of differentiation in significant life history and demographic parameters.Of the various reproductive characteristics, differences in ovule number, reproductive output, seed setting rate, and seed weight clearly reflect the degree of differentiation in these significant fitness components of each species. In spite of the similarity in floral morphology, Japanese erect‐flowered species showed much larger ovule numbers and larger reproductive outputs than those of eastern North American erect‐flowered species. The declinate‐flowered species differed from erect‐flowered species in having lower seed‐setting rates. Furthermore, several sessile‐flowered species with vegetative reproduction exhibited lower ovule numbers and lower seed‐setting rates. These species with vegetative reproduction showed similar convex‐shaped population structures, while sexual reproducing species possessed population structures of a typical sigmoid type. Vegetative reproduction in the genusTrilliumseems to have differentiated to supplement the inefficiency of offspring recruitment by sexual reproduction in ecologically somewhat unstable habitats, such as flood plains of rivers. However, these sessile‐flowered species showed higher relative energy allocations to single propagules (RA), suggesting that the energy cost of producing seeds proportionately increases in harsher and unstable habitats. The results of the present study clearly demonstrate that life history and demographic parameters of the species in the genusTrilliumhave differentiated in direct relation to different underlying environmental regimes peculiar to each s

ISSN:0913-557X    

DOI:10.1111/j.1442-1984.1989.tb00044.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractElectrophoretic data were used to assess levels of clonal diversity within and among populations ofTaraxacum albidumDahlst., a pentaploid obligate agamosperm indigenous to Japan. All specimens sampled from the entire distribution range shared the same 19‐locus genotypic profile except for one. This single mutant differed in one allele at one locus only. Contrary to this extreme monomorphism, clonally reproducing species usually consist of multiclonal populations. It is hypothesized thatT. albidumrecently originated through hybridization between a sexual diploid species of the section Mongolica (most likelyT. japonicumKoidz.) and an unknown polyploid Mongolica specie

ISSN:0913-557X    

DOI:10.1111/j.1442-1984.1989.tb00045.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractExaminations of chromosome number voucher specimens show that sexual diploid and agamospermous polyploid plants ofEupatoriumin Asia can be distinguished by morphology, fertility, and stainability of pollen grains. Using these criteria, reproductive systems (sexual vs. agamospermous) were estimated for 558 herbarium specimens ofEupatoriumin East Asia. Of 22 taxa examined, six included both sexual and agamospermous specimens; those of one taxon were all agamospermous; and those of 15 taxa were all sexual. This result shows that 21 taxa are not agamospermous microspecies but are differentiated at the diploid level. Sexual populations of most taxa had restricted geographical distributions.Eupatorium chinense var. chinenseand var.oppositifoliumconsisted of both sexual and agamospermous populations. Sexual populations of these two varieties were allopatric and distinct in external morphology, suggesting differentiation at the species level. The specimens ofE. heterophyllums. str. were all agamospermous, while those ofE. mairel, often treated as synonymous withE. heterophyllum, were sexual.In comparing East Asian and North AmericanEupatoriumfor the distributional patterns of sexual and agamospermous populations, three differences can be pointed out: (1) Agamospermous plants of autopolyploid origin have evolved in eight species and are widespread in North America; while most agamospermous plants in East Asia may be of allopolyploid origin, have relatively restricted ranges, and are less frequent than the diploid plants with the exception of inE. chinense var. oppositifolium, (2) The number of sexual species with wide range is greater in North America than in East Asia. (3) The number of sexual species with restricted ranges is greater in East Asia than in North America. The results obtained suggest that speciation among the plants ofEupatoriumhas occurred more recently in East Asia than in North America.

ISSN:0913-557X    

DOI:10.1111/j.1442-1984.1989.tb00046.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractIn 554 bulbs from 38 populations ofLycoris sanguinea, several chromosomal variations have been discovered. Most of the bulbs have a common karyotype consisting of 22 acrocentric (A) chromosomes. Though their frequencies are low, some rearranged chromosomes which are aberrant have been found. The aberrants are as follows: 1. Subtelocentrics (ST); 2. Telocentrics (T′); 3. Metacentrics (M′); 4. Very small acrocentrics (a); 5. Very small metacentrics (m); 6. Acentric fragments (Ac); and 7. Dicentrics (Di) chromosome. All can be easily suspected to be derived fromAs. Some aberrations of the satellite chromosomes have been observed also. In addition, a new karyotype composed of 2n=32=31A+ 1M′chromosomes has been

ISSN:0913-557X    

DOI:10.1111/j.1442-1984.1989.tb00047.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractThe floral biology ofTricyrtis affiniswas investigated and compared with that of four species ofTricyrtiswhich had been reported by the author. The flower opens for two days and is protandrous as inT. latifolia, T. flava, andT. ohsumiensis.The primary pollinators ofT. affiniswereBombus diversus diversusandAmegillasp., which were not different from those of the previous species although the shape and the color of theT. affinisflower are somewhat different from the others. The whole perianth ofT. affinisabsorbs UV light fairly well, and the large purple spotted area near the base absorbs it markedly well. The UV absorption pattern of theT. affinisflower is similar to that ofT. latifolia. T. affinisis also self‐compatible, like the others, and seeds obtained by self‐pollination germinated well. Pollination ofT. affinisis characterized by a refined sys

ISSN:0913-557X    

DOI:10.1111/j.1442-1984.1989.tb00048.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Thermal germination responses of eight seed populations ofCampanula punctata, two from Honshu (Kanto District) and six from the Izu Islands, were compared in a laboratory test. Eight populations showed different germination patterns with regard to presence/absence of thermal induction of secondary dormancy and within‐population variation in germination rate of non‐dormant seeds. The adaptive significance of observed germination patterns is discus

ISSN:0913-557X    

DOI:10.1111/j.1442-1984.1989.tb00049.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

AbstractPlasticity in growth, reproductive energy allocation (RA), reproductive output (PN), propagule weight (Pw), fecundity, and relative cost of producing single propagules (RA) and their interlinked properties were critically investigated in two grass species,Oryza sativaL. ev.AkihikariandCoix ma‐yuenRoman., grown under varying densities and soil nitrogen levels.In these two species, exceedingly marked plastic but parallel responses were detected in all significant yield and reproductive traits under changing growing conditions. The results obtained also corresponded very well with those forCoix ma‐yuen, Helianthus annuusandGlycine maxreported in our previous works in this series (Kawano and Hayashi, 1977; Kawano and Nagai, 1986; Nagai and Kawano, 1986).InOryza sativa, plants cultivated at higher densities exhibited proportionately lower individual biomasses, lower seed outputs, and smaller grain size in response to increasing density, although RA remained more or less constant throughout all five different densities, and fecundity showed an abrupt decrease in the overcrowded cohort beyond 400 plants/m2. In this experiment,Coix ma‐yuenwas grown only under conditions of extraordinarily overcrowded density (over ca. 4,500 plants/m2) with extremely broad nitrogen fertilizer levels from 20 N (20 kg ammonium sulfate/10 ARE) to 100 N (100 kg/10 ARE). This species likewise demonstrated a remarkably sharp responsive plasticity in significant reproductive parameters with increasing N‐levels, just as was found with changing density (Kawano and Hayashi, 1977).One common significant conclusion obtained from the present series of studies was that sexual propagule production under limited resource availability—for example, a sharp decline in solar radiation and soil nutrients, due to strong interference in higher density plots—is exceedingly costly, implying that there occurs a significant change and variance in this important fitness component under changing environmental conditions. This was most conspicuously demonstrated by a very sharp increase in relative energy partitioning to a single propagule in response to increased density and decreasing nitrogen levels, the relative energy cost to a single seed (RA) increasing from 1.00 to 31.02, and from 1.00 to 10.31 in both paddy field and pot populations ofOryza sativacv.Akihikari, respectively, and from 1.00 to 4.23 in field populations ofCoix ma‐yuen.The adaptive significance of induced changes in several reproductive traits under changing environmental conditions was also discussed in the light of all the evidence av

ISSN:0913-557X    

DOI:10.1111/j.1442-1984.1989.tb00050.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY